imgui/backends/imgui_impl_sdl2.cpp

// dear imgui: Platform Backend for SDL2
// This needs to be used along with a Renderer (e.g. DirectX11, OpenGL3, Vulkan..)
// (Info: SDL2 is a cross-platform general purpose library for handling windows, inputs, graphics context creation, etc.)
// (Prefer SDL 2.0.5+ for full feature support.)

// Implemented features:
//  [X] Platform: Clipboard support.
//  [X] Platform: Mouse support. Can discriminate Mouse/TouchScreen.
//  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy SDL_SCANCODE_* values will also be supported unless IMGUI_DISABLE_OBSOLETE_KEYIO is set]
//  [X] Platform: Gamepad support. Enabled with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
//  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
//  [X] Platform: Multi-viewport support (multiple windows). Enable with 'io.ConfigFlags |= ImGuiConfigFlags_ViewportsEnable'.
// Issues:
//  [ ] Platform: Multi-viewport: Minimized windows seems to break mouse wheel events (at least under Windows).
//  [ ] Platform: Multi-viewport: ParentViewportID not honored, and so io.ConfigViewportsNoDefaultParent has no effect (minor).
//  [x] Platform: Basic IME support. App needs to call 'SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");' before SDL_CreateWindow()!.

// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
// Learn about Dear ImGui:
// - FAQ                  https://dearimgui.com/faq
// - Getting Started      https://dearimgui.com/getting-started
// - Documentation        https://dearimgui.com/docs (same as your local docs/ folder).
// - Introduction, links and more at the top of imgui.cpp

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2024-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
//  2024-08-19: Storing SDL's Uint32 WindowID inside ImGuiViewport::PlatformHandle instead of SDL_Window*.
//  2024-08-19: ImGui_ImplSDL2_ProcessEvent() now ignores events intended for other SDL windows. (#7853)
//  2024-07-02: Emscripten: Added io.PlatformOpenInShellFn() handler for Emscripten versions.
//  2024-07-02: Update for io.SetPlatformImeDataFn() -> io.PlatformSetImeDataFn() renaming in main library.
//  2024-02-14: Inputs: Handle gamepad disconnection. Added ImGui_ImplSDL2_SetGamepadMode().
//  2023-10-05: Inputs: Added support for extra ImGuiKey values: F13 to F24 function keys, app back/forward keys.
//  2023-04-06: Inputs: Avoid calling SDL_StartTextInput()/SDL_StopTextInput() as they don't only pertain to IME. It's unclear exactly what their relation is to IME. (#6306)
//  2023-04-04: Inputs: Added support for io.AddMouseSourceEvent() to discriminate ImGuiMouseSource_Mouse/ImGuiMouseSource_TouchScreen. (#2702)
//  2023-02-23: Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. (#6189, #6114, #3644)
//  2023-02-07: Implement IME handler (io.SetPlatformImeDataFn will call SDL_SetTextInputRect()/SDL_StartTextInput()).
//  2023-02-07: *BREAKING CHANGE* Renamed this backend file from imgui_impl_sdl.cpp/.h to imgui_impl_sdl2.cpp/.h in prevision for the future release of SDL3.
//  2023-02-02: Avoid calling SDL_SetCursor() when cursor has not changed, as the function is surprisingly costly on Mac with latest SDL (may be fixed in next SDL version).
//  2023-02-02: Added support for SDL 2.0.18+ preciseX/preciseY mouse wheel data for smooth scrolling + Scaling X value on Emscripten (bug?). (#4019, #6096)
//  2023-02-02: Removed SDL_MOUSEWHEEL value clamping, as values seem correct in latest Emscripten. (#4019)
//  2023-02-01: Flipping SDL_MOUSEWHEEL 'wheel.x' value to match other backends and offer consistent horizontal scrolling direction. (#4019, #6096, #1463)
//  2022-10-11: Using 'nullptr' instead of 'NULL' as per our switch to C++11.
//  2022-09-26: Inputs: Disable SDL 2.0.22 new "auto capture" (SDL_HINT_MOUSE_AUTO_CAPTURE) which prevents drag and drop across windows for multi-viewport support + don't capture when drag and dropping. (#5710)
//  2022-09-26: Inputs: Renamed ImGuiKey_ModXXX introduced in 1.87 to ImGuiMod_XXX (old names still supported).
//  2022-03-22: Inputs: Fix mouse position issues when dragging outside of boundaries. SDL_CaptureMouse() erroneously still gives out LEAVE events when hovering OS decorations.
//  2022-03-22: Inputs: Added support for extra mouse buttons (SDL_BUTTON_X1/SDL_BUTTON_X2).
//  2022-02-04: Added SDL_Renderer* parameter to ImGui_ImplSDL2_InitForSDLRenderer(), so we can use SDL_GetRendererOutputSize() instead of SDL_GL_GetDrawableSize() when bound to a SDL_Renderer.
//  2022-01-26: Inputs: replaced short-lived io.AddKeyModsEvent() (added two weeks ago) with io.AddKeyEvent() using ImGuiKey_ModXXX flags. Sorry for the confusion.
//  2021-01-20: Inputs: calling new io.AddKeyAnalogEvent() for gamepad support, instead of writing directly to io.NavInputs[].
//  2022-01-17: Inputs: calling new io.AddMousePosEvent(), io.AddMouseButtonEvent(), io.AddMouseWheelEvent() API (1.87+).
//  2022-01-17: Inputs: always update key mods next and before key event (not in NewFrame) to fix input queue with very low framerates.
//  2022-01-12: Update mouse inputs using SDL_MOUSEMOTION/SDL_WINDOWEVENT_LEAVE + fallback to provide it when focused but not hovered/captured. More standard and will allow us to pass it to future input queue API.
//  2022-01-12: Maintain our own copy of MouseButtonsDown mask instead of using ImGui::IsAnyMouseDown() which will be obsoleted.
//  2022-01-10: Inputs: calling new io.AddKeyEvent(), io.AddKeyModsEvent() + io.SetKeyEventNativeData() API (1.87+). Support for full ImGuiKey range.
//  2021-08-17: Calling io.AddFocusEvent() on SDL_WINDOWEVENT_FOCUS_GAINED/SDL_WINDOWEVENT_FOCUS_LOST.
//  2021-07-29: Inputs: MousePos is correctly reported when the host platform window is hovered but not focused (using SDL_GetMouseFocus() + SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH, requires SDL 2.0.5+)
//  2021-06:29: *BREAKING CHANGE* Removed 'SDL_Window* window' parameter to ImGui_ImplSDL2_NewFrame() which was unnecessary.
//  2021-06-29: Reorganized backend to pull data from a single structure to facilitate usage with multiple-contexts (all g_XXXX access changed to bd->XXXX).
//  2021-03-22: Rework global mouse pos availability check listing supported platforms explicitly, effectively fixing mouse access on Raspberry Pi. (#2837, #3950)
//  2020-05-25: Misc: Report a zero display-size when window is minimized, to be consistent with other backends.
//  2020-02-20: Inputs: Fixed mapping for ImGuiKey_KeyPadEnter (using SDL_SCANCODE_KP_ENTER instead of SDL_SCANCODE_RETURN2).
//  2019-12-17: Inputs: On Wayland, use SDL_GetMouseState (because there is no global mouse state).
//  2019-12-05: Inputs: Added support for ImGuiMouseCursor_NotAllowed mouse cursor.
//  2019-07-21: Inputs: Added mapping for ImGuiKey_KeyPadEnter.
//  2019-04-23: Inputs: Added support for SDL_GameController (if ImGuiConfigFlags_NavEnableGamepad is set by user application).
//  2019-03-12: Misc: Preserve DisplayFramebufferScale when main window is minimized.
//  2018-12-21: Inputs: Workaround for Android/iOS which don't seem to handle focus related calls.
//  2018-11-30: Misc: Setting up io.BackendPlatformName so it can be displayed in the About Window.
//  2018-11-14: Changed the signature of ImGui_ImplSDL2_ProcessEvent() to take a 'const SDL_Event*'.
//  2018-08-01: Inputs: Workaround for Emscripten which doesn't seem to handle focus related calls.
//  2018-06-29: Inputs: Added support for the ImGuiMouseCursor_Hand cursor.
//  2018-06-08: Misc: Extracted imgui_impl_sdl.cpp/.h away from the old combined SDL2+OpenGL/Vulkan examples.
//  2018-06-08: Misc: ImGui_ImplSDL2_InitForOpenGL() now takes a SDL_GLContext parameter.
//  2018-05-09: Misc: Fixed clipboard paste memory leak (we didn't call SDL_FreeMemory on the data returned by SDL_GetClipboardText).
//  2018-03-20: Misc: Setup io.BackendFlags ImGuiBackendFlags_HasMouseCursors flag + honor ImGuiConfigFlags_NoMouseCursorChange flag.
//  2018-02-16: Inputs: Added support for mouse cursors, honoring ImGui::GetMouseCursor() value.
//  2018-02-06: Misc: Removed call to ImGui::Shutdown() which is not available from 1.60 WIP, user needs to call CreateContext/DestroyContext themselves.
//  2018-02-06: Inputs: Added mapping for ImGuiKey_Space.
//  2018-02-05: Misc: Using SDL_GetPerformanceCounter() instead of SDL_GetTicks() to be able to handle very high framerate (1000+ FPS).
//  2018-02-05: Inputs: Keyboard mapping is using scancodes everywhere instead of a confusing mixture of keycodes and scancodes.
//  2018-01-20: Inputs: Added Horizontal Mouse Wheel support.
//  2018-01-19: Inputs: When available (SDL 2.0.4+) using SDL_CaptureMouse() to retrieve coordinates outside of client area when dragging. Otherwise (SDL 2.0.3 and before) testing for SDL_WINDOW_INPUT_FOCUS instead of SDL_WINDOW_MOUSE_FOCUS.
//  2018-01-18: Inputs: Added mapping for ImGuiKey_Insert.
//  2017-08-25: Inputs: MousePos set to -FLT_MAX,-FLT_MAX when mouse is unavailable/missing (instead of -1,-1).
//  2016-10-15: Misc: Added a void* user_data parameter to Clipboard function handlers.

#include "imgui.h"
#ifndef IMGUI_DISABLE
#include "imgui_impl_sdl2.h"

// Clang warnings with -Weverything
#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wimplicit-int-float-conversion"  // warning: implicit conversion from 'xxx' to 'float' may lose precision
#endif

// SDL
// (the multi-viewports feature requires SDL features supported from SDL 2.0.4+. SDL 2.0.5+ is highly recommended)
#include <SDL.h>
#include <SDL_syswm.h>
#ifdef __APPLE__
#include <TargetConditionals.h>
#endif
#ifdef __EMSCRIPTEN__
#include <emscripten/em_js.h>
#endif

#if SDL_VERSION_ATLEAST(2,0,4) && !defined(__EMSCRIPTEN__) && !defined(__ANDROID__) && !(defined(__APPLE__) && TARGET_OS_IOS) && !defined(__amigaos4__)
#define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    1
#else
#define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    0
#endif
#define SDL_HAS_WINDOW_ALPHA                SDL_VERSION_ATLEAST(2,0,5)
#define SDL_HAS_ALWAYS_ON_TOP               SDL_VERSION_ATLEAST(2,0,5)
#define SDL_HAS_USABLE_DISPLAY_BOUNDS       SDL_VERSION_ATLEAST(2,0,5)
#define SDL_HAS_PER_MONITOR_DPI             SDL_VERSION_ATLEAST(2,0,4)
#define SDL_HAS_VULKAN                      SDL_VERSION_ATLEAST(2,0,6)
#define SDL_HAS_DISPLAY_EVENT               SDL_VERSION_ATLEAST(2,0,9)
#define SDL_HAS_SHOW_WINDOW_ACTIVATION_HINT SDL_VERSION_ATLEAST(2,0,18)
#if !SDL_HAS_VULKAN
static const Uint32 SDL_WINDOW_VULKAN = 0x10000000;
#endif

// SDL Data
struct ImGui_ImplSDL2_Data
{
    SDL_Window*             Window;
    Uint32                  WindowID;
    SDL_Renderer*           Renderer;
    Uint64                  Time;
    char*                   ClipboardTextData;
    bool                    UseVulkan;
    bool                    WantUpdateMonitors;

    // Mouse handling
    Uint32                  MouseWindowID;
    int                     MouseButtonsDown;
    SDL_Cursor*             MouseCursors[ImGuiMouseCursor_COUNT];
    SDL_Cursor*             MouseLastCursor;
    int                     MouseLastLeaveFrame;
    bool                    MouseCanUseGlobalState;
    bool                    MouseCanReportHoveredViewport;  // This is hard to use/unreliable on SDL so we'll set ImGuiBackendFlags_HasMouseHoveredViewport dynamically based on state.

    // Gamepad handling
    ImVector<SDL_GameController*> Gamepads;
    ImGui_ImplSDL2_GamepadMode    GamepadMode;
    bool                          WantUpdateGamepadsList;

    ImGui_ImplSDL2_Data()   { memset((void*)this, 0, sizeof(*this)); }
};

// Backend data stored in io.BackendPlatformUserData to allow support for multiple Dear ImGui contexts
// It is STRONGLY preferred that you use docking branch with multi-viewports (== single Dear ImGui context + multiple windows) instead of multiple Dear ImGui contexts.
// FIXME: multi-context support is not well tested and probably dysfunctional in this backend.
// FIXME: some shared resources (mouse cursor shape, gamepad) are mishandled when using multi-context.
static ImGui_ImplSDL2_Data* ImGui_ImplSDL2_GetBackendData()
{
    return ImGui::GetCurrentContext() ? (ImGui_ImplSDL2_Data*)ImGui::GetIO().BackendPlatformUserData : nullptr;
}

// Forward Declarations
static void ImGui_ImplSDL2_UpdateMonitors();
static void ImGui_ImplSDL2_InitPlatformInterface(SDL_Window* window, void* sdl_gl_context);
static void ImGui_ImplSDL2_ShutdownPlatformInterface();

// Functions
static const char* ImGui_ImplSDL2_GetClipboardText(void*)
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    if (bd->ClipboardTextData)
        SDL_free(bd->ClipboardTextData);
    bd->ClipboardTextData = SDL_GetClipboardText();
    return bd->ClipboardTextData;
}

static void ImGui_ImplSDL2_SetClipboardText(void*, const char* text)
{
    SDL_SetClipboardText(text);
}

// Note: native IME will only display if user calls SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1") _before_ SDL_CreateWindow().
static void ImGui_ImplSDL2_PlatformSetImeData(ImGuiContext*, ImGuiViewport* viewport, ImGuiPlatformImeData* data)
{
    if (data->WantVisible)
    {
        SDL_Rect r;
        r.x = (int)(data->InputPos.x - viewport->Pos.x);
        r.y = (int)(data->InputPos.y - viewport->Pos.y + data->InputLineHeight);
        r.w = 1;
        r.h = (int)data->InputLineHeight;
        SDL_SetTextInputRect(&r);
    }
}

static ImGuiKey ImGui_ImplSDL2_KeyEventToImGuiKey(SDL_Keycode keycode, SDL_Scancode scancode)
{
    IM_UNUSED(scancode);
    switch (keycode)
    {
        case SDLK_TAB: return ImGuiKey_Tab;
        case SDLK_LEFT: return ImGuiKey_LeftArrow;
        case SDLK_RIGHT: return ImGuiKey_RightArrow;
        case SDLK_UP: return ImGuiKey_UpArrow;
        case SDLK_DOWN: return ImGuiKey_DownArrow;
        case SDLK_PAGEUP: return ImGuiKey_PageUp;
        case SDLK_PAGEDOWN: return ImGuiKey_PageDown;
        case SDLK_HOME: return ImGuiKey_Home;
        case SDLK_END: return ImGuiKey_End;
        case SDLK_INSERT: return ImGuiKey_Insert;
        case SDLK_DELETE: return ImGuiKey_Delete;
        case SDLK_BACKSPACE: return ImGuiKey_Backspace;
        case SDLK_SPACE: return ImGuiKey_Space;
        case SDLK_RETURN: return ImGuiKey_Enter;
        case SDLK_ESCAPE: return ImGuiKey_Escape;
        case SDLK_QUOTE: return ImGuiKey_Apostrophe;
        case SDLK_COMMA: return ImGuiKey_Comma;
        case SDLK_MINUS: return ImGuiKey_Minus;
        case SDLK_PERIOD: return ImGuiKey_Period;
        case SDLK_SLASH: return ImGuiKey_Slash;
        case SDLK_SEMICOLON: return ImGuiKey_Semicolon;
        case SDLK_EQUALS: return ImGuiKey_Equal;
        case SDLK_LEFTBRACKET: return ImGuiKey_LeftBracket;
        case SDLK_BACKSLASH: return ImGuiKey_Backslash;
        case SDLK_RIGHTBRACKET: return ImGuiKey_RightBracket;
        case SDLK_BACKQUOTE: return ImGuiKey_GraveAccent;
        case SDLK_CAPSLOCK: return ImGuiKey_CapsLock;
        case SDLK_SCROLLLOCK: return ImGuiKey_ScrollLock;
        case SDLK_NUMLOCKCLEAR: return ImGuiKey_NumLock;
        case SDLK_PRINTSCREEN: return ImGuiKey_PrintScreen;
        case SDLK_PAUSE: return ImGuiKey_Pause;
        case SDLK_KP_0: return ImGuiKey_Keypad0;
        case SDLK_KP_1: return ImGuiKey_Keypad1;
        case SDLK_KP_2: return ImGuiKey_Keypad2;
        case SDLK_KP_3: return ImGuiKey_Keypad3;
        case SDLK_KP_4: return ImGuiKey_Keypad4;
        case SDLK_KP_5: return ImGuiKey_Keypad5;
        case SDLK_KP_6: return ImGuiKey_Keypad6;
        case SDLK_KP_7: return ImGuiKey_Keypad7;
        case SDLK_KP_8: return ImGuiKey_Keypad8;
        case SDLK_KP_9: return ImGuiKey_Keypad9;
        case SDLK_KP_PERIOD: return ImGuiKey_KeypadDecimal;
        case SDLK_KP_DIVIDE: return ImGuiKey_KeypadDivide;
        case SDLK_KP_MULTIPLY: return ImGuiKey_KeypadMultiply;
        case SDLK_KP_MINUS: return ImGuiKey_KeypadSubtract;
        case SDLK_KP_PLUS: return ImGuiKey_KeypadAdd;
        case SDLK_KP_ENTER: return ImGuiKey_KeypadEnter;
        case SDLK_KP_EQUALS: return ImGuiKey_KeypadEqual;
        case SDLK_LCTRL: return ImGuiKey_LeftCtrl;
        case SDLK_LSHIFT: return ImGuiKey_LeftShift;
        case SDLK_LALT: return ImGuiKey_LeftAlt;
        case SDLK_LGUI: return ImGuiKey_LeftSuper;
        case SDLK_RCTRL: return ImGuiKey_RightCtrl;
        case SDLK_RSHIFT: return ImGuiKey_RightShift;
        case SDLK_RALT: return ImGuiKey_RightAlt;
        case SDLK_RGUI: return ImGuiKey_RightSuper;
        case SDLK_APPLICATION: return ImGuiKey_Menu;
        case SDLK_0: return ImGuiKey_0;
        case SDLK_1: return ImGuiKey_1;
        case SDLK_2: return ImGuiKey_2;
        case SDLK_3: return ImGuiKey_3;
        case SDLK_4: return ImGuiKey_4;
        case SDLK_5: return ImGuiKey_5;
        case SDLK_6: return ImGuiKey_6;
        case SDLK_7: return ImGuiKey_7;
        case SDLK_8: return ImGuiKey_8;
        case SDLK_9: return ImGuiKey_9;
        case SDLK_a: return ImGuiKey_A;
        case SDLK_b: return ImGuiKey_B;
        case SDLK_c: return ImGuiKey_C;
        case SDLK_d: return ImGuiKey_D;
        case SDLK_e: return ImGuiKey_E;
        case SDLK_f: return ImGuiKey_F;
        case SDLK_g: return ImGuiKey_G;
        case SDLK_h: return ImGuiKey_H;
        case SDLK_i: return ImGuiKey_I;
        case SDLK_j: return ImGuiKey_J;
        case SDLK_k: return ImGuiKey_K;
        case SDLK_l: return ImGuiKey_L;
        case SDLK_m: return ImGuiKey_M;
        case SDLK_n: return ImGuiKey_N;
        case SDLK_o: return ImGuiKey_O;
        case SDLK_p: return ImGuiKey_P;
        case SDLK_q: return ImGuiKey_Q;
        case SDLK_r: return ImGuiKey_R;
        case SDLK_s: return ImGuiKey_S;
        case SDLK_t: return ImGuiKey_T;
        case SDLK_u: return ImGuiKey_U;
        case SDLK_v: return ImGuiKey_V;
        case SDLK_w: return ImGuiKey_W;
        case SDLK_x: return ImGuiKey_X;
        case SDLK_y: return ImGuiKey_Y;
        case SDLK_z: return ImGuiKey_Z;
        case SDLK_F1: return ImGuiKey_F1;
        case SDLK_F2: return ImGuiKey_F2;
        case SDLK_F3: return ImGuiKey_F3;
        case SDLK_F4: return ImGuiKey_F4;
        case SDLK_F5: return ImGuiKey_F5;
        case SDLK_F6: return ImGuiKey_F6;
        case SDLK_F7: return ImGuiKey_F7;
        case SDLK_F8: return ImGuiKey_F8;
        case SDLK_F9: return ImGuiKey_F9;
        case SDLK_F10: return ImGuiKey_F10;
        case SDLK_F11: return ImGuiKey_F11;
        case SDLK_F12: return ImGuiKey_F12;
        case SDLK_F13: return ImGuiKey_F13;
        case SDLK_F14: return ImGuiKey_F14;
        case SDLK_F15: return ImGuiKey_F15;
        case SDLK_F16: return ImGuiKey_F16;
        case SDLK_F17: return ImGuiKey_F17;
        case SDLK_F18: return ImGuiKey_F18;
        case SDLK_F19: return ImGuiKey_F19;
        case SDLK_F20: return ImGuiKey_F20;
        case SDLK_F21: return ImGuiKey_F21;
        case SDLK_F22: return ImGuiKey_F22;
        case SDLK_F23: return ImGuiKey_F23;
        case SDLK_F24: return ImGuiKey_F24;
        case SDLK_AC_BACK: return ImGuiKey_AppBack;
        case SDLK_AC_FORWARD: return ImGuiKey_AppForward;
        default: break;
    }
    return ImGuiKey_None;
}

static void ImGui_ImplSDL2_UpdateKeyModifiers(SDL_Keymod sdl_key_mods)
{
    ImGuiIO& io = ImGui::GetIO();
    io.AddKeyEvent(ImGuiMod_Ctrl, (sdl_key_mods & KMOD_CTRL) != 0);
    io.AddKeyEvent(ImGuiMod_Shift, (sdl_key_mods & KMOD_SHIFT) != 0);
    io.AddKeyEvent(ImGuiMod_Alt, (sdl_key_mods & KMOD_ALT) != 0);
    io.AddKeyEvent(ImGuiMod_Super, (sdl_key_mods & KMOD_GUI) != 0);
}

static ImGuiViewport* ImGui_ImplSDL2_GetViewportForWindowID(Uint32 window_id)
{
    return ImGui::FindViewportByPlatformHandle((void*)(intptr_t)window_id);
}

// You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
// - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application, or clear/overwrite your copy of the mouse data.
// - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
// Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDL2_Init()?");
    ImGuiIO& io = ImGui::GetIO();

    switch (event->type)
    {
        case SDL_MOUSEMOTION:
        {
            if (ImGui_ImplSDL2_GetViewportForWindowID(event->motion.windowID) == NULL)
                return false;
            ImVec2 mouse_pos((float)event->motion.x, (float)event->motion.y);
            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
            {
                int window_x, window_y;
                SDL_GetWindowPosition(SDL_GetWindowFromID(event->motion.windowID), &window_x, &window_y);
                mouse_pos.x += window_x;
                mouse_pos.y += window_y;
            }
            io.AddMouseSourceEvent(event->motion.which == SDL_TOUCH_MOUSEID ? ImGuiMouseSource_TouchScreen : ImGuiMouseSource_Mouse);
            io.AddMousePosEvent(mouse_pos.x, mouse_pos.y);
            return true;
        }
        case SDL_MOUSEWHEEL:
        {
            if (ImGui_ImplSDL2_GetViewportForWindowID(event->wheel.windowID) == NULL)
                return false;
            //IMGUI_DEBUG_LOG("wheel %.2f %.2f, precise %.2f %.2f\n", (float)event->wheel.x, (float)event->wheel.y, event->wheel.preciseX, event->wheel.preciseY);
#if SDL_VERSION_ATLEAST(2,0,18) // If this fails to compile on Emscripten: update to latest Emscripten!
            float wheel_x = -event->wheel.preciseX;
            float wheel_y = event->wheel.preciseY;
#else
            float wheel_x = -(float)event->wheel.x;
            float wheel_y = (float)event->wheel.y;
#endif
#ifdef __EMSCRIPTEN__
            wheel_x /= 100.0f;
#endif
            io.AddMouseSourceEvent(event->wheel.which == SDL_TOUCH_MOUSEID ? ImGuiMouseSource_TouchScreen : ImGuiMouseSource_Mouse);
            io.AddMouseWheelEvent(wheel_x, wheel_y);
            return true;
        }
        case SDL_MOUSEBUTTONDOWN:
        case SDL_MOUSEBUTTONUP:
        {
            if (ImGui_ImplSDL2_GetViewportForWindowID(event->button.windowID) == NULL)
                return false;
            int mouse_button = -1;
            if (event->button.button == SDL_BUTTON_LEFT) { mouse_button = 0; }
            if (event->button.button == SDL_BUTTON_RIGHT) { mouse_button = 1; }
            if (event->button.button == SDL_BUTTON_MIDDLE) { mouse_button = 2; }
            if (event->button.button == SDL_BUTTON_X1) { mouse_button = 3; }
            if (event->button.button == SDL_BUTTON_X2) { mouse_button = 4; }
            if (mouse_button == -1)
                break;
            io.AddMouseSourceEvent(event->button.which == SDL_TOUCH_MOUSEID ? ImGuiMouseSource_TouchScreen : ImGuiMouseSource_Mouse);
            io.AddMouseButtonEvent(mouse_button, (event->type == SDL_MOUSEBUTTONDOWN));
            bd->MouseButtonsDown = (event->type == SDL_MOUSEBUTTONDOWN) ? (bd->MouseButtonsDown | (1 << mouse_button)) : (bd->MouseButtonsDown & ~(1 << mouse_button));
            return true;
        }
        case SDL_TEXTINPUT:
        {
            if (ImGui_ImplSDL2_GetViewportForWindowID(event->text.windowID) == NULL)
                return false;
            io.AddInputCharactersUTF8(event->text.text);
            return true;
        }
        case SDL_KEYDOWN:
        case SDL_KEYUP:
        {
            if (ImGui_ImplSDL2_GetViewportForWindowID(event->key.windowID) == NULL)
                return false;
            ImGui_ImplSDL2_UpdateKeyModifiers((SDL_Keymod)event->key.keysym.mod);
            ImGuiKey key = ImGui_ImplSDL2_KeyEventToImGuiKey(event->key.keysym.sym, event->key.keysym.scancode);
            io.AddKeyEvent(key, (event->type == SDL_KEYDOWN));
            io.SetKeyEventNativeData(key, event->key.keysym.sym, event->key.keysym.scancode, event->key.keysym.scancode); // To support legacy indexing (<1.87 user code). Legacy backend uses SDLK_*** as indices to IsKeyXXX() functions.
            return true;
        }
#if SDL_HAS_DISPLAY_EVENT
        case SDL_DISPLAYEVENT:
        {
            // 2.0.26 has SDL_DISPLAYEVENT_CONNECTED/SDL_DISPLAYEVENT_DISCONNECTED/SDL_DISPLAYEVENT_ORIENTATION,
            // so change of DPI/Scaling are not reflected in this event. (SDL3 has it)
            bd->WantUpdateMonitors = true;
            return true;
        }
#endif
        case SDL_WINDOWEVENT:
        {
            ImGuiViewport* viewport = ImGui_ImplSDL2_GetViewportForWindowID(event->window.windowID);
            if (viewport == NULL)
                return false;

            // - When capturing mouse, SDL will send a bunch of conflicting LEAVE/ENTER event on every mouse move, but the final ENTER tends to be right.
            // - However we won't get a correct LEAVE event for a captured window.
            // - In some cases, when detaching a window from main viewport SDL may send SDL_WINDOWEVENT_ENTER one frame too late,
            //   causing SDL_WINDOWEVENT_LEAVE on previous frame to interrupt drag operation by clear mouse position. This is why
            //   we delay process the SDL_WINDOWEVENT_LEAVE events by one frame. See issue #5012 for details.
            Uint8 window_event = event->window.event;
            if (window_event == SDL_WINDOWEVENT_ENTER)
            {
                bd->MouseWindowID = event->window.windowID;
                bd->MouseLastLeaveFrame = 0;
            }
            if (window_event == SDL_WINDOWEVENT_LEAVE)
                bd->MouseLastLeaveFrame = ImGui::GetFrameCount() + 1;
            if (window_event == SDL_WINDOWEVENT_FOCUS_GAINED)
                io.AddFocusEvent(true);
            else if (window_event == SDL_WINDOWEVENT_FOCUS_LOST)
                io.AddFocusEvent(false);
            else if (window_event == SDL_WINDOWEVENT_CLOSE)
                viewport->PlatformRequestClose = true;
            else if (window_event == SDL_WINDOWEVENT_MOVED)
                viewport->PlatformRequestMove = true;
            else if (window_event == SDL_WINDOWEVENT_RESIZED)
                viewport->PlatformRequestResize = true;
            return true;
        }
        case SDL_CONTROLLERDEVICEADDED:
        case SDL_CONTROLLERDEVICEREMOVED:
        {
            bd->WantUpdateGamepadsList = true;
            return true;
        }
    }
    return false;
}

#ifdef __EMSCRIPTEN__
EM_JS(void, ImGui_ImplSDL2_EmscriptenOpenURL, (char const* url), { url = url ? UTF8ToString(url) : null; if (url) window.open(url, '_blank'); });
#endif

static bool ImGui_ImplSDL2_Init(SDL_Window* window, SDL_Renderer* renderer, void* sdl_gl_context)
{
    ImGuiIO& io = ImGui::GetIO();
    IMGUI_CHECKVERSION();
    IM_ASSERT(io.BackendPlatformUserData == nullptr && "Already initialized a platform backend!");

    // Check and store if we are on a SDL backend that supports global mouse position
    // ("wayland" and "rpi" don't support it, but we chose to use a white-list instead of a black-list)
    bool mouse_can_use_global_state = false;
#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
    const char* sdl_backend = SDL_GetCurrentVideoDriver();
    const char* global_mouse_whitelist[] = { "windows", "cocoa", "x11", "DIVE", "VMAN" };
    for (int n = 0; n < IM_ARRAYSIZE(global_mouse_whitelist); n++)
        if (strncmp(sdl_backend, global_mouse_whitelist[n], strlen(global_mouse_whitelist[n])) == 0)
            mouse_can_use_global_state = true;
#endif

    // Setup backend capabilities flags
    ImGui_ImplSDL2_Data* bd = IM_NEW(ImGui_ImplSDL2_Data)();
    io.BackendPlatformUserData = (void*)bd;
    io.BackendPlatformName = "imgui_impl_sdl2";
    io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;           // We can honor GetMouseCursor() values (optional)
    io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;            // We can honor io.WantSetMousePos requests (optional, rarely used)
    if (mouse_can_use_global_state)
        io.BackendFlags |= ImGuiBackendFlags_PlatformHasViewports;  // We can create multi-viewports on the Platform side (optional)

    bd->Window = window;
    bd->WindowID = SDL_GetWindowID(window);
    bd->Renderer = renderer;

    // SDL on Linux/OSX doesn't report events for unfocused windows (see https://github.com/ocornut/imgui/issues/4960)
    // We will use 'MouseCanReportHoveredViewport' to set 'ImGuiBackendFlags_HasMouseHoveredViewport' dynamically each frame.
    bd->MouseCanUseGlobalState = mouse_can_use_global_state;
#ifndef __APPLE__
    bd->MouseCanReportHoveredViewport = bd->MouseCanUseGlobalState;
#else
    bd->MouseCanReportHoveredViewport = false;
#endif
    bd->WantUpdateMonitors = true;

    io.SetClipboardTextFn = ImGui_ImplSDL2_SetClipboardText;
    io.GetClipboardTextFn = ImGui_ImplSDL2_GetClipboardText;
    io.ClipboardUserData = nullptr;
    io.PlatformSetImeDataFn = ImGui_ImplSDL2_PlatformSetImeData;
#ifdef __EMSCRIPTEN__
    io.PlatformOpenInShellFn = [](ImGuiContext*, const char* url) { ImGui_ImplSDL2_EmscriptenOpenURL(url); return true; };
#endif

    // Gamepad handling
    bd->GamepadMode = ImGui_ImplSDL2_GamepadMode_AutoFirst;
    bd->WantUpdateGamepadsList = true;

    // Load mouse cursors
    bd->MouseCursors[ImGuiMouseCursor_Arrow] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_ARROW);
    bd->MouseCursors[ImGuiMouseCursor_TextInput] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_IBEAM);
    bd->MouseCursors[ImGuiMouseCursor_ResizeAll] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEALL);
    bd->MouseCursors[ImGuiMouseCursor_ResizeNS] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENS);
    bd->MouseCursors[ImGuiMouseCursor_ResizeEW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEWE);
    bd->MouseCursors[ImGuiMouseCursor_ResizeNESW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENESW);
    bd->MouseCursors[ImGuiMouseCursor_ResizeNWSE] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENWSE);
    bd->MouseCursors[ImGuiMouseCursor_Hand] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_HAND);
    bd->MouseCursors[ImGuiMouseCursor_NotAllowed] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_NO);

    // Set platform dependent data in viewport
    // Our mouse update function expect PlatformHandle to be filled for the main viewport
    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
    main_viewport->PlatformHandle = (void*)(intptr_t)bd->WindowID;
    main_viewport->PlatformHandleRaw = nullptr;
    SDL_SysWMinfo info;
    SDL_VERSION(&info.version);
    if (SDL_GetWindowWMInfo(window, &info))
    {
#if defined(SDL_VIDEO_DRIVER_WINDOWS)
        main_viewport->PlatformHandleRaw = (void*)info.info.win.window;
#elif defined(__APPLE__) && defined(SDL_VIDEO_DRIVER_COCOA)
        main_viewport->PlatformHandleRaw = (void*)info.info.cocoa.window;
#endif
    }

    // From 2.0.5: Set SDL hint to receive mouse click events on window focus, otherwise SDL doesn't emit the event.
    // Without this, when clicking to gain focus, our widgets wouldn't activate even though they showed as hovered.
    // (This is unfortunately a global SDL setting, so enabling it might have a side-effect on your application.
    // It is unlikely to make a difference, but if your app absolutely needs to ignore the initial on-focus click:
    // you can ignore SDL_MOUSEBUTTONDOWN events coming right after a SDL_WINDOWEVENT_FOCUS_GAINED)
#ifdef SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH
    SDL_SetHint(SDL_HINT_MOUSE_FOCUS_CLICKTHROUGH, "1");
#endif

    // From 2.0.18: Enable native IME.
    // IMPORTANT: This is used at the time of SDL_CreateWindow() so this will only affects secondary windows, if any.
    // For the main window to be affected, your application needs to call this manually before calling SDL_CreateWindow().
#ifdef SDL_HINT_IME_SHOW_UI
    SDL_SetHint(SDL_HINT_IME_SHOW_UI, "1");
#endif

    // From 2.0.22: Disable auto-capture, this is preventing drag and drop across multiple windows (see #5710)
#ifdef SDL_HINT_MOUSE_AUTO_CAPTURE
    SDL_SetHint(SDL_HINT_MOUSE_AUTO_CAPTURE, "0");
#endif

    // We need SDL_CaptureMouse(), SDL_GetGlobalMouseState() from SDL 2.0.4+ to support multiple viewports.
    // We left the call to ImGui_ImplSDL2_InitPlatformInterface() outside of #ifdef to avoid unused-function warnings.
    if ((io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable) && (io.BackendFlags & ImGuiBackendFlags_PlatformHasViewports))
        ImGui_ImplSDL2_InitPlatformInterface(window, sdl_gl_context);

    return true;
}

bool ImGui_ImplSDL2_InitForOpenGL(SDL_Window* window, void* sdl_gl_context)
{
    return ImGui_ImplSDL2_Init(window, nullptr, sdl_gl_context);
}

bool ImGui_ImplSDL2_InitForVulkan(SDL_Window* window)
{
#if !SDL_HAS_VULKAN
    IM_ASSERT(0 && "Unsupported");
#endif
    if (!ImGui_ImplSDL2_Init(window, nullptr, nullptr))
        return false;
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    bd->UseVulkan = true;
    return true;
}

bool ImGui_ImplSDL2_InitForD3D(SDL_Window* window)
{
#if !defined(_WIN32)
    IM_ASSERT(0 && "Unsupported");
#endif
    return ImGui_ImplSDL2_Init(window, nullptr, nullptr);
}

bool ImGui_ImplSDL2_InitForMetal(SDL_Window* window)
{
    return ImGui_ImplSDL2_Init(window, nullptr, nullptr);
}

bool ImGui_ImplSDL2_InitForSDLRenderer(SDL_Window* window, SDL_Renderer* renderer)
{
    return ImGui_ImplSDL2_Init(window, renderer, nullptr);
}

bool ImGui_ImplSDL2_InitForOther(SDL_Window* window)
{
    return ImGui_ImplSDL2_Init(window, nullptr, nullptr);
}

static void ImGui_ImplSDL2_CloseGamepads();

void ImGui_ImplSDL2_Shutdown()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    IM_ASSERT(bd != nullptr && "No platform backend to shutdown, or already shutdown?");
    ImGuiIO& io = ImGui::GetIO();

    ImGui_ImplSDL2_ShutdownPlatformInterface();

    if (bd->ClipboardTextData)
        SDL_free(bd->ClipboardTextData);
    for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++)
        SDL_FreeCursor(bd->MouseCursors[cursor_n]);
    ImGui_ImplSDL2_CloseGamepads();

    io.BackendPlatformName = nullptr;
    io.BackendPlatformUserData = nullptr;
    io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
    IM_DELETE(bd);
}

// This code is incredibly messy because some of the functions we need for full viewport support are not available in SDL < 2.0.4.
static void ImGui_ImplSDL2_UpdateMouseData()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    ImGuiIO& io = ImGui::GetIO();

    // We forward mouse input when hovered or captured (via SDL_MOUSEMOTION) or when focused (below)
#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
    // SDL_CaptureMouse() let the OS know e.g. that our imgui drag outside the SDL window boundaries shouldn't e.g. trigger other operations outside
    SDL_CaptureMouse((bd->MouseButtonsDown != 0) ? SDL_TRUE : SDL_FALSE);
    SDL_Window* focused_window = SDL_GetKeyboardFocus();
    const bool is_app_focused = (focused_window && (bd->Window == focused_window || ImGui_ImplSDL2_GetViewportForWindowID(SDL_GetWindowID(focused_window)) != NULL));
#else
    SDL_Window* focused_window = bd->Window;
    const bool is_app_focused = (SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_INPUT_FOCUS) != 0; // SDL 2.0.3 and non-windowed systems: single-viewport only
#endif

    if (is_app_focused)
    {
        // (Optional) Set OS mouse position from Dear ImGui if requested (rarely used, only when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
        if (io.WantSetMousePos)
        {
#if SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE
            if (io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable)
                SDL_WarpMouseGlobal((int)io.MousePos.x, (int)io.MousePos.y);
            else
#endif
                SDL_WarpMouseInWindow(bd->Window, (int)io.MousePos.x, (int)io.MousePos.y);
        }

        // (Optional) Fallback to provide mouse position when focused (SDL_MOUSEMOTION already provides this when hovered or captured)
        if (bd->MouseCanUseGlobalState && bd->MouseButtonsDown == 0)
        {
            // Single-viewport mode: mouse position in client window coordinates (io.MousePos is (0,0) when the mouse is on the upper-left corner of the app window)
            // Multi-viewport mode: mouse position in OS absolute coordinates (io.MousePos is (0,0) when the mouse is on the upper-left of the primary monitor)
            int mouse_x, mouse_y, window_x, window_y;
            SDL_GetGlobalMouseState(&mouse_x, &mouse_y);
            if (!(io.ConfigFlags & ImGuiConfigFlags_ViewportsEnable))
            {
                SDL_GetWindowPosition(focused_window, &window_x, &window_y);
                mouse_x -= window_x;
                mouse_y -= window_y;
            }
            io.AddMousePosEvent((float)mouse_x, (float)mouse_y);
        }
    }

    // (Optional) When using multiple viewports: call io.AddMouseViewportEvent() with the viewport the OS mouse cursor is hovering.
    // If ImGuiBackendFlags_HasMouseHoveredViewport is not set by the backend, Dear imGui will ignore this field and infer the information using its flawed heuristic.
    // - [!] SDL backend does NOT correctly ignore viewports with the _NoInputs flag.
    //       Some backend are not able to handle that correctly. If a backend report an hovered viewport that has the _NoInputs flag (e.g. when dragging a window
    //       for docking, the viewport has the _NoInputs flag in order to allow us to find the viewport under), then Dear ImGui is forced to ignore the value reported
    //       by the backend, and use its flawed heuristic to guess the viewport behind.
    // - [X] SDL backend correctly reports this regardless of another viewport behind focused and dragged from (we need this to find a useful drag and drop target).
    if (io.BackendFlags & ImGuiBackendFlags_HasMouseHoveredViewport)
    {
        ImGuiID mouse_viewport_id = 0;
        if (ImGuiViewport* mouse_viewport = ImGui_ImplSDL2_GetViewportForWindowID(bd->MouseWindowID))
            mouse_viewport_id = mouse_viewport->ID;
        io.AddMouseViewportEvent(mouse_viewport_id);
    }
}

static void ImGui_ImplSDL2_UpdateMouseCursor()
{
    ImGuiIO& io = ImGui::GetIO();
    if (io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange)
        return;
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();

    ImGuiMouseCursor imgui_cursor = ImGui::GetMouseCursor();
    if (io.MouseDrawCursor || imgui_cursor == ImGuiMouseCursor_None)
    {
        // Hide OS mouse cursor if imgui is drawing it or if it wants no cursor
        SDL_ShowCursor(SDL_FALSE);
    }
    else
    {
        // Show OS mouse cursor
        SDL_Cursor* expected_cursor = bd->MouseCursors[imgui_cursor] ? bd->MouseCursors[imgui_cursor] : bd->MouseCursors[ImGuiMouseCursor_Arrow];
        if (bd->MouseLastCursor != expected_cursor)
        {
            SDL_SetCursor(expected_cursor); // SDL function doesn't have an early out (see #6113)
            bd->MouseLastCursor = expected_cursor;
        }
        SDL_ShowCursor(SDL_TRUE);
    }
}

static void ImGui_ImplSDL2_CloseGamepads()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    if (bd->GamepadMode != ImGui_ImplSDL2_GamepadMode_Manual)
        for (SDL_GameController* gamepad : bd->Gamepads)
            SDL_GameControllerClose(gamepad);
    bd->Gamepads.resize(0);
}

void ImGui_ImplSDL2_SetGamepadMode(ImGui_ImplSDL2_GamepadMode mode, struct _SDL_GameController** manual_gamepads_array, int manual_gamepads_count)
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    ImGui_ImplSDL2_CloseGamepads();
    if (mode == ImGui_ImplSDL2_GamepadMode_Manual)
    {
        IM_ASSERT(manual_gamepads_array != nullptr && manual_gamepads_count > 0);
        for (int n = 0; n < manual_gamepads_count; n++)
            bd->Gamepads.push_back(manual_gamepads_array[n]);
    }
    else
    {
        IM_ASSERT(manual_gamepads_array == nullptr && manual_gamepads_count <= 0);
        bd->WantUpdateGamepadsList = true;
    }
    bd->GamepadMode = mode;
}

static void ImGui_ImplSDL2_UpdateGamepadButton(ImGui_ImplSDL2_Data* bd, ImGuiIO& io, ImGuiKey key, SDL_GameControllerButton button_no)
{
    bool merged_value = false;
    for (SDL_GameController* gamepad : bd->Gamepads)
        merged_value |= SDL_GameControllerGetButton(gamepad, button_no) != 0;
    io.AddKeyEvent(key, merged_value);
}

static inline float Saturate(float v) { return v < 0.0f ? 0.0f : v  > 1.0f ? 1.0f : v; }
static void ImGui_ImplSDL2_UpdateGamepadAnalog(ImGui_ImplSDL2_Data* bd, ImGuiIO& io, ImGuiKey key, SDL_GameControllerAxis axis_no, float v0, float v1)
{
    float merged_value = 0.0f;
    for (SDL_GameController* gamepad : bd->Gamepads)
    {
        float vn = Saturate((float)(SDL_GameControllerGetAxis(gamepad, axis_no) - v0) / (float)(v1 - v0));
        if (merged_value < vn)
            merged_value = vn;
    }
    io.AddKeyAnalogEvent(key, merged_value > 0.1f, merged_value);
}

static void ImGui_ImplSDL2_UpdateGamepads()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    ImGuiIO& io = ImGui::GetIO();

    // Update list of controller(s) to use
    if (bd->WantUpdateGamepadsList && bd->GamepadMode != ImGui_ImplSDL2_GamepadMode_Manual)
    {
        ImGui_ImplSDL2_CloseGamepads();
        int joystick_count = SDL_NumJoysticks();
        for (int n = 0; n < joystick_count; n++)
            if (SDL_IsGameController(n))
                if (SDL_GameController* gamepad = SDL_GameControllerOpen(n))
                {
                    bd->Gamepads.push_back(gamepad);
                    if (bd->GamepadMode == ImGui_ImplSDL2_GamepadMode_AutoFirst)
                        break;
                }
        bd->WantUpdateGamepadsList = false;
    }

    // FIXME: Technically feeding gamepad shouldn't depend on this now that they are regular inputs.
    if ((io.ConfigFlags & ImGuiConfigFlags_NavEnableGamepad) == 0)
        return;
    io.BackendFlags &= ~ImGuiBackendFlags_HasGamepad;
    if (bd->Gamepads.Size == 0)
        return;
    io.BackendFlags |= ImGuiBackendFlags_HasGamepad;

    // Update gamepad inputs
    const int thumb_dead_zone = 8000; // SDL_gamecontroller.h suggests using this value.
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadStart,       SDL_CONTROLLER_BUTTON_START);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadBack,        SDL_CONTROLLER_BUTTON_BACK);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadFaceLeft,    SDL_CONTROLLER_BUTTON_X);              // Xbox X, PS Square
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadFaceRight,   SDL_CONTROLLER_BUTTON_B);              // Xbox B, PS Circle
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadFaceUp,      SDL_CONTROLLER_BUTTON_Y);              // Xbox Y, PS Triangle
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadFaceDown,    SDL_CONTROLLER_BUTTON_A);              // Xbox A, PS Cross
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadDpadLeft,    SDL_CONTROLLER_BUTTON_DPAD_LEFT);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadDpadRight,   SDL_CONTROLLER_BUTTON_DPAD_RIGHT);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadDpadUp,      SDL_CONTROLLER_BUTTON_DPAD_UP);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadDpadDown,    SDL_CONTROLLER_BUTTON_DPAD_DOWN);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadL1,          SDL_CONTROLLER_BUTTON_LEFTSHOULDER);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadR1,          SDL_CONTROLLER_BUTTON_RIGHTSHOULDER);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadL2,          SDL_CONTROLLER_AXIS_TRIGGERLEFT,  0.0f, 32767);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadR2,          SDL_CONTROLLER_AXIS_TRIGGERRIGHT, 0.0f, 32767);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadL3,          SDL_CONTROLLER_BUTTON_LEFTSTICK);
    ImGui_ImplSDL2_UpdateGamepadButton(bd, io, ImGuiKey_GamepadR3,          SDL_CONTROLLER_BUTTON_RIGHTSTICK);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadLStickLeft,  SDL_CONTROLLER_AXIS_LEFTX,  -thumb_dead_zone, -32768);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadLStickRight, SDL_CONTROLLER_AXIS_LEFTX,  +thumb_dead_zone, +32767);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadLStickUp,    SDL_CONTROLLER_AXIS_LEFTY,  -thumb_dead_zone, -32768);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadLStickDown,  SDL_CONTROLLER_AXIS_LEFTY,  +thumb_dead_zone, +32767);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickLeft,  SDL_CONTROLLER_AXIS_RIGHTX, -thumb_dead_zone, -32768);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickRight, SDL_CONTROLLER_AXIS_RIGHTX, +thumb_dead_zone, +32767);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickUp,    SDL_CONTROLLER_AXIS_RIGHTY, -thumb_dead_zone, -32768);
    ImGui_ImplSDL2_UpdateGamepadAnalog(bd, io, ImGuiKey_GamepadRStickDown,  SDL_CONTROLLER_AXIS_RIGHTY, +thumb_dead_zone, +32767);
}

// FIXME: Note that doesn't update with DPI/Scaling change only as SDL2 doesn't have an event for it (SDL3 has).
static void ImGui_ImplSDL2_UpdateMonitors()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
    platform_io.Monitors.resize(0);
    bd->WantUpdateMonitors = false;
    int display_count = SDL_GetNumVideoDisplays();
    for (int n = 0; n < display_count; n++)
    {
        // Warning: the validity of monitor DPI information on Windows depends on the application DPI awareness settings, which generally needs to be set in the manifest or at runtime.
        ImGuiPlatformMonitor monitor;
        SDL_Rect r;
        SDL_GetDisplayBounds(n, &r);
        monitor.MainPos = monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
        monitor.MainSize = monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
#if SDL_HAS_USABLE_DISPLAY_BOUNDS
        SDL_GetDisplayUsableBounds(n, &r);
        monitor.WorkPos = ImVec2((float)r.x, (float)r.y);
        monitor.WorkSize = ImVec2((float)r.w, (float)r.h);
#endif
#if SDL_HAS_PER_MONITOR_DPI
        // FIXME-VIEWPORT: On MacOS SDL reports actual monitor DPI scale, ignoring OS configuration. We may want to set
        //  DpiScale to cocoa_window.backingScaleFactor here.
        float dpi = 0.0f;
        if (!SDL_GetDisplayDPI(n, &dpi, nullptr, nullptr))
        {
            if (dpi <= 0.0f)
                continue; // Some accessibility applications are declaring virtual monitors with a DPI of 0, see #7902.
            monitor.DpiScale = dpi / 96.0f;
        }
#endif
        monitor.PlatformHandle = (void*)(intptr_t)n;
        platform_io.Monitors.push_back(monitor);
    }
}

void ImGui_ImplSDL2_NewFrame()
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    IM_ASSERT(bd != nullptr && "Context or backend not initialized! Did you call ImGui_ImplSDL2_Init()?");
    ImGuiIO& io = ImGui::GetIO();

    // Setup display size (every frame to accommodate for window resizing)
    int w, h;
    int display_w, display_h;
    SDL_GetWindowSize(bd->Window, &w, &h);
    if (SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_MINIMIZED)
        w = h = 0;
    if (bd->Renderer != nullptr)
        SDL_GetRendererOutputSize(bd->Renderer, &display_w, &display_h);
    else
        SDL_GL_GetDrawableSize(bd->Window, &display_w, &display_h);
    io.DisplaySize = ImVec2((float)w, (float)h);
    if (w > 0 && h > 0)
        io.DisplayFramebufferScale = ImVec2((float)display_w / w, (float)display_h / h);

    // Update monitors
    if (bd->WantUpdateMonitors)
        ImGui_ImplSDL2_UpdateMonitors();

    // Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
    // (Accept SDL_GetPerformanceCounter() not returning a monotonically increasing value. Happens in VMs and Emscripten, see #6189, #6114, #3644)
    static Uint64 frequency = SDL_GetPerformanceFrequency();
    Uint64 current_time = SDL_GetPerformanceCounter();
    if (current_time <= bd->Time)
        current_time = bd->Time + 1;
    io.DeltaTime = bd->Time > 0 ? (float)((double)(current_time - bd->Time) / frequency) : (float)(1.0f / 60.0f);
    bd->Time = current_time;

    if (bd->MouseLastLeaveFrame && bd->MouseLastLeaveFrame >= ImGui::GetFrameCount() && bd->MouseButtonsDown == 0)
    {
        bd->MouseWindowID = 0;
        bd->MouseLastLeaveFrame = 0;
        io.AddMousePosEvent(-FLT_MAX, -FLT_MAX);
    }

    // Our io.AddMouseViewportEvent() calls will only be valid when not capturing.
    // Technically speaking testing for 'bd->MouseButtonsDown == 0' would be more rigorous, but testing for payload reduces noise and potential side-effects.
    if (bd->MouseCanReportHoveredViewport && ImGui::GetDragDropPayload() == nullptr)
        io.BackendFlags |= ImGuiBackendFlags_HasMouseHoveredViewport;
    else
        io.BackendFlags &= ~ImGuiBackendFlags_HasMouseHoveredViewport;

    ImGui_ImplSDL2_UpdateMouseData();
    ImGui_ImplSDL2_UpdateMouseCursor();

    // Update game controllers (if enabled and available)
    ImGui_ImplSDL2_UpdateGamepads();
}

//--------------------------------------------------------------------------------------------------------
// MULTI-VIEWPORT / PLATFORM INTERFACE SUPPORT
// This is an _advanced_ and _optional_ feature, allowing the backend to create and handle multiple viewports simultaneously.
// If you are new to dear imgui or creating a new binding for dear imgui, it is recommended that you completely ignore this section first..
//--------------------------------------------------------------------------------------------------------

// Helper structure we store in the void* RendererUserData field of each ImGuiViewport to easily retrieve our backend data.
struct ImGui_ImplSDL2_ViewportData
{
    SDL_Window*     Window;
    Uint32          WindowID;
    bool            WindowOwned;
    SDL_GLContext   GLContext;

    ImGui_ImplSDL2_ViewportData() { Window = nullptr; WindowID = 0; WindowOwned = false; GLContext = nullptr; }
    ~ImGui_ImplSDL2_ViewportData() { IM_ASSERT(Window == nullptr && GLContext == nullptr); }
};

static void ImGui_ImplSDL2_CreateWindow(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
    ImGui_ImplSDL2_ViewportData* vd = IM_NEW(ImGui_ImplSDL2_ViewportData)();
    viewport->PlatformUserData = vd;

    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
    ImGui_ImplSDL2_ViewportData* main_viewport_data = (ImGui_ImplSDL2_ViewportData*)main_viewport->PlatformUserData;

    // Share GL resources with main context
    bool use_opengl = (main_viewport_data->GLContext != nullptr);
    SDL_GLContext backup_context = nullptr;
    if (use_opengl)
    {
        backup_context = SDL_GL_GetCurrentContext();
        SDL_GL_SetAttribute(SDL_GL_SHARE_WITH_CURRENT_CONTEXT, 1);
        SDL_GL_MakeCurrent(main_viewport_data->Window, main_viewport_data->GLContext);
    }

    Uint32 sdl_flags = 0;
    sdl_flags |= use_opengl ? SDL_WINDOW_OPENGL : (bd->UseVulkan ? SDL_WINDOW_VULKAN : 0);
    sdl_flags |= SDL_GetWindowFlags(bd->Window) & SDL_WINDOW_ALLOW_HIGHDPI;
    sdl_flags |= SDL_WINDOW_HIDDEN;
    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? SDL_WINDOW_BORDERLESS : 0;
    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? 0 : SDL_WINDOW_RESIZABLE;
#if !defined(_WIN32)
    // See SDL hack in ImGui_ImplSDL2_ShowWindow().
    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon) ? SDL_WINDOW_SKIP_TASKBAR : 0;
#endif
#if SDL_HAS_ALWAYS_ON_TOP
    sdl_flags |= (viewport->Flags & ImGuiViewportFlags_TopMost) ? SDL_WINDOW_ALWAYS_ON_TOP : 0;
#endif
    vd->Window = SDL_CreateWindow("No Title Yet", (int)viewport->Pos.x, (int)viewport->Pos.y, (int)viewport->Size.x, (int)viewport->Size.y, sdl_flags);
    vd->WindowOwned = true;
    if (use_opengl)
    {
        vd->GLContext = SDL_GL_CreateContext(vd->Window);
        SDL_GL_SetSwapInterval(0);
    }
    if (use_opengl && backup_context)
        SDL_GL_MakeCurrent(vd->Window, backup_context);

    viewport->PlatformHandle = (void*)(intptr_t)SDL_GetWindowID(vd->Window);
    viewport->PlatformHandleRaw = nullptr;
    SDL_SysWMinfo info;
    SDL_VERSION(&info.version);
    if (SDL_GetWindowWMInfo(vd->Window, &info))
    {
#if defined(SDL_VIDEO_DRIVER_WINDOWS)
        viewport->PlatformHandleRaw = info.info.win.window;
#elif defined(__APPLE__) && defined(SDL_VIDEO_DRIVER_COCOA)
        viewport->PlatformHandleRaw = (void*)info.info.cocoa.window;
#endif
    }
}

static void ImGui_ImplSDL2_DestroyWindow(ImGuiViewport* viewport)
{
    if (ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData)
    {
        if (vd->GLContext && vd->WindowOwned)
            SDL_GL_DeleteContext(vd->GLContext);
        if (vd->Window && vd->WindowOwned)
            SDL_DestroyWindow(vd->Window);
        vd->GLContext = nullptr;
        vd->Window = nullptr;
        IM_DELETE(vd);
    }
    viewport->PlatformUserData = viewport->PlatformHandle = nullptr;
}

static void ImGui_ImplSDL2_ShowWindow(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
#if defined(_WIN32)
    HWND hwnd = (HWND)viewport->PlatformHandleRaw;

    // SDL hack: Hide icon from task bar
    // Note: SDL 2.0.6+ has a SDL_WINDOW_SKIP_TASKBAR flag which is supported under Windows but the way it create the window breaks our seamless transition.
    if (viewport->Flags & ImGuiViewportFlags_NoTaskBarIcon)
    {
        LONG ex_style = ::GetWindowLong(hwnd, GWL_EXSTYLE);
        ex_style &= ~WS_EX_APPWINDOW;
        ex_style |= WS_EX_TOOLWINDOW;
        ::SetWindowLong(hwnd, GWL_EXSTYLE, ex_style);
    }
#endif

#if SDL_HAS_SHOW_WINDOW_ACTIVATION_HINT
    SDL_SetHint(SDL_HINT_WINDOW_NO_ACTIVATION_WHEN_SHOWN, (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing) ? "1" : "0");
#elif defined(_WIN32)
    // SDL hack: SDL always activate/focus windows :/
    if (viewport->Flags & ImGuiViewportFlags_NoFocusOnAppearing)
    {
        ::ShowWindow(hwnd, SW_SHOWNA);
        return;
    }
#endif
    SDL_ShowWindow(vd->Window);
}

static ImVec2 ImGui_ImplSDL2_GetWindowPos(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    int x = 0, y = 0;
    SDL_GetWindowPosition(vd->Window, &x, &y);
    return ImVec2((float)x, (float)y);
}

static void ImGui_ImplSDL2_SetWindowPos(ImGuiViewport* viewport, ImVec2 pos)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_SetWindowPosition(vd->Window, (int)pos.x, (int)pos.y);
}

static ImVec2 ImGui_ImplSDL2_GetWindowSize(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    int w = 0, h = 0;
    SDL_GetWindowSize(vd->Window, &w, &h);
    return ImVec2((float)w, (float)h);
}

static void ImGui_ImplSDL2_SetWindowSize(ImGuiViewport* viewport, ImVec2 size)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_SetWindowSize(vd->Window, (int)size.x, (int)size.y);
}

static void ImGui_ImplSDL2_SetWindowTitle(ImGuiViewport* viewport, const char* title)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_SetWindowTitle(vd->Window, title);
}

#if SDL_HAS_WINDOW_ALPHA
static void ImGui_ImplSDL2_SetWindowAlpha(ImGuiViewport* viewport, float alpha)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_SetWindowOpacity(vd->Window, alpha);
}
#endif

static void ImGui_ImplSDL2_SetWindowFocus(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    SDL_RaiseWindow(vd->Window);
}

static bool ImGui_ImplSDL2_GetWindowFocus(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    return (SDL_GetWindowFlags(vd->Window) & SDL_WINDOW_INPUT_FOCUS) != 0;
}

static bool ImGui_ImplSDL2_GetWindowMinimized(ImGuiViewport* viewport)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    return (SDL_GetWindowFlags(vd->Window) & SDL_WINDOW_MINIMIZED) != 0;
}

static void ImGui_ImplSDL2_RenderWindow(ImGuiViewport* viewport, void*)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    if (vd->GLContext)
        SDL_GL_MakeCurrent(vd->Window, vd->GLContext);
}

static void ImGui_ImplSDL2_SwapBuffers(ImGuiViewport* viewport, void*)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    if (vd->GLContext)
    {
        SDL_GL_MakeCurrent(vd->Window, vd->GLContext);
        SDL_GL_SwapWindow(vd->Window);
    }
}

// Vulkan support (the Vulkan renderer needs to call a platform-side support function to create the surface)
// SDL is graceful enough to _not_ need <vulkan/vulkan.h> so we can safely include this.
#if SDL_HAS_VULKAN
#include <SDL_vulkan.h>
static int ImGui_ImplSDL2_CreateVkSurface(ImGuiViewport* viewport, ImU64 vk_instance, const void* vk_allocator, ImU64* out_vk_surface)
{
    ImGui_ImplSDL2_ViewportData* vd = (ImGui_ImplSDL2_ViewportData*)viewport->PlatformUserData;
    (void)vk_allocator;
    SDL_bool ret = SDL_Vulkan_CreateSurface(vd->Window, (VkInstance)vk_instance, (VkSurfaceKHR*)out_vk_surface);
    return ret ? 0 : 1; // ret ? VK_SUCCESS : VK_NOT_READY
}
#endif // SDL_HAS_VULKAN

static void ImGui_ImplSDL2_InitPlatformInterface(SDL_Window* window, void* sdl_gl_context)
{
    // Register platform interface (will be coupled with a renderer interface)
    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
    platform_io.Platform_CreateWindow = ImGui_ImplSDL2_CreateWindow;
    platform_io.Platform_DestroyWindow = ImGui_ImplSDL2_DestroyWindow;
    platform_io.Platform_ShowWindow = ImGui_ImplSDL2_ShowWindow;
    platform_io.Platform_SetWindowPos = ImGui_ImplSDL2_SetWindowPos;
    platform_io.Platform_GetWindowPos = ImGui_ImplSDL2_GetWindowPos;
    platform_io.Platform_SetWindowSize = ImGui_ImplSDL2_SetWindowSize;
    platform_io.Platform_GetWindowSize = ImGui_ImplSDL2_GetWindowSize;
    platform_io.Platform_SetWindowFocus = ImGui_ImplSDL2_SetWindowFocus;
    platform_io.Platform_GetWindowFocus = ImGui_ImplSDL2_GetWindowFocus;
    platform_io.Platform_GetWindowMinimized = ImGui_ImplSDL2_GetWindowMinimized;
    platform_io.Platform_SetWindowTitle = ImGui_ImplSDL2_SetWindowTitle;
    platform_io.Platform_RenderWindow = ImGui_ImplSDL2_RenderWindow;
    platform_io.Platform_SwapBuffers = ImGui_ImplSDL2_SwapBuffers;
#if SDL_HAS_WINDOW_ALPHA
    platform_io.Platform_SetWindowAlpha = ImGui_ImplSDL2_SetWindowAlpha;
#endif
#if SDL_HAS_VULKAN
    platform_io.Platform_CreateVkSurface = ImGui_ImplSDL2_CreateVkSurface;
#endif

    // Register main window handle (which is owned by the main application, not by us)
    // This is mostly for simplicity and consistency, so that our code (e.g. mouse handling etc.) can use same logic for main and secondary viewports.
    ImGuiViewport* main_viewport = ImGui::GetMainViewport();
    ImGui_ImplSDL2_ViewportData* vd = IM_NEW(ImGui_ImplSDL2_ViewportData)();
    vd->Window = window;
    vd->WindowID = SDL_GetWindowID(window);
    vd->WindowOwned = false;
    vd->GLContext = sdl_gl_context;
    main_viewport->PlatformUserData = vd;
    main_viewport->PlatformHandle = (void*)(intptr_t)vd->WindowID;
}

static void ImGui_ImplSDL2_ShutdownPlatformInterface()
{
    ImGui::DestroyPlatformWindows();
}

//-----------------------------------------------------------------------------

#if defined(__clang__)
#pragma clang diagnostic pop
#endif

#endif // #ifndef IMGUI_DISABLE