Fonts: automatically set current rasterizer density to viewport density. Effectively should fix most things on macOS.

# Conflicts:
#	imgui.cpp
#	imgui.h

docs/FONTS.md

@@ -130,7 +130,7 @@ ImGui::PopFont();
 **For advanced options create a ImFontConfig structure and pass it to the AddFont() function (it will be copied internally):**
 ```cpp
 ImFontConfig config;
-config.RasterizerDensity = 2.0f;
+config.OversampleH = 1.0f;
 ImFont* font = io.Fonts->AddFontFromFileTTF("font.ttf", size_pixels, &config);
 ```
 

imgui.cpp

@@ -4398,6 +4398,8 @@ static void SetCurrentWindow(ImGuiWindow* window)
     g.CurrentDpiScale = 1.0f; // FIXME-DPI: WIP this is modified in docking
     if (window)
     {
+        if (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasTextures)
+            g.FontRasterizerDensity = window->Viewport->FramebufferScale.x; // == SetFontRasterizerDensity()
         ImGui::UpdateCurrentFontSize();
         ImGui::NavUpdateCurrentWindowIsScrollPushableX();
     }
@@ -8699,7 +8701,8 @@ void ImGui::UpdateCurrentFontSize()
     g.DrawListSharedData.FontScale = g.FontScale;
 }
 
-// FIXME-DPI: Not sure how to expose this. It may be automatically applied based on current viewport, if we had this information stored in viewport or monitor.
+// Exposed in case user may want to override setting density.
+// IMPORTANT: Begin()/End() is overriding density. Be considerate of this you change it.
 void ImGui::SetFontRasterizerDensity(float rasterizer_density)
 {
     ImGuiContext& g = *GImGui;
@@ -15240,6 +15243,7 @@ static void ImGui::UpdateViewportsNewFrame()
     main_viewport->Flags = ImGuiViewportFlags_IsPlatformWindow | ImGuiViewportFlags_OwnedByApp;
     main_viewport->Pos = ImVec2(0.0f, 0.0f);
     main_viewport->Size = g.IO.DisplaySize;
+    main_viewport->FramebufferScale = g.IO.DisplayFramebufferScale;
 
     for (ImGuiViewportP* viewport : g.Viewports)
     {

imgui.h

@@ -2322,7 +2322,8 @@ struct ImGuiIO
 
     ImGuiConfigFlags   ConfigFlags;             // = 0              // See ImGuiConfigFlags_ enum. Set by user/application. Keyboard/Gamepad navigation options, etc.
     ImGuiBackendFlags  BackendFlags;            // = 0              // See ImGuiBackendFlags_ enum. Set by backend (imgui_impl_xxx files or custom backend) to communicate features supported by the backend.
-    ImVec2      DisplaySize;                    // <unset>          // Main display size, in pixels (generally == GetMainViewport()->Size). May change every frame.
+    ImVec2      DisplaySize;                    // <unset>          // Main display size, in pixels (== GetMainViewport()->Size). May change every frame.
+    ImVec2      DisplayFramebufferScale;        // = (1, 1)         // Main display density. For retina display where window coordinates are different from framebuffer coordinates. This will affect font density + will end up in ImDrawData::FramebufferScale.
     float       DeltaTime;                      // = 1.0f/60.0f     // Time elapsed since last frame, in seconds. May change every frame.
     float       IniSavingRate;                  // = 5.0f           // Minimum time between saving positions/sizes to .ini file, in seconds.
     const char* IniFilename;                    // = "imgui.ini"    // Path to .ini file (important: default "imgui.ini" is relative to current working dir!). Set NULL to disable automatic .ini loading/saving or if you want to manually call LoadIniSettingsXXX() / SaveIniSettingsXXX() functions.
@@ -2334,7 +2335,6 @@ struct ImGuiIO
     float       FontGlobalScale;                // = 1.0f           // Global scale all fonts
     bool        FontAllowUserScaling;           // = false          // [OBSOLETE] Allow user scaling text of individual window with CTRL+Wheel.
     ImFont*     FontDefault;                    // = NULL           // Font to use on NewFrame(). Use NULL to uses Fonts->Fonts[0].
-    ImVec2      DisplayFramebufferScale;        // = (1, 1)         // For retina display or other situations where window coordinates are different from framebuffer coordinates. This generally ends up in ImDrawData::FramebufferScale.
 
     // Keyboard/Gamepad Navigation options
     bool        ConfigNavSwapGamepadButtons;    // = false          // Swap Activate<>Cancel (A<>B) buttons, matching typical "Nintendo/Japanese style" gamepad layout.
@@ -3341,7 +3341,7 @@ struct ImDrawData
     ImVector<ImDrawList*> CmdLists;         // Array of ImDrawList* to render. The ImDrawLists are owned by ImGuiContext and only pointed to from here.
     ImVec2              DisplayPos;         // Top-left position of the viewport to render (== top-left of the orthogonal projection matrix to use) (== GetMainViewport()->Pos for the main viewport, == (0.0) in most single-viewport applications)
     ImVec2              DisplaySize;        // Size of the viewport to render (== GetMainViewport()->Size for the main viewport, == io.DisplaySize in most single-viewport applications)
-    ImVec2              FramebufferScale;   // Amount of pixels for each unit of DisplaySize. Based on io.DisplayFramebufferScale. Generally (1,1) on normal display, (2,2) on OSX with Retina display.
+    ImVec2              FramebufferScale;   // Amount of pixels for each unit of DisplaySize. Copied from viewport->FramebufferScale (== io.DisplayFramebufferScale for main viewport). Generally (1,1) on normal display, (2,2) on OSX with Retina display.
     ImGuiViewport*      OwnerViewport;      // Viewport carrying the ImDrawData instance, might be of use to the renderer (generally not).
     ImVector<ImTextureData*>* Textures;     // List of textures to update. Most of the times the list is shared by all ImDrawData, has only 1 texture and it doesn't need any update. This almost always points to ImGui::GetPlatformIO().Textures[]. May be overriden or set to NULL if you want to manually update textures.
 
@@ -3734,8 +3734,8 @@ enum ImFontFlags_
     ImFontFlags_None                    = 0,
     ImFontFlags_UseDefaultSize          = 1 << 0,   // Legacy compatibility: make PushFont() calls without explicit size use font->DefaultSize instead of current font size.
     ImFontFlags_NoLoadError             = 1 << 1,   // Disable throwing an error/assert when calling AddFontXXX() with missing file/data. Calling code is expected to check AddFontXXX() return value.
-    ImFontFlags_NoLoadGlyphs            = 1 << 2,   // Disable loading new glyphs.
-    ImFontFlags_LockBakedSizes          = 1 << 3,   // Disable loading new baked sizes, disable garbage collecting current ones. e.g. if you want to lock a font to a single size.
+    ImFontFlags_NoLoadGlyphs            = 1 << 2,   // [Internal] Disable loading new glyphs.
+    ImFontFlags_LockBakedSizes          = 1 << 3,   // [Internal] Disable loading new baked sizes, disable garbage collecting current ones. e.g. if you want to lock a font to a single size. Important: if you use this to preload given sizes, consider the possibility of multiple font density used on Retina display.
 };
 
 // Font runtime data and rendering
@@ -3766,7 +3766,7 @@ struct ImFont
     // Methods
     IMGUI_API ImFont();
     IMGUI_API ~ImFont();
-    IMGUI_API ImFontBaked*      GetFontBaked(float font_size);  // Get or create baked data for given size
+    IMGUI_API ImFontBaked*      GetFontBaked(float font_size, float density = -1.0f);  // Get or create baked data for given size
     IMGUI_API bool              IsGlyphInFont(ImWchar c);
     bool                        IsLoaded() const                { return ContainerAtlas != NULL; }
     const char*                 GetDebugName() const            { return Sources.Size ? Sources[0]->Name : "<unknown>"; } // Fill ImFontConfig::Name.
@@ -3832,6 +3832,7 @@ struct ImGuiViewport
     ImGuiViewportFlags  Flags;                  // See ImGuiViewportFlags_
     ImVec2              Pos;                    // Main Area: Position of the viewport (Dear ImGui coordinates are the same as OS desktop/native coordinates)
     ImVec2              Size;                   // Main Area: Size of the viewport.
+    ImVec2              FramebufferScale;       // Density of the viewport for Retina display (always 1,1 on Windows, may be 2,2 etc on macOS/iOS). This will affect font rasterizer density.
     ImVec2              WorkPos;                // Work Area: Position of the viewport minus task bars, menus bars, status bars (>= Pos)
     ImVec2              WorkSize;               // Work Area: Size of the viewport minus task bars, menu bars, status bars (<= Size)
 

imgui_draw.cpp

@@ -3786,25 +3786,28 @@ ImFontBaked* ImFontAtlasBakedAdd(ImFontAtlas* atlas, ImFont* font, float font_si
 ImFontBaked* ImFontAtlasBakedGetClosestMatch(ImFontAtlas* atlas, ImFont* font, float font_size, float font_rasterizer_density)
 {
     ImFontAtlasBuilder* builder = atlas->Builder;
-    ImFontBaked* closest_larger_match = NULL;
-    ImFontBaked* closest_smaller_match = NULL;
-    for (int baked_n = 0; baked_n < builder->BakedPool.Size; baked_n++)
+    for (int step_n = 0; step_n < 2; step_n++)
     {
-        ImFontBaked* baked = &builder->BakedPool[baked_n];
-        if (baked->ContainerFont != font || baked->WantDestroy)
-            continue;
-        if (baked->RasterizerDensity != font_rasterizer_density)
-            continue;
-        if (baked->Size > font_size && (closest_larger_match == NULL || baked->Size < closest_larger_match->Size))
-            closest_larger_match = baked;
-        if (baked->Size < font_size && (closest_smaller_match == NULL || baked->Size > closest_smaller_match->Size))
-            closest_smaller_match = baked;
-    }
-    if (closest_larger_match)
-        if (closest_smaller_match == NULL || (closest_larger_match->Size >= font_size * 2.0f && closest_smaller_match->Size > font_size * 0.5f))
-            return closest_larger_match;
-    if (closest_smaller_match)
-        return closest_smaller_match;
+        ImFontBaked* closest_larger_match = NULL;
+        ImFontBaked* closest_smaller_match = NULL;
+        for (int baked_n = 0; baked_n < builder->BakedPool.Size; baked_n++)
+        {
+            ImFontBaked* baked = &builder->BakedPool[baked_n];
+            if (baked->ContainerFont != font || baked->WantDestroy)
+                continue;
+            if (step_n == 0 && baked->RasterizerDensity != font_rasterizer_density) // First try with same density
+                continue;
+            if (baked->Size > font_size && (closest_larger_match == NULL || baked->Size < closest_larger_match->Size))
+                closest_larger_match = baked;
+            if (baked->Size < font_size && (closest_smaller_match == NULL || baked->Size > closest_smaller_match->Size))
+                closest_smaller_match = baked;
+        }
+        if (closest_larger_match)
+            if (closest_smaller_match == NULL || (closest_larger_match->Size >= font_size * 2.0f && closest_smaller_match->Size > font_size * 0.5f))
+                return closest_larger_match;
+        if (closest_smaller_match)
+            return closest_smaller_match;
+    }
     return NULL;
 }
 
@@ -5195,7 +5198,7 @@ ImGuiID ImFontAtlasBakedGetId(ImGuiID font_id, float baked_size, float rasterize
 }
 
 // ImFontBaked pointers are valid for the entire frame but shall never be kept between frames.
-ImFontBaked* ImFont::GetFontBaked(float size)
+ImFontBaked* ImFont::GetFontBaked(float size, float density)
 {
     ImFontBaked* baked = LastBaked;
 
@@ -5203,12 +5206,14 @@ ImFontBaked* ImFont::GetFontBaked(float size)
     // - ImGui::PushFontSize() will already round, but other paths calling GetFontBaked() directly also needs it (e.g. ImFontAtlasBuildPreloadAllGlyphRanges)
     size = ImGui::GetRoundedFontSize(size);
 
-    if (baked && baked->Size == size && baked->RasterizerDensity == CurrentRasterizerDensity)
+    if (density < 0.0f)
+        density = CurrentRasterizerDensity;
+    if (baked && baked->Size == size && baked->RasterizerDensity == density)
         return baked;
 
     ImFontAtlas* atlas = ContainerAtlas;
     ImFontAtlasBuilder* builder = atlas->Builder;
-    baked = ImFontAtlasBakedGetOrAdd(atlas, this, size, CurrentRasterizerDensity);
+    baked = ImFontAtlasBakedGetOrAdd(atlas, this, size, density);
     if (baked == NULL)
         return NULL;
     baked->LastUsedFrame = builder->FrameCount;