Refactor focusable/tabbalbe item registration toward allowing to handle it prior to clipping (not yet the case) (#343, #4079)

Now performed in ItemAdd(). It can't be trivially moved above clipping effectively because it would require us to scroll to be useful, meaning we'd be better off locking the bounding box a frame earlier. Still wip.
As-is this commit has no value for end-user, but it's a reengineering that moves us closer to the solution. + Internals: moved internal flags.

imgui.cpp

@@ -3249,11 +3249,13 @@ void ImGui::SetLastItemData(ImGuiWindow* window, ImGuiID item_id, ImGuiItemStatu
 }
 
 // Process TAB/Shift+TAB. Be mindful that this function may _clear_ the ActiveID when tabbing out.
-bool ImGui::FocusableItemRegister(ImGuiWindow* window, ImGuiID id)
+void ImGui::ItemFocusable(ImGuiWindow* window, ImGuiID id)
 {
     ImGuiContext& g = *GImGui;
+    IM_ASSERT(id != 0 && id == window->DC.LastItemId);
 
     // Increment counters
+    // FIXME: ImGuiItemFlags_Disabled should disable more.
     const bool is_tab_stop = (g.CurrentItemFlags & (ImGuiItemFlags_NoTabStop | ImGuiItemFlags_Disabled)) == 0;
     window->DC.FocusCounterRegular++;
     if (is_tab_stop)
@@ -3275,25 +3277,21 @@ bool ImGui::FocusableItemRegister(ImGuiWindow* window, ImGuiID id)
     if (g.TabFocusRequestCurrWindow == window)
     {
         if (window->DC.FocusCounterRegular == g.TabFocusRequestCurrCounterRegular)
-            return true;
+        {
+            window->DC.LastItemStatusFlags |= ImGuiItemStatusFlags_FocusedByCode;
+            return;
+        }
         if (is_tab_stop && window->DC.FocusCounterTabStop == g.TabFocusRequestCurrCounterTabStop)
         {
             g.NavJustTabbedId = id;
-            return true;
+            window->DC.LastItemStatusFlags |= ImGuiItemStatusFlags_FocusedByTabbing;
+            return;
         }
 
         // If another item is about to be focused, we clear our own active id
         if (g.ActiveId == id)
             ClearActiveID();
     }
-
-    return false;
-}
-
-void ImGui::FocusableItemUnregister(ImGuiWindow* window)
-{
-    window->DC.FocusCounterRegular--;
-    window->DC.FocusCounterTabStop--;
 }
 
 float ImGui::CalcWrapWidthForPos(const ImVec2& pos, float wrap_pos_x)
@@ -7384,7 +7382,7 @@ void ImGui::ItemSize(const ImRect& bb, float text_baseline_y)
 // Declare item bounding box for clipping and interaction.
 // Note that the size can be different than the one provided to ItemSize(). Typically, widgets that spread over available surface
 // declare their minimum size requirement to ItemSize() and provide a larger region to ItemAdd() which is used drawing/interaction.
-bool ImGui::ItemAdd(const ImRect& bb, ImGuiID id, const ImRect* nav_bb_arg)
+bool ImGui::ItemAdd(const ImRect& bb, ImGuiID id, const ImRect* nav_bb_arg, ImGuiItemAddFlags flags)
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
@@ -7433,6 +7431,11 @@ bool ImGui::ItemAdd(const ImRect& bb, ImGuiID id, const ImRect* nav_bb_arg)
         return false;
     //if (g.IO.KeyAlt) window->DrawList->AddRect(bb.Min, bb.Max, IM_COL32(255,255,0,120)); // [DEBUG]
 
+    // Tab stop handling (previously was using internal ItemFocusable() api)
+    // FIXME-NAV: We would now want to move this above the clipping test, but this would require being able to scroll and currently this would mean an extra frame. (#4079, #343)
+    if (flags & ImGuiItemAddFlags_Focusable)
+        ItemFocusable(window, id);
+
     // We need to calculate this now to take account of the current clipping rectangle (as items like Selectable may change them)
     if (IsMouseHoveringRect(bb.Min, bb.Max))
         window->DC.LastItemStatusFlags |= ImGuiItemStatusFlags_HoveredRect;

imgui.h

@@ -61,7 +61,7 @@ Index of this file:
 // Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals. Work in progress versions typically starts at XYY99 then bounce up to XYY00, XYY01 etc. when release tagging happens)
 #define IMGUI_VERSION               "1.83 WIP"
-#define IMGUI_VERSION_NUM           18208
+#define IMGUI_VERSION_NUM           18209
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 #define IMGUI_HAS_TABLE
 
@@ -380,7 +380,7 @@ namespace ImGui
     IMGUI_API void          PushStyleVar(ImGuiStyleVar idx, float val);                     // modify a style float variable. always use this if you modify the style after NewFrame().
     IMGUI_API void          PushStyleVar(ImGuiStyleVar idx, const ImVec2& val);             // modify a style ImVec2 variable. always use this if you modify the style after NewFrame().
     IMGUI_API void          PopStyleVar(int count = 1);
-    IMGUI_API void          PushAllowKeyboardFocus(bool allow_keyboard_focus);              // allow focusing using TAB/Shift-TAB, enabled by default but you can disable it for certain widgets
+    IMGUI_API void          PushAllowKeyboardFocus(bool allow_keyboard_focus);              // == tab stop enable. Allow focusing using TAB/Shift-TAB, enabled by default but you can disable it for certain widgets
     IMGUI_API void          PopAllowKeyboardFocus();
     IMGUI_API void          PushButtonRepeat(bool repeat);                                  // in 'repeat' mode, Button*() functions return repeated true in a typematic manner (using io.KeyRepeatDelay/io.KeyRepeatRate setting). Note that you can call IsItemActive() after any Button() to tell if the button is held in the current frame.
     IMGUI_API void          PopButtonRepeat();
@@ -961,10 +961,7 @@ enum ImGuiInputTextFlags_
     ImGuiInputTextFlags_NoUndoRedo          = 1 << 16,  // Disable undo/redo. Note that input text owns the text data while active, if you want to provide your own undo/redo stack you need e.g. to call ClearActiveID().
     ImGuiInputTextFlags_CharsScientific     = 1 << 17,  // Allow 0123456789.+-*/eE (Scientific notation input)
     ImGuiInputTextFlags_CallbackResize      = 1 << 18,  // Callback on buffer capacity changes request (beyond 'buf_size' parameter value), allowing the string to grow. Notify when the string wants to be resized (for string types which hold a cache of their Size). You will be provided a new BufSize in the callback and NEED to honor it. (see misc/cpp/imgui_stdlib.h for an example of using this)
-    ImGuiInputTextFlags_CallbackEdit        = 1 << 19,  // Callback on any edit (note that InputText() already returns true on edit, the callback is useful mainly to manipulate the underlying buffer while focus is active)
-    // [Internal]
-    ImGuiInputTextFlags_Multiline           = 1 << 20,  // For internal use by InputTextMultiline()
-    ImGuiInputTextFlags_NoMarkEdited        = 1 << 21   // For internal use by functions using InputText() before reformatting data
+    ImGuiInputTextFlags_CallbackEdit        = 1 << 19   // Callback on any edit (note that InputText() already returns true on edit, the callback is useful mainly to manipulate the underlying buffer while focus is active)
 
     // Obsolete names (will be removed soon)
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS

imgui_internal.h

@@ -133,6 +133,7 @@ struct ImGuiWindowSettings;         // Storage for a window .ini settings (we ke
 // Use your programming IDE "Go to definition" facility on the names of the center columns to find the actual flags/enum lists.
 typedef int ImGuiLayoutType;            // -> enum ImGuiLayoutType_         // Enum: Horizontal or vertical
 typedef int ImGuiItemFlags;             // -> enum ImGuiItemFlags_          // Flags: for PushItemFlag()
+typedef int ImGuiItemAddFlags;          // -> enum ImGuiItemAddFlags_       // Flags: for ItemAdd()
 typedef int ImGuiItemStatusFlags;       // -> enum ImGuiItemStatusFlags_    // Flags: for DC.LastItemStatusFlags
 typedef int ImGuiOldColumnFlags;        // -> enum ImGuiOldColumnFlags_     // Flags: for BeginColumns()
 typedef int ImGuiNavHighlightFlags;     // -> enum ImGuiNavHighlightFlags_  // Flags: for RenderNavHighlight()
@@ -710,6 +711,14 @@ enum ImGuiItemFlags_
     ImGuiItemFlags_ReadOnly                 = 1 << 7   // false    // [ALPHA] Allow hovering interactions but underlying value is not changed.
 };
 
+// Flags for ItemAdd()
+// FIXME-NAV: _Focusable is _ALMOST_ what you would expect to be called '_TabStop' but because SetKeyboardFocusHere() works on items with no TabStop we distinguish Focusable from TabStop.
+enum ImGuiItemAddFlags_
+{
+    ImGuiItemAddFlags_None                  = 0,
+    ImGuiItemAddFlags_Focusable             = 1 << 0    // FIXME-NAV: In current/legacy scheme, Focusable+TabStop support are opt-in by widgets. We will transition it toward being opt-out, so this flag is expected to eventually disappear.
+};
+
 // Storage for LastItem data
 enum ImGuiItemStatusFlags_
 {
@@ -721,7 +730,10 @@ enum ImGuiItemStatusFlags_
     ImGuiItemStatusFlags_ToggledOpen        = 1 << 4,   // Set when TreeNode() reports toggling their open state.
     ImGuiItemStatusFlags_HasDeactivated     = 1 << 5,   // Set if the widget/group is able to provide data for the ImGuiItemStatusFlags_Deactivated flag.
     ImGuiItemStatusFlags_Deactivated        = 1 << 6,   // Only valid if ImGuiItemStatusFlags_HasDeactivated is set.
-    ImGuiItemStatusFlags_HoveredWindow      = 1 << 7    // Override the HoveredWindow test to allow cross-window hover testing.
+    ImGuiItemStatusFlags_HoveredWindow      = 1 << 7,   // Override the HoveredWindow test to allow cross-window hover testing.
+    ImGuiItemStatusFlags_FocusedByCode      = 1 << 8,   // Set when the Focusable item just got focused from code.
+    ImGuiItemStatusFlags_FocusedByTabbing   = 1 << 9,   // Set when the Focusable item just got focused by Tabbing.
+    ImGuiItemStatusFlags_Focused            = ImGuiItemStatusFlags_FocusedByCode | ImGuiItemStatusFlags_FocusedByTabbing
 
 #ifdef IMGUI_ENABLE_TEST_ENGINE
     , // [imgui_tests only]
@@ -732,6 +744,15 @@ enum ImGuiItemStatusFlags_
 #endif
 };
 
+// Extend ImGuiInputTextFlags_
+enum ImGuiInputTextFlagsPrivate_
+{
+    // [Internal]
+    ImGuiInputTextFlags_Multiline           = 1 << 26,  // For internal use by InputTextMultiline()
+    ImGuiInputTextFlags_NoMarkEdited        = 1 << 27,  // For internal use by functions using InputText() before reformatting data
+    ImGuiInputTextFlags_MergedItem          = 1 << 28   // For internal use by TempInputText(), will skip calling ItemAdd(). Require bounding-box to strictly match.
+};
+
 // Extend ImGuiButtonFlags_
 enum ImGuiButtonFlagsPrivate_
 {
@@ -2301,12 +2322,11 @@ namespace ImGui
     // Basic Helpers for widget code
     IMGUI_API void          ItemSize(const ImVec2& size, float text_baseline_y = -1.0f);
     IMGUI_API void          ItemSize(const ImRect& bb, float text_baseline_y = -1.0f);
-    IMGUI_API bool          ItemAdd(const ImRect& bb, ImGuiID id, const ImRect* nav_bb = NULL);
+    IMGUI_API bool          ItemAdd(const ImRect& bb, ImGuiID id, const ImRect* nav_bb = NULL, ImGuiItemAddFlags flags = 0);
     IMGUI_API bool          ItemHoverable(const ImRect& bb, ImGuiID id);
+    IMGUI_API void          ItemFocusable(ImGuiWindow* window, ImGuiID id);
     IMGUI_API bool          IsClippedEx(const ImRect& bb, ImGuiID id, bool clip_even_when_logged);
     IMGUI_API void          SetLastItemData(ImGuiWindow* window, ImGuiID item_id, ImGuiItemStatusFlags status_flags, const ImRect& item_rect);
-    IMGUI_API bool          FocusableItemRegister(ImGuiWindow* window, ImGuiID id);   // Return true if focus is requested
-    IMGUI_API void          FocusableItemUnregister(ImGuiWindow* window);
     IMGUI_API ImVec2        CalcItemSize(ImVec2 size, float default_w, float default_h);
     IMGUI_API float         CalcWrapWidthForPos(const ImVec2& pos, float wrap_pos_x);
     IMGUI_API void          PushMultiItemsWidths(int components, float width_full);
@@ -2316,6 +2336,15 @@ namespace ImGui
     IMGUI_API ImVec2        GetContentRegionMaxAbs();
     IMGUI_API void          ShrinkWidths(ImGuiShrinkWidthItem* items, int count, float width_excess);
 
+#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
+    // If you have old/custom copy-and-pasted widgets that used FocusableItemRegister():
+    //  (Old) IMGUI_VERSION_NUM  < 18209: using 'ItemAdd(....)'                              and 'bool focused = FocusableItemRegister(...)'
+    //  (New) IMGUI_VERSION_NUM >= 18209: using 'ItemAdd(..., ImGuiItemAddFlags_Focusable)'  and 'bool focused = (GetItemStatusFlags() & ImGuiItemStatusFlags_Focused) != 0'
+    // Widget code are simplified as there's no need to call FocusableItemUnregister() while managing the transition from regular widget to TempInputText()
+    inline bool FocusableItemRegister(ImGuiWindow* window, ImGuiID id)  { IM_ASSERT(0); IM_UNUSED(window); IM_UNUSED(id); return false; } // -> pass ImGuiItemAddFlags_Focusable flag to ItemAdd()
+    inline void FocusableItemUnregister(ImGuiWindow* window)            { IM_ASSERT(0); IM_UNUSED(window); }                              // -> unnecessary: TempInputText() uses ImGuiInputTextFlags_MergedItem
+#endif
+
     // Logging/Capture
     IMGUI_API void          LogBegin(ImGuiLogType type, int auto_open_depth);           // -> BeginCapture() when we design v2 api, for now stay under the radar by using the old name.
     IMGUI_API void          LogToBuffer(int auto_open_depth = -1);                      // Start logging/capturing to internal buffer

imgui_widgets.cpp

@@ -2315,8 +2315,9 @@ bool ImGui::DragScalar(const char* label, ImGuiDataType data_type, void* p_data,
     const ImRect frame_bb(window->DC.CursorPos, window->DC.CursorPos + ImVec2(w, label_size.y + style.FramePadding.y * 2.0f));
     const ImRect total_bb(frame_bb.Min, frame_bb.Max + ImVec2(label_size.x > 0.0f ? style.ItemInnerSpacing.x + label_size.x : 0.0f, 0.0f));
 
+    const bool temp_input_allowed = (flags & ImGuiSliderFlags_NoInput) == 0;
     ItemSize(total_bb, style.FramePadding.y);
-    if (!ItemAdd(total_bb, id, &frame_bb))
+    if (!ItemAdd(total_bb, id, &frame_bb, temp_input_allowed ? ImGuiItemAddFlags_Focusable : 0))
         return false;
 
     // Default format string when passing NULL
@@ -2327,11 +2328,10 @@ bool ImGui::DragScalar(const char* label, ImGuiDataType data_type, void* p_data,
 
     // Tabbing or CTRL-clicking on Drag turns it into an InputText
     const bool hovered = ItemHoverable(frame_bb, id);
-    const bool temp_input_allowed = (flags & ImGuiSliderFlags_NoInput) == 0;
     bool temp_input_is_active = temp_input_allowed && TempInputIsActive(id);
     if (!temp_input_is_active)
     {
-        const bool focus_requested = temp_input_allowed && FocusableItemRegister(window, id);
+        const bool focus_requested = temp_input_allowed && (window->DC.LastItemStatusFlags & ImGuiItemStatusFlags_Focused) != 0;
         const bool clicked = (hovered && g.IO.MouseClicked[0]);
         const bool double_clicked = (hovered && g.IO.MouseDoubleClicked[0]);
         if (focus_requested || clicked || double_clicked || g.NavActivateId == id || g.NavInputId == id)
@@ -2341,10 +2341,7 @@ bool ImGui::DragScalar(const char* label, ImGuiDataType data_type, void* p_data,
             FocusWindow(window);
             g.ActiveIdUsingNavDirMask = (1 << ImGuiDir_Left) | (1 << ImGuiDir_Right);
             if (temp_input_allowed && (focus_requested || (clicked && g.IO.KeyCtrl) || double_clicked || g.NavInputId == id))
-            {
                 temp_input_is_active = true;
-                FocusableItemUnregister(window);
-            }
         }
         // Experimental: simple click (without moving) turns Drag into an InputText
         // FIXME: Currently polling ImGuiConfigFlags_IsTouchScreen, may either poll an hypothetical ImGuiBackendFlags_HasKeyboard and/or an explicit drag settings.
@@ -2353,7 +2350,6 @@ bool ImGui::DragScalar(const char* label, ImGuiDataType data_type, void* p_data,
             {
                 g.NavInputId = id;
                 temp_input_is_active = true;
-                FocusableItemUnregister(window);
             }
     }
 
@@ -2934,8 +2930,9 @@ bool ImGui::SliderScalar(const char* label, ImGuiDataType data_type, void* p_dat
     const ImRect frame_bb(window->DC.CursorPos, window->DC.CursorPos + ImVec2(w, label_size.y + style.FramePadding.y * 2.0f));
     const ImRect total_bb(frame_bb.Min, frame_bb.Max + ImVec2(label_size.x > 0.0f ? style.ItemInnerSpacing.x + label_size.x : 0.0f, 0.0f));
 
+    const bool temp_input_allowed = (flags & ImGuiSliderFlags_NoInput) == 0;
     ItemSize(total_bb, style.FramePadding.y);
-    if (!ItemAdd(total_bb, id, &frame_bb))
+    if (!ItemAdd(total_bb, id, &frame_bb, temp_input_allowed ? ImGuiItemAddFlags_Focusable : 0))
         return false;
 
     // Default format string when passing NULL
@@ -2946,11 +2943,10 @@ bool ImGui::SliderScalar(const char* label, ImGuiDataType data_type, void* p_dat
 
     // Tabbing or CTRL-clicking on Slider turns it into an input box
     const bool hovered = ItemHoverable(frame_bb, id);
-    const bool temp_input_allowed = (flags & ImGuiSliderFlags_NoInput) == 0;
     bool temp_input_is_active = temp_input_allowed && TempInputIsActive(id);
     if (!temp_input_is_active)
     {
-        const bool focus_requested = temp_input_allowed && FocusableItemRegister(window, id);
+        const bool focus_requested = temp_input_allowed && (window->DC.LastItemStatusFlags & ImGuiItemStatusFlags_Focused) != 0;
         const bool clicked = (hovered && g.IO.MouseClicked[0]);
         if (focus_requested || clicked || g.NavActivateId == id || g.NavInputId == id)
         {
@@ -2959,10 +2955,7 @@ bool ImGui::SliderScalar(const char* label, ImGuiDataType data_type, void* p_dat
             FocusWindow(window);
             g.ActiveIdUsingNavDirMask |= (1 << ImGuiDir_Left) | (1 << ImGuiDir_Right);
             if (temp_input_allowed && (focus_requested || (clicked && g.IO.KeyCtrl) || g.NavInputId == id))
-            {
                 temp_input_is_active = true;
-                FocusableItemUnregister(window);
-            }
         }
     }
 
@@ -3289,7 +3282,7 @@ bool ImGui::TempInputText(const ImRect& bb, ImGuiID id, const char* label, char*
         ClearActiveID();
 
     g.CurrentWindow->DC.CursorPos = bb.Min;
-    bool value_changed = InputTextEx(label, NULL, buf, buf_size, bb.GetSize(), flags);
+    bool value_changed = InputTextEx(label, NULL, buf, buf_size, bb.GetSize(), flags | ImGuiInputTextFlags_MergedItem);
     if (init)
     {
         // First frame we started displaying the InputText widget, we expect it to take the active id.
@@ -3901,7 +3894,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
     ImVec2 inner_size = frame_size;
     if (is_multiline)
     {
-        if (!ItemAdd(total_bb, id, &frame_bb))
+        if (!ItemAdd(total_bb, id, &frame_bb, ImGuiItemAddFlags_Focusable))
         {
             ItemSize(total_bb, style.FramePadding.y);
             EndGroup();
@@ -3928,9 +3921,11 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
     }
     else
     {
+        // Support for internal ImGuiInputTextFlags_MergedItem flag, which could be redesigned as an ItemFlags if needed (with test performed in ItemAdd)
         ItemSize(total_bb, style.FramePadding.y);
-        if (!ItemAdd(total_bb, id, &frame_bb))
-            return false;
+        if (!(flags & ImGuiInputTextFlags_MergedItem))
+            if (!ItemAdd(total_bb, id, &frame_bb, ImGuiItemAddFlags_Focusable))
+                return false;
     }
     const bool hovered = ItemHoverable(frame_bb, id);
     if (hovered)
@@ -3939,9 +3934,8 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
     // We are only allowed to access the state if we are already the active widget.
     ImGuiInputTextState* state = GetInputTextState(id);
 
-    const bool focus_requested = FocusableItemRegister(window, id);
-    const bool focus_requested_by_code = focus_requested && (g.TabFocusRequestCurrWindow == window && g.TabFocusRequestCurrCounterRegular == window->DC.FocusCounterRegular);
-    const bool focus_requested_by_tab = focus_requested && !focus_requested_by_code;
+    const bool focus_requested_by_code = (window->DC.LastItemStatusFlags & ImGuiItemStatusFlags_FocusedByCode) != 0;
+    const bool focus_requested_by_tabbing = (window->DC.LastItemStatusFlags & ImGuiItemStatusFlags_FocusedByTabbing) != 0;
 
     const bool user_clicked = hovered && io.MouseClicked[0];
     const bool user_nav_input_start = (g.ActiveId != id) && ((g.NavInputId == id) || (g.NavActivateId == id && g.NavInputSource == ImGuiInputSource_Keyboard));
@@ -3954,7 +3948,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
     float scroll_y = is_multiline ? draw_window->Scroll.y : FLT_MAX;
 
     const bool init_changed_specs = (state != NULL && state->Stb.single_line != !is_multiline);
-    const bool init_make_active = (focus_requested || user_clicked || user_scroll_finish || user_nav_input_start);
+    const bool init_make_active = (user_clicked || user_scroll_finish || user_nav_input_start || focus_requested_by_code || focus_requested_by_tabbing);
     const bool init_state = (init_make_active || user_scroll_active);
     if ((init_state && g.ActiveId != id) || init_changed_specs)
     {
@@ -3995,7 +3989,7 @@ bool ImGui::InputTextEx(const char* label, const char* hint, char* buf, int buf_
         }
         if (flags & ImGuiInputTextFlags_AlwaysOverwrite)
             state->Stb.insert_mode = 1; // stb field name is indeed incorrect (see #2863)
-        if (!is_multiline && (focus_requested_by_tab || (user_clicked && io.KeyCtrl)))
+        if (!is_multiline && (focus_requested_by_tabbing || (user_clicked && io.KeyCtrl)))
             select_all = true;
     }