Misc comments + Demo: use IsItemVisible() when using direct ImDrawList calls.

imgui.h

@@ -1340,6 +1340,8 @@ enum ImGuiSortDirection_
     ImGuiSortDirection_Descending   = 2     // Descending = 9->0, Z->A etc.
 };
 
+// Keys value 0 to 511 are left unused as legacy native/opaque key values (< 1.87)
+// Keys value >= 512 are named keys (>= 1.87)
 enum ImGuiKey_
 {
     // Keyboard
@@ -1440,10 +1442,10 @@ enum ImGuiKey_
     ImGuiKey_NamedKey_COUNT         = ImGuiKey_NamedKey_END - ImGuiKey_NamedKey_BEGIN,
 #ifdef IMGUI_DISABLE_OBSOLETE_KEYIO
     ImGuiKey_KeysData_SIZE          = ImGuiKey_NamedKey_COUNT,          // Size of KeysData[]: only hold named keys
-    ImGuiKey_KeysData_OFFSET        = ImGuiKey_NamedKey_BEGIN           // First key stored in KeysData[0]
+    ImGuiKey_KeysData_OFFSET        = ImGuiKey_NamedKey_BEGIN           // First key stored in io.KeysData[0]. Accesses to io.KeysData[] must use (key - ImGuiKey_KeysData_OFFSET).
 #else
     ImGuiKey_KeysData_SIZE          = ImGuiKey_COUNT,                   // Size of KeysData[]: hold legacy 0..512 keycodes + named keys
-    ImGuiKey_KeysData_OFFSET        = 0                                 // First key stored in KeysData[0]
+    ImGuiKey_KeysData_OFFSET        = 0                                 // First key stored in io.KeysData[0]. Accesses to io.KeysData[] must use (key - ImGuiKey_KeysData_OFFSET).
 #endif
 
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
@@ -1462,6 +1464,7 @@ enum ImGuiModFlags_
 };
 
 // Gamepad/Keyboard navigation
+// Since >= 1.87 backends you generally don't need to care about this enum since io.NavInputs[] is setup automatically. This might become private/internal some day.
 // Keyboard: Set io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard to enable. NewFrame() will automatically fill io.NavInputs[] based on your io.AddKeyEvent() calls.
 // Gamepad:  Set io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad to enable. Backend: set ImGuiBackendFlags_HasGamepad and fill the io.NavInputs[] fields before calling NewFrame(). Note that io.NavInputs[] is cleared by EndFrame().
 // Read instructions in imgui.cpp for more details. Download PNG/PSD at http://dearimgui.org/controls_sheets.
@@ -1505,7 +1508,7 @@ enum ImGuiConfigFlags_
     ImGuiConfigFlags_NoMouse                = 1 << 4,   // Instruct imgui to clear mouse position/buttons in NewFrame(). This allows ignoring the mouse information set by the backend.
     ImGuiConfigFlags_NoMouseCursorChange    = 1 << 5,   // Instruct backend to not alter mouse cursor shape and visibility. Use if the backend cursor changes are interfering with yours and you don't want to use SetMouseCursor() to change mouse cursor. You may want to honor requests from imgui by reading GetMouseCursor() yourself instead.
 
-    // User storage (to allow your backend/engine to communicate to code that may be shared between multiple projects. Those flags are not used by core Dear ImGui)
+    // User storage (to allow your backend/engine to communicate to code that may be shared between multiple projects. Those flags are NOT used by core Dear ImGui)
     ImGuiConfigFlags_IsSRGB                 = 1 << 20,  // Application is SRGB-aware.
     ImGuiConfigFlags_IsTouchScreen          = 1 << 21   // Application is using a touch screen instead of a mouse.
 };
@@ -1553,10 +1556,10 @@ enum ImGuiCol_
     ImGuiCol_Separator,
     ImGuiCol_SeparatorHovered,
     ImGuiCol_SeparatorActive,
-    ImGuiCol_ResizeGrip,
+    ImGuiCol_ResizeGrip,            // Resize grip in lower-right and lower-left corners of windows.
     ImGuiCol_ResizeGripHovered,
     ImGuiCol_ResizeGripActive,
-    ImGuiCol_Tab,
+    ImGuiCol_Tab,                   // TabItem in a TabBar
     ImGuiCol_TabHovered,
     ImGuiCol_TabActive,
     ImGuiCol_TabUnfocused,
@@ -1571,7 +1574,7 @@ enum ImGuiCol_
     ImGuiCol_TableRowBg,            // Table row background (even rows)
     ImGuiCol_TableRowBgAlt,         // Table row background (odd rows)
     ImGuiCol_TextSelectedBg,
-    ImGuiCol_DragDropTarget,
+    ImGuiCol_DragDropTarget,        // Rectangle highlighting a drop target
     ImGuiCol_NavHighlight,          // Gamepad/keyboard: current highlighted item
     ImGuiCol_NavWindowingHighlight, // Highlight window when using CTRL+TAB
     ImGuiCol_NavWindowingDimBg,     // Darken/colorize entire screen behind the CTRL+TAB window list, when active

imgui_demo.cpp

@@ -3202,59 +3202,58 @@ static void ShowDemoWindowLayout()
         ImGui::DragFloat2("size", (float*)&size, 0.5f, 1.0f, 200.0f, "%.0f");
         ImGui::TextWrapped("(Click and drag to scroll)");
 
+        HelpMarker(
+            "(Left) Using ImGui::PushClipRect():\n"
+            "Will alter ImGui hit-testing logic + ImDrawList rendering.\n"
+            "(use this if you want your clipping rectangle to affect interactions)\n\n"
+            "(Center) Using ImDrawList::PushClipRect():\n"
+            "Will alter ImDrawList rendering only.\n"
+            "(use this as a shortcut if you are only using ImDrawList calls)\n\n"
+            "(Right) Using ImDrawList::AddText() with a fine ClipRect:\n"
+            "Will alter only this specific ImDrawList::AddText() rendering.\n"
+            "This is often used internally to avoid altering the clipping rectangle and minimize draw calls.");
+
         for (int n = 0; n < 3; n++)
         {
             if (n > 0)
                 ImGui::SameLine();
-            ImGui::PushID(n);
-            ImGui::BeginGroup(); // Lock X position
 
-            ImGui::InvisibleButton("##empty", size);
+            ImGui::PushID(n);
+            ImGui::InvisibleButton("##canvas", size);
             if (ImGui::IsItemActive() && ImGui::IsMouseDragging(ImGuiMouseButton_Left))
             {
                 offset.x += ImGui::GetIO().MouseDelta.x;
                 offset.y += ImGui::GetIO().MouseDelta.y;
             }
+            ImGui::PopID();
+            if (!ImGui::IsItemVisible()) // Skip rendering as ImDrawList elements are not clipped.
+                continue;
+
             const ImVec2 p0 = ImGui::GetItemRectMin();
             const ImVec2 p1 = ImGui::GetItemRectMax();
             const char* text_str = "Line 1 hello\nLine 2 clip me!";
             const ImVec2 text_pos = ImVec2(p0.x + offset.x, p0.y + offset.y);
             ImDrawList* draw_list = ImGui::GetWindowDrawList();
-
             switch (n)
             {
             case 0:
-                HelpMarker(
-                    "Using ImGui::PushClipRect():\n"
-                    "Will alter ImGui hit-testing logic + ImDrawList rendering.\n"
-                    "(use this if you want your clipping rectangle to affect interactions)");
                 ImGui::PushClipRect(p0, p1, true);
                 draw_list->AddRectFilled(p0, p1, IM_COL32(90, 90, 120, 255));
                 draw_list->AddText(text_pos, IM_COL32_WHITE, text_str);
                 ImGui::PopClipRect();
                 break;
             case 1:
-                HelpMarker(
-                    "Using ImDrawList::PushClipRect():\n"
-                    "Will alter ImDrawList rendering only.\n"
-                    "(use this as a shortcut if you are only using ImDrawList calls)");
                 draw_list->PushClipRect(p0, p1, true);
                 draw_list->AddRectFilled(p0, p1, IM_COL32(90, 90, 120, 255));
                 draw_list->AddText(text_pos, IM_COL32_WHITE, text_str);
                 draw_list->PopClipRect();
                 break;
             case 2:
-                HelpMarker(
-                    "Using ImDrawList::AddText() with a fine ClipRect:\n"
-                    "Will alter only this specific ImDrawList::AddText() rendering.\n"
-                    "(this is often used internally to avoid altering the clipping rectangle and minimize draw calls)");
                 ImVec4 clip_rect(p0.x, p0.y, p1.x, p1.y); // AddText() takes a ImVec4* here so let's convert.
                 draw_list->AddRectFilled(p0, p1, IM_COL32(90, 90, 120, 255));
                 draw_list->AddText(ImGui::GetFont(), ImGui::GetFontSize(), text_pos, IM_COL32_WHITE, text_str, NULL, 0.0f, &clip_rect);
                 break;
             }
-            ImGui::EndGroup();
-            ImGui::PopID();
         }
 
         ImGui::TreePop();
@@ -4841,7 +4840,7 @@ static void ShowDemoWindowTables()
                 ImGui::TableSetColumnIndex(1);
                 ImGui::SliderFloat("float1", &dummy_f, 0.0f, 1.0f);
                 ImGui::TableSetColumnIndex(2);
-                ImGui::SliderFloat("float2", &dummy_f, 0.0f, 1.0f);
+                ImGui::SliderFloat("##float2", &dummy_f, 0.0f, 1.0f); // No visible label since right-aligned
                 ImGui::PopID();
             }
             ImGui::EndTable();
@@ -5755,26 +5754,31 @@ static void ShowDemoWindowMisc()
                     { 2, 0, "", ImGuiKey_LeftShift },{ 2, 1, "Z", ImGuiKey_Z }, { 2, 2, "X", ImGuiKey_X }, { 2, 3, "C", ImGuiKey_C }, { 2, 4, "V", ImGuiKey_V }
                 };
 
-                ImDrawList* draw_list = ImGui::GetWindowDrawList();
+                // Elements rendered manually via ImDrawList API are not clipped automatically.
-                draw_list->PushClipRect(board_min, board_max, true);
+                // While not strictly necessary, here IsItemVisible() is used to avoid rendering these shapes when they are out of view.
-                for (int n = 0; n < IM_ARRAYSIZE(keys_to_display); n++)
-                {
-                    const KeyLayoutData* key_data = &keys_to_display[n];
-                    ImVec2 key_min = ImVec2(start_pos.x + key_data->Col * key_step.x + key_data->Row * key_row_offset, start_pos.y + key_data->Row * key_step.y);
-                    ImVec2 key_max = ImVec2(key_min.x + key_size.x, key_min.y + key_size.y);
-                    draw_list->AddRectFilled(key_min, key_max, IM_COL32(204, 204, 204, 255), key_rounding);
-                    draw_list->AddRect(key_min, key_max, IM_COL32(24, 24, 24, 255), key_rounding);
-                    ImVec2 face_min = ImVec2(key_min.x + key_face_pos.x, key_min.y + key_face_pos.y);
-                    ImVec2 face_max = ImVec2(face_min.x + key_face_size.x, face_min.y + key_face_size.y);
-                    draw_list->AddRect(face_min, face_max, IM_COL32(193, 193, 193, 255), key_face_rounding, ImDrawFlags_None, 2.0f);
-                    draw_list->AddRectFilled(face_min, face_max, IM_COL32(252, 252, 252, 255), key_face_rounding);
-                    ImVec2 label_min = ImVec2(key_min.x + key_label_pos.x, key_min.y + key_label_pos.y);
-                    draw_list->AddText(label_min, IM_COL32(64, 64, 64, 255), key_data->Label);
-                    if (ImGui::IsKeyDown(key_data->Key))
-                        draw_list->AddRectFilled(key_min, key_max, IM_COL32(255, 0, 0, 128), key_rounding);
-                }
-                draw_list->PopClipRect();
                 ImGui::Dummy(ImVec2(board_max.x - board_min.x, board_max.y - board_min.y));
+                if (ImGui::IsItemVisible())
+                {
+                    ImDrawList* draw_list = ImGui::GetWindowDrawList();
+                    draw_list->PushClipRect(board_min, board_max, true);
+                    for (int n = 0; n < IM_ARRAYSIZE(keys_to_display); n++)
+                    {
+                        const KeyLayoutData* key_data = &keys_to_display[n];
+                        ImVec2 key_min = ImVec2(start_pos.x + key_data->Col * key_step.x + key_data->Row * key_row_offset, start_pos.y + key_data->Row * key_step.y);
+                        ImVec2 key_max = ImVec2(key_min.x + key_size.x, key_min.y + key_size.y);
+                        draw_list->AddRectFilled(key_min, key_max, IM_COL32(204, 204, 204, 255), key_rounding);
+                        draw_list->AddRect(key_min, key_max, IM_COL32(24, 24, 24, 255), key_rounding);
+                        ImVec2 face_min = ImVec2(key_min.x + key_face_pos.x, key_min.y + key_face_pos.y);
+                        ImVec2 face_max = ImVec2(face_min.x + key_face_size.x, face_min.y + key_face_size.y);
+                        draw_list->AddRect(face_min, face_max, IM_COL32(193, 193, 193, 255), key_face_rounding, ImDrawFlags_None, 2.0f);
+                        draw_list->AddRectFilled(face_min, face_max, IM_COL32(252, 252, 252, 255), key_face_rounding);
+                        ImVec2 label_min = ImVec2(key_min.x + key_label_pos.x, key_min.y + key_label_pos.y);
+                        draw_list->AddText(label_min, IM_COL32(64, 64, 64, 255), key_data->Label);
+                        if (ImGui::IsKeyDown(key_data->Key))
+                            draw_list->AddRectFilled(key_min, key_max, IM_COL32(255, 0, 0, 128), key_rounding);
+                    }
+                    draw_list->PopClipRect();
+                }
             }
             ImGui::TreePop();
         }

imgui_widgets.cpp

@@ -6887,7 +6887,7 @@ bool ImGui::BeginMenuEx(const char* label, const char* icon, bool enabled)
     bool menu_is_open = IsPopupOpen(id, ImGuiPopupFlags_None);
 
     // Sub-menus are ChildWindow so that mouse can be hovering across them (otherwise top-most popup menu would steal focus and not allow hovering on parent menu)
-    // The first menu in a hierarchy isn't so hovering doesn't get accross (otherwise e.g. resizing borders with ImGuiButtonFlags_FlattenChildren would react), but top-most BeginMenu() will bypass that limitation.
+    // The first menu in a hierarchy isn't so hovering doesn't get across (otherwise e.g. resizing borders with ImGuiButtonFlags_FlattenChildren would react), but top-most BeginMenu() will bypass that limitation.
     ImGuiWindowFlags flags = ImGuiWindowFlags_ChildMenu | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoNavFocus;
     if (window->Flags & ImGuiWindowFlags_ChildMenu)
         flags |= ImGuiWindowFlags_ChildWindow;