MultiSelect: Box-Select: fixes for checkboxes support. Comments.

imgui.h

@@ -2775,8 +2775,8 @@ enum ImGuiMultiSelectFlags_
     ImGuiMultiSelectFlags_NoRangeSelect         = 1 << 2,   // Disable Shift+Click/Shift+Keyboard handling (useful for unordered 2D selection).
     ImGuiMultiSelectFlags_NoAutoSelect          = 1 << 3,   // Disable selecting items when navigating (useful for e.g. supporting range-select in a list of checkboxes)
     ImGuiMultiSelectFlags_NoAutoClear           = 1 << 4,   // Disable clearing other items when navigating or selecting another one (generally used with ImGuiMultiSelectFlags_NoAutoSelect. useful for e.g. supporting range-select in a list of checkboxes)
-    ImGuiMultiSelectFlags_BoxSelect             = 1 << 5,   // Enable box-selection (only supporting 1D list when using clipper, not 2D grids). Box-selection works better with little bit of spacing between items hit-box in order to be able to aim at empty space.
-    ImGuiMultiSelectFlags_BoxSelect2d           = 1 << 6,   // Enable box-selection with 2D layout/grid support. This alters clipping logic so that e.g. horizontal movements will update selection of normally clipped items.
+    ImGuiMultiSelectFlags_BoxSelect             = 1 << 5,   // Enable box-selection with same width and same x pos items. Box-selection works better with little bit of spacing between items hit-box in order to be able to aim at empty space.
+    ImGuiMultiSelectFlags_BoxSelect2d           = 1 << 6,   // Enable box-selection with varying width or varying x pos items (e.g. different width labels, or 2D layout/grid). This alters clipping logic so that e.g. horizontal movements will update selection of normally clipped items.
     ImGuiMultiSelectFlags_BoxSelectNoScroll     = 1 << 7,   // Disable scrolling when box-selecting near edges of scope.
     ImGuiMultiSelectFlags_ClearOnEscape         = 1 << 8,   // Clear selection when pressing Escape while scope is focused.
     ImGuiMultiSelectFlags_ClearOnClickVoid      = 1 << 9,   // Clear selection when clicking on empty location within scope.

imgui_demo.cpp

@@ -3215,7 +3215,7 @@ static void ShowDemoWindowMultiSelect()
             static ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_NoAutoSelect | ImGuiMultiSelectFlags_NoAutoClear | ImGuiMultiSelectFlags_ClearOnEscape;
             ImGui::CheckboxFlags("ImGuiMultiSelectFlags_NoAutoSelect", &flags, ImGuiMultiSelectFlags_NoAutoSelect);
             ImGui::CheckboxFlags("ImGuiMultiSelectFlags_NoAutoClear", &flags, ImGuiMultiSelectFlags_NoAutoClear);
-            ImGui::CheckboxFlags("ImGuiMultiSelectFlags_BoxSelect", &flags, ImGuiMultiSelectFlags_BoxSelect);
+            ImGui::CheckboxFlags("ImGuiMultiSelectFlags_BoxSelect2d", &flags, ImGuiMultiSelectFlags_BoxSelect2d); // Use 2D version as checkboxes are not same width.
 
             struct Funcs
             {

imgui_widgets.cpp

@@ -1136,10 +1136,11 @@ bool ImGui::Checkbox(const char* label, bool* v)
     ItemSize(total_bb, style.FramePadding.y);
     const bool is_visible = ItemAdd(total_bb, id);
     if (!is_visible)
-    {
-        IMGUI_TEST_ENGINE_ITEM_INFO(id, label, g.LastItemData.StatusFlags | ImGuiItemStatusFlags_Checkable | (*v ? ImGuiItemStatusFlags_Checked : 0));
-        return false;
-    }
+        if (!g.BoxSelectState.UnclipMode || (g.LastItemData.InFlags & ImGuiItemFlags_IsMultiSelect) == 0 || !g.BoxSelectState.UnclipRect.Overlaps(total_bb)) // Extra layer of "no logic clip" for box-select support
+        {
+            IMGUI_TEST_ENGINE_ITEM_INFO(id, label, g.LastItemData.StatusFlags | ImGuiItemStatusFlags_Checkable | (*v ? ImGuiItemStatusFlags_Checked : 0));
+            return false;
+        }
 
     // Range-Selection/Multi-selection support (header)
     bool checked = *v;
@@ -6801,13 +6802,8 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
 
     const bool is_multi_select = (g.LastItemData.InFlags & ImGuiItemFlags_IsMultiSelect) != 0;
     if (!is_visible)
-    {
-        // Extra layer of "no logic clip" for box-select support
-        if (!is_multi_select)
-            return false;
-        if (!g.BoxSelectState.UnclipMode || !g.BoxSelectState.UnclipRect.Overlaps(bb))
+        if (!is_multi_select || !g.BoxSelectState.UnclipMode || !g.BoxSelectState.UnclipRect.Overlaps(bb)) // Extra layer of "no logic clip" for box-select support (would be more overhead to add to ItemAdd)
             return false;
-    }
 
     const bool disabled_global = (g.CurrentItemFlags & ImGuiItemFlags_Disabled) != 0;
     if (disabled_item && !disabled_global) // Only testing this as an optimization
@@ -7242,9 +7238,9 @@ bool ImGui::BeginBoxSelect(ImGuiWindow* window, ImGuiID box_select_id, ImGuiMult
     if (ms_flags & ImGuiMultiSelectFlags_BoxSelect2d)
         if (bs->BoxSelectRectPrev.Min.x != bs->BoxSelectRectCurr.Min.x || bs->BoxSelectRectPrev.Max.x != bs->BoxSelectRectCurr.Max.x)
         {
-            bs->UnclipRect = bs->BoxSelectRectPrev;
-            bs->UnclipRect.Add(bs->BoxSelectRectCurr);
             bs->UnclipMode = true;
+            bs->UnclipRect = bs->BoxSelectRectPrev; // FIXME-OPT: UnclipRect x coordinates could be intersection of Prev and Curr rect on X axis.
+            bs->UnclipRect.Add(bs->BoxSelectRectCurr);
         }
 
     //GetForegroundDrawList()->AddRect(bs->UnclipRect.Min, bs->UnclipRect.Max, IM_COL32(255,0,0,200), 0.0f, 0, 3.0f);