MultiSelect: Box-Select: Added ImGuiMultiSelectFlags_BoxSelect2d support. Enabled in Asset Browser. Selectable() supports it.

imgui.cpp

@@ -3091,6 +3091,10 @@ static bool ImGuiListClipper_StepInternal(ImGuiListClipper* clipper)
                     // As a workaround we currently half ItemSpacing worth on each side.
                     min_y -= g.Style.ItemSpacing.y;
                     max_y += g.Style.ItemSpacing.y;
+
+                    // Box-select on 2D area requires different clipping.
+                    if (ms->BoxSelectUnclipMode)
+                        data->Ranges.push_back(ImGuiListClipperRange::FromPositions(ms->BoxSelectUnclipRect.Min.y, ms->BoxSelectUnclipRect.Max.y, 0, 0));
                 }
 
             const int off_min = (is_nav_request && g.NavMoveClipDir == ImGuiDir_Up) ? -1 : 0;

imgui.h

@@ -2774,14 +2774,15 @@ enum ImGuiMultiSelectFlags_
     ImGuiMultiSelectFlags_None                  = 0,
     ImGuiMultiSelectFlags_SingleSelect          = 1 << 0,   // Disable selecting more than one item. This is available to allow single-selection code to share same code/logic if desired. It essentially disables the main purpose of BeginMultiSelect() tho!
     ImGuiMultiSelectFlags_NoSelectAll           = 1 << 1,   // Disable CTRL+A shortcut sending a SelectAll request.
-    ImGuiMultiSelectFlags_BoxSelect             = 1 << 2,   // Enable box-selection. Box-selection + clipper is currently only supported for 1D list (not with 2D grid). Box-selection works better with little bit of spacing between items hit-box in order to be able to aim at empty space.
-    ImGuiMultiSelectFlags_BoxSelectNoScroll     = 1 << 3,   // Disable scrolling when box-selecting near edges of scope.
-    ImGuiMultiSelectFlags_ClearOnEscape         = 1 << 4,   // Clear selection when pressing Escape while scope is focused.
-    ImGuiMultiSelectFlags_ClearOnClickVoid      = 1 << 5,   // Clear selection when clicking on empty location within scope.
-    ImGuiMultiSelectFlags_ScopeWindow           = 1 << 6,   // Scope for _ClearOnClickVoid and _BoxSelect is whole window (Default). Use if BeginMultiSelect() covers a whole window.
-    ImGuiMultiSelectFlags_ScopeRect             = 1 << 7,   // Scope for _ClearOnClickVoid and _BoxSelect is rectangle covering submitted items. Use if multiple BeginMultiSelect() are used in the same host window.
-    ImGuiMultiSelectFlags_SelectOnClick         = 1 << 8,   // Apply selection on mouse down when clicking on unselected item. (Default)
-    ImGuiMultiSelectFlags_SelectOnClickRelease  = 1 << 9,   // Apply selection on mouse release when clicking an unselected item. Allow dragging an unselected item without altering selection.
+    ImGuiMultiSelectFlags_BoxSelect             = 1 << 2,   // 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 << 3,   // 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_BoxSelectNoScroll     = 1 << 4,   // Disable scrolling when box-selecting near edges of scope.
+    ImGuiMultiSelectFlags_ClearOnEscape         = 1 << 5,   // Clear selection when pressing Escape while scope is focused.
+    ImGuiMultiSelectFlags_ClearOnClickVoid      = 1 << 6,   // Clear selection when clicking on empty location within scope.
+    ImGuiMultiSelectFlags_ScopeWindow           = 1 << 7,   // Scope for _ClearOnClickVoid and _BoxSelect is whole window (Default). Use if BeginMultiSelect() covers a whole window.
+    ImGuiMultiSelectFlags_ScopeRect             = 1 << 8,   // Scope for _ClearOnClickVoid and _BoxSelect is rectangle covering submitted items. Use if multiple BeginMultiSelect() are used in the same host window.
+    ImGuiMultiSelectFlags_SelectOnClick         = 1 << 9,   // Apply selection on mouse down when clicking on unselected item. (Default)
+    ImGuiMultiSelectFlags_SelectOnClickRelease  = 1 << 10,  // Apply selection on mouse release when clicking an unselected item. Allow dragging an unselected item without altering selection.
 };
 
 enum ImGuiSelectionRequestType

imgui_demo.cpp

@@ -9622,7 +9622,7 @@ struct ExampleAssetsBrowser
     // Options
     bool            ShowTypeOverlay = true;
     bool            AllowDragUnselected = false;
-    bool            AllowBoxSelect = false;     // Unsupported for 2D selection for now.
+    bool            AllowBoxSelect = true;
     float           IconSize = 32.0f;
     int             IconSpacing = 10;
     int             IconHitSpacing = 4;         // Increase hit-spacing if you want to make it possible to clear or box-select from gaps. Some spacing is required to able to amend with Shift+box-select. Value is small in Explorer.
@@ -9726,9 +9726,7 @@ struct ExampleAssetsBrowser
 
                 ImGui::SeparatorText("Selection Behavior");
                 ImGui::Checkbox("Allow dragging unselected item", &AllowDragUnselected);
-                ImGui::BeginDisabled(); // Unsupported for 2D selection for now.
                 ImGui::Checkbox("Allow box-selection", &AllowBoxSelect);
-                ImGui::EndDisabled();
 
                 ImGui::SeparatorText("Layout");
                 ImGui::SliderFloat("Icon Size", &IconSize, 16.0f, 128.0f, "%.0f");
@@ -9778,7 +9776,7 @@ struct ExampleAssetsBrowser
             if (AllowDragUnselected)
                 ms_flags |= ImGuiMultiSelectFlags_SelectOnClickRelease; // To allow dragging an unselected item without altering selection.
             if (AllowBoxSelect)
-                ms_flags |= ImGuiMultiSelectFlags_BoxSelect; // FIXME-MULTISELECT: Box-select not yet supported for 2D selection when using clipper.
+                ms_flags |= ImGuiMultiSelectFlags_BoxSelect2d; // Enable box-select in 2D mode.
             ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(ms_flags);
 
             // Use custom selection adapter: store ID in selection (recommended)
@@ -9798,7 +9796,6 @@ struct ExampleAssetsBrowser
             ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(LayoutSelectableSpacing, LayoutSelectableSpacing));
 
             // Rendering parameters
-            const ImU32 icon_bg_color = IM_COL32(48, 48, 48, 128);
             const ImU32 icon_type_overlay_colors[3] = { 0, IM_COL32(200, 70, 70, 255), IM_COL32(70, 170, 70, 255) };
             const ImVec2 icon_type_overlay_size = ImVec2(4.0f, 4.0f);
             const bool display_label = (LayoutItemSize.x >= ImGui::CalcTextSize("999").x);
@@ -9825,13 +9822,9 @@ struct ExampleAssetsBrowser
                         ImVec2 pos = ImVec2(start_pos.x + (item_idx % column_count) * LayoutItemStep.x, start_pos.y + line_idx * LayoutItemStep.y);
                         ImGui::SetCursorScreenPos(pos);
 
-                        // Draw box
-                        ImVec2 box_min(pos.x - 1, pos.y - 1);
-                        ImVec2 box_max(box_min.x + LayoutItemSize.x + 2, box_min.y + LayoutItemSize.y + 2);
-                        draw_list->AddRect(box_min, box_max, IM_COL32(90, 90, 90, 255));
-
                         ImGui::SetNextItemSelectionUserData(item_idx);
                         bool item_is_selected = Selection.Contains((ImGuiID)item_data->ID);
+                        bool item_is_visible = ImGui::IsRectVisible(LayoutItemSize);
                         ImGui::Selectable("", item_is_selected, ImGuiSelectableFlags_None, LayoutItemSize);
 
                         // Update our selection state immediately (without waiting for EndMultiSelect() requests)
@@ -9856,19 +9849,26 @@ struct ExampleAssetsBrowser
                             ImGui::EndDragDropSource();
                         }
 
-                        // A real app would likely display an image/thumbnail here.
-                        draw_list->AddRectFilled(box_min, box_max, icon_bg_color);
-                        if (ShowTypeOverlay && item_data->Type != 0)
-                        {
-                            ImU32 type_col = icon_type_overlay_colors[item_data->Type % IM_ARRAYSIZE(icon_type_overlay_colors)];
-                            draw_list->AddRectFilled(ImVec2(box_max.x - 2 - icon_type_overlay_size.x, box_min.y + 2), ImVec2(box_max.x - 2, box_min.y + 2 + icon_type_overlay_size.y), type_col);
-                        }
-                        if (display_label)
+                        // Render icon (a real app would likely display an image/thumbnail here)
+                        // Because we use ImGuiMultiSelectFlags_BoxSelect2d mode,
+                        // clipping vertical range may occasionally be larger so we coarse-clip our rendering.
+                        if (item_is_visible)
                         {
-                            ImU32 label_col = item_is_selected ? IM_COL32(255, 255, 255, 255) : ImGui::GetColorU32(ImGuiCol_TextDisabled);
-                            char label[32];
-                            sprintf(label, "%d", item_data->ID);
-                            draw_list->AddText(ImVec2(box_min.x, box_max.y - ImGui::GetFontSize()), label_col, label);
+                            ImVec2 box_min(pos.x - 1, pos.y - 1);
+                            ImVec2 box_max(box_min.x + LayoutItemSize.x + 2, box_min.y + LayoutItemSize.y + 2); // Dubious
+                            draw_list->AddRectFilled(box_min, box_max, IM_COL32(48, 48, 48, 200)); // Background color
+                            if (ShowTypeOverlay && item_data->Type != 0)
+                            {
+                                ImU32 type_col = icon_type_overlay_colors[item_data->Type % IM_ARRAYSIZE(icon_type_overlay_colors)];
+                                draw_list->AddRectFilled(ImVec2(box_max.x - 2 - icon_type_overlay_size.x, box_min.y + 2), ImVec2(box_max.x - 2, box_min.y + 2 + icon_type_overlay_size.y), type_col);
+                            }
+                            if (display_label)
+                            {
+                                ImU32 label_col = item_is_selected ? IM_COL32(255, 255, 255, 255) : ImGui::GetColorU32(ImGuiCol_TextDisabled);
+                                char label[32];
+                                sprintf(label, "%d", item_data->ID);
+                                draw_list->AddText(ImVec2(box_min.x, box_max.y - ImGui::GetFontSize()), label_col, label);
+                            }
                         }
 
                         ImGui::PopID();
@@ -9893,7 +9893,8 @@ struct ExampleAssetsBrowser
             if (want_delete)
                 Selection.ApplyDeletionPostLoop(ms_io, Items, item_curr_idx_to_focus);
 
-            // FIXME-MULTISELECT: Find a way to expose this in public API. This currently requires "imgui_internal.h"
+            // Keyboard/Gamepad Wrapping
+            // FIXME-MULTISELECT: Currently an imgui_internal.h API. Find a design/way to expose this in public API.
             //ImGui::NavMoveRequestTryWrapping(ImGui::GetCurrentWindow(), ImGuiNavMoveFlags_WrapX);
 
             // Zooming with CTRL+Wheel

imgui_internal.h

@@ -1726,8 +1726,10 @@ struct IMGUI_API ImGuiMultiSelectTempData
     ImGuiID                 BoxSelectId;
     ImRect                  BoxSelectRectPrev;
     ImRect                  BoxSelectRectCurr;  // Selection rectangle in absolute coordinates (derived every frame from Storage->BoxSelectStartPosRel + MousePos)
+    ImRect                  BoxSelectUnclipRect;// Rectangle where ItemAdd() clipping may be temporarily disabled. Need support by multi-select supporting widgets.
     ImGuiSelectionUserData  BoxSelectLastitem;
     ImGuiKeyChord           KeyMods;
+    bool                    BoxSelectUnclipMode;
     bool                    LoopRequestClear;
     bool                    LoopRequestSelectAll;
     bool                    IsEndIO;            // Set when switching IO from BeginMultiSelect() to EndMultiSelect() state.

imgui_widgets.cpp

@@ -6775,7 +6775,7 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
 
     const bool disabled_item = (flags & ImGuiSelectableFlags_Disabled) != 0;
     const bool is_multi_select = (g.NextItemData.ItemFlags & ImGuiItemFlags_IsMultiSelect) != 0; // Before ItemAdd()
-    const bool item_add = ItemAdd(bb, id, NULL, disabled_item ? (ImGuiItemFlags)ImGuiItemFlags_Disabled : ImGuiItemFlags_None);
+    const bool is_visible = ItemAdd(bb, id, NULL, disabled_item ? (ImGuiItemFlags)ImGuiItemFlags_Disabled : ImGuiItemFlags_None);
 
     if (span_all_columns)
     {
@@ -6783,8 +6783,14 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
         window->ClipRect.Max.x = backup_clip_rect_max_x;
     }
 
-    if (!item_add)
-        return false;
+    if (!is_visible)
+    {
+        if (!is_multi_select)
+            return false;
+        // Extra layer of "no logic clip" for box-select support
+        if (!g.CurrentMultiSelect->BoxSelectUnclipMode || !g.CurrentMultiSelect->BoxSelectUnclipRect.Overlaps(bb))
+            return false;
+    }
 
     const bool disabled_global = (g.CurrentItemFlags & ImGuiItemFlags_Disabled) != 0;
     if (disabled_item && !disabled_global) // Only testing this as an optimization
@@ -6857,22 +6863,25 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
         g.LastItemData.StatusFlags |= ImGuiItemStatusFlags_ToggledSelection;
 
     // Render
-    if (hovered || selected)
-    {
-        // FIXME-MULTISELECT: Styling: Color for 'selected' elements? ImGuiCol_HeaderSelected
-        ImU32 col;
-        if (selected && !hovered)
-            col = GetColorU32(ImLerp(GetStyleColorVec4(ImGuiCol_Header), GetStyleColorVec4(ImGuiCol_HeaderHovered), 0.5f));
-        else
-            col = GetColorU32((held && hovered) ? ImGuiCol_HeaderActive : hovered ? ImGuiCol_HeaderHovered : ImGuiCol_Header);
-        RenderFrame(bb.Min, bb.Max, col, false, 0.0f);
-    }
-    if (g.NavId == id)
+    if (is_visible)
     {
-        ImGuiNavHighlightFlags nav_highlight_flags = ImGuiNavHighlightFlags_Compact | ImGuiNavHighlightFlags_NoRounding;
-        if (is_multi_select)
-            nav_highlight_flags |= ImGuiNavHighlightFlags_AlwaysDraw; // Always show the nav rectangle
-        RenderNavHighlight(bb, id, nav_highlight_flags);
+        if (hovered || selected)
+        {
+            // FIXME-MULTISELECT: Styling: Color for 'selected' elements? ImGuiCol_HeaderSelected
+            ImU32 col;
+            if (selected && !hovered)
+                col = GetColorU32(ImLerp(GetStyleColorVec4(ImGuiCol_Header), GetStyleColorVec4(ImGuiCol_HeaderHovered), 0.5f));
+            else
+                col = GetColorU32((held && hovered) ? ImGuiCol_HeaderActive : hovered ? ImGuiCol_HeaderHovered : ImGuiCol_Header);
+            RenderFrame(bb.Min, bb.Max, col, false, 0.0f);
+        }
+        if (g.NavId == id)
+        {
+            ImGuiNavHighlightFlags nav_highlight_flags = ImGuiNavHighlightFlags_Compact | ImGuiNavHighlightFlags_NoRounding;
+            if (is_multi_select)
+                nav_highlight_flags |= ImGuiNavHighlightFlags_AlwaysDraw; // Always show the nav rectangle
+            RenderNavHighlight(bb, id, nav_highlight_flags);
+        }
     }
 
     if (span_all_columns)
@@ -6883,7 +6892,8 @@ bool ImGui::Selectable(const char* label, bool selected, ImGuiSelectableFlags fl
             PopColumnsBackground();
     }
 
-    RenderTextClipped(text_min, text_max, label, NULL, &label_size, style.SelectableTextAlign, &bb);
+    if (is_visible)
+        RenderTextClipped(text_min, text_max, label, NULL, &label_size, style.SelectableTextAlign, &bb);
 
     // Automatically close popups
     if (pressed && (window->Flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiSelectableFlags_NoAutoClosePopups) && (g.LastItemData.InFlags & ImGuiItemFlags_AutoClosePopups))
@@ -7169,7 +7179,9 @@ ImGuiMultiSelectIO* ImGui::BeginMultiSelect(ImGuiMultiSelectFlags flags)
     if ((flags & (ImGuiMultiSelectFlags_ScopeWindow | ImGuiMultiSelectFlags_ScopeRect)) == 0)
         flags |= ImGuiMultiSelectFlags_ScopeWindow;
     if (flags & ImGuiMultiSelectFlags_SingleSelect)
-        flags &= ~ImGuiMultiSelectFlags_BoxSelect;
+        flags &= ~(ImGuiMultiSelectFlags_BoxSelect | ImGuiMultiSelectFlags_BoxSelect2d);
+    if (flags & ImGuiMultiSelectFlags_BoxSelect2d)
+        flags |= ImGuiMultiSelectFlags_BoxSelect;
 
     // FIXME: BeginFocusScope()
     const ImGuiID id = window->IDStack.back();
@@ -7233,6 +7245,7 @@ ImGuiMultiSelectIO* ImGui::BeginMultiSelect(ImGuiMultiSelectFlags flags)
     }
 
     // Box-select handling: update active state.
+    ms->BoxSelectUnclipMode = false;
     if (flags & ImGuiMultiSelectFlags_BoxSelect)
     {
         ms->BoxSelectId = GetID("##BoxSelect");
@@ -7267,6 +7280,18 @@ ImGuiMultiSelectIO* ImGui::BeginMultiSelect(ImGuiMultiSelectFlags flags)
             ms->BoxSelectRectPrev.Max = ImMax(start_pos_abs, prev_end_pos_abs);
             ms->BoxSelectRectCurr.Min = ImMin(start_pos_abs, curr_end_pos_abs);
             ms->BoxSelectRectCurr.Max = ImMax(start_pos_abs, curr_end_pos_abs);
+
+            // Box-select 2D mode detects horizontal changes (vertical ones are already picked by Clipper)
+            // Storing an extra rect used by widgets supporting box-select.
+            if (flags & ImGuiMultiSelectFlags_BoxSelect2d)
+                if (ms->BoxSelectRectPrev.Min.x != ms->BoxSelectRectCurr.Min.x || ms->BoxSelectRectPrev.Max.x != ms->BoxSelectRectCurr.Max.x)
+                {
+                    ms->BoxSelectUnclipRect = ms->BoxSelectRectPrev;
+                    ms->BoxSelectUnclipRect.Add(ms->BoxSelectRectCurr);
+                    ms->BoxSelectUnclipMode = true;
+                }
+
+            //GetForegroundDrawList()->AddRect(ms->BoxSelectNoClipRect.Min, ms->BoxSelectNoClipRect.Max, IM_COL32(255,0,0,200), 0.0f, 0, 3.0f);
             //GetForegroundDrawList()->AddRect(ms->BoxSelectRectPrev.Min, ms->BoxSelectRectPrev.Max, IM_COL32(255,0,0,200), 0.0f, 0, 3.0f);
             //GetForegroundDrawList()->AddRect(ms->BoxSelectRectCurr.Min, ms->BoxSelectRectCurr.Max, IM_COL32(0,255,0,200), 0.0f, 0, 1.0f);
         }