MultiSelect: added ImGuiMultiSelectFlags_SelectOnClickAlways mode. Prevents Drag and Drop of multiple items but allows BoxSelect to always reselect even when clicking inside a selecttion. (#9307, #1861)

docs/CHANGELOG.txt

@@ -53,7 +53,7 @@ Breaking Changes:
       BeginChild("ScrollingRegion", { 0, -footer_height });
    When such idiom was used and assuming zero-height Separator, it is likely that
    in 1.92.7 the resulting window will have unexpected 1 pixel scrolling range.
- - MultiSelect: renamed ImGuiMultiSelectFlags_SelectOnClick to ImGuiMultiSelectFlags_SelectOnAuto.
+ - Multi-Select: renamed ImGuiMultiSelectFlags_SelectOnClick to ImGuiMultiSelectFlags_SelectOnAuto.
    Kept inline redirection enum (will obsolete).
  - Combo(), ListBox(): commented out legacy signatures which were obsoleted in 1.90
    (Nov 2023), when the getter callback type was changed from:
@@ -105,6 +105,10 @@ Other Changes:
     BeginPopupContextItem(), BeginPopupContextWindow() or OpenPopupOnItemClick().
     (#8803, #9270) [@exelix11, @ocornut]
   - Popups: pressing North button (PS4/PS5 triangle, SwitchX, Xbox Y) also open popups menus.
+- Multi-Select:
+  - Added ImGuiMultiSelectFlags_SelectOnClickAlways mode (rarely used).
+    This prevents Drag and Drop of multiple items, but it allows to start a new Box-Selection
+    from inside an existing selection (Excel style). (#9307, #1861)
 - Clipper:
   - Clear `DisplayStart`/`DisplayEnd` fields when `Step()` returns false.
   - Added `UserIndex` helper storage. This is solely a convenience for cases where

imgui.h

@@ -3031,11 +3031,12 @@ enum ImGuiMultiSelectFlags_
     ImGuiMultiSelectFlags_ScopeWindow           = 1 << 11,  // Scope for _BoxSelect and _ClearOnClickVoid is whole window (Default). Use if BeginMultiSelect() covers a whole window or used a single time in same window.
     ImGuiMultiSelectFlags_ScopeRect             = 1 << 12,  // Scope for _BoxSelect and _ClearOnClickVoid is rectangle encompassing BeginMultiSelect()/EndMultiSelect(). Use if BeginMultiSelect() is called multiple times in same window.
     ImGuiMultiSelectFlags_SelectOnAuto          = 1 << 13,  // Apply selection on mouse down when clicking on unselected item, on mouse up when clicking on selected item. (Default)
-    ImGuiMultiSelectFlags_SelectOnClickRelease  = 1 << 14,  // Apply selection on mouse release when clicking an unselected item. Allow dragging an unselected item without altering selection.
+    ImGuiMultiSelectFlags_SelectOnClickAlways   = 1 << 14,  // Apply selection on mouse down when clicking on any items. Prevents Drag and Drop from being used on multiple-selection, but allows e.g. BoxSelect to always reselect even when clicking inside an existing selection. (Excel style behavior)
+    ImGuiMultiSelectFlags_SelectOnClickRelease  = 1 << 15,  // Apply selection on mouse release when clicking an unselected item. Allow dragging an unselected item without altering selection.
     //ImGuiMultiSelectFlags_RangeSelect2d       = 1 << 15,  // Shift+Selection uses 2d geometry instead of linear sequence, so possible to use Shift+up/down to select vertically in grid. Analogous to what BoxSelect does.
     ImGuiMultiSelectFlags_NavWrapX              = 1 << 16,  // [Temporary] Enable navigation wrapping on X axis. Provided as a convenience because we don't have a design for the general Nav API for this yet. When the more general feature be public we may obsolete this flag in favor of new one.
     ImGuiMultiSelectFlags_NoSelectOnRightClick  = 1 << 17,  // Disable default right-click processing, which selects item on mouse down, and is designed for context-menus.
-    ImGuiMultiSelectFlags_SelectOnMask_         = ImGuiMultiSelectFlags_SelectOnAuto | ImGuiMultiSelectFlags_SelectOnClickRelease,
+    ImGuiMultiSelectFlags_SelectOnMask_         = ImGuiMultiSelectFlags_SelectOnAuto | ImGuiMultiSelectFlags_SelectOnClickAlways | ImGuiMultiSelectFlags_SelectOnClickRelease,
 
     // Obsolete names
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS

imgui_demo.cpp

@@ -2632,7 +2632,7 @@ struct ExampleDualListBox
                 }
                 if (child_visible)
                 {
-                    ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_None;
+                    ImGuiMultiSelectFlags flags = ImGuiMultiSelectFlags_BoxSelect1d;
                     ImGuiMultiSelectIO* ms_io = ImGui::BeginMultiSelect(flags, selection.Size, items.Size);
                     ApplySelectionRequests(ms_io, side);
 
@@ -3243,6 +3243,10 @@ static void DemoWindowWidgetsSelectionAndMultiSelect(ImGuiDemoWindowData* demo_d
                     flags &= ~ImGuiMultiSelectFlags_ScopeWindow;
                 if (ImGui::CheckboxFlags("ImGuiMultiSelectFlags_SelectOnAuto", &flags, ImGuiMultiSelectFlags_SelectOnAuto))
                     flags &= ~(ImGuiMultiSelectFlags_SelectOnMask_ ^ ImGuiMultiSelectFlags_SelectOnAuto);
+                ImGui::SameLine(); HelpMarker("Apply selection on mouse down when clicking on unselected item, on mouse up when clicking on selected item. (Default)");
+                if (ImGui::CheckboxFlags("ImGuiMultiSelectFlags_SelectOnClickAlways", &flags, ImGuiMultiSelectFlags_SelectOnClickAlways))
+                    flags &= ~(ImGuiMultiSelectFlags_SelectOnMask_ ^ ImGuiMultiSelectFlags_SelectOnClickAlways);
+                ImGui::SameLine(); HelpMarker("Prevents Drag and Drop from being used on multi-selection, but allows e.g. BoxSelect to always reselect even when clicking inside an existing selection. (Excel style behavior)");
                 if (ImGui::CheckboxFlags("ImGuiMultiSelectFlags_SelectOnClickRelease", &flags, ImGuiMultiSelectFlags_SelectOnClickRelease))
                     flags &= ~(ImGuiMultiSelectFlags_SelectOnMask_ ^ ImGuiMultiSelectFlags_SelectOnClickRelease);
                 ImGui::SameLine(); HelpMarker("Allow dragging an unselected item without altering selection.");
@@ -10716,8 +10720,9 @@ struct ExampleAssetsBrowser
     // Options
     bool            ShowTypeOverlay = true;
     bool            AllowSorting = true;
-    bool            AllowDragUnselected = false;
+    bool            AllowBoxSelect = true;                  // Will set ImGuiMultiSelectFlags_BoxSelect2d
-    bool            AllowBoxSelect = true;
+    bool            AllowBoxSelectInsideSelection = false;  // Will set ImGuiMultiSelectFlags_SelectOnClickAlways
+    bool            AllowDragUnselected = false;            // Will set ImGuiMultiSelectFlags_SelectOnClickRelease
     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.
@@ -10822,8 +10827,11 @@ struct ExampleAssetsBrowser
                 ImGui::Checkbox("Allow Sorting", &AllowSorting);
 
                 ImGui::SeparatorText("Selection Behavior");
-                ImGui::Checkbox("Allow dragging unselected item", &AllowDragUnselected);
                 ImGui::Checkbox("Allow box-selection", &AllowBoxSelect);
+                if (ImGui::Checkbox("Allow box-selection from selected items", &AllowBoxSelectInsideSelection) && AllowBoxSelectInsideSelection)
+                    AllowDragUnselected = false;
+                if (ImGui::Checkbox("Allow dragging unselected item", &AllowDragUnselected) && AllowDragUnselected)
+                    AllowBoxSelectInsideSelection = false;
 
                 ImGui::SeparatorText("Layout");
                 ImGui::SliderFloat("Icon Size", &IconSize, 16.0f, 128.0f, "%.0f");
@@ -10879,9 +10887,11 @@ struct ExampleAssetsBrowser
             if (AllowBoxSelect)
                 ms_flags |= ImGuiMultiSelectFlags_BoxSelect2d;
 
-            // - This feature allows dragging an unselected item without selecting it (rarely used)
+            // - Selection mode
             if (AllowDragUnselected)
-                ms_flags |= ImGuiMultiSelectFlags_SelectOnClickRelease;
+                ms_flags |= ImGuiMultiSelectFlags_SelectOnClickRelease; // Rarely used: Allows dragging an unselected item without selecting it(rarely used)
+            else if (AllowBoxSelectInsideSelection)
+                ms_flags |= ImGuiMultiSelectFlags_SelectOnClickAlways; // Rarely used: Prevents Drag and Drop from being used on multiple-selection, but allows e.g. BoxSelect to always reselect even when clicking inside an existing selection.
 
             // - Enable keyboard wrapping on X axis
             // (FIXME-MULTISELECT: We haven't designed/exposed a general nav wrapping api yet, so this flag is provided as a courtesy to avoid doing:

imgui_widgets.cpp

@@ -8170,10 +8170,13 @@ void ImGui::MultiSelectItemHeader(ImGuiID id, bool* p_selected, ImGuiButtonFlags
     {
         ImGuiButtonFlags button_flags = *p_button_flags;
         button_flags |= ImGuiButtonFlags_NoHoveredOnFocus;
-        if ((!selected || (g.ActiveId == id && g.ActiveIdHasBeenPressedBefore)) && !(ms->Flags & ImGuiMultiSelectFlags_SelectOnClickRelease))
+        button_flags &= ~(ImGuiButtonFlags_PressedOnClickRelease | ImGuiButtonFlags_PressedOnClickRelease);
-            button_flags = (button_flags | ImGuiButtonFlags_PressedOnClick) & ~ImGuiButtonFlags_PressedOnClickRelease;
+        if (ms->Flags & ImGuiMultiSelectFlags_SelectOnClickAlways)
-        else
+            button_flags |= ImGuiButtonFlags_PressedOnClick;
+        else if (ms->Flags & ImGuiMultiSelectFlags_SelectOnClickRelease)
             button_flags |= ImGuiButtonFlags_PressedOnClickRelease;
+        else // ImGuiMultiSelectFlags_SelectOnAuto
+            button_flags |= (!selected || (g.ActiveId == id && g.ActiveIdHasBeenPressedBefore)) ? ImGuiButtonFlags_PressedOnClick : ImGuiButtonFlags_PressedOnClickRelease;
         *p_button_flags = button_flags;
     }
 }