Scrollbar: added io.ConfigScrollbarScrollByPage setting. (#8002, #7328)

docs/CHANGELOG.txt

@@ -43,8 +43,9 @@ Breaking changes:
 
 Other changes:
 
-- Scrollbar: Shift+Click always use absolute positionning scroll (which was the default
-  before 1.90.8). (#8002, #7328)
+- Scrollbar: Shift+Click scroll to clicked location (pre-1.90.8 default). (#8002, #7328)
+- Scrollbar: added io.ConfigScrollbarScrollByPage setting (default to true). (#8002, #7328)
+  Set io.ConfigScrollbarScrollByPage=false to enforce always scrolling to clicked location.
 - Backends: SDL3: Update for API changes: SDL_bool removal. SDL_INIT_TIMER removal.
 
 

imgui.cpp

@@ -1394,6 +1394,7 @@ ImGuiIO::ImGuiIO()
     ConfigDragClickToInputText = false;
     ConfigWindowsResizeFromEdges = true;
     ConfigWindowsMoveFromTitleBarOnly = false;
+    ConfigScrollbarScrollByPage = true;
     ConfigMemoryCompactTimer = 60.0f;
     ConfigDebugIsDebuggerPresent = false;
     ConfigDebugHighlightIdConflicts = true;

imgui.h

@@ -2250,6 +2250,7 @@ struct ImGuiIO
     bool        ConfigDragClickToInputText;     // = false          // [BETA] Enable turning DragXXX widgets into text input with a simple mouse click-release (without moving). Not desirable on devices without a keyboard.
     bool        ConfigWindowsResizeFromEdges;   // = true           // Enable resizing of windows from their edges and from the lower-left corner. This requires (io.BackendFlags & ImGuiBackendFlags_HasMouseCursors) because it needs mouse cursor feedback. (This used to be a per-window ImGuiWindowFlags_ResizeFromAnySide flag)
     bool        ConfigWindowsMoveFromTitleBarOnly; // = false       // Enable allowing to move windows only when clicking on their title bar. Does not apply to windows without a title bar.
+    bool        ConfigScrollbarScrollByPage;    // = true           // Enable scrolling page by page when clicking outside the scrollbar grab. When disabled, always scroll to clicked location. When enabled, Shift+Click scrolls to clicked location.
     float       ConfigMemoryCompactTimer;       // = 60.0f          // Timer (in seconds) to free transient windows/tables memory buffers when unused. Set to -1.0f to disable.
 
     // Inputs Behaviors

imgui_demo.cpp

@@ -539,6 +539,8 @@ void ImGui::ShowDemoWindow(bool* p_open)
             ImGui::Checkbox("io.ConfigWindowsResizeFromEdges", &io.ConfigWindowsResizeFromEdges);
             ImGui::SameLine(); HelpMarker("Enable resizing of windows from their edges and from the lower-left corner.\nThis requires (io.BackendFlags & ImGuiBackendFlags_HasMouseCursors) because it needs mouse cursor feedback.");
             ImGui::Checkbox("io.ConfigWindowsMoveFromTitleBarOnly", &io.ConfigWindowsMoveFromTitleBarOnly);
+            ImGui::Checkbox("io.ConfigScrollbarScrollByPage", &io.ConfigScrollbarScrollByPage);
+            ImGui::SameLine(); HelpMarker("Enable scrolling page by page when clicking outside the scrollbar grab.\nWhen disabled, always scroll to clicked location.\nWhen enabled, Shift+Click scrolls to clicked location.");
             ImGui::Checkbox("io.ConfigMacOSXBehaviors", &io.ConfigMacOSXBehaviors);
             ImGui::SameLine(); HelpMarker("Swap Cmd<>Ctrl keys, enable various MacOS style behaviors.");
             ImGui::Text("Also see Style->Rendering for rendering options.");

imgui_internal.h

@@ -2259,8 +2259,8 @@ struct ImGuiContext
     ImGuiComboPreviewData   ComboPreviewData;
     ImRect                  WindowResizeBorderExpectedRect;     // Expected border rect, switch to relative edit if moving
     bool                    WindowResizeRelativeMode;
-    short                   ScrollbarSeekMode;                  // 0: relative, -1/+1: prev/next page.
-    float                   ScrollbarClickDeltaToGrabCenter;    // Distance between mouse and center of grab box, normalized in parent space. Use storage?
+    short                   ScrollbarSeekMode;                  // 0: scroll to clicked location, -1/+1: prev/next page.
+    float                   ScrollbarClickDeltaToGrabCenter;    // When scrolling to mouse location: distance between mouse and center of grab box, normalized in parent space.
     float                   SliderGrabClickOffset;
     float                   SliderCurrentAccum;                 // Accumulated slider delta when using navigation controls.
     bool                    SliderCurrentAccumDirty;            // Has the accumulated slider delta changed since last time we tried to apply it?

imgui_widgets.cpp

@@ -999,9 +999,10 @@ bool ImGui::ScrollbarEx(const ImRect& bb_frame, ImGuiID id, ImGuiAxis axis, ImS6
         const int held_dir = (clicked_v_norm < grab_v_norm) ? -1 : (clicked_v_norm > grab_v_norm + grab_h_norm) ? +1 : 0;
         if (g.ActiveIdIsJustActivated)
         {
-            // On initial click calculate the distance between mouse and the center of the grab
-            g.ScrollbarSeekMode = g.IO.KeyShift ? 0 : (short)held_dir;
-            g.ScrollbarClickDeltaToGrabCenter = (g.ScrollbarSeekMode == 0 && !g.IO.KeyShift) ? clicked_v_norm - grab_v_norm - grab_h_norm * 0.5f : 0.0f;
+            // On initial click when held_dir == 0 (clicked over grab): calculate the distance between mouse and the center of the grab
+            const bool scroll_to_clicked_location = (g.IO.ConfigScrollbarScrollByPage == false || g.IO.KeyShift || held_dir == 0);
+            g.ScrollbarSeekMode = scroll_to_clicked_location ? 0 : (short)held_dir;
+            g.ScrollbarClickDeltaToGrabCenter = (held_dir == 0 && !g.IO.KeyShift) ? clicked_v_norm - grab_v_norm - grab_h_norm * 0.5f : 0.0f;
         }
 
         // Apply scroll (p_scroll_v will generally point on one member of window->Scroll)