Scrollbar, Style: added style.ScrollbarPadding, ImGuiStyleVar_ScrollbarPadding. (#8895)

docs/CHANGELOG.txt

@@ -43,6 +43,8 @@ Breaking Changes:
 
 Other Changes:
 
+- Scrollbar, Style: added configurable style.ScrollbarPadding value and corresponding
+  ImGuiStyleVar_ScrollbarPadding enum, instead of hardcoded computed default. (#8895)
 - DrawList: Fixed CloneOutput() unnecessarily taking a copy of the ImDrawListSharedData
   pointer, which could to issue when deleting the cloned list. (#8894, #1860)
 - Examples: Android: Android+OpenGL3: update Gradle project (#8888, #8878) [@scribam]

imgui.cpp

@@ -1413,6 +1413,7 @@ ImGuiStyle::ImGuiStyle()
     ColumnsMinSpacing           = 6.0f;             // Minimum horizontal spacing between two columns. Preferably > (FramePadding.x + 1).
     ScrollbarSize               = 14.0f;            // Width of the vertical scrollbar, Height of the horizontal scrollbar
     ScrollbarRounding           = 9.0f;             // Radius of grab corners rounding for scrollbar
+    ScrollbarPadding            = 2.0f;             // Padding of scrollbar grab within its frame (same for both axises)
     GrabMinSize                 = 12.0f;            // Minimum width/height of a grab box for slider/scrollbar
     GrabRounding                = 0.0f;             // Radius of grabs corners rounding. Set to 0.0f to have rectangular slider grabs.
     LogSliderDeadzone           = 4.0f;             // The size in pixels of the dead-zone around zero on logarithmic sliders that cross zero.
@@ -1482,6 +1483,7 @@ void ImGuiStyle::ScaleAllSizes(float scale_factor)
     ColumnsMinSpacing = ImTrunc(ColumnsMinSpacing * scale_factor);
     ScrollbarSize = ImTrunc(ScrollbarSize * scale_factor);
     ScrollbarRounding = ImTrunc(ScrollbarRounding * scale_factor);
+    ScrollbarPadding = ImTrunc(ScrollbarPadding * scale_factor);
     GrabMinSize = ImTrunc(GrabMinSize * scale_factor);
     GrabRounding = ImTrunc(GrabRounding * scale_factor);
     LogSliderDeadzone = ImTrunc(LogSliderDeadzone * scale_factor);
@@ -3503,6 +3505,7 @@ static const ImGuiStyleVarInfo GStyleVarsInfo[] =
     { 2, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, CellPadding) },               // ImGuiStyleVar_CellPadding
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, ScrollbarSize) },             // ImGuiStyleVar_ScrollbarSize
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, ScrollbarRounding) },         // ImGuiStyleVar_ScrollbarRounding
+    { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, ScrollbarPadding) },          // ImGuiStyleVar_ScrollbarPadding
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, GrabMinSize) },               // ImGuiStyleVar_GrabMinSize
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, GrabRounding) },              // ImGuiStyleVar_GrabRounding
     { 1, ImGuiDataType_Float, (ImU32)offsetof(ImGuiStyle, ImageBorderSize) },           // ImGuiStyleVar_ImageBorderSize

imgui.h

@@ -1805,6 +1805,7 @@ enum ImGuiStyleVar_
     ImGuiStyleVar_CellPadding,              // ImVec2    CellPadding
     ImGuiStyleVar_ScrollbarSize,            // float     ScrollbarSize
     ImGuiStyleVar_ScrollbarRounding,        // float     ScrollbarRounding
+    ImGuiStyleVar_ScrollbarPadding,         // float     ScrollbarPadding
     ImGuiStyleVar_GrabMinSize,              // float     GrabMinSize
     ImGuiStyleVar_GrabRounding,             // float     GrabRounding
     ImGuiStyleVar_ImageBorderSize,          // float     ImageBorderSize
@@ -2271,6 +2272,7 @@ struct ImGuiStyle
     float       ColumnsMinSpacing;          // Minimum horizontal spacing between two columns. Preferably > (FramePadding.x + 1).
     float       ScrollbarSize;              // Width of the vertical scrollbar, Height of the horizontal scrollbar.
     float       ScrollbarRounding;          // Radius of grab corners for scrollbar.
+    float       ScrollbarPadding;           // Padding of scrollbar grab within its frame (same for both axises).
     float       GrabMinSize;                // Minimum width/height of a grab box for slider/scrollbar.
     float       GrabRounding;               // Radius of grabs corners rounding. Set to 0.0f to have rectangular slider grabs.
     float       LogSliderDeadzone;          // The size in pixels of the dead-zone around zero on logarithmic sliders that cross zero.

imgui_demo.cpp

@@ -8325,7 +8325,6 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
             SliderFloat2("ItemInnerSpacing", (float*)&style.ItemInnerSpacing, 0.0f, 20.0f, "%.0f");
             SliderFloat2("TouchExtraPadding", (float*)&style.TouchExtraPadding, 0.0f, 10.0f, "%.0f");
             SliderFloat("IndentSpacing", &style.IndentSpacing, 0.0f, 30.0f, "%.0f");
-            SliderFloat("ScrollbarSize", &style.ScrollbarSize, 1.0f, 20.0f, "%.0f");
             SliderFloat("GrabMinSize", &style.GrabMinSize, 1.0f, 20.0f, "%.0f");
 
             SeparatorText("Borders");
@@ -8339,9 +8338,13 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
             SliderFloat("ChildRounding", &style.ChildRounding, 0.0f, 12.0f, "%.0f");
             SliderFloat("FrameRounding", &style.FrameRounding, 0.0f, 12.0f, "%.0f");
             SliderFloat("PopupRounding", &style.PopupRounding, 0.0f, 12.0f, "%.0f");
-            SliderFloat("ScrollbarRounding", &style.ScrollbarRounding, 0.0f, 12.0f, "%.0f");
             SliderFloat("GrabRounding", &style.GrabRounding, 0.0f, 12.0f, "%.0f");
 
+            SeparatorText("Scrollbar");
+            SliderFloat("ScrollbarSize", &style.ScrollbarSize, 1.0f, 20.0f, "%.0f");
+            SliderFloat("ScrollbarRounding", &style.ScrollbarRounding, 0.0f, 12.0f, "%.0f");
+            SliderFloat("ScrollbarPadding", &style.ScrollbarPadding, 0.0f, 10.0f, "%.0f");
+
             SeparatorText("Tabs");
             SliderFloat("TabBorderSize", &style.TabBorderSize, 0.0f, 1.0f, "%.0f");
             SliderFloat("TabBarBorderSize", &style.TabBarBorderSize, 0.0f, 2.0f, "%.0f");

imgui_widgets.cpp

@@ -1026,7 +1026,8 @@ bool ImGui::ScrollbarEx(const ImRect& bb_frame, ImGuiID id, ImGuiAxis axis, ImS6
     const bool allow_interaction = (alpha >= 1.0f);
 
     ImRect bb = bb_frame;
-    bb.Expand(ImVec2(-ImClamp(IM_TRUNC((bb_frame_width - 2.0f) * 0.5f), 0.0f, 3.0f), -ImClamp(IM_TRUNC((bb_frame_height - 2.0f) * 0.5f), 0.0f, 3.0f)));
+    float padding = IM_TRUNC(ImMin(style.ScrollbarPadding, ImMin(bb_frame_width, bb_frame_height) * 0.5f));
+    bb.Expand(-padding);
 
     // V denote the main, longer axis of the scrollbar (= height for a vertical scrollbar)
     const float scrollbar_size_v = (axis == ImGuiAxis_X) ? bb.GetWidth() : bb.GetHeight();