Scrolling: Fix scroll tracking with e.g. SetScrollHereX/Y() when WindowPadding < ItemSpacing. Fix scroll snapping on edge of scroll region when both scrollbars are enabled.

CalcNextScrollFromScrollTargetAndClamp() fixed snapping edge calculation missing ScrollbarSizes.y

docs/CHANGELOG.txt

@@ -39,6 +39,8 @@ Breaking Changes:
 
 Other Changes:
 
+- Scrolling: Fix scroll tracking with e.g. SetScrollHereX/Y() when WindowPadding < ItemSpacing.
+- Scrolling: Fix scroll snapping on edge of scroll region when both scrollbars are enabled.
 - Drags, Sliders, Inputs: Specifying a NULL format to Float functions default them to "%.3f" to be
   consistent with the compile-time default. (#3922)
 - DragScalar: Add default value for v_speed argument to match higher-level functions. (#3922) [@eliasdaler]

imgui.cpp

@@ -5172,8 +5172,9 @@ static ImVec2 CalcWindowSizeAfterConstraint(ImGuiWindow* window, const ImVec2& s
     if (!(window->Flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_AlwaysAutoResize)))
     {
         ImGuiWindow* window_for_height = window;
+        const float decoration_up_height = window_for_height->TitleBarHeight() + window_for_height->MenuBarHeight();
         new_size = ImMax(new_size, g.Style.WindowMinSize);
-        new_size.y = ImMax(new_size.y, window_for_height->TitleBarHeight() + window_for_height->MenuBarHeight() + ImMax(0.0f, g.Style.WindowRounding - 1.0f)); // Reduce artifacts with very small windows
+        new_size.y = ImMax(new_size.y, decoration_up_height + ImMax(0.0f, g.Style.WindowRounding - 1.0f)); // Reduce artifacts with very small windows
     }
     return new_size;
 }
@@ -5202,9 +5203,9 @@ static ImVec2 CalcWindowAutoFitSize(ImGuiWindow* window, const ImVec2& size_cont
 {
     ImGuiContext& g = *GImGui;
     ImGuiStyle& style = g.Style;
-    ImVec2 size_decorations = ImVec2(0.0f, window->TitleBarHeight() + window->MenuBarHeight());
+    const float decoration_up_height = window->TitleBarHeight() + window->MenuBarHeight();
     ImVec2 size_pad = window->WindowPadding * 2.0f;
-    ImVec2 size_desired = size_contents + size_pad + size_decorations;
+    ImVec2 size_desired = size_contents + size_pad + ImVec2(0.0f, decoration_up_height);
     if (window->Flags & ImGuiWindowFlags_Tooltip)
     {
         // Tooltip always resize
@@ -5226,8 +5227,8 @@ static ImVec2 CalcWindowAutoFitSize(ImGuiWindow* window, const ImVec2& size_cont
         // When the window cannot fit all contents (either because of constraints, either because screen is too small),
         // we are growing the size on the other axis to compensate for expected scrollbar. FIXME: Might turn bigger than ViewportSize-WindowPadding.
         ImVec2 size_auto_fit_after_constraint = CalcWindowSizeAfterConstraint(window, size_auto_fit);
-        bool will_have_scrollbar_x = (size_auto_fit_after_constraint.x - size_pad.x - size_decorations.x < size_contents.x && !(window->Flags & ImGuiWindowFlags_NoScrollbar) && (window->Flags & ImGuiWindowFlags_HorizontalScrollbar)) || (window->Flags & ImGuiWindowFlags_AlwaysHorizontalScrollbar);
+        bool will_have_scrollbar_x = (size_auto_fit_after_constraint.x - size_pad.x - 0.0f                 < size_contents.x && !(window->Flags & ImGuiWindowFlags_NoScrollbar) && (window->Flags & ImGuiWindowFlags_HorizontalScrollbar)) || (window->Flags & ImGuiWindowFlags_AlwaysHorizontalScrollbar);
-        bool will_have_scrollbar_y = (size_auto_fit_after_constraint.y - size_pad.y - size_decorations.y < size_contents.y && !(window->Flags & ImGuiWindowFlags_NoScrollbar)) || (window->Flags & ImGuiWindowFlags_AlwaysVerticalScrollbar);
+        bool will_have_scrollbar_y = (size_auto_fit_after_constraint.y - size_pad.y - decoration_up_height < size_contents.y && !(window->Flags & ImGuiWindowFlags_NoScrollbar)) || (window->Flags & ImGuiWindowFlags_AlwaysVerticalScrollbar);
         if (will_have_scrollbar_x)
             size_auto_fit.y += style.ScrollbarSize;
         if (will_have_scrollbar_y)
@@ -7774,24 +7775,29 @@ static ImVec2 CalcNextScrollFromScrollTargetAndClamp(ImGuiWindow* window)
     ImVec2 scroll = window->Scroll;
     if (window->ScrollTarget.x < FLT_MAX)
     {
+        float decoration_total_width = window->ScrollbarSizes.x;
         float center_x_ratio = window->ScrollTargetCenterRatio.x;
         float scroll_target_x = window->ScrollTarget.x;
-        float snap_x_min = 0.0f;
-        float snap_x_max = window->ScrollMax.x + window->Size.x;
         if (window->ScrollTargetEdgeSnapDist.x > 0.0f)
+        {
+            float snap_x_min = 0.0f;
+            float snap_x_max = window->ScrollMax.x + window->SizeFull.x - decoration_total_width;
             scroll_target_x = CalcScrollEdgeSnap(scroll_target_x, snap_x_min, snap_x_max, window->ScrollTargetEdgeSnapDist.x, center_x_ratio);
-        scroll.x = scroll_target_x - center_x_ratio * (window->SizeFull.x - window->ScrollbarSizes.x);
+        }
+        scroll.x = scroll_target_x - center_x_ratio * (window->SizeFull.x - decoration_total_width);
     }
     if (window->ScrollTarget.y < FLT_MAX)
     {
-        float decoration_up_height = window->TitleBarHeight() + window->MenuBarHeight();
+        float decoration_total_height = window->TitleBarHeight() + window->MenuBarHeight() + window->ScrollbarSizes.y;
         float center_y_ratio = window->ScrollTargetCenterRatio.y;
         float scroll_target_y = window->ScrollTarget.y;
-        float snap_y_min = 0.0f;
-        float snap_y_max = window->ScrollMax.y + window->Size.y - decoration_up_height;
         if (window->ScrollTargetEdgeSnapDist.y > 0.0f)
+        {
+            float snap_y_min = 0.0f;
+            float snap_y_max = window->ScrollMax.y + window->SizeFull.y - decoration_total_height;
             scroll_target_y = CalcScrollEdgeSnap(scroll_target_y, snap_y_min, snap_y_max, window->ScrollTargetEdgeSnapDist.y, center_y_ratio);
-        scroll.y = scroll_target_y - center_y_ratio * (window->SizeFull.y - window->ScrollbarSizes.y - decoration_up_height);
+        }
+        scroll.y = scroll_target_y - center_y_ratio * (window->SizeFull.y - decoration_total_height);
     }
     scroll.x = IM_FLOOR(ImMax(scroll.x, 0.0f));
     scroll.y = IM_FLOOR(ImMax(scroll.y, 0.0f));
@@ -7904,7 +7910,8 @@ void ImGui::SetScrollFromPosX(ImGuiWindow* window, float local_x, float center_x
 void ImGui::SetScrollFromPosY(ImGuiWindow* window, float local_y, float center_y_ratio)
 {
     IM_ASSERT(center_y_ratio >= 0.0f && center_y_ratio <= 1.0f);
-    local_y -= window->TitleBarHeight() + window->MenuBarHeight(); // FIXME: Would be nice to have a more standardized access to our scrollable/client rect
+    const float decoration_up_height = window->TitleBarHeight() + window->MenuBarHeight(); // FIXME: Would be nice to have a more standardized access to our scrollable/client rect;
+    local_y -= decoration_up_height;
     window->ScrollTarget.y = IM_FLOOR(local_y + window->Scroll.y); // Convert local position to scroll offset
     window->ScrollTargetCenterRatio.y = center_y_ratio;
     window->ScrollTargetEdgeSnapDist.y = 0.0f;
@@ -7927,7 +7934,7 @@ void ImGui::SetScrollHereX(float center_x_ratio)
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
-    float spacing_x = g.Style.ItemSpacing.x;
+    float spacing_x = ImMax(window->WindowPadding.x, g.Style.ItemSpacing.x);
     float target_pos_x = ImLerp(window->DC.LastItemRect.Min.x - spacing_x, window->DC.LastItemRect.Max.x + spacing_x, center_x_ratio);
     SetScrollFromPosX(window, target_pos_x - window->Pos.x, center_x_ratio); // Convert from absolute to local pos
 
@@ -7940,7 +7947,7 @@ void ImGui::SetScrollHereY(float center_y_ratio)
 {
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
-    float spacing_y = g.Style.ItemSpacing.y;
+    float spacing_y = ImMax(window->WindowPadding.y, g.Style.ItemSpacing.y);
     float target_pos_y = ImLerp(window->DC.CursorPosPrevLine.y - spacing_y, window->DC.CursorPosPrevLine.y + window->DC.PrevLineSize.y + spacing_y, center_y_ratio);
     SetScrollFromPosY(window, target_pos_y - window->Pos.y, center_y_ratio); // Convert from absolute to local pos
 

imgui.h

@@ -61,7 +61,7 @@ Index of this file:
 // Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals. Work in progress versions typically starts at XYY99 then bounce up to XYY00, XYY01 etc. when release tagging happens)
 #define IMGUI_VERSION               "1.83 WIP"
-#define IMGUI_VERSION_NUM           18201
+#define IMGUI_VERSION_NUM           18202
 #define IMGUI_CHECKVERSION()        ImGui::DebugCheckVersionAndDataLayout(IMGUI_VERSION, sizeof(ImGuiIO), sizeof(ImGuiStyle), sizeof(ImVec2), sizeof(ImVec4), sizeof(ImDrawVert), sizeof(ImDrawIdx))
 #define IMGUI_HAS_TABLE
 

imgui_demo.cpp

@@ -2838,6 +2838,8 @@ static void ShowDemoWindowLayout()
             {
                 for (int item = 0; item < 100; item++)
                 {
+                    if (item > 0)
+                        ImGui::SameLine();
                     if (enable_track && item == track_item)
                     {
                         ImGui::TextColored(ImVec4(1, 1, 0, 1), "Item %d", item);
@@ -2847,7 +2849,6 @@ static void ShowDemoWindowLayout()
                     {
                         ImGui::Text("Item %d", item);
                     }
-                    ImGui::SameLine();
                 }
             }
             float scroll_x = ImGui::GetScrollX();

imgui_widgets.cpp

@@ -6594,7 +6594,7 @@ void ImGui::EndMenuBar()
     IM_ASSERT(window->DC.MenuBarAppending);
     PopClipRect();
     PopID();
-    window->DC.MenuBarOffset.x = window->DC.CursorPos.x - window->MenuBarRect().Min.x; // Save horizontal position so next append can reuse it. This is kinda equivalent to a per-layer CursorPos.
+    window->DC.MenuBarOffset.x = window->DC.CursorPos.x - window->Pos.x; // Save horizontal position so next append can reuse it. This is kinda equivalent to a per-layer CursorPos.
     g.GroupStack.back().EmitItem = false;
     EndGroup(); // Restore position on layer 0
     window->DC.LayoutType = ImGuiLayoutType_Vertical;