Internals: Storing ScrollMax into a member. Mostly to facilitate debugging. Also locking down window->Scroll slightly lower in the Begin function.

imgui.cpp

@@ -4747,16 +4747,6 @@ ImVec2 ImGui::CalcWindowExpectedSize(ImGuiWindow* window)
     return CalcSizeAfterConstraint(window, CalcSizeAutoFit(window, size_contents));
 }
 
-float ImGui::GetWindowScrollMaxX(ImGuiWindow* window)
-{
-    return ImMax(0.0f, window->ContentSize.x + window->WindowPadding.x * 2.0f - window->InnerRect.GetWidth());
-}
-
-float ImGui::GetWindowScrollMaxY(ImGuiWindow* window)
-{
-    return ImMax(0.0f, window->ContentSize.y + window->WindowPadding.y * 2.0f - window->InnerRect.GetHeight());
-}
-
 static ImVec2 CalcNextScrollFromScrollTargetAndClamp(ImGuiWindow* window, bool snap_on_edges)
 {
     ImGuiContext& g = *GImGui;
@@ -4780,8 +4770,8 @@ static ImVec2 CalcNextScrollFromScrollTargetAndClamp(ImGuiWindow* window, bool s
     scroll = ImMax(scroll, ImVec2(0.0f, 0.0f));
     if (!window->Collapsed && !window->SkipItems)
     {
-        scroll.x = ImMin(scroll.x, ImGui::GetWindowScrollMaxX(window));
-        scroll.y = ImMin(scroll.y, ImGui::GetWindowScrollMaxY(window));
+        scroll.x = ImMin(scroll.x, window->ScrollMax.x);
+        scroll.y = ImMin(scroll.y, window->ScrollMax.y);
     }
     return scroll;
 }
@@ -5470,10 +5460,6 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         // Lock window rounding for the frame (so that altering them doesn't cause inconsistencies)
         window->WindowRounding = (flags & ImGuiWindowFlags_ChildWindow) ? style.ChildRounding : ((flags & ImGuiWindowFlags_Popup) && !(flags & ImGuiWindowFlags_Modal)) ? style.PopupRounding : style.WindowRounding;
 
-        // Apply scrolling
-        window->Scroll = CalcNextScrollFromScrollTargetAndClamp(window, true);
-        window->ScrollTarget = ImVec2(FLT_MAX, FLT_MAX);
-
         // Apply window focus (new and reactivated windows are moved to front)
         bool want_focus = false;
         if (window_just_activated_by_user && !(flags & ImGuiWindowFlags_NoFocusOnAppearing))
@@ -5538,6 +5524,18 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         window->InnerClipRect.Max.y = ImFloor(0.5f + window->InnerRect.Max.y - window->WindowBorderSize);
         window->InnerClipRect.ClipWithFull(host_rect);
 
+        // SCROLLING
+
+        // Lock down maximum scrolling
+        // The value of ScrollMax are ahead from ScrollbarX/ScrollbarY which is intentionally using InnerRect from previous rect in order to accommodate
+        // for right/bottom aligned items without creating a scrollbar.
+        window->ScrollMax.x = ImMax(0.0f, window->ContentSize.x + window->WindowPadding.x * 2.0f - window->InnerRect.GetWidth());
+        window->ScrollMax.y = ImMax(0.0f, window->ContentSize.y + window->WindowPadding.y * 2.0f - window->InnerRect.GetHeight());
+
+        // Apply scrolling
+        window->Scroll = CalcNextScrollFromScrollTargetAndClamp(window, true);
+        window->ScrollTarget = ImVec2(FLT_MAX, FLT_MAX);
+
         // DRAWING
 
         // Setup draw list and outer clipping rectangle
@@ -5619,7 +5617,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         window->DC.CurrLineSize = window->DC.PrevLineSize = ImVec2(0.0f, 0.0f);
         window->DC.CurrLineTextBaseOffset = window->DC.PrevLineTextBaseOffset = 0.0f;
         window->DC.NavHideHighlightOneFrame = false;
-        window->DC.NavHasScroll = (GetWindowScrollMaxY(window) > 0.0f);
+        window->DC.NavHasScroll = (window->ScrollMax.y > 0.0f);
         window->DC.NavLayerActiveMask = window->DC.NavLayerActiveMaskNext;
         window->DC.NavLayerActiveMaskNext = 0x00;
         window->DC.MenuBarAppending = false;
@@ -6687,22 +6685,26 @@ void ImGui::SetCursorScreenPos(const ImVec2& pos)
 
 float ImGui::GetScrollX()
 {
-    return GImGui->CurrentWindow->Scroll.x;
+    ImGuiWindow* window = GImGui->CurrentWindow;
+    return window->Scroll.x;
 }
 
 float ImGui::GetScrollY()
 {
-    return GImGui->CurrentWindow->Scroll.y;
+    ImGuiWindow* window = GImGui->CurrentWindow;
+    return window->Scroll.y;
 }
 
 float ImGui::GetScrollMaxX()
 {
-    return GetWindowScrollMaxX(GImGui->CurrentWindow);
+    ImGuiWindow* window = GImGui->CurrentWindow;
+    return window->ScrollMax.x;
 }
 
 float ImGui::GetScrollMaxY()
 {
-    return GetWindowScrollMaxY(GImGui->CurrentWindow);
+    ImGuiWindow* window = GImGui->CurrentWindow;
+    return window->ScrollMax.y;
 }
 
 void ImGui::SetScrollX(float scroll_x)
@@ -9906,7 +9908,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                 (flags & ImGuiWindowFlags_ChildWindow)  ? "Child " : "",      (flags & ImGuiWindowFlags_Tooltip)     ? "Tooltip "   : "",  (flags & ImGuiWindowFlags_Popup) ? "Popup " : "",
                 (flags & ImGuiWindowFlags_Modal)        ? "Modal " : "",      (flags & ImGuiWindowFlags_ChildMenu)   ? "ChildMenu " : "",  (flags & ImGuiWindowFlags_NoSavedSettings) ? "NoSavedSettings " : "",
                 (flags & ImGuiWindowFlags_NoMouseInputs)? "NoMouseInputs":"", (flags & ImGuiWindowFlags_NoNavInputs) ? "NoNavInputs" : "", (flags & ImGuiWindowFlags_AlwaysAutoResize) ? "AlwaysAutoResize" : "");
-            ImGui::BulletText("Scroll: (%.2f/%.2f,%.2f/%.2f)", window->Scroll.x, GetWindowScrollMaxX(window), window->Scroll.y, GetWindowScrollMaxY(window));
+            ImGui::BulletText("Scroll: (%.2f/%.2f,%.2f/%.2f)", window->Scroll.x, window->ScrollMax.x, window->Scroll.y, window->ScrollMax.y);
             ImGui::BulletText("Active: %d/%d, WriteAccessed: %d, BeginOrderWithinContext: %d", window->Active, window->WasActive, window->WriteAccessed, (window->Active || window->WasActive) ? window->BeginOrderWithinContext : -1);
             ImGui::BulletText("Appearing: %d, Hidden: %d (CanSkip %d Cannot %d), SkipItems: %d", window->Appearing, window->Hidden, window->HiddenFramesCanSkipItems, window->HiddenFramesCannotSkipItems, window->SkipItems);
             ImGui::BulletText("NavLastIds: 0x%08X,0x%08X, NavLayerActiveMask: %X", window->NavLastIds[0], window->NavLastIds[1], window->DC.NavLayerActiveMask);

imgui_internal.h

@@ -1262,6 +1262,7 @@ struct IMGUI_API ImGuiWindow
     ImGuiID                 MoveId;                             // == window->GetID("#MOVE")
     ImGuiID                 ChildId;                            // ID of corresponding item in parent window (for navigation to return from child window to parent window)
     ImVec2                  Scroll;
+    ImVec2                  ScrollMax;
     ImVec2                  ScrollTarget;                       // target scroll position. stored as cursor position with scrolling canceled out, so the highest point is always 0.0f. (FLT_MAX for no change)
     ImVec2                  ScrollTargetCenterRatio;            // 0.0f = scroll so that target position is at top, 0.5f = scroll so that target position is centered
     ImVec2                  ScrollbarSizes;                     // Size taken by scrollbars on each axis
@@ -1450,8 +1451,6 @@ namespace ImGui
     IMGUI_API bool          IsWindowNavFocusable(ImGuiWindow* window);
     IMGUI_API void          SetWindowScrollX(ImGuiWindow* window, float new_scroll_x);
     IMGUI_API void          SetWindowScrollY(ImGuiWindow* window, float new_scroll_y);
-    IMGUI_API float         GetWindowScrollMaxX(ImGuiWindow* window);
-    IMGUI_API float         GetWindowScrollMaxY(ImGuiWindow* window);
     IMGUI_API ImRect        GetWindowAllowedExtentRect(ImGuiWindow* window);
     IMGUI_API void          SetWindowPos(ImGuiWindow* window, const ImVec2& pos, ImGuiCond cond = 0);
     IMGUI_API void          SetWindowSize(ImGuiWindow* window, const ImVec2& size, ImGuiCond cond = 0);