Scrolling: Exposed SetNextWindowScroll() in public API. (#1526)

docs/CHANGELOG.txt

@@ -122,6 +122,8 @@ Other Changes:
   whenever scrolling again (#2604).
 - Scrolling: Mitigated issue where multi-axis mouse-wheel inputs (usually from touch pad
   events) are incorrectly locking scrolling in a parent window. (#4559, #3795, #2604)
+- Scrolling: Exposed SetNextWindowScroll() in public API. Useful to remove a scrolling
+  delay in some situations where e.g. windows need to be synched. (#1526)
 - InputText: added experimental io.ConfigInputTextEnterKeepActive feature to make pressing
   Enter keep the input active and select all text.
 - InputText: numerical fields automatically accept full-width characters (U+FF01..U+FF5E)

imgui.h

@@ -23,7 +23,7 @@
 // Library Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals, e.g. '#if IMGUI_VERSION_NUM > 12345')
 #define IMGUI_VERSION               "1.89 WIP"
-#define IMGUI_VERSION_NUM           18837
+#define IMGUI_VERSION_NUM           18838
 #define IMGUI_HAS_TABLE
 
 /*
@@ -362,6 +362,7 @@ namespace ImGui
     IMGUI_API void          SetNextWindowContentSize(const ImVec2& size);                               // set next window content size (~ scrollable client area, which enforce the range of scrollbars). Not including window decorations (title bar, menu bar, etc.) nor WindowPadding. set an axis to 0.0f to leave it automatic. call before Begin()
     IMGUI_API void          SetNextWindowCollapsed(bool collapsed, ImGuiCond cond = 0);                 // set next window collapsed state. call before Begin()
     IMGUI_API void          SetNextWindowFocus();                                                       // set next window to be focused / top-most. call before Begin()
+    IMGUI_API void          SetNextWindowScroll(const ImVec2& scroll);                                  // set next window scrolling value (use < 0.0f to not affect a given axis).
     IMGUI_API void          SetNextWindowBgAlpha(float alpha);                                          // set next window background color alpha. helper to easily override the Alpha component of ImGuiCol_WindowBg/ChildBg/PopupBg. you may also use ImGuiWindowFlags_NoBackground.
     IMGUI_API void          SetWindowPos(const ImVec2& pos, ImGuiCond cond = 0);                        // (not recommended) set current window position - call within Begin()/End(). prefer using SetNextWindowPos(), as this may incur tearing and side-effects.
     IMGUI_API void          SetWindowSize(const ImVec2& size, ImGuiCond cond = 0);                      // (not recommended) set current window size - call within Begin()/End(). set to ImVec2(0, 0) to force an auto-fit. prefer using SetNextWindowSize(), as this may incur tearing and minor side-effects.
@@ -382,6 +383,8 @@ namespace ImGui
     IMGUI_API ImVec2        GetWindowContentRegionMax();                                    // content boundaries max for the full window (roughly (0,0)+Size-Scroll) where Size can be overridden with SetNextWindowContentSize(), in window coordinates
 
     // Windows Scrolling
+    // - Any change of Scroll will be applied at the beginning of next frame in the first call to Begin().
+    // - You may instead use SetNextWindowScroll() prior to calling Begin() to avoid this delay, as an alternative to using SetScrollX()/SetScrollY().
     IMGUI_API float         GetScrollX();                                                   // get scrolling amount [0 .. GetScrollMaxX()]
     IMGUI_API float         GetScrollY();                                                   // get scrolling amount [0 .. GetScrollMaxY()]
     IMGUI_API void          SetScrollX(float scroll_x);                                     // set scrolling amount [0 .. GetScrollMaxX()]

imgui_demo.cpp

@@ -6721,6 +6721,8 @@ struct ExampleAppConsole
             if (copy_to_clipboard)
                 ImGui::LogFinish();
 
+            // Keep up at the bottom of the scroll region if we were already at the bottom at the beginning of the frame.
+            // Using a scrollbar or mouse-wheel will take away from the bottom edge.
             if (ScrollToBottom || (AutoScroll && ImGui::GetScrollY() >= ImGui::GetScrollMaxY()))
                 ImGui::SetScrollHereY(1.0f);
             ScrollToBottom = false;
@@ -7029,6 +7031,8 @@ struct ExampleAppLog
             }
             ImGui::PopStyleVar();
 
+            // Keep up at the bottom of the scroll region if we were already at the bottom at the beginning of the frame.
+            // Using a scrollbar or mouse-wheel will take away from the bottom edge.
             if (AutoScroll && ImGui::GetScrollY() >= ImGui::GetScrollMaxY())
                 ImGui::SetScrollHereY(1.0f);
         }

imgui_internal.h

@@ -2724,7 +2724,6 @@ namespace ImGui
     IMGUI_API ImGuiSettingsHandler* FindSettingsHandler(const char* type_name);
 
     // Scrolling
-    IMGUI_API void          SetNextWindowScroll(const ImVec2& scroll); // Use -1.0f on one axis to leave as-is
     IMGUI_API void          SetScrollX(ImGuiWindow* window, float scroll_x);
     IMGUI_API void          SetScrollY(ImGuiWindow* window, float scroll_y);
     IMGUI_API void          SetScrollFromPosX(ImGuiWindow* window, float local_x, float center_x_ratio);