Text: Fixed large Text/TextUnformatted call not declaring its size when starting below the lower point of the current clipping rectangle. Somehow this bug has been there since v1.0! It was hardly noticeable but would affect the scrolling range, which in turn would affect some scrolling request functions when called during the opening frame of a window.

docs/CHANGELOG.txt

@@ -63,6 +63,10 @@ Other Changes:
 - TabBar: Fixed a crash when using BeginTabBar() recursively (didn't affect docking). (#2371)
 - TabBar: Added extra mis-usage error recovery. Past the assert, common mis-usage don't lead to
   hard crashes any more, facilitating integration with scripting languages. (#1651)
+- Text: Fixed large Text/TextUnformatted call not declaring its size when starting below the
+  lower point of the current clipping rectangle. Somehow this bug has been there since v1.0!
+  It was hardly noticeable but would affect the scrolling range, which in turn would affect
+  some scrolling request functions when called during the opening frame of a window.
 - Plot: Fixed divide-by-zero in PlotLines() when passing a count of 1. (#2387) [@Lectem]
 - Log/Capture: Fixed extraneous leading carriage return.
 - Log/Capture: Fixed an issue when empty string on a new line would not emit a carriage return.

docs/TODO.txt

@@ -191,6 +191,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - text wrapped: figure out better way to use TextWrapped() in an always auto-resize context (tooltip, etc.) (#249)
  - text: it's currently impossible to have a window title with "##". perhaps an official workaround would be nice. \ style inhibitor? non-visible ascii code to insert between #?
  - text: provided a framed text helper, e.g. https://pastebin.com/1Laxy8bT
+ - text: refactor TextUnformatted (or underlying function) to more explicitly request if we need width measurement or not
  - text link/url button: underlined. should api expose an ID or use text contents as ID? which colors enum to use?
 
  - tree node / optimization: avoid formatting when clipped.
@@ -222,7 +223,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - log: let user copy any window content to clipboard easily (CTRL+C on windows? while moving it? context menu?). code is commented because it fails with multiple Begin/End pairs.
  - log: obsolete LogButtons() all together.
  - log: LogButtons() options for specifying depth and/or hiding depth slider
- 
+
  - filters: set a current filter that tree node can automatically query to hide themselves
  - filters: handle wild-cards (with implicit leading/trailing *), reg-exprs
  - filters: fuzzy matches (may use code at blog.forrestthewoods.com/4cffeed33fdb)

imgui.h

@@ -297,7 +297,7 @@ namespace ImGui
     IMGUI_API void          SetScrollX(float scroll_x);                                     // set scrolling amount [0..GetScrollMaxX()]
     IMGUI_API void          SetScrollY(float scroll_y);                                     // set scrolling amount [0..GetScrollMaxY()]
     IMGUI_API void          SetScrollHereY(float center_y_ratio = 0.5f);                    // adjust scrolling amount to make current cursor position visible. center_y_ratio=0.0: top, 0.5: center, 1.0: bottom. When using to make a "default/current item" visible, consider using SetItemDefaultFocus() instead.
-    IMGUI_API void          SetScrollFromPosY(float local_y, float center_y_ratio = 0.5f);  // adjust scrolling amount to make given position valid. use GetCursorPos() or GetCursorStartPos()+offset to get valid positions.
+    IMGUI_API void          SetScrollFromPosY(float local_y, float center_y_ratio = 0.5f);  // adjust scrolling amount to make given position visible. Generally GetCursorStartPos() + offset to compute a valid position.
 
     // Parameters stacks (shared)
     IMGUI_API void          PushFont(ImFont* font);                                         // use NULL as a shortcut to push default font

imgui_widgets.cpp

@@ -159,53 +159,15 @@ void ImGui::TextUnformatted(const char* text, const char* text_end)
         const ImRect clip_rect = window->ClipRect;
         ImVec2 text_size(0,0);
 
-        if (text_pos.y <= clip_rect.Max.y)
+        // Lines to skip (can't skip when logging text)
+        ImVec2 pos = text_pos;
+        if (!g.LogEnabled)
         {
-            ImVec2 pos = text_pos;
+            int lines_skippable = (int)((clip_rect.Min.y - text_pos.y) / line_height);
-
+            if (lines_skippable > 0)
-            // Lines to skip (can't skip when logging text)
-            if (!g.LogEnabled)
             {
-                int lines_skippable = (int)((clip_rect.Min.y - text_pos.y) / line_height);
-                if (lines_skippable > 0)
-                {
-                    int lines_skipped = 0;
-                    while (line < text_end && lines_skipped < lines_skippable)
-                    {
-                        const char* line_end = (const char*)memchr(line, '\n', text_end - line);
-                        if (!line_end)
-                            line_end = text_end;
-                        line = line_end + 1;
-                        lines_skipped++;
-                    }
-                    pos.y += lines_skipped * line_height;
-                }
-            }
-
-            // Lines to render
-            if (line < text_end)
-            {
-                ImRect line_rect(pos, pos + ImVec2(FLT_MAX, line_height));
-                while (line < text_end)
-                {
-                    if (IsClippedEx(line_rect, 0, false))
-                        break;
-
-                    const char* line_end = (const char*)memchr(line, '\n', text_end - line);
-                    if (!line_end)
-                        line_end = text_end;
-                    const ImVec2 line_size = CalcTextSize(line, line_end, false);
-                    text_size.x = ImMax(text_size.x, line_size.x);
-                    RenderText(pos, line, line_end, false);
-                    line = line_end + 1;
-                    line_rect.Min.y += line_height;
-                    line_rect.Max.y += line_height;
-                    pos.y += line_height;
-                }
-
-                // Count remaining lines
                 int lines_skipped = 0;
-                while (line < text_end)
+                while (line < text_end && lines_skipped < lines_skippable)
                 {
                     const char* line_end = (const char*)memchr(line, '\n', text_end - line);
                     if (!line_end)
@@ -215,10 +177,43 @@ void ImGui::TextUnformatted(const char* text, const char* text_end)
                 }
                 pos.y += lines_skipped * line_height;
             }
-
-            text_size.y += (pos - text_pos).y;
         }
 
+        // Lines to render
+        if (line < text_end)
+        {
+            ImRect line_rect(pos, pos + ImVec2(FLT_MAX, line_height));
+            while (line < text_end)
+            {
+                if (IsClippedEx(line_rect, 0, false))
+                    break;
+
+                const char* line_end = (const char*)memchr(line, '\n', text_end - line);
+                if (!line_end)
+                    line_end = text_end;
+                const ImVec2 line_size = CalcTextSize(line, line_end, false);
+                text_size.x = ImMax(text_size.x, line_size.x);
+                RenderText(pos, line, line_end, false);
+                line = line_end + 1;
+                line_rect.Min.y += line_height;
+                line_rect.Max.y += line_height;
+                pos.y += line_height;
+            }
+
+            // Count remaining lines
+            int lines_skipped = 0;
+            while (line < text_end)
+            {
+                const char* line_end = (const char*)memchr(line, '\n', text_end - line);
+                if (!line_end)
+                    line_end = text_end;
+                line = line_end + 1;
+                lines_skipped++;
+            }
+            pos.y += lines_skipped * line_height;
+        }
+        text_size.y = (pos - text_pos).y;
+
         ImRect bb(text_pos, text_pos + text_size);
         ItemSize(text_size);
         ItemAdd(bb, 0);