Fix issue with OverhangLeading (#18438)

* Fix issue with MinTextWidth (Fixes #18372)

* Make sure that MeasureOverride for TextPresenter and TextBlock are using same textWidth

* Revert #16601 that is introducing an invalid calculation for the OverhangLeading

Add tests for OverhangLeading and OverhangTrailing

* Revert MinTextWidth

* Fix tests to not rely on fixed values

* Fix remaining issues

* Fix comment in Direct2D1 GlyphRunImpl.cs

* Fix Direct2D1 rendering

* Fix gold images

* Restore TextLineImpl

* Update gold image

* Restore Math.Max on OverhangLeading and Trailing

* Adopt similar behavior to WPF: don't use OverhangLeading/Trailing for measuring and remove clip by default.

But it requires further support with NeedsClipBounds

* Remove MinTextWidth
Keep ClipToBounds=true default for TextBlock

* Revert change

---------

Co-authored-by: Benedikt Stebner <[email protected]>
#Conflicts:
#	src/Avalonia.Controls/TextBlock.cs
#	tests/Avalonia.Controls.UnitTests/TextBlockTests.cs

Author: 2 people

src/Avalonia.Base/Media/TextFormatting/TextLayout.cs

@@ -273,11 +273,6 @@ public double WidthIncludingTrailingWhitespace
             }
         }
 
-        /// <summary>
-        /// Get minimum width of all text lines that can be layouted horizontally without trimming or wrapping.
-        /// </summary>
-        internal double MinTextWidth => _metrics.MinTextWidth;
-
         /// <summary>
         /// Draws the text layout.
         /// </summary>
@@ -679,45 +674,30 @@ private TextLine[] CreateTextLines()
 
         private void UpdateMetrics(TextLineImpl currentLine, ref bool first)
         {
-            // 1) Offset each line’s bounding rectangles by the total height so far,
-            //    so we keep an overall bounding box for the entire text block.
-            var lineTop = _metrics.Height;
-
-            // Offset the line's Bounds
-            var lineBoundsRect = new Rect(
-                currentLine.Bounds.X,
-                lineTop + currentLine.Bounds.Y,
-                currentLine.Bounds.Width,
-                currentLine.Bounds.Height);
-
-            _metrics.Bounds = _metrics.Bounds.Union(lineBoundsRect);
-
-            // Offset the line's InkBounds
-            var lineInkRect = new Rect(
-                currentLine.InkBounds.X,
-                lineTop + currentLine.InkBounds.Y,
-                currentLine.InkBounds.Width,
-                currentLine.InkBounds.Height);
-
-            _metrics.InkBounds = _metrics.InkBounds.Union(lineInkRect);
-
-            // 2) Accumulate total layout height by adding the line’s Height.
+            // 1) Accumulate total layout height by adding the line’s Height.
             _metrics.Height += currentLine.Height;
 
-            // 3) For the layout’s Width and WidthIncludingTrailingWhitespace,
+            // 2) For the layout’s Width and WidthIncludingTrailingWhitespace,
             //    use the maximum of the line widths rather than the bounding box.
             _metrics.Width = Math.Max(_metrics.Width, currentLine.Width);
-            _metrics.WidthIncludingTrailingWhitespace = Math.Max(_metrics.WidthIncludingTrailingWhitespace, currentLine.WidthIncludingTrailingWhitespace);
 
-            // 4) Extent is the max black-pixel extent among lines.
+            // 3) Extent is the max black-pixel extent among lines.
             _metrics.Extent = Math.Max(_metrics.Extent, currentLine.Extent);
 
-            // 5) We can track min-text-width or overhangs similarly if needed.
-            _metrics.MinTextWidth = Math.Max(_metrics.MinTextWidth, currentLine.Width);
+            // 4) TextWidth is the max of the text width among lines.
+            // We choose to update all related metrics at once (OverhangLeading, WidthIncludingTrailingWhitespace, OverhangTrailing)
+            // if the current line has a larger text width.
+            var previousTextWidth = _metrics.OverhangLeading + _metrics.WidthIncludingTrailingWhitespace + _metrics.OverhangTrailing;
+            var textWidth = currentLine.OverhangLeading + currentLine.WidthIncludingTrailingWhitespace + currentLine.OverhangTrailing;
+            if (previousTextWidth < textWidth)
+            {
+                _metrics.WidthIncludingTrailingWhitespace = currentLine.WidthIncludingTrailingWhitespace;
+                _metrics.OverhangLeading = currentLine.OverhangLeading;
+                _metrics.OverhangTrailing = currentLine.OverhangTrailing;
+            }
 
-            _metrics.OverhangLeading = Math.Max(_metrics.OverhangLeading, currentLine.OverhangLeading);
-            _metrics.OverhangTrailing = Math.Max(_metrics.OverhangTrailing, currentLine.OverhangTrailing);
-            _metrics.OverhangAfter = Math.Max(_metrics.OverhangAfter, currentLine.OverhangAfter);
+            // 5) OverhangAfter is the last line’s OverhangAfter.
+            _metrics.OverhangAfter = currentLine.OverhangAfter;
 
             // 6) Capture the baseline from the first line.
             if (first)
@@ -768,11 +748,6 @@ private class CachedMetrics
             // horizontal bounding box metrics
             public double OverhangLeading;
             public double OverhangTrailing;
-
-            public Rect Bounds;
-            public Rect InkBounds;
-
-            public double MinTextWidth;
         }
     }
 }

src/Avalonia.Controls/Presenters/TextPresenter.cs

@@ -627,16 +627,17 @@ protected override Size MeasureOverride(Size availableSize)
 
             InvalidateArrange();
 
+            // The textWidth used here is matching that TextBlock uses to measure the text.
             var textWidth = TextLayout.OverhangLeading + TextLayout.WidthIncludingTrailingWhitespace + TextLayout.OverhangTrailing;
-
             return new Size(textWidth, TextLayout.Height);
         }
 
         protected override Size ArrangeOverride(Size finalSize)
         {
             var finalWidth = finalSize.Width;
 
-            var textWidth = Math.Ceiling(TextLayout.OverhangLeading + TextLayout.WidthIncludingTrailingWhitespace + TextLayout.OverhangTrailing);
+            var textWidth = TextLayout.OverhangLeading + TextLayout.WidthIncludingTrailingWhitespace + TextLayout.OverhangTrailing;
+            textWidth = Math.Ceiling(textWidth);
 
             if (finalSize.Width < textWidth)
             {

src/Avalonia.Controls/TextBlock.cs

@@ -628,7 +628,7 @@ private protected virtual void RenderCore(DrawingContext context)
 
         protected virtual void RenderTextLayout(DrawingContext context, Point origin)
         {
-            TextLayout.Draw(context, origin + new Point(TextLayout.OverhangLeading, 0));
+            TextLayout.Draw(context, origin);
         }
 
         private bool _clearTextInternal;
@@ -740,7 +740,8 @@ protected override Size MeasureOverride(Size availableSize)
             //This implicitly recreated the TextLayout with a new constraint if we previously reset it.
             var textLayout = TextLayout;
 
-            var size = LayoutHelper.RoundLayoutSizeUp(new Size(textLayout.MinTextWidth, textLayout.Height).Inflate(padding), 1, 1);
+            // The textWidth used here is matching that TextPresenter uses to measure the text.
+            var size = LayoutHelper.RoundLayoutSizeUp(new Size(textLayout.WidthIncludingTrailingWhitespace, textLayout.Height).Inflate(padding), 1, 1);
 
             return size;
         }

src/Skia/Avalonia.Skia/GlyphRunImpl.cs

@@ -74,12 +74,6 @@ public GlyphRunImpl(IGlyphTypeface glyphTypeface, double fontRenderingEmSize,
 
                 currentX += advance;
             }
-
-            if (runBounds.Left < 0)
-            {
-                runBounds = runBounds.Translate(new Vector(-runBounds.Left, 0));
-            }
-
             ArrayPool<SKRect>.Shared.Return(glyphBounds);
 
             BaselineOrigin = baselineOrigin;

src/Windows/Avalonia.Direct2D1/Media/GlyphRunImpl.cs

@@ -50,7 +50,10 @@ public GlyphRunImpl(IGlyphTypeface glyphTypeface, double fontRenderingEmSize,
             }
 
             _glyphOffsets = new GlyphOffset[glyphCount];
-
+            
+            var runBounds = new Rect();
+            var currentX = 0.0;
+            var scale = fontRenderingEmSize / glyphTypeface.Metrics.DesignEmHeight;
             for (var i = 0; i < glyphCount; i++)
             {
                 var (x, y) = glyphInfos[i].GlyphOffset;
@@ -60,13 +63,29 @@ public GlyphRunImpl(IGlyphTypeface glyphTypeface, double fontRenderingEmSize,
                     AdvanceOffset = (float)x,
                     AscenderOffset = (float)y
                 };
-            }
 
-            var scale = fontRenderingEmSize / glyphTypeface.Metrics.DesignEmHeight;
+                if (_glyphTypefaceImpl.TryGetGlyphMetrics(glyphInfos[i].GlyphIndex, out var metrics))
+                {
+                    // Found metrics with negative height, prefer to adjust it to positive.
+                    var ybearing = metrics.YBearing;
+                    var height = metrics.Height;
+                    if (height < 0)
+                    {
+                        ybearing += height;
+                        height = -height;
+                    }
+
+                    // Not entirely sure about why we need to do this, but it seems to work
+                    var xOffset = metrics.XBearing * scale;
+                    var xWidth = xOffset > 0 ? xOffset : 0;
+                    var xBearing = xOffset < 0 ? xOffset : 0;
+                    runBounds = runBounds.Union(new Rect(currentX + xBearing, baselineOrigin.Y + ybearing, xWidth + metrics.Width * scale, height * scale));
+                }
 
-            var height = glyphTypeface.Metrics.LineSpacing * scale;
+                currentX += glyphInfos[i].GlyphAdvance;
+            }
 
-            Bounds = new Rect(baselineOrigin.X, 0, width, height);
+            Bounds = runBounds.Translate(new Vector(baselineOrigin.X, 0));
         }
 
         public SharpDX.DirectWrite.GlyphRun GlyphRun

tests/Avalonia.Controls.UnitTests/TextBlockTests.cs

@@ -66,7 +66,7 @@ public void Should_Measure_MinTextWith()
 
                 var textLayout = textBlock.TextLayout;
 
-                var constraint = LayoutHelper.RoundLayoutSizeUp(new Size(textLayout.MinTextWidth, textLayout.Height), 1, 1);
+                var constraint = LayoutHelper.RoundLayoutSizeUp(new Size(textLayout.Width, textLayout.Height), 1, 1);
 
                 Assert.Equal(textBlock.DesiredSize, constraint);
             }