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fix bounds and justification calculations to prevent clipping #20449

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fix bounds and justification calculations to prevent clipping #20449

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22 changes: 21 additions & 1 deletion src/Avalonia.Base/Media/TextFormatting/TextLayout.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -294,7 +294,27 @@ public Rect HitTestTextPosition(int textPosition)

var endX = textLine.GetDistanceFromCharacterHit(nextCharacterHit);

return new Rect(startX, currentY, endX - startX, textLine.Height);
var width = endX - startX;
var adjustedX = startX;

var lineContentLength = textLine.Length - textLine.NewLineLength;

if (lineContentLength > 0)
{
if (textPosition == textLine.FirstTextSourceIndex && textLine.OverhangLeading < 0 && startX > 0)
{
adjustedX += textLine.OverhangLeading;
width -= textLine.OverhangLeading;
}

var lastCharacterPosition = textLine.FirstTextSourceIndex + lineContentLength - 1;
if (textPosition >= lastCharacterPosition && textLine.OverhangTrailing < 0)
{
width -= textLine.OverhangTrailing;
}
}

return new Rect(adjustedX, currentY, width, textLine.Height);
}

return new Rect();
Expand Down
49 changes: 37 additions & 12 deletions src/Avalonia.Base/Media/TextFormatting/TextLineImpl.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1328,7 +1328,7 @@ private TextLineMetrics CreateLineMetrics()
}
}

var inkBounds = new Rect();
Rect? inkBounds = null;

for (var index = 0; index < _textRuns.Length; index++)
{
Expand All @@ -1342,7 +1342,14 @@ private TextLineMetrics CreateLineMetrics()

var runBounds = glyphRun.InkBounds.Translate(new Vector(widthIncludingWhitespace, offsetY));

inkBounds = inkBounds.Union(runBounds);
if (inkBounds == null)
{
inkBounds = runBounds;
}
else
{
inkBounds = inkBounds.Value.Union(runBounds);
}

widthIncludingWhitespace += textRun.Size.Width;

Expand All @@ -1354,14 +1361,25 @@ private TextLineMetrics CreateLineMetrics()
//Align the bounds at the common baseline
var offsetY = -ascent - drawableTextRun.Baseline;

inkBounds = inkBounds.Union(new Rect(new Point(widthIncludingWhitespace, offsetY), drawableTextRun.Size));
var drawableBounds = new Rect(new Point(widthIncludingWhitespace, offsetY), drawableTextRun.Size);

if (inkBounds == null)
{
inkBounds = drawableBounds;
}
else
{
inkBounds = inkBounds.Value.Union(drawableBounds);
}

widthIncludingWhitespace += drawableTextRun.Size.Width;

break;
}
}
}

var finalInkBounds = inkBounds ?? new Rect();

var halfLineGap = lineGap * 0.5;
var naturalHeight = descent - ascent + lineGap;
Expand Down Expand Up @@ -1416,18 +1434,18 @@ private TextLineMetrics CreateLineMetrics()
}
}

var extent = inkBounds.Height;
var extent = finalInkBounds.Height;
//The height of overhanging pixels at the bottom
var overhangAfter = inkBounds.Bottom - height + halfLineGap;
var overhangAfter = finalInkBounds.Bottom - height + halfLineGap;
//The width of overhanging pixels at the natural alignment point. Positive value means we are inside.
var overhangLeading = inkBounds.Left;
var overhangLeading = finalInkBounds.Left;
//The width of overhanging pixels at the end of the natural bounds. Positive value means we are inside.
var overhangTrailing = widthIncludingWhitespace - inkBounds.Right;
var hasOverflowed = MathUtilities.GreaterThan(width, _paragraphWidth);
var overhangTrailing = widthIncludingWhitespace - finalInkBounds.Right;
var hasOverflowed = width > _paragraphWidth;

var start = GetParagraphOffsetX(width, widthIncludingWhitespace);
var start = GetParagraphOffsetX(width, widthIncludingWhitespace, overhangLeading, overhangTrailing);

_inkBounds = inkBounds.Translate(new Vector(start, 0));
_inkBounds = finalInkBounds.Translate(new Vector(start, 0));

_bounds = new Rect(start, 0, widthIncludingWhitespace, height);

Expand All @@ -1453,9 +1471,11 @@ private TextLineMetrics CreateLineMetrics()
/// </summary>
/// <param name="width">The line width.</param>
/// <param name="widthIncludingTrailingWhitespace">The paragraph width including whitespace.</param>
/// <param name="overhangLeading">The leading overhang.</param>
/// <param name="overhangTrailing">The trailing overhang.</param>

/// <returns>The paragraph offset.</returns>
private double GetParagraphOffsetX(double width, double widthIncludingTrailingWhitespace)
private double GetParagraphOffsetX(double width, double widthIncludingTrailingWhitespace, double overhangLeading, double overhangTrailing)
{
if (double.IsPositiveInfinity(_paragraphWidth))
{
Expand Down Expand Up @@ -1492,6 +1512,7 @@ private double GetParagraphOffsetX(double width, double widthIncludingTrailingWh
switch (textAlignment)
{
case TextAlignment.Center:
{
var start = (_paragraphWidth - width) / 2;

if (paragraphFlowDirection == FlowDirection.RightToLeft)
Expand All @@ -1500,8 +1521,12 @@ private double GetParagraphOffsetX(double width, double widthIncludingTrailingWh
}

return Math.Max(0, start);
}
case TextAlignment.Right:
return Math.Max(0, _paragraphWidth - widthIncludingTrailingWhitespace);
{
var overhangAdjustment = Math.Min(0, overhangTrailing);
return Math.Max(0, _paragraphWidth - widthIncludingTrailingWhitespace + overhangAdjustment);
}
default:
return 0;
}
Expand Down
156 changes: 145 additions & 11 deletions src/Avalonia.Controls/Presenters/TextPresenter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -370,6 +370,41 @@ private TextLayout CreateTextLayoutInternal(Size constraint, string? text, Typef
return textLayout;
}

private double GetLineOffsetX(TextLine line, double controlWidth, TextAlignment textAlignment)
{
var lineInkStartOffset = line.OverhangLeading;
var lineTrailingOverhang = -Math.Min(0, line.OverhangTrailing);
var lineLeadingOverhang = -Math.Min(0, line.OverhangLeading);
var lineInkWidth = line.WidthIncludingTrailingWhitespace + lineLeadingOverhang + lineTrailingOverhang;

switch (textAlignment)
{
case TextAlignment.Center:
return (controlWidth - lineInkWidth) / 2 - lineInkStartOffset - line.Start;

case TextAlignment.Right:
return controlWidth - line.WidthIncludingTrailingWhitespace - lineTrailingOverhang - line.Start;

default: // Left, Justify
return -lineInkStartOffset - line.Start;
}
}

private TextAlignment GetResolvedTextAlignment()
{
var textAlignment = TextAlignment;
var flowDirection = FlowDirection;

if (textAlignment == TextAlignment.Start)
return flowDirection == FlowDirection.LeftToRight ? TextAlignment.Left : TextAlignment.Right;
else if (textAlignment == TextAlignment.End)
return flowDirection == FlowDirection.RightToLeft ? TextAlignment.Left : TextAlignment.Right;
else if (textAlignment == TextAlignment.DetectFromContent)
return TextAlignment.Left;

return textAlignment;
}

/// <summary>
/// Renders the <see cref="TextPresenter"/> to a drawing context.
/// </summary>
Expand All @@ -383,8 +418,12 @@ private void RenderInternal(DrawingContext context)
context.FillRectangle(background, new Rect(Bounds.Size));
}

if (TextLayout.TextLines.Count == 0)
{
return;
}

var top = 0d;
var left = 0.0;

var textHeight = TextLayout.Height;

Expand All @@ -402,7 +441,17 @@ private void RenderInternal(DrawingContext context)
}
}

TextLayout.Draw(context, new Point(left, top));
var controlWidth = Bounds.Width;
var textAlignment = GetResolvedTextAlignment();

var currentY = top;

foreach (var line in TextLayout.TextLines)
{
var offsetX = GetLineOffsetX(line, controlWidth, textAlignment);
line.Draw(context, new Point(offsetX, currentY));
currentY += line.Height;
}
}

public sealed override void Render(DrawingContext context)
Expand All @@ -417,10 +466,35 @@ public sealed override void Render(DrawingContext context)
var length = Math.Max(selectionStart, selectionEnd) - start;

var rects = TextLayout.HitTestTextRange(start, length);

var controlWidth = Bounds.Width;
var textAlignment = GetResolvedTextAlignment();

foreach (var rect in rects)
{
context.FillRectangle(selectionBrush, PixelRect.FromRect(rect, 1).ToRect(1));
var currentY = 0d;
TextLine? targetLine = null;

foreach (var line in TextLayout.TextLines)
{
if (currentY + line.Height > rect.Y)
{
targetLine = line;
break;
}
currentY += line.Height;
}

if (targetLine != null)
{
var offsetX = GetLineOffsetX(targetLine, controlWidth, textAlignment);
var transformedRect = rect.WithX(rect.X + offsetX);
context.FillRectangle(selectionBrush, PixelRect.FromRect(transformedRect, 1).ToRect(1));
}
else
{
context.FillRectangle(selectionBrush, PixelRect.FromRect(rect, 1).ToRect(1));
}
}
}

Expand Down Expand Up @@ -472,11 +546,18 @@ public sealed override void Render(DrawingContext context)
var lineIndex = TextLayout.GetLineIndexFromCharacterIndex(caretIndex, _lastCharacterHit.TrailingLength > 0);
var textLine = TextLayout.TextLines[lineIndex];

var x = Math.Floor(_caretBounds.X) + 0.5;
var caretX = Math.Max(0, _caretBounds.X);

var x = Math.Floor(caretX) + 0.5;
var y = Math.Floor(_caretBounds.Y) + 0.5;
var b = Math.Ceiling(_caretBounds.Bottom) - 0.5;

if (_caretBounds.X > 0 && _caretBounds.X >= textLine.WidthIncludingTrailingWhitespace)
var controlWidth = Bounds.Width;
var textAlignment = GetResolvedTextAlignment();
var offsetX = GetLineOffsetX(textLine, controlWidth, textAlignment);
var lineEndX = textLine.WidthIncludingTrailingWhitespace + offsetX + textLine.Start;

if (caretX > 0 && caretX >= lineEndX)
{
x -= 1;
}
Expand Down Expand Up @@ -646,17 +727,34 @@ 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;
var maxLeadingOverhang = 0.0;
var maxTrailingOverhang = 0.0;

foreach (var line in TextLayout.TextLines)
{
maxLeadingOverhang = Math.Max(maxLeadingOverhang, -Math.Min(0, line.OverhangLeading));
maxTrailingOverhang = Math.Max(maxTrailingOverhang, -Math.Min(0, line.OverhangTrailing));
}

var textWidth = TextLayout.WidthIncludingTrailingWhitespace + maxLeadingOverhang + maxTrailingOverhang;

return new Size(textWidth, TextLayout.Height);
}

protected override Size ArrangeOverride(Size finalSize)
{
var finalWidth = finalSize.Width;

var textWidth = TextLayout.OverhangLeading + TextLayout.WidthIncludingTrailingWhitespace + TextLayout.OverhangTrailing;
textWidth = Math.Ceiling(textWidth);
var maxLeadingOverhang = 0.0;
var maxTrailingOverhang = 0.0;

foreach (var line in TextLayout.TextLines)
{
maxLeadingOverhang = Math.Max(maxLeadingOverhang, -Math.Min(0, line.OverhangLeading));
maxTrailingOverhang = Math.Max(maxTrailingOverhang, -Math.Min(0, line.OverhangTrailing));
}

var textWidth = Math.Ceiling(TextLayout.WidthIncludingTrailingWhitespace + maxLeadingOverhang + maxTrailingOverhang);

if (finalSize.Width < textWidth)
{
Expand Down Expand Up @@ -715,14 +813,46 @@ public void MoveCaretToTextPosition(int textPosition, bool trailingEdge = false)

public void MoveCaretToPoint(Point point)
{
var hit = TextLayout.HitTestPoint(point);
var transformedPoint = TransformPointToTextLayout(point);

var hit = TextLayout.HitTestPoint(transformedPoint);

UpdateCaret(hit.CharacterHit);

_navigationPosition = _caretBounds.Position;

CaretChanged();
}

private Point TransformPointToTextLayout(Point point)
{
if (TextLayout.TextLines.Count == 0)
{
return point;
}

var controlWidth = Bounds.Width;
var textAlignment = GetResolvedTextAlignment();

var currentY = 0d;
TextLine? targetLine = null;

foreach (var line in TextLayout.TextLines)
{
if (currentY + line.Height > point.Y)
{
targetLine = line;
break;
}
currentY += line.Height;
}

targetLine ??= TextLayout.TextLines[TextLayout.TextLines.Count - 1];

var offsetX = GetLineOffsetX(targetLine, controlWidth, textAlignment);

return new Point(point.X - offsetX, point.Y);
}

public void MoveCaretVertical(LogicalDirection direction = LogicalDirection.Forward)
{
Expand Down Expand Up @@ -917,7 +1047,11 @@ internal void UpdateCaret(CharacterHit characterHit, bool notify = true)
distanceY += currentLine.Height;
}

var caretBounds = new Rect(distanceX, distanceY, 0, textLine.Height);
var controlWidth = Bounds.Width;
var textAlignment = GetResolvedTextAlignment();
var offsetX = GetLineOffsetX(textLine, controlWidth, textAlignment);

var caretBounds = new Rect(distanceX + offsetX, distanceY, 0, textLine.Height);

if (caretBounds != _caretBounds)
{
Expand Down
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