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Fix missing thin outlines in BDN XML / Blu-ray SUP export #12372

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Merged
niksedk merged 1 commit into from
Jul 11, 2026
+49 −6
Merged

Fix missing thin outlines in BDN XML / Blu-ray SUP export #12372

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55 changes: 49 additions & 6 deletions src/libuilogic/Export/ImageRenderer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,16 @@ public static SKBitmap GenerateBitmap(ImageParameter ip)
using var italicFont = new SKFont(ip.IsBold ? boldItalicTypeface : italicTypeface, fontSize);
using var boldItalicFont = new SKFont(boldItalicTypeface, fontSize);

// Hinting snaps glyph edges to the pixel grid, which breaks the registration
// between the fill and the outline stroked from the raw glyph path - thin
// outlines then vanish on horizontal edges (issue #12206). Export renders at
// video resolution, so hinting is not needed.
foreach (var font in new[] { regularFont, boldFont, italicFont, boldItalicFont })
{
font.Hinting = SKFontHinting.None;
font.Subpixel = true;
}

// Split segments into lines
var lines = SplitIntoSegments(segments);

Expand Down Expand Up @@ -320,25 +330,35 @@ private static void RenderTextToCanvas(
var segment = segmentsToRender[i];
var currentFont = GetFont(segment, regularFont, boldFont, italicFont, boldItalicFont);

// Outlines are stroked on the raw glyph path with doubled width: the fill
// drawn on top covers the inner half, so the visible outline matches the
// requested width. Stroking through the glyph rasterizer instead loses thin
// horizontal outline edges entirely (issue #12206).
using var textPath = outlineWidth > 0
? GetShapedTextPath(segment.Text, currentX, textStartY + currentY, currentFont)
: null;

// Draw shadow first (if shadow width > 0)
if (shadowWidth > 0)
{
var shadowOffsetX = currentX + (float)shadowWidth;
var shadowOffsetY = textStartY + currentY + (float)shadowWidth;

if (outlineWidth > 0)
if (textPath != null)
{
using var shadowOutlinePaint = new SKPaint
{
Color = shadowColor,
IsAntialias = true,
Style = SKPaintStyle.Stroke,
StrokeWidth = (float)outlineWidth,
StrokeWidth = (float)outlineWidth * 2,
StrokeJoin = SKStrokeJoin.Round,
StrokeCap = SKStrokeCap.Round,
};

DrawShapedText(canvas, segment.Text, shadowOffsetX, shadowOffsetY, currentFont, shadowOutlinePaint);
using var shadowPath = new SKPath(textPath);
shadowPath.Offset((float)shadowWidth, (float)shadowWidth);
canvas.DrawPath(shadowPath, shadowOutlinePaint);
}

using var shadowTextPaint = new SKPaint
Expand All @@ -352,19 +372,19 @@ private static void RenderTextToCanvas(
}

// Draw outline second (if outline width > 0)
if (outlineWidth > 0)
if (textPath != null)
{
using var outlinePaint = new SKPaint
{
Color = outlineColor,
IsAntialias = true,
Style = SKPaintStyle.Stroke,
StrokeWidth = (float)outlineWidth,
StrokeWidth = (float)outlineWidth * 2,
StrokeJoin = SKStrokeJoin.Round,
StrokeCap = SKStrokeCap.Round,
};

DrawShapedText(canvas, segment.Text, currentX, textStartY + currentY, currentFont, outlinePaint);
canvas.DrawPath(textPath, outlinePaint);
}

// Draw the main text on top
Expand Down Expand Up @@ -413,6 +433,29 @@ private static void DrawShapedText(SKCanvas canvas, string text, float x, float
canvas.DrawShapedText(shaper, text, x, y, SKTextAlign.Left, font, paint);
}

// Builds the combined glyph outline path for shaped text, positioned like
// DrawShapedText draws it. Glyphs without an outline (whitespace, color emoji)
// are skipped - they get no stroke, but the fill still renders them.
private static SKPath GetShapedTextPath(string text, float x, float y, SKFont font)
{
using var shaper = new SKShaper(font.Typeface);
var result = shaper.Shape(text, x, y, font);

var path = new SKPath();
for (var i = 0; i < result.Codepoints.Length; i++)
{
using var glyphPath = font.GetGlyphPath((ushort)result.Codepoints[i]);
if (glyphPath == null || glyphPath.IsEmpty)
{
continue;
}

path.AddPath(glyphPath, result.Points[i].X, result.Points[i].Y);
}

return path;
}

private static SKFont GetFont(TextSegment segment, SKFont regular, SKFont bold, SKFont italic, SKFont boldItalic)
{
if (segment.IsBold && segment.IsItalic)
Expand Down