1 files changed, 44 insertions, 0 deletions
diff --git a/gfx/cairo/dwrite-glyph-extents.patch b/gfx/cairo/dwrite-glyph-extents.patch
new file mode 100644
index 0000000000..d3625e1986
--- /dev/null
+++ b/gfx/cairo/dwrite-glyph-extents.patch
@@ -0,0 +1,44 @@
+diff --git a/gfx/cairo/cairo/src/cairo-dwrite-font.cpp b/gfx/cairo/cairo/src/cairo-dwrite-font.cpp
+--- a/gfx/cairo/cairo/src/cairo-dwrite-font.cpp
++++ b/gfx/cairo/cairo/src/cairo-dwrite-font.cpp
+@@ -582,22 +582,37 @@ _cairo_dwrite_scaled_font_init_glyph_met
+     DWRITE_FONT_METRICS fontMetrics;
+     font_face->dwriteface->GetMetrics(&fontMetrics);
+     HRESULT hr = font_face->dwriteface->GetDesignGlyphMetrics(&charIndex, 1, &metrics);
+     if (FAILED(hr)) {
+ 	return CAIRO_INT_STATUS_UNSUPPORTED;
+     }
+ 
+     // TODO: Treat swap_xy.
+-    extents.width = (FLOAT)(metrics.advanceWidth - metrics.leftSideBearing - metrics.rightSideBearing) / fontMetrics.designUnitsPerEm;
+-    extents.height = (FLOAT)(metrics.advanceHeight - metrics.topSideBearing - metrics.bottomSideBearing) / fontMetrics.designUnitsPerEm;
++    extents.width = (FLOAT)(metrics.advanceWidth - metrics.leftSideBearing - metrics.rightSideBearing) /
++        fontMetrics.designUnitsPerEm;
++    extents.height = (FLOAT)(metrics.advanceHeight - metrics.topSideBearing - metrics.bottomSideBearing) /
++        fontMetrics.designUnitsPerEm;
+     extents.x_advance = (FLOAT)metrics.advanceWidth / fontMetrics.designUnitsPerEm;
+     extents.x_bearing = (FLOAT)metrics.leftSideBearing / fontMetrics.designUnitsPerEm;
+     extents.y_advance = 0.0;
+-    extents.y_bearing = (FLOAT)(metrics.topSideBearing - metrics.verticalOriginY) / fontMetrics.designUnitsPerEm;
++    extents.y_bearing = (FLOAT)(metrics.topSideBearing - metrics.verticalOriginY) /
++        fontMetrics.designUnitsPerEm;
++
++    // We pad the extents here because GetDesignGlyphMetrics returns "ideal" metrics
++    // for the glyph outline, without accounting for hinting/gridfitting/antialiasing,
++    // and therefore it does not always cover all pixels that will actually be touched.
++    if (scaled_font->base.options.antialias != CAIRO_ANTIALIAS_NONE &&
++        extents.width > 0 && extents.height > 0) {
++        extents.width += scaled_font->mat_inverse.xx * 2;
++        extents.x_bearing -= scaled_font->mat_inverse.xx;
++        extents.height += scaled_font->mat_inverse.yy * 2;
++        extents.y_bearing -= scaled_font->mat_inverse.yy;
++    }
++
+     _cairo_scaled_glyph_set_metrics (scaled_glyph,
+ 				     &scaled_font->base,
+ 				     &extents);
+     return CAIRO_INT_STATUS_SUCCESS;
+ }
+ 
+ /**
+  * Stack-based helper implementing IDWriteGeometrySink.