I got a step further with this issue, that some content can be displayed
on Win7, but not on XP.
The actual error happens in drawGlyphsToContext(cr, font, glyphs,
numGlyphs), when 0 is passed as the cr argument.
in FontCairo.cpp, there is a statement in Font::drawGlyphs that says:
cairo_t* cr = platformContext->cr();
I assume that this should return a valid context (m_cr), but in my case
it returns a null pointer. And as this context is used in further calls,
all these cairo calls fail, some gracefully, the last one with the
access violation in pixman called from the cairo,dll.
Does anybody know why the cr is 0x00, when the platformContext.m_cr
seems to be a valid context? And this only on Windows XP?
Any comments are welcome
Thomas
=================================================================
void Font::drawGlyphs(GraphicsContext* context, const SimpleFontData*
font, const GlyphBuffer& glyphBuffer,
int from, int numGlyphs, const FloatPoint& point)
const
{
if (!font->platformData().size())
return;
GlyphBufferGlyph* glyphs =
const_cast<GlyphBufferGlyph*>(glyphBuffer.glyphs(from));
float offset = point.x();
for (int i = 0; i < numGlyphs; i++) {
glyphs[i].x = offset;
glyphs[i].y = point.y();
offset += glyphBuffer.advanceAt(from + i);
}
PlatformContextCairo* platformContext = context->platformContext();
drawGlyphsShadow(context, point, font, glyphs, numGlyphs);
cairo_t* cr = platformContext->cr();
/*** here cr is 0x00000000 ***/
cairo_save(cr);
if (context->textDrawingMode() & TextModeFill) {
platformContext->prepareForFilling(context->state(),
PlatformContextCairo::AdjustPatternForGlobalAlpha);
drawGlyphsToContext(cr, font, glyphs, numGlyphs);
}
// Prevent running into a long computation within cairo. If the
stroke width is
// twice the size of the width of the text we will not ask cairo to
stroke
// the text as even one single stroke would cover the full wdth of
the text.
// See https://bugs.webkit.org/show_bug.cgi?id=33759.
if (context->textDrawingMode() & TextModeStroke &&
context->strokeThickness() < 2 * offset) {
platformContext->prepareForStroking(context->state());
cairo_set_line_width(cr, context->strokeThickness());
// This may disturb the CTM, but we are going to call
cairo_restore soon after.
cairo_set_scaled_font(cr, font->platformData().scaledFont());
cairo_glyph_path(cr, glyphs, numGlyphs);
cairo_stroke(cr);
}
cairo_restore(cr);
}
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