float CanvasRenderingContext2D::getFontBaseline(
const FontMetrics& fontMetrics) const {
// If the font is so tiny that the lroundf operations result in two
// different types of text baselines to return the same baseline, use
// floating point metrics (crbug.com/338908).
// If you changed the heuristic here, for consistency please also change it
// in SimpleFontData::platformInit().
bool useFloatAscentDescent =
fontMetrics.ascent() < 3 || fontMetrics.height() < 2;
switch (state().getTextBaseline()) {
case TopTextBaseline:
return useFloatAscentDescent ? fontMetrics.floatAscent()
: fontMetrics.ascent();
case HangingTextBaseline:
// According to
// http://wiki.apache.org/xmlgraphics-fop/LineLayout/AlignmentHandling
// "FOP (Formatting Objects Processor) puts the hanging baseline at 80% of
// the ascender height"
return useFloatAscentDescent ? (fontMetrics.floatAscent() * 4.0) / 5.0
: (fontMetrics.ascent() * 4) / 5;
case BottomTextBaseline:
case IdeographicTextBaseline:
return useFloatAscentDescent ? -fontMetrics.floatDescent()
: -fontMetrics.descent();
case MiddleTextBaseline:
return useFloatAscentDescent
? -fontMetrics.floatDescent() + fontMetrics.floatHeight() / 2.0
: -fontMetrics.descent() + fontMetrics.height() / 2;
case AlphabeticTextBaseline:
default:
// Do nothing.
break;
}
return 0;
}
std::string Font::clipped_text(const CanvasPtr &canvas, const Sizef &box_size, const std::string &text, const std::string &ellipsis_text)
{
std::string out_string;
out_string.reserve(text.length());
Pointf pos;
FontMetrics fm = font_metrics(canvas);
float descent = fm.descent();
float line_spacing = fm.line_height();
std::vector<std::string> lines = Text::split(text, "\n", false);
for (std::vector<std::string>::size_type i = 0; i < lines.size(); i++)
{
if (i == 0 || pos.y + descent < box_size.height)
{
Sizef size = measure_text(canvas, lines[i]).bbox_size;
if (pos.x + size.width <= box_size.width)
{
if (!out_string.empty())
out_string += "\n";
out_string += lines[i];
}
else
{
Sizef ellipsis = measure_text(canvas, ellipsis_text).bbox_size;
int seek_start = 0;
int seek_end = lines[i].size();
int seek_center = (seek_start + seek_end) / 2;
UTF8_Reader utf8_reader(lines[i].data(), lines[i].length());
while (true)
{
utf8_reader.set_position(seek_center);
utf8_reader.move_to_leadbyte();
if (seek_center != utf8_reader.position())
utf8_reader.next();
seek_center = utf8_reader.position();
if (seek_center == seek_end)
break;
utf8_reader.set_position(seek_start);
utf8_reader.next();
if (utf8_reader.position() == seek_end)
break;
Sizef text_size = measure_text(canvas, lines[i].substr(0, seek_center)).bbox_size;
if (pos.x + text_size.width + ellipsis.width >= box_size.width)
seek_end = seek_center;
else
seek_start = seek_center;
seek_center = (seek_start + seek_end) / 2;
}
if (!out_string.empty())
out_string += "\n";
out_string += lines[i].substr(0, seek_center) + ellipsis_text;
}
pos.y += line_spacing;
}
}
return out_string;
}