tei/MapLibreParticleLab
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[core][qt] Check if QFont supports glyph and adjust backing image width

Browse Source 
- Don't rasterize glyphs if font does not support requested code point
- Render symbols at hardcoded baseline, so that locally rasterized glyphs
  align better with server side generated fonts.
- Resize backing QImage width to be at least 24px
This commit is contained in:
Alexander Shalamov
2019-08-23 18:34:26 +03:00
parent e3795f2a5c
commit 5d316a8076
1 changed files with 16 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
platform/qt/src/local_glyph_rasterizer.cpp
View File

@@ -1,5 +1,6 @@
#include <mbgl/text/local_glyph_rasterizer.hpp>
#include <mbgl/util/i18n.hpp>
#include <mbgl/util/constants.hpp>
#include <QtCore/QFile>
#include <QtGui/QFont>
@@ -17,13 +18,15 @@ public:
optional<std::string> fontFamily;
QFont font;
optional<QFontMetrics> metrics;
};
LocalGlyphRasterizer::Impl::Impl(const optional<std::string> fontFamily_)
: fontFamily(fontFamily_) {
if (isConfigured()) {
font.setFamily(QString::fromStdString(*fontFamily));
font.setPixelSize(24);
font.setPixelSize(util::ONE_EM);
metrics = QFontMetrics(font);
}
}
@@ -39,29 +42,33 @@ LocalGlyphRasterizer::~LocalGlyphRasterizer() {
}
bool LocalGlyphRasterizer::canRasterizeGlyph(const FontStack&, GlyphID glyphID) {
return util::i18n::allowsFixedWidthGlyphGeneration(glyphID) && impl->isConfigured();
return impl->isConfigured() && impl->metrics->inFont(glyphID) && util::i18n::allowsFixedWidthGlyphGeneration(glyphID);
}
Glyph LocalGlyphRasterizer::rasterizeGlyph(const FontStack&, GlyphID glyphID) {
Glyph glyph;
glyph.id = glyphID;
QFontMetrics metrics(impl->font);
Size size(metrics.width(glyphID), metrics.height());
if (!impl->isConfigured()) {
assert(false);
return glyph;
}
glyph.metrics.width = size.width;
glyph.metrics.height = size.height;
glyph.metrics.width = impl->metrics->width(glyphID);
glyph.metrics.height = impl->metrics->height();
glyph.metrics.left = 3;
glyph.metrics.top = -8;
glyph.metrics.advance = metrics.width(glyphID);
glyph.metrics.advance = glyph.metrics.width;
// Set width of a glyph's backing image to be util::ONE_EM.
Size size(util::ONE_EM, glyph.metrics.height);
QImage image(QSize(size.width, size.height), QImage::Format_Alpha8);
image.fill(qRgba(0, 0, 0, 0));
QPainter painter(&image);
painter.setFont(impl->font);
painter.setRenderHints(QPainter::TextAntialiasing);
painter.drawText(QPointF(0, metrics.ascent()), QString(QChar(glyphID)));
// Render at constant baseline, to align with glyphs that are rendered by node-fontnik.
painter.drawText(QPointF(0, 20), QString(QChar(glyphID)));
auto img = std::make_unique<uint8_t[]>(image.byteCount());
memcpy(img.get(), image.constBits(), image.byteCount());