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feat(core): render local CJK glyphs at 2x texture resolution (#4304)

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Bart Louwers <bart@emeel.net>
This commit is contained in:
Taku Fukada
2026-07-01 20:52:01 +09:00
committed by GitHub
parent 60f15190c3
commit 887e6021e6
22 changed files with 357 additions and 84 deletions
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36
platform/android/MapLibreAndroid/src/cpp/text/local_glyph_rasterizer.cpp
View File

@@ -59,6 +59,15 @@ PremultipliedImage LocalGlyphRasterizer::drawGlyphBitmap(const std::string& font
static_cast<jni::jchar>(glyphID)));
}
float LocalGlyphRasterizer::getLastGlyphTop() {
UniqueEnv env{AttachEnv()};
static auto& javaClass = jni::Class<LocalGlyphRasterizer>::Singleton(*env);
static auto getLastGlyphTop = javaClass.GetMethod<jni::jfloat()>(*env, "getLastGlyphTop");
return javaObject.Call(*env, getLastGlyphTop);
}
void LocalGlyphRasterizer::registerNative(jni::JNIEnv& env) {
jni::Class<LocalGlyphRasterizer>::Singleton(env);
}
@@ -84,6 +93,8 @@ public:
return androidLocalGlyphRasterizer.drawGlyphBitmap(*fontFamily, bold, glyphID);
}
float getLastGlyphTop() { return androidLocalGlyphRasterizer.getLastGlyphTop(); }
private:
std::optional<std::string> fontFamily;
android::LocalGlyphRasterizer androidLocalGlyphRasterizer;
@@ -98,6 +109,11 @@ bool LocalGlyphRasterizer::canRasterizeGlyph(const FontStack&, GlyphID glyphID)
return util::i18n::allowsFixedWidthGlyphGeneration(glyphID) && impl->isConfigured();
}
// 2x bitmap with 1x logical metrics.
constexpr uint32_t kLocalGlyphTextureScale = 2;
constexpr uint32_t kLocalGlyphLogicalSize = 30;
constexpr uint32_t kLocalGlyphBitmapSize = kLocalGlyphLogicalSize * kLocalGlyphTextureScale;
Glyph LocalGlyphRasterizer::rasterizeGlyph(const FontStack& fontStack, GlyphID glyphID) {
Glyph fixedMetrics;
if (!impl->isConfigured()) {
@@ -106,19 +122,21 @@ Glyph LocalGlyphRasterizer::rasterizeGlyph(const FontStack& fontStack, GlyphID g
fixedMetrics.id = glyphID;
Size size(35, 35);
fixedMetrics.metrics.width = size.width;
fixedMetrics.metrics.height = size.height;
fixedMetrics.metrics.left = -2;
fixedMetrics.metrics.top = -5;
// Metrics are reported in 1x logical units; the bitmap is allocated at 2x.
fixedMetrics.metrics.width = kLocalGlyphLogicalSize;
fixedMetrics.metrics.height = kLocalGlyphLogicalSize;
fixedMetrics.metrics.left = -1.5f;
fixedMetrics.metrics.advance = 24;
fixedMetrics.metrics.isDoubleResolution = true;
PremultipliedImage rgbaBitmap = impl->drawGlyphBitmap(fontStack, glyphID);
fixedMetrics.metrics.top = impl->getLastGlyphTop();
// Copy alpha values from RGBA bitmap into the AlphaImage output
fixedMetrics.bitmap = AlphaImage(size);
for (uint32_t i = 0; i < size.width * size.height; i++) {
// Copy alpha values from RGBA bitmap into the AlphaImage output. The Java side
// produces a kLocalGlyphBitmapSize x kLocalGlyphBitmapSize bitmap.
const Size bitmapSize(kLocalGlyphBitmapSize, kLocalGlyphBitmapSize);
fixedMetrics.bitmap = AlphaImage(bitmapSize);
for (uint32_t i = 0; i < bitmapSize.width * bitmapSize.height; i++) {
fixedMetrics.bitmap.data[i] = 0xff -
round(0.2126 * rgbaBitmap.data[4 * i] + 0.7152 * rgbaBitmap.data[4 * i + 1] +
0.0722 * rgbaBitmap.data[4 * i + 2]);

3
platform/android/MapLibreAndroid/src/cpp/text/local_glyph_rasterizer_jni.hpp
View File

@@ -4,6 +4,8 @@
#include <jni/jni.hpp>
#include <cstdint>
/*
android::LocalGlyphRasterizer is the JNI wrapper of
org/maplibre/android/text/LocalGlyphRasterizer
@@ -24,6 +26,7 @@ public:
LocalGlyphRasterizer();
PremultipliedImage drawGlyphBitmap(const std::string& fontFamily, const bool bold, const char16_t glyphID);
float getLastGlyphTop();
private:
jni::Global<jni::Object<LocalGlyphRasterizer>, jni::EnvAttachingDeleter> javaObject;