1 files changed, 126 insertions, 0 deletions
diff --git a/platform/android/src/text/local_glyph_rasterizer.cpp b/platform/android/src/text/local_glyph_rasterizer.cpp
new file mode 100644
index 0000000000..ce1b0fc8fd
--- /dev/null
+++ b/platform/android/src/text/local_glyph_rasterizer.cpp
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+#include <mbgl/text/local_glyph_rasterizer.hpp>
+#include <mbgl/util/i18n.hpp>
+#include <mbgl/util/platform.hpp>
+
+#include <jni/jni.hpp>
+
+#include "../attach_env.hpp"
+#include "../bitmap.hpp"
+
+#include "local_glyph_rasterizer_jni.hpp"
+
+/*
+    Android implementation of LocalGlyphRasterizer:
+     Draws CJK glyphs using locally available fonts.
+
+    Follows pattern of GL JS implementation in that:
+     - Only CJK glyphs are drawn locally (because we can guess their metrics effectively)
+        * Render size/metrics determined experimentally using Noto Sans
+     - Configuration is done at map creation time by setting a "font family"
+        * JS uses a CSS font-family, this uses android.graphics.Typeface
+          https://developer.android.com/reference/android/graphics/Typeface.html
+     - We use heuristics to extract a font-weight based on the incoming font stack
+        * JS tries to extract multiple weights, this implementation only looks for
+          "bold"
+
+     mbgl::LocalGlyphRasterizer is the portable interface
+     mbgl::LocalGlyphRasterizer::Impl stores platform-specific configuration data
+     mbgl::android::LocalGlyphRasterizer is the JNI wrapper
+     com.mapbox.mapboxsdk.text.LocalGlyphRasterizer is the Java implementation that
+      actually does the drawing
+ */
+
+namespace mbgl {
+namespace android {
+
+PremultipliedImage LocalGlyphRasterizer::drawGlyphBitmap(const std::string& fontFamily, const bool bold, const GlyphID glyphID) {
+    UniqueEnv env { AttachEnv() };
+
+    using Signature = jni::Object<Bitmap>(jni::String, jni::jboolean, jni::jchar);
+    auto method = javaClass.GetStaticMethod<Signature>(*env, "drawGlyphBitmap");
+
+    jni::String jniFontFamily = jni::Make<jni::String>(*env, fontFamily);
+
+    auto javaBitmap = javaClass.Call(*env,
+                                     method,
+                                     jniFontFamily,
+                                     static_cast<jni::jboolean>(bold),
+                                     static_cast<jni::jchar>(glyphID));
+
+    PremultipliedImage result = Bitmap::GetImage(*env, javaBitmap);
+    jni::DeleteLocalRef(*env, javaBitmap);
+    return result;
+}
+
+void LocalGlyphRasterizer::registerNative(jni::JNIEnv& env) {
+    javaClass = *jni::Class<LocalGlyphRasterizer>::Find(env).NewGlobalRef(env).release();
+}
+
+jni::Class<LocalGlyphRasterizer> LocalGlyphRasterizer::javaClass;
+
+} // namespace android
+
+class LocalGlyphRasterizer::Impl {
+public:
+    Impl(const optional<std::string> fontFamily_)
+        : fontFamily(fontFamily_)
+    {}
+
+    bool isConfigured() const {
+        return bool(fontFamily);
+    }
+
+    PremultipliedImage drawGlyphBitmap(const FontStack& fontStack, GlyphID glyphID) {
+        bool bold = false;
+        for (auto font : fontStack) {
+            std::string lowercaseFont = platform::lowercase(font);
+            if (lowercaseFont.find("bold") != std::string::npos) {
+                bold = true;
+            }
+        }
+        return android::LocalGlyphRasterizer::drawGlyphBitmap(*fontFamily, bold, glyphID);
+    }
+
+private:
+    optional<std::string> fontFamily;
+};
+
+LocalGlyphRasterizer::LocalGlyphRasterizer(const optional<std::string> fontFamily)
+    : impl(std::make_unique<Impl>(fontFamily))
+{}
+
+LocalGlyphRasterizer::~LocalGlyphRasterizer()
+{}
+
+bool LocalGlyphRasterizer::canRasterizeGlyph(const FontStack&, GlyphID glyphID) {
+     return util::i18n::allowsFixedWidthGlyphGeneration(glyphID) && impl->isConfigured();
+}
+
+Glyph LocalGlyphRasterizer::rasterizeGlyph(const FontStack& fontStack, GlyphID glyphID) {
+    Glyph fixedMetrics;
+    if (!impl->isConfigured()) {
+        return fixedMetrics;
+    }
+
+    fixedMetrics.id = glyphID;
+
+    Size size(35, 35);
+
+    fixedMetrics.metrics.width = size.width;
+    fixedMetrics.metrics.height = size.height;
+    fixedMetrics.metrics.left = 3;
+    fixedMetrics.metrics.top = -10;
+    fixedMetrics.metrics.advance = 24;
+
+    PremultipliedImage rgbaBitmap = impl->drawGlyphBitmap(fontStack, glyphID);
+
+    // 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++) {
+        fixedMetrics.bitmap.data[i] = rgbaBitmap.data[4 * i + 3];
+    }
+
+    return fixedMetrics;
+}
+
+} // namespace mbgl