Add Paint.hasGlyph method
This patch adds a method to determine whether a typeface has a glyph
to support a particular Unicode character or sequence.
The implementation is based on shaping the text and checking for the
presence of .notdef glyphs, and counting the number of glyphs in the
ligature case. In the case of variation selector control characters, it
currently just returns false because there is no variation selector
support yet (Mongolian Free Variation Selectors work because they're
shaped with GSUB instead).
Change-Id: I8ee4ae0d6e81a0ac57f961eb02dcc35aabd87042
diff --git a/core/jni/android/graphics/Paint.cpp b/core/jni/android/graphics/Paint.cpp
index 4b43de3..873b516 100644
--- a/core/jni/android/graphics/Paint.cpp
+++ b/core/jni/android/graphics/Paint.cpp
@@ -23,6 +23,7 @@
#include "GraphicsJNI.h"
#include "core_jni_helpers.h"
#include <ScopedUtfChars.h>
+#include <ScopedStringChars.h>
#include "SkBlurDrawLooper.h"
#include "SkColorFilter.h"
@@ -41,6 +42,8 @@
#include "Paint.h"
#include "TypefaceImpl.h"
+#include <vector>
+
// temporary for debugging
#include <Caches.h>
#include <utils/Log.h>
@@ -972,6 +975,68 @@
JNI_ABORT);
}
+ static jboolean layoutContainsNotdef(const Layout& layout) {
+ for (size_t i = 0; i < layout.nGlyphs(); i++) {
+ if (layout.getGlyphId(i) == 0) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ static jboolean hasGlyphVariation(const Paint* paint, TypefaceImpl* typeface, jint bidiFlags,
+ const jchar* chars, size_t size) {
+ // TODO: query font for whether character has variation selector; requires a corresponding
+ // function in Minikin.
+ return false;
+ }
+
+ static jboolean hasGlyph(JNIEnv *env, jclass, jlong paintHandle, jlong typefaceHandle,
+ jint bidiFlags, jstring string) {
+ const Paint* paint = reinterpret_cast<Paint*>(paintHandle);
+ TypefaceImpl* typeface = reinterpret_cast<TypefaceImpl*>(typefaceHandle);
+ ScopedStringChars str(env, string);
+
+ /* start by rejecting variation selectors (not supported yet) */
+ size_t nChars = 0;
+ for (size_t i = 0; i < str.size(); i++) {
+ jchar c = str[i];
+ if (0xDC00 <= c && c <= 0xDFFF) {
+ // invalid UTF-16, unpaired trailing surrogate
+ return false;
+ } else if (0xD800 <= c && c <= 0xDBFF) {
+ if (i + 1 == str.size()) {
+ // invalid UTF-16, unpaired leading surrogate at end of string
+ return false;
+ }
+ i++;
+ jchar c2 = str[i];
+ if (!(0xDC00 <= c2 && c2 <= 0xDFFF)) {
+ // invalid UTF-16, unpaired leading surrogate
+ return false;
+ }
+ // UTF-16 encoding of range U+E0100..U+E01EF is DB40 DD00 .. DB40 DDEF
+ if (c == 0xDB40 && 0xDD00 <= c2 && c2 <= 0xDDEF) {
+ return hasGlyphVariation(paint, typeface, bidiFlags, str.get(), str.size());
+ }
+ } else if (0xFE00 <= c && c <= 0xFE0F) {
+ return hasGlyphVariation(paint, typeface, bidiFlags, str.get(), str.size());
+ }
+ nChars++;
+ }
+ Layout layout;
+ MinikinUtils::doLayout(&layout, paint, bidiFlags, typeface, str.get(), 0, str.size(),
+ str.size());
+ size_t nGlyphs = layout.nGlyphs();
+ if (nGlyphs != 1 && nChars > 1) {
+ // multiple-character input, and was not a ligature
+ // TODO: handle ZWJ/ZWNJ characters specially so we can detect certain ligatures
+ // in joining scripts, such as Arabic and Mongolian.
+ return false;
+ }
+ return nGlyphs > 0 && !layoutContainsNotdef(layout);
+ }
+
};
static JNINativeMethod methods[] = {
@@ -1057,6 +1122,7 @@
(void*) PaintGlue::getStringBounds },
{"nativeGetCharArrayBounds", "(JJ[CIIILandroid/graphics/Rect;)V",
(void*) PaintGlue::getCharArrayBounds },
+ {"native_hasGlyph", "(JJILjava/lang/String;)Z", (void*) PaintGlue::hasGlyph },
{"native_setShadowLayer", "!(JFFFI)V", (void*)PaintGlue::setShadowLayer},
{"native_hasShadowLayer", "!(J)Z", (void*)PaintGlue::hasShadowLayer}