SkPDF: SkShaper_primitive uses new textblob API

tools/SkShaper_primitive.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkShaper.h"
 #include "SkStream.h"
 #include "SkTextBlob.h"
 #include "SkTypeface.h"
 
 struct SkShaper::Impl {
     sk_sp<SkTypeface> fTypeface;
 };
 
 SkShaper::SkShaper(sk_sp<SkTypeface> tf) : fImpl(new Impl) {
     fImpl->fTypeface = tf ? std::move(tf) : SkTypeface::MakeDefault();
 }
 
 SkShaper::~SkShaper() {}
 
 bool SkShaper::good() const { return true; }
 
+// This example only uses public API, so we don't use SkUTF8_NextUnichar.
+unsigned utf8_lead_byte_to_count(const char* ptr) {
+    uint8_t c = *(const uint8_t*)ptr;
+    SkASSERT(c <= 0xF7);
+    SkASSERT((c & 0xC0) != 0x80);
+    return (((0xE5 << 24) >> ((unsigned)c >> 4 << 1)) & 3) + 1;
+}
+
 SkScalar SkShaper::shape(SkTextBlobBuilder* builder,
                          const SkPaint& srcPaint,
                          const char* utf8text,
                          size_t textBytes,
                          SkPoint point) const {
     SkPaint paint(srcPaint);
     paint.setTypeface(fImpl->fTypeface);
     paint.setTextEncoding(SkPaint::kUTF8_TextEncoding);
     int glyphCount = paint.countText(utf8text, textBytes);
     if (glyphCount <= 0) {
         return 0;
     }
     SkRect bounds;
     (void)paint.measureText(utf8text, textBytes, &bounds);
     paint.setTextEncoding(SkPaint::kGlyphID_TextEncoding);
-    const SkTextBlobBuilder::RunBuffer& runBuffer = builder->allocRunPosH(
-            paint, glyphCount, point.y(), &bounds);
+    const SkTextBlobBuilder::RunBuffer& runBuffer =
+        builder->allocRunTextPosH(paint, glyphCount, point.y(), textBytes, SkString(), &bounds);
+    memcpy(runBuffer.utf8text, utf8text, textBytes);
+    const char* txtPtr = utf8text;
+    for (int i = 0; i < glyphCount; ++i) {
+        // Each charater maps to exactly one glyph via SkGlyphCache::unicharToGlyph().
+        runBuffer.clusters[i] = SkToU32(txtPtr - utf8text);
+        txtPtr += utf8_lead_byte_to_count(txtPtr);
+        SkASSERT(txtPtr <= utf8text + textBytes);
+    }
     paint.setTextEncoding(SkPaint::kUTF8_TextEncoding);
     (void)paint.textToGlyphs(utf8text, textBytes, runBuffer.glyphs);
     (void)paint.getTextWidths(utf8text, textBytes, runBuffer.pos);
     SkScalar x = point.x();
     for (int i = 0; i < glyphCount; ++i) {
         SkScalar w = runBuffer.pos[i];
         runBuffer.pos[i] = x;
         x += w;
     }
     return (SkScalar)x;
 }