1 /*
2 * Copyright 2016 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "SkShaper.h"
9 #include "SkFontMetrics.h"
10 #include "SkStream.h"
11 #include "SkTo.h"
12 #include "SkTypeface.h"
13
14 struct SkShaper::Impl {
15 sk_sp<SkTypeface> fTypeface;
16 };
17
SkShaper(sk_sp<SkTypeface> tf)18 SkShaper::SkShaper(sk_sp<SkTypeface> tf) : fImpl(new Impl) {
19 fImpl->fTypeface = tf ? std::move(tf) : SkTypeface::MakeDefault();
20 }
21
~SkShaper()22 SkShaper::~SkShaper() {}
23
good() const24 bool SkShaper::good() const { return true; }
25
26 // This example only uses public API, so we don't use SkUTF8_NextUnichar.
utf8_lead_byte_to_count(const char * ptr)27 unsigned utf8_lead_byte_to_count(const char* ptr) {
28 uint8_t c = *(const uint8_t*)ptr;
29 SkASSERT(c <= 0xF7);
30 SkASSERT((c & 0xC0) != 0x80);
31 return (((0xE5 << 24) >> ((unsigned)c >> 4 << 1)) & 3) + 1;
32 }
33
shape(RunHandler * handler,const SkFont & srcFont,const char * utf8text,size_t textBytes,bool leftToRight,SkPoint point,SkScalar width) const34 SkPoint SkShaper::shape(RunHandler* handler,
35 const SkFont& srcFont,
36 const char* utf8text,
37 size_t textBytes,
38 bool leftToRight,
39 SkPoint point,
40 SkScalar width) const {
41 sk_ignore_unused_variable(leftToRight);
42 sk_ignore_unused_variable(width);
43
44 SkFont font(srcFont);
45 font.setTypeface(fImpl->fTypeface);
46 int glyphCount = font.countText(utf8text, textBytes, SkTextEncoding::kUTF8);
47 if (glyphCount <= 0) {
48 return point;
49 }
50
51 SkFontMetrics metrics;
52 font.getMetrics(&metrics);
53 point.fY -= metrics.fAscent;
54
55 const RunHandler::RunInfo info = {
56 0,
57 { font.measureText(utf8text, textBytes, SkTextEncoding::kUTF8), 0 },
58 metrics.fAscent,
59 metrics.fDescent,
60 metrics.fLeading,
61 };
62 const auto buffer = handler->newRunBuffer(info, font, glyphCount, textBytes);
63 SkAssertResult(font.textToGlyphs(utf8text, textBytes, SkTextEncoding::kUTF8, buffer.glyphs,
64 glyphCount) == glyphCount);
65 font.getPos(buffer.glyphs, glyphCount, buffer.positions, point);
66
67 if (buffer.utf8text) {
68 memcpy(buffer.utf8text, utf8text, textBytes);
69 }
70
71 if (buffer.clusters) {
72 const char* txtPtr = utf8text;
73 for (int i = 0; i < glyphCount; ++i) {
74 // Each charater maps to exactly one glyph via SkGlyphCache::unicharToGlyph().
75 buffer.clusters[i] = SkToU32(txtPtr - utf8text);
76 txtPtr += utf8_lead_byte_to_count(txtPtr);
77 SkASSERT(txtPtr <= utf8text + textBytes);
78 }
79 }
80
81 return point + SkVector::Make(0, metrics.fDescent + metrics.fLeading);
82 }
83