1 /*
2 * Copyright 2018 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 "src/pdf/SkClusterator.h"
9
10 #include "include/core/SkSpan.h"
11 #include "include/private/base/SkAssert.h"
12 #include "include/private/base/SkTo.h"
13 #include "src/text/GlyphRun.h"
14
is_reversed(const uint32_t * clusters,uint32_t count)15 static bool is_reversed(const uint32_t* clusters, uint32_t count) {
16 // "ReversedChars" is how PDF deals with RTL text.
17 // return true if more than one cluster and monotonicly decreasing to zero.
18 if (count < 2 || clusters[0] == 0 || clusters[count - 1] != 0) {
19 return false;
20 }
21 for (uint32_t i = 0; i + 1 < count; ++i) {
22 if (clusters[i + 1] > clusters[i]) {
23 return false;
24 }
25 }
26 return true;
27 }
28
SkClusterator(const sktext::GlyphRun & run)29 SkClusterator::SkClusterator(const sktext::GlyphRun& run)
30 : fClusters(run.clusters().data())
31 , fUtf8Text(run.text().data())
32 , fGlyphCount(SkToU32(run.glyphsIDs().size()))
33 , fTextByteLength(SkToU32(run.text().size()))
34 , fReversedChars(fClusters ? is_reversed(fClusters, fGlyphCount) : false)
35 {
36 if (fClusters) {
37 SkASSERT(fUtf8Text && fTextByteLength > 0 && fGlyphCount > 0);
38 } else {
39 SkASSERT(!fUtf8Text && fTextByteLength == 0);
40 }
41 }
42
next()43 SkClusterator::Cluster SkClusterator::next() {
44 if (fCurrentGlyphIndex >= fGlyphCount) {
45 return Cluster{nullptr, 0, 0, 0};
46 }
47 if (!fClusters || !fUtf8Text) {
48 return Cluster{nullptr, 0, fCurrentGlyphIndex++, 1};
49 }
50 uint32_t clusterGlyphIndex = fCurrentGlyphIndex;
51 uint32_t cluster = fClusters[clusterGlyphIndex];
52 do {
53 ++fCurrentGlyphIndex;
54 } while (fCurrentGlyphIndex < fGlyphCount && cluster == fClusters[fCurrentGlyphIndex]);
55 uint32_t clusterGlyphCount = fCurrentGlyphIndex - clusterGlyphIndex;
56 uint32_t clusterEnd = fTextByteLength;
57 for (unsigned i = 0; i < fGlyphCount; ++i) {
58 uint32_t c = fClusters[i];
59 if (c > cluster && c < clusterEnd) {
60 clusterEnd = c;
61 }
62 }
63 uint32_t clusterLen = clusterEnd - cluster;
64 return Cluster{fUtf8Text + cluster, clusterLen, clusterGlyphIndex, clusterGlyphCount};
65 }
66