1 files changed, 64 insertions, 0 deletions
diff --git a/gfx/skia/skia/src/pdf/SkClusterator.cpp b/gfx/skia/skia/src/pdf/SkClusterator.cpp
new file mode 100644
index 0000000000..5eaed752da
--- /dev/null
+++ b/gfx/skia/skia/src/pdf/SkClusterator.cpp
@@ -0,0 +1,64 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "src/pdf/SkClusterator.h"
+
+#include "include/private/base/SkTo.h"
+#include "src/base/SkUTF.h"
+#include "src/text/GlyphRun.h"
+
+static bool is_reversed(const uint32_t* clusters, uint32_t count) {
+    // "ReversedChars" is how PDF deals with RTL text.
+    // return true if more than one cluster and monotonicly decreasing to zero.
+    if (count < 2 || clusters[0] == 0 || clusters[count - 1] != 0) {
+        return false;
+    }
+    for (uint32_t i = 0; i + 1 < count; ++i) {
+        if (clusters[i + 1] > clusters[i]) {
+            return false;
+        }
+    }
+    return true;
+}
+
+SkClusterator::SkClusterator(const sktext::GlyphRun& run)
+    : fClusters(run.clusters().data())
+    , fUtf8Text(run.text().data())
+    , fGlyphCount(SkToU32(run.glyphsIDs().size()))
+    , fTextByteLength(SkToU32(run.text().size()))
+    , fReversedChars(fClusters ? is_reversed(fClusters, fGlyphCount) : false)
+{
+    if (fClusters) {
+        SkASSERT(fUtf8Text && fTextByteLength > 0 && fGlyphCount > 0);
+    } else {
+        SkASSERT(!fUtf8Text && fTextByteLength == 0);
+    }
+}
+
+SkClusterator::Cluster SkClusterator::next() {
+    if (fCurrentGlyphIndex >= fGlyphCount) {
+        return Cluster{nullptr, 0, 0, 0};
+    }
+    if (!fClusters || !fUtf8Text) {
+        return Cluster{nullptr, 0, fCurrentGlyphIndex++, 1};
+    }
+    uint32_t clusterGlyphIndex = fCurrentGlyphIndex;
+    uint32_t cluster = fClusters[clusterGlyphIndex];
+    do {
+        ++fCurrentGlyphIndex;
+    } while (fCurrentGlyphIndex < fGlyphCount && cluster == fClusters[fCurrentGlyphIndex]);
+    uint32_t clusterGlyphCount = fCurrentGlyphIndex - clusterGlyphIndex;
+    uint32_t clusterEnd = fTextByteLength;
+    for (unsigned i = 0; i < fGlyphCount; ++i) {
+       uint32_t c = fClusters[i];
+       if (c > cluster && c < clusterEnd) {
+           clusterEnd = c;
+       }
+    }
+    uint32_t clusterLen = clusterEnd - cluster;
+    return Cluster{fUtf8Text + cluster, clusterLen, clusterGlyphIndex, clusterGlyphCount};
+}