SkTextBlob

src/core/SkTextBlob.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkTextBlob.h"
+
+SkTextBlob::SkTextBlob(uint16_t *glyphs, SkScalar *pos, const SkTArray<Run> *runs,
+                       const SkRect& bounds)
+    : fGlyphBuffer(glyphs)
+    , fPosBuffer(pos)
+    , fRuns(runs)
+    , fBounds(bounds) {
+}
+
+uint32_t SkTextBlob::uniqueID() const {
+    static int32_t  gTextBlobGenerationID; // = 0;
+
+    // loop in case our global wraps around, as we never want to return SK_InvalidGenID
+    while (SK_InvalidGenID == fUniqueID) {
+        fUniqueID = sk_atomic_inc(&gTextBlobGenerationID) + 1;
+    }
+
+    return fUniqueID;
+}
+
+SkTextBlob::RunIterator::RunIterator(const SkTextBlob* blob)
+    : fBlob(blob)
+    , fIndex(0) {
+    SkASSERT(NULL != blob);
+}
+
+bool SkTextBlob::RunIterator::done() const {
+    return NULL == fBlob->fRuns.get() || fIndex >= fBlob->fRuns->count();
+}
+
+void SkTextBlob::RunIterator::next() {
+    SkASSERT(!this->done());
+    fIndex++;
+}
+
+uint32_t SkTextBlob::RunIterator::glyphCount() const {
+    SkASSERT(!this->done());
+    return (*fBlob->fRuns)[fIndex].count;
+}
+
+const uint16_t* SkTextBlob::RunIterator::glyphs() const {
+    SkASSERT(!this->done());
+    return fBlob->fGlyphBuffer.get() + (*fBlob->fRuns)[fIndex].glyphStart;
+}
+
+const SkScalar* SkTextBlob::RunIterator::pos() const {
+    SkASSERT(!this->done());
+    return fBlob->fPosBuffer.get() + (*fBlob->fRuns)[fIndex].posStart;
+}
+
+const SkPoint& SkTextBlob::RunIterator::offset() const {
+    SkASSERT(!this->done());
+    return (*fBlob->fRuns)[fIndex].offset;
+}
+
+const SkPaint& SkTextBlob::RunIterator::font() const {
+    SkASSERT(!this->done());
+    return (*fBlob->fRuns)[fIndex].font;
+}
+
+SkTextBlob::GlyphPositioning SkTextBlob::RunIterator::positioning() const {
+    SkASSERT(!this->done());
+    return (*fBlob->fRuns)[fIndex].positioning;
+}
+
+SkTextBlobBuilder::SkTextBlobBuilder(unsigned runs)
+    : fRuns(NULL)
+    , fDeferredBounds(false) {
+
+    if (runs > 0) {
+        // if the number of runs is known, size our run storage accordingly.
+        fRuns = SkNEW(SkTArray<SkTextBlob::Run>(runs));
+    }
+    fBounds.setEmpty();
+}
+
+SkTextBlobBuilder::~SkTextBlobBuilder() {
+    // unused runs
+    SkDELETE(fRuns);
+}
+
+void SkTextBlobBuilder::updateDeferredBounds() {
+    SkASSERT(!fDeferredBounds || (NULL != fRuns && !fRuns->empty()));
+
+    if (!fDeferredBounds) {
+        return;
+    }
+
+    // FIXME: measure the current run & union bounds
+    fDeferredBounds = false;
+}
+
+void SkTextBlobBuilder::ensureRun(const SkPaint& font, SkTextBlob::GlyphPositioning pos,
+                                  const SkPoint& offset) {
+    SkASSERT(SkPaint::kGlyphID_TextEncoding == font.getTextEncoding());
+
+    if (NULL == fRuns) {
+        fRuns = SkNEW(SkTArray<SkTextBlob::Run>());
+    }
+
+    // we can merge same-font/same-positioning runs in the following cases:
+    //   * fully positioned run following another fully positioned run
+    //   * horizontally postioned run following another horizontally positioned run with the same
+    //     y-offset
+    if (!fRuns->empty()
+        && fRuns->back().positioning == pos
+        && fRuns->back().font == font
+        && (SkTextBlob::kFull_Positioning == fRuns->back().positioning
+            || (SkTextBlob::kHorizontal_Positioning == fRuns->back().positioning
+                && fRuns->back().offset.y() == offset.y()))){
+        return;
+    }
+
+    this->updateDeferredBounds();
+
+    // start a new run
+    SkTextBlob::Run& newRun = fRuns->push_back();
+    newRun.count = 0;
+    newRun.glyphStart = fGlyphBuffer.count();
+    newRun.posStart = fPosBuffer.count();
+    newRun.offset = offset;
+    newRun.font = font;
+    newRun.positioning = pos;
+}
+
+void SkTextBlobBuilder::allocInternal(const SkPaint &font,
+                                      SkTextBlob::GlyphPositioning positioning,
+                                      int count, SkPoint offset, const SkRect* bounds) {
+    SkASSERT(count > 0);
+
+    this->ensureRun(font, positioning, offset);
+
+    // SkTextBlob::GlyphPositioning values are directly mapped to scalars-per-glyph.
+    unsigned posScalarsPerGlyph = positioning;
+    SkASSERT(posScalarsPerGlyph <= 2);
+
+    fGlyphBuffer.append(count);
+    fPosBuffer.append(count * posScalarsPerGlyph);
+
+    SkASSERT(NULL != fRuns && !fRuns->empty());
+    SkTextBlob::Run& run = fRuns->back();
+
+    run.count += count;
+
+    // The current run might have been merged, so the start offset may point to prev run data.
+    // Start from the back (which always points to the end of the current run buffers) instead.
+    fCurrentRunBuffer.glyphs = fGlyphBuffer.isEmpty()
+            ? NULL : fGlyphBuffer.end() - count;
+    SkASSERT(NULL == fCurrentRunBuffer.glyphs || fCurrentRunBuffer.glyphs >= fGlyphBuffer.begin());
+    fCurrentRunBuffer.pos = fPosBuffer.isEmpty()
+            ? NULL : fPosBuffer.end() - count * posScalarsPerGlyph;
+    SkASSERT(NULL == fCurrentRunBuffer.pos || fCurrentRunBuffer.pos >= fPosBuffer.begin());
+
+    if (!fDeferredBounds) {
+        if (NULL != bounds) {
+            fBounds.join(*bounds);
+        } else {
+            fDeferredBounds = true;
+        }
+    }
+}
+
+const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRun(const SkPaint& font, int count,
+                                                                SkScalar x, SkScalar y,
+                                                                const SkRect* bounds) {
+    this->allocInternal(font, SkTextBlob::kDefault_Positioning, count, SkPoint::Make(x, y), bounds);
+
+    return fCurrentRunBuffer;
+}
+
+const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRunPosH(const SkPaint& font, int count,
+                                                                    SkScalar y,
+                                                                    const SkRect* bounds) {
+    this->allocInternal(font, SkTextBlob::kHorizontal_Positioning, count, SkPoint::Make(0, y),
+                        bounds);
+
+    return fCurrentRunBuffer;
+}
+
+const SkTextBlobBuilder::RunBuffer& SkTextBlobBuilder::allocRunPos(const SkPaint& font, int count,
+                                                                   const SkRect *bounds) {
+    this->allocInternal(font, SkTextBlob::kFull_Positioning, count, SkPoint::Make(0, 0), bounds);
+
+    return fCurrentRunBuffer;
+}
+
+const SkTextBlob* SkTextBlobBuilder::build() {
+    const SkTextBlob* blob;
+
+    if (fGlyphBuffer.count() > 0) {
+        // we have some glyphs, construct a real blob
+        SkASSERT(NULL != fRuns && !fRuns->empty());
+
+        this->updateDeferredBounds();
+
+        // ownership of all buffers is transferred to the blob
+        blob = SkNEW_ARGS(SkTextBlob, (fGlyphBuffer.detach(),
+                                       fPosBuffer.detach(),
+                                       fRuns,
+                                       fBounds));
+        fRuns = NULL;
+        fBounds.setEmpty();
+    } else {
+        // empty blob
+        SkASSERT(NULL == fRuns || fRuns->empty());
+        SkASSERT(fBounds.isEmpty());
+
+        blob = SkNEW_ARGS(SkTextBlob, (NULL, NULL, NULL, SkRect::MakeEmpty()));
+    }
+
+    return blob;
+}
+