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cf6d68c32c
This patch adds caching for both layouts and for HarfBuzz face objects. The granularity of the cache for layouts is words, so it splits the input string at word boundaries (using a heuristic). There are is also some refactoring to reduce the amount of allocation and copying, and movement towards properly supporting contexts. The size of the caches is a fixed number of entries; thus, it is possible to consume a large amount of memory by filling the cache with lots of large strings. This should be refined towards a scheme that bounds the total memory used by the cache. Change-Id: Ie8176857e2d78656ce5479a7c04969819ef2718d
136 lines
4.2 KiB
C++
136 lines
4.2 KiB
C++
/*
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* Copyright (C) 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef MINIKIN_LAYOUT_H
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#define MINIKIN_LAYOUT_H
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#include <hb.h>
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#include <vector>
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#include <minikin/CssParse.h>
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#include <minikin/FontCollection.h>
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#include <minikin/MinikinFontFreeType.h>
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namespace android {
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// The Bitmap class is for debugging. We'll probably move it out
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// of here into a separate lightweight software rendering module
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// (optional, as we'd hope most clients would do their own)
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class Bitmap {
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public:
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Bitmap(int width, int height);
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~Bitmap();
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void writePnm(std::ofstream& o) const;
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void drawGlyph(const GlyphBitmap& bitmap, int x, int y);
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private:
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int width;
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int height;
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uint8_t* buf;
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};
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struct LayoutGlyph {
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// index into mFaces and mHbFonts vectors. We could imagine
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// moving this into a run length representation, because it's
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// more efficient for long strings, and we'll probably need
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// something like that for paint attributes (color, underline,
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// fake b/i, etc), as having those per-glyph is bloated.
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int font_ix;
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unsigned int glyph_id;
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float x;
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float y;
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};
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// Internal state used during layout operation
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class LayoutContext;
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// Lifecycle and threading assumptions for Layout:
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// The object is assumed to be owned by a single thread; multiple threads
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// may not mutate it at the same time.
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// The lifetime of the FontCollection set through setFontCollection must
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// extend through the lifetime of the Layout object.
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class Layout {
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public:
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void dump() const;
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void setFontCollection(const FontCollection* collection);
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// deprecated - missing functionality
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void doLayout(const uint16_t* buf, size_t nchars);
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void doLayout(const uint16_t* buf, size_t start, size_t count, size_t bufSize,
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const std::string& css);
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void draw(Bitmap*, int x0, int y0, float size) const;
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// deprecated - pass as argument to doLayout instead
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void setProperties(const std::string& css);
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// This must be called before any invocations.
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// TODO: probably have a factory instead
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static void init();
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// public accessors
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size_t nGlyphs() const;
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// Does not bump reference; ownership is still layout
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MinikinFont *getFont(int i) const;
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unsigned int getGlyphId(int i) const;
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float getX(int i) const;
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float getY(int i) const;
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float getAdvance() const;
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// Get advances, copying into caller-provided buffer. The size of this
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// buffer must match the length of the string (nchars arg to doLayout).
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void getAdvances(float* advances);
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void getBounds(MinikinRect* rect);
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private:
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// Find a face in the mFaces vector, or create a new entry
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int findFace(MinikinFont* face, LayoutContext* ctx);
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// Lay out a single bidi run
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void doLayoutRunCached(const uint16_t* buf, size_t start, size_t count, size_t bufSize,
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bool isRtl, LayoutContext* ctx);
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// Lay out a single word
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void doLayoutWord(const uint16_t* buf, size_t start, size_t count, size_t bufSize,
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bool isRtl, LayoutContext* ctx, size_t bufStart);
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// Lay out a single bidi run
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void doLayoutRun(const uint16_t* buf, size_t start, size_t count, size_t bufSize,
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bool isRtl, LayoutContext* ctx);
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// Append another layout (for example, cached value) into this one
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void appendLayout(Layout* src, size_t start);
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// deprecated - remove when setProperties is removed
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std::string mCssString;
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std::vector<LayoutGlyph> mGlyphs;
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std::vector<float> mAdvances;
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const FontCollection* mCollection;
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std::vector<MinikinFont *> mFaces;
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float mAdvance;
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MinikinRect mBounds;
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};
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} // namespace android
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#endif // MINIKIN_LAYOUT_H
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