Layout.h revision f0a1e5b2da5aaccbc1c010413365cd8c304cf5d9 
1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef MINIKIN_LAYOUT_H
18#define MINIKIN_LAYOUT_H
19
20#include <hb.h>
21
22#include <vector>
23
24#include <minikin/CssParse.h>
25#include <minikin/FontCollection.h>
26#include <minikin/MinikinFontFreeType.h>
27
28namespace android {
29
30// The Bitmap class is for debugging. We'll probably move it out
31// of here into a separate lightweight software rendering module
32// (optional, as we'd hope most clients would do their own)
33class Bitmap {
34public:
35    Bitmap(int width, int height);
36    ~Bitmap();
37    void writePnm(std::ofstream& o) const;
38    void drawGlyph(const GlyphBitmap& bitmap, int x, int y);
39private:
40    int width;
41    int height;
42    uint8_t* buf;
43};
44
45struct LayoutGlyph {
46    // index into mFaces and mHbFonts vectors. We could imagine
47    // moving this into a run length representation, because it's
48    // more efficient for long strings, and we'll probably need
49    // something like that for paint attributes (color, underline,
50    // fake b/i, etc), as having those per-glyph is bloated.
51    int font_ix;
52
53    unsigned int glyph_id;
54    float x;
55    float y;
56};
57
58// Internal state used during layout operation
59class LayoutContext;
60
61// Lifecycle and threading assumptions for Layout:
62// The object is assumed to be owned by a single thread; multiple threads
63// may not mutate it at the same time.
64// The lifetime of the FontCollection set through setFontCollection must
65// extend through the lifetime of the Layout object.
66class Layout {
67public:
68    void dump() const;
69    void setFontCollection(const FontCollection* collection);
70
71    void doLayout(const uint16_t* buf, size_t start, size_t count, size_t bufSize,
72        const std::string& css);
73
74    void draw(Bitmap*, int x0, int y0, float size) const;
75
76    // This must be called before any invocations.
77    // TODO: probably have a factory instead
78    static void init();
79
80    // public accessors
81    size_t nGlyphs() const;
82    // Does not bump reference; ownership is still layout
83    MinikinFont *getFont(int i) const;
84    FontFakery getFakery(int i) const;
85    unsigned int getGlyphId(int i) const;
86    float getX(int i) const;
87    float getY(int i) const;
88
89    float getAdvance() const;
90
91    // Get advances, copying into caller-provided buffer. The size of this
92    // buffer must match the length of the string (nchars arg to doLayout).
93    void getAdvances(float* advances);
94
95    void getBounds(MinikinRect* rect);
96
97    // Purge all caches, useful in low memory conditions
98    static void purgeCaches();
99
100private:
101    // Find a face in the mFaces vector, or create a new entry
102    int findFace(FakedFont face, LayoutContext* ctx);
103
104    // Lay out a single bidi run
105    void doLayoutRunCached(const uint16_t* buf, size_t start, size_t count, size_t bufSize,
106        bool isRtl, LayoutContext* ctx, size_t dstStart);
107
108    // Lay out a single word
109    void doLayoutWord(const uint16_t* buf, size_t start, size_t count, size_t bufSize,
110        bool isRtl, LayoutContext* ctx, size_t bufStart);
111
112    // Lay out a single bidi run
113    void doLayoutRun(const uint16_t* buf, size_t start, size_t count, size_t bufSize,
114        bool isRtl, LayoutContext* ctx);
115
116    // Append another layout (for example, cached value) into this one
117    void appendLayout(Layout* src, size_t start);
118
119    std::vector<LayoutGlyph> mGlyphs;
120    std::vector<float> mAdvances;
121
122    const FontCollection* mCollection;
123    std::vector<FakedFont> mFaces;
124    float mAdvance;
125    MinikinRect mBounds;
126};
127
128}  // namespace android
129
130#endif  // MINIKIN_LAYOUT_H
131