cc/font_atlas.h

   1 // Copyright 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CC_FONT_ATLAS_H_
   6 #define CC_FONT_ATLAS_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "base/memory/scoped_ptr.h"
  12 #include "cc/cc_export.h"
  13 #include "third_party/skia/include/core/SkBitmap.h"
  14 #include "ui/gfx/rect.h"
  15
  16 class SkCanvas;
  17
  18 namespace gfx {
  19 class Point;
  20 class Size;
  21 }
  22
  23 namespace cc {
  24
  25 // This class provides basic ability to draw text onto the heads-up display.
  26 class CC_EXPORT FontAtlas {
  27 public:
  28     static scoped_ptr<FontAtlas> create(SkBitmap bitmap, gfx::Rect asciiToRectTable[128], int fontHeight)
  29     {
  30         return make_scoped_ptr(new FontAtlas(bitmap, asciiToRectTable, fontHeight));
  31     }
  32     ~FontAtlas();
  33
  34     // Current font height.
  35     int fontHeight() const { return m_fontHeight; }
  36
  37     // Draws multiple lines of text where each line of text is separated by '\n'.
  38     // - Correct glyphs will be drawn for ASCII codes in the range 32-127; any characters
  39     //   outside that range will be displayed as a default rectangle glyph.
  40     // - gfx::Size clip is used to avoid wasting time drawing things that are outside the
  41     //   target canvas bounds.
  42     // - Should only be called only on the impl thread.
  43     void drawText(SkCanvas*, const SkPaint&, const std::string& text, const gfx::Point& destPosition, const gfx::Size& clip) const;
  44
  45     // Gives a text's width and height on the canvas.
  46     gfx::Size textSize(const std::string& text);
  47
  48     // Draws the entire atlas at the specified position, just for debugging purposes.
  49     void drawDebugAtlas(SkCanvas*, const gfx::Point& destPosition) const;
  50
  51 private:
  52     FontAtlas(SkBitmap, gfx::Rect asciiToRectTable[128], int fontHeight);
  53
  54     void drawOneLineOfTextInternal(SkCanvas*, const SkPaint&, const std::string&, const gfx::Point& destPosition) const;
  55
  56     // The actual texture atlas containing all the pre-rendered glyphs.
  57     SkBitmap m_atlas;
  58
  59     // The look-up tables mapping ascii characters to their gfx::Rect locations on the atlas.
  60     gfx::Rect m_asciiToRectTable[128];
  61
  62     int m_fontHeight;
  63
  64     DISALLOW_COPY_AND_ASSIGN(FontAtlas);
  65 };
  66
  67 }  // namespace cc
  68
  69 #endif  // CC_FONT_ATLAS_H_