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      1 // Copyright (c) 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 UI_GFX_PANGO_UTIL_H_
      6 #define UI_GFX_PANGO_UTIL_H_
      7 
      8 #include <cairo/cairo.h>
      9 #include <pango/pango.h>
     10 #include <string>
     11 
     12 #include "base/i18n/rtl.h"
     13 #include "base/logging.h"
     14 #include "base/strings/string16.h"
     15 #include "third_party/skia/include/core/SkColor.h"
     16 #include "ui/base/ui_export.h"
     17 
     18 typedef struct _PangoContext PangoContext;
     19 
     20 namespace gfx {
     21 
     22 class Font;
     23 class PlatformFontPango;
     24 class Rect;
     25 
     26 // Creates and returns a PangoContext. The caller owns the context.
     27 PangoContext* GetPangoContext();
     28 
     29 // Returns the resolution (DPI) used by pango. A negative values means the
     30 // resolution hasn't been set.
     31 double GetPangoResolution();
     32 
     33 // Utility class to ensure that PangoFontDescription is freed.
     34 class ScopedPangoFontDescription {
     35  public:
     36   explicit ScopedPangoFontDescription(PangoFontDescription* description)
     37       : description_(description) {
     38     DCHECK(description);
     39   }
     40 
     41   ~ScopedPangoFontDescription() {
     42     pango_font_description_free(description_);
     43   }
     44 
     45   PangoFontDescription* get() { return description_; }
     46 
     47  private:
     48   PangoFontDescription* description_;
     49 
     50   DISALLOW_COPY_AND_ASSIGN(ScopedPangoFontDescription);
     51 };
     52 
     53 // Uses Pango to draw text onto |cr|. This is the public method for d
     54 void UI_EXPORT DrawTextOntoCairoSurface(cairo_t* cr,
     55                                         const base::string16& text,
     56                                         const gfx::Font& font,
     57                                         const gfx::Rect& bounds,
     58                                         const gfx::Rect& clip,
     59                                         SkColor text_color,
     60                                         int flags);
     61 
     62 // ----------------------------------------------------------------------------
     63 // All other methods in this file are only to be used within the ui/ directory.
     64 // They are shared with internal skia interfaces.
     65 // ----------------------------------------------------------------------------
     66 
     67 // Setup pango |layout|; set the |text|, the font description based on |font|,
     68 // the |width| in PANGO_SCALE for RTL locale, the base |text_direction|,
     69 // alignment, ellipsis, word wrapping, resolution, etc.
     70 void SetupPangoLayout(PangoLayout* layout,
     71                       const base::string16& text,
     72                       const gfx::Font& font,
     73                       int width,
     74                       base::i18n::TextDirection text_direction,
     75                       int flags);
     76 
     77 // Setup pango layout |layout| the same way as SetupPangoLayout(), except this
     78 // sets the font description based on |font_description|.
     79 void SetupPangoLayoutWithFontDescription(
     80     PangoLayout* layout,
     81     const base::string16& text,
     82     const std::string& font_description,
     83     int width,
     84     base::i18n::TextDirection text_direction,
     85     int flags);
     86 
     87 // Draws the |layout| (pango tuple of font, actual text, etc) onto |cr| using
     88 // |text_color| as the cairo pattern.
     89 void DrawPangoLayout(cairo_t* cr,
     90                      PangoLayout* layout,
     91                      const Font& font,
     92                      const gfx::Rect& bounds,
     93                      const gfx::Rect& text_rect,
     94                      SkColor text_color,
     95                      base::i18n::TextDirection text_direction,
     96                      int flags);
     97 
     98 // Draw an underline under the text using |cr|, which must already be
     99 // initialized with the correct source. |extra_edge_width| is added to the
    100 // outer edge of the line.
    101 void DrawPangoTextUnderline(cairo_t* cr,
    102                             gfx::PlatformFontPango* platform_font,
    103                             double extra_edge_width,
    104                             const Rect& text_rect);
    105 
    106 // Returns the size in pixels for the specified |pango_font|.
    107 size_t GetPangoFontSizeInPixels(PangoFontDescription* pango_font);
    108 
    109 // Retrieves the Pango metrics for a Pango font description. Caches the metrics
    110 // and never frees them. The metrics objects are relatively small and very
    111 // expensive to look up.
    112 PangoFontMetrics* GetPangoFontMetrics(PangoFontDescription* desc);
    113 
    114 }  // namespace gfx
    115 
    116 #endif  // UI_GFX_PANGO_UTIL_H_
    117