ui/gfx/platform_font_win.h

   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_PLATFORM_FONT_WIN_H_
   6 #define UI_GFX_PLATFORM_FONT_WIN_H_
   7 #pragma once
   8
   9 #include <string>
  10
  11 #include "base/compiler_specific.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "ui/base/ui_export.h"
  14 #include "ui/gfx/platform_font.h"
  15
  16 namespace gfx {
  17
  18 class UI_EXPORT PlatformFontWin : public PlatformFont {
  19  public:
  20   PlatformFontWin();
  21   explicit PlatformFontWin(const Font& other);
  22   explicit PlatformFontWin(NativeFont native_font);
  23   PlatformFontWin(const std::string& font_name, int font_size);
  24
  25   // Dialog units to pixels conversion.
  26   // See http://support.microsoft.com/kb/145994 for details.
  27   int horizontal_dlus_to_pixels(int dlus) const {
  28     return dlus * font_ref_->GetDluBaseX() / 4;
  29   }
  30   int vertical_dlus_to_pixels(int dlus)  const {
  31     return dlus * font_ref_->height() / 8;
  32   }
  33
  34   // Callback that returns the minimum height that should be used for
  35   // gfx::Fonts. Optional. If not specified, the minimum font size is 0.
  36   typedef int (*GetMinimumFontSizeCallback)();
  37   static GetMinimumFontSizeCallback get_minimum_font_size_callback;
  38
  39   // Callback that adjusts a LOGFONT to meet suitability requirements of the
  40   // embedding application. Optional. If not specified, no adjustments are
  41   // performed other than clamping to a minimum font height if
  42   // |get_minimum_font_size_callback| is specified.
  43   typedef void (*AdjustFontCallback)(LOGFONT* lf);
  44   static AdjustFontCallback adjust_font_callback;
  45
  46   // Returns the font name for the system locale. Some fonts, particularly
  47   // East Asian fonts, have different names per locale. If the localized font
  48   // name could not be retrieved, returns GetFontName().
  49   std::string GetLocalizedFontName() const;
  50
  51   // Overridden from PlatformFont:
  52   virtual Font DeriveFont(int size_delta, int style) const OVERRIDE;
  53   virtual int GetHeight() const OVERRIDE;
  54   virtual int GetBaseline() const OVERRIDE;
  55   virtual int GetAverageCharacterWidth() const OVERRIDE;
  56   virtual int GetStringWidth(const string16& text) const OVERRIDE;
  57   virtual int GetExpectedTextWidth(int length) const OVERRIDE;
  58   virtual int GetStyle() const OVERRIDE;
  59   virtual std::string GetFontName() const OVERRIDE;
  60   virtual int GetFontSize() const OVERRIDE;
  61   virtual NativeFont GetNativeFont() const OVERRIDE;
  62
  63  private:
  64   virtual ~PlatformFontWin() {}
  65
  66   // Chrome text drawing bottoms out in the Windows GDI functions that take an
  67   // HFONT (an opaque handle into Windows). To avoid lots of GDI object
  68   // allocation and destruction, Font indirectly refers to the HFONT by way of
  69   // an HFontRef. That is, every Font has an HFontRef, which has an HFONT.
  70   //
  71   // HFontRef is reference counted. Upon deletion, it deletes the HFONT.
  72   // By making HFontRef maintain the reference to the HFONT, multiple
  73   // HFontRefs can share the same HFONT, and Font can provide value semantics.
  74   class HFontRef : public base::RefCounted<HFontRef> {
  75    public:
  76     // This constructor takes control of the HFONT, and will delete it when
  77     // the HFontRef is deleted.
  78     HFontRef(HFONT hfont,
  79              int height,
  80              int baseline,
  81              int ave_char_width,
  82              int style);
  83
  84     // Accessors
  85     HFONT hfont() const { return hfont_; }
  86     int height() const { return height_; }
  87     int baseline() const { return baseline_; }
  88     int ave_char_width() const { return ave_char_width_; }
  89     int style() const { return style_; }
  90     const std::string& font_name() const { return font_name_; }
  91     int font_size() const { return font_size_; }
  92
  93     // Returns the average character width in dialog units.
  94     int GetDluBaseX();
  95
  96    private:
  97     friend class base::RefCounted<HFontRef>;
  98
  99     ~HFontRef();
 100
 101     const HFONT hfont_;
 102     const int height_;
 103     const int baseline_;
 104     const int ave_char_width_;
 105     const int style_;
 106     // Average character width in dialog units. This is queried lazily from the
 107     // system, with an initial value of -1 meaning it hasn't yet been queried.
 108     int dlu_base_x_;
 109     std::string font_name_;
 110     int font_size_;
 111
 112     DISALLOW_COPY_AND_ASSIGN(HFontRef);
 113   };
 114
 115   // Initializes this object with a copy of the specified HFONT.
 116   void InitWithCopyOfHFONT(HFONT hfont);
 117
 118   // Initializes this object with the specified font name and size.
 119   void InitWithFontNameAndSize(const std::string& font_name,
 120                                int font_size);
 121
 122   // Returns the base font ref. This should ONLY be invoked on the
 123   // UI thread.
 124   static HFontRef* GetBaseFontRef();
 125
 126   // Creates and returns a new HFONTRef from the specified HFONT.
 127   static HFontRef* CreateHFontRef(HFONT font);
 128
 129   // Creates a new PlatformFontWin with the specified HFontRef. Used when
 130   // constructing a Font from a HFONT we don't want to copy.
 131   explicit PlatformFontWin(HFontRef* hfont_ref);
 132
 133     // Reference to the base font all fonts are derived from.
 134   static HFontRef* base_font_ref_;
 135
 136   // Indirect reference to the HFontRef, which references the underlying HFONT.
 137   scoped_refptr<HFontRef> font_ref_;
 138 };
 139
 140 }  // namespace gfx
 141
 142 #endif  // UI_GFX_PLATFORM_FONT_WIN_H_
 143