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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_GFX_PLATFORM_FONT_WIN_H_
#define UI_GFX_PLATFORM_FONT_WIN_H_
#include <string>
#include "base/compiler_specific.h"
#include "base/memory/ref_counted.h"
#include "ui/gfx/gfx_export.h"
#include "ui/gfx/platform_font.h"
namespace gfx {
class GFX_EXPORT PlatformFontWin : public PlatformFont {
public:
PlatformFontWin();
explicit PlatformFontWin(NativeFont native_font);
PlatformFontWin(const std::string& font_name, int font_size);
// Dialog units to pixels conversion.
// See http://support.microsoft.com/kb/145994 for details.
int horizontal_dlus_to_pixels(int dlus) const {
return dlus * font_ref_->GetDluBaseX() / 4;
}
int vertical_dlus_to_pixels(int dlus) const {
return dlus * font_ref_->height() / 8;
}
// Callback that returns the minimum height that should be used for
// gfx::Fonts. Optional. If not specified, the minimum font size is 0.
typedef int (*GetMinimumFontSizeCallback)();
static GetMinimumFontSizeCallback get_minimum_font_size_callback;
// Callback that adjusts a LOGFONT to meet suitability requirements of the
// embedding application. Optional. If not specified, no adjustments are
// performed other than clamping to a minimum font height if
// |get_minimum_font_size_callback| is specified.
typedef void (*AdjustFontCallback)(LOGFONT* lf);
static AdjustFontCallback adjust_font_callback;
// Returns the font name for the system locale. Some fonts, particularly
// East Asian fonts, have different names per locale. If the localized font
// name could not be retrieved, returns GetFontName().
std::string GetLocalizedFontName() const;
// Returns a derived Font with the specified |style| and with height at most
// |height|. If the height and style of the receiver already match, it is
// returned. Otherwise, the returned Font will have the largest size such that
// its height is less than or equal to |height| (since there may not exist a
// size that matches the exact |height| specified).
Font DeriveFontWithHeight(int height, int style);
// Overridden from PlatformFont:
virtual Font DeriveFont(int size_delta, int style) const OVERRIDE;
virtual int GetHeight() const OVERRIDE;
virtual int GetBaseline() const OVERRIDE;
virtual int GetCapHeight() const OVERRIDE;
virtual int GetExpectedTextWidth(int length) const OVERRIDE;
virtual int GetStyle() const OVERRIDE;
virtual std::string GetFontName() const OVERRIDE;
virtual std::string GetActualFontNameForTesting() const OVERRIDE;
virtual int GetFontSize() const OVERRIDE;
virtual const FontRenderParams& GetFontRenderParams() const OVERRIDE;
virtual NativeFont GetNativeFont() const OVERRIDE;
private:
virtual ~PlatformFontWin() {}
// Chrome text drawing bottoms out in the Windows GDI functions that take an
// HFONT (an opaque handle into Windows). To avoid lots of GDI object
// allocation and destruction, Font indirectly refers to the HFONT by way of
// an HFontRef. That is, every Font has an HFontRef, which has an HFONT.
//
// HFontRef is reference counted. Upon deletion, it deletes the HFONT.
// By making HFontRef maintain the reference to the HFONT, multiple
// HFontRefs can share the same HFONT, and Font can provide value semantics.
class GFX_EXPORT HFontRef : public base::RefCounted<HFontRef> {
public:
// This constructor takes control of the HFONT, and will delete it when
// the HFontRef is deleted.
HFontRef(HFONT hfont,
int font_size,
int height,
int baseline,
int cap_height,
int ave_char_width,
int style);
// Accessors
HFONT hfont() const { return hfont_; }
int height() const { return height_; }
int baseline() const { return baseline_; }
int cap_height() const { return cap_height_; }
int ave_char_width() const { return ave_char_width_; }
int style() const { return style_; }
const std::string& font_name() const { return font_name_; }
int font_size() const { return font_size_; }
int requested_font_size() const { return requested_font_size_; }
// Returns the average character width in dialog units.
int GetDluBaseX();
private:
friend class base::RefCounted<HFontRef>;
~HFontRef();
const HFONT hfont_;
const int font_size_;
const int height_;
const int baseline_;
const int cap_height_;
const int ave_char_width_;
const int style_;
// Average character width in dialog units. This is queried lazily from the
// system, with an initial value of -1 meaning it hasn't yet been queried.
int dlu_base_x_;
std::string font_name_;
// If the requested font size is not possible for the font, |font_size_|
// will be different than |requested_font_size_|. This is stored separately
// so that code that increases the font size in a loop will not cause the
// loop to get stuck on the same size.
int requested_font_size_;
DISALLOW_COPY_AND_ASSIGN(HFontRef);
};
// Initializes this object with a copy of the specified HFONT.
void InitWithCopyOfHFONT(HFONT hfont);
// Initializes this object with the specified font name and size.
void InitWithFontNameAndSize(const std::string& font_name,
int font_size);
// Returns the base font ref. This should ONLY be invoked on the
// UI thread.
static HFontRef* GetBaseFontRef();
// Creates and returns a new HFONTRef from the specified HFONT.
static HFontRef* CreateHFontRef(HFONT font);
// Creates and returns a new HFONTRef from the specified HFONT. Uses provided
// |font_metrics| instead of calculating new one.
static HFontRef* CreateHFontRef(HFONT font, const TEXTMETRIC& font_metrics);
// Returns a largest derived Font whose height does not exceed the height of
// |base_font|.
static Font DeriveWithCorrectedSize(HFONT base_font);
// Creates a new PlatformFontWin with the specified HFontRef. Used when
// constructing a Font from a HFONT we don't want to copy.
explicit PlatformFontWin(HFontRef* hfont_ref);
// Reference to the base font all fonts are derived from.
static HFontRef* base_font_ref_;
// Indirect reference to the HFontRef, which references the underlying HFONT.
scoped_refptr<HFontRef> font_ref_;
DISALLOW_COPY_AND_ASSIGN(PlatformFontWin);
};
} // namespace gfx
#endif // UI_GFX_PLATFORM_FONT_WIN_H_
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