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// Copyright (c) 2006-2008 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 CHROME_COMMON_GFX_CHROME_FONT_H_
#define CHROME_COMMON_GFX_CHROME_FONT_H_
#include "build/build_config.h"
#include <string>
#if defined(OS_WIN)
typedef struct HFONT__* HFONT;
#endif
#include "base/basictypes.h"
#include "base/ref_counted.h"
// ChromeFont provides a wrapper around an underlying font. Copy and assignment
// operators are explicitly allowed, and cheap.
class ChromeFont {
public:
// The following constants indicate the font style.
static const int BOLD = 1;
static const int ITALIC = 2;
static const int UNDERLINED = 4;
static const int WEB = 8;
// Creates a ChromeFont from the specified HFONT. The supplied HFONT is
// effectively copied.
static ChromeFont CreateFont(HFONT hfont);
// Creates a ChromeFont given font name (e.g. arial), font size (e.g. 12).
static ChromeFont CreateFont(const std::wstring& font_name, int font_size);
// Creates a font with the default name and style.
ChromeFont() : font_ref_(GetBaseFontRef()) { }
~ChromeFont() { }
// Returns a new Font derived from the existing font.
// size_deta is the size to add to the current font. For example, a value
// of 5 results in a font 5 units bigger than this font.
ChromeFont DeriveFont(int size_delta) const {
return DeriveFont(size_delta, style());
}
// Returns a new Font derived from the existing font.
// size_deta is the size to add to the current font. See the single
// argument version of this method for an example.
// The style parameter specifies the new style for the font, and is a
// bitmask of the values: BOLD, ITALIC, UNDERLINED and WEB.
ChromeFont DeriveFont(int size_delta, int style) const;
// Returns the number of vertical pixels needed to display characters from
// the specified font.
int height() const { return font_ref_->height(); }
// Returns the baseline, or ascent, of the font.
int baseline() const { return font_ref_->baseline(); }
// Returns the average character width for the font.
int ave_char_width() const { return font_ref_->ave_char_width(); }
// Returns the number of horizontal pixels needed to display the specified
// string.
int GetStringWidth(const std::wstring& text) const;
// Returns the expected number of horizontal pixels needed to display
// the specified length of characters.
// Call the GetStringWidth() function to retrieve the actual number.
int GetExpectedTextWidth(int length) const {
return length * font_ref_->dlu_base_x();
}
// Returns the style of the font.
int style() const { return font_ref_->style(); }
// Returns the handle to the underlying HFONT. This is used by ChromeCanvas to
// draw text.
HFONT hfont() const { return font_ref_->hfont(); }
// Dialog units to pixels conversion.
// See http://support.microsoft.com/kb/145994 for details.
int horizontal_dlus_to_pixels(int dlus) {
return dlus * font_ref_->dlu_base_x() / 4;
}
int vertical_dlus_to_pixels(int dlus) {
return dlus * font_ref_->height() / 8;
}
// Font Name.
std::wstring FontName();
// Font Size.
int FontSize();
private:
// 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, ChromeFont indirectly refers to the HFONT
// by way of an HFontRef. That is, every ChromeFont 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 ChromeFont can provide value
// semantics.
class 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 height,
int baseline,
int ave_char_width,
int style,
int dlu_base_x);
~HFontRef();
// Accessors
HFONT hfont() const { return hfont_; }
int height() const { return height_; }
int baseline() const { return baseline_; }
int ave_char_width() const { return ave_char_width_; }
int style() const { return style_; }
int dlu_base_x() const { return dlu_base_x_; }
private:
const HFONT hfont_;
const int height_;
const int baseline_;
const int ave_char_width_;
const int style_;
// Constants used in converting dialog units to pixels.
const int dlu_base_x_;
DISALLOW_COPY_AND_ASSIGN(HFontRef);
};
// 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);
explicit ChromeFont(HFontRef* font_ref) : font_ref_(font_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_;
};
#endif // CHROME_COMMON_GFX_CHROME_FONT_H_
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