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1 /*
2  * Copyright (C) 2010 Google Inc. All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are
6  * met:
7  *
8  *     * Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  *     * Redistributions in binary form must reproduce the above
11  * copyright notice, this list of conditions and the following disclaimer
12  * in the documentation and/or other materials provided with the
13  * distribution.
14  *     * Neither the name of Google Inc. nor the names of its
15  * contributors may be used to endorse or promote products derived from
16  * this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 
31 #ifndef WebFont_h
32 #define WebFont_h
33 
34 #include "WebCanvas.h"
35 #include "WebColor.h"
36 #include "WebCommon.h"
37 
38 namespace WebKit {
39 
40 struct WebFontDescription;
41 struct WebFloatPoint;
42 struct WebFloatRect;
43 struct WebPoint;
44 struct WebRect;
45 struct WebTextRun;
46 
47 class WebFont {
48 public:
~WebFont()49     virtual ~WebFont() { }
50 
51     WEBKIT_API static WebFont* create(const WebFontDescription&);
52 
53     virtual WebFontDescription fontDescription() const = 0;
54 
55     virtual int ascent() const = 0;
56     virtual int descent() const = 0;
57     virtual int height() const = 0;
58     virtual int lineSpacing() const = 0;
59     virtual float xHeight() const = 0;
60 
61     // Draws the text run to the given canvas. The text is positioned at the
62     // given left-hand point at the baseline.
63     //
64     // The text will be clipped to the given clip rect. |canvasIsOpaque| is
65     // used to control whether subpixel antialiasing is possible. If there is a
66     // possibility the area drawn could be semi-transparent, subpixel
67     // antialiasing will be disabled.
68     //
69     // |from| and |to| allow the caller to specify a subrange of the given text
70     // run to draw. If |to| is -1, the entire run will be drawn.
71     virtual void drawText(WebCanvas*, const WebTextRun&, const WebFloatPoint& leftBaseline, WebColor,
72                           const WebRect& clip, bool canvasIsOpaque,
73                           int from = 0, int to = -1) const = 0;
74 
75     // Measures the width in pixels of the given text run.
76     virtual int calculateWidth(const WebTextRun&) const = 0;
77 
78     // Returns the character offset corresponding to the given horizontal pixel
79     // position as measured from from the left of the run.
80     virtual int offsetForPosition(const WebTextRun&, float position) const = 0;
81 
82     // Returns the rectangle representing the selection rect for the subrange
83     // |from| -> |to| of the given text run. You can use -1 for |to| to specify
84     // the entire run (this will do something similar to calling width()).
85     //
86     // The rect will be positioned as if the text was drawn at the given
87     // |leftBaseline| position. |height| indicates the height of the selection
88     // rect you want, typically this will just be the height() of this font.
89     //
90     // To get the pixel offset of some character (the opposite of
91     // offsetForPosition()), pass in a |leftBaseline| = (0, 0), |from| = 0, and
92     // |to| = the character you want. The right edge of the resulting selection
93     // rect will tell you the right side of the character.
94     virtual WebFloatRect selectionRectForText(const WebTextRun&, const WebFloatPoint& leftBaseline,
95                                               int height, int from = 0, int to = -1) const = 0;
96 };
97 
98 } // namespace WebKit
99 
100 #endif
101