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 "../platform/WebCanvas.h"
35#include "../platform/WebColor.h"
36#include "../platform/WebCommon.h"
37
38namespace blink {
39
40struct WebFontDescription;
41struct WebFloatPoint;
42struct WebFloatRect;
43struct WebPoint;
44struct WebRect;
45struct WebTextRun;
46
47class WebFont {
48public:
49    virtual ~WebFont() { }
50
51    BLINK_EXPORT 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 blink
99
100#endif
101