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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:
     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