1 /*
2 * %W% %E%
3 *
4 * © 2016 and later: Unicode, Inc. and others.
5 * License & terms of use: http://www.unicode.org/copyright.html#License
6 *
7 * (C) Copyright IBM Corp. 1998-2011 - All Rights Reserved
8 *
9 */
10
11 #ifndef __SCRIPTCOMPOSITEFONTINSTANCE_H
12 #define __SCRIPTCOMPOSITEFONTINSTANCE_H
13
14 #include "layout/LETypes.h"
15 #include "layout/LEFontInstance.h"
16
17 #include "FontMap.h"
18
19 // U_NAMESPACE_BEGIN
20
21 class ScriptCompositeFontInstance : public LEFontInstance
22 {
23 public:
24
25 ScriptCompositeFontInstance(FontMap *fontMap);
26
27 virtual ~ScriptCompositeFontInstance();
28
29 /**
30 * Get a physical font which can render the given text. For composite fonts,
31 * if there is no single physical font which can render all of the text,
32 * return a physical font which can render an initial substring of the text,
33 * and set the <code>offset</code> parameter to the end of that substring.
34 *
35 * Internally, the LayoutEngine works with runs of text all in the same
36 * font and script, so it is best to call this method with text which is
37 * in a single script, passing the script code in as a hint. If you don't
38 * know the script of the text, you can use zero, which is the script code
39 * for characters used in more than one script.
40 *
41 * The default implementation of this method is intended for instances of
42 * <code>LEFontInstance</code> which represent a physical font. It returns
43 * <code>this</code> and indicates that the entire string can be rendered.
44 *
45 * This method will return a valid <code>LEFontInstance</code> unless you
46 * have passed illegal parameters, or an internal error has been encountered.
47 * For composite fonts, it may return the warning <code>LE_NO_SUBFONT_WARNING</code>
48 * to indicate that the returned font may not be able to render all of
49 * the text. Whenever a valid font is returned, the <code>offset</code> parameter
50 * will be advanced by at least one.
51 *
52 * Subclasses which implement composite fonts must override this method.
53 * Where it makes sense, they should use the script code as a hint to render
54 * characters from the COMMON script in the font which is used for the given
55 * script. For example, if the input text is a series of Arabic words separated
56 * by spaces, and the script code passed in is <code>arabScriptCode</code> you
57 * should return the font used for Arabic characters for all of the input text,
58 * including the spaces. If, on the other hand, the input text contains characters
59 * which cannot be rendered by the font used for Arabic characters, but which can
60 * be rendered by another font, you should return that font for those characters.
61 *
62 * @param chars - the array of Unicode characters.
63 * @param offset - a pointer to the starting offset in the text. On exit this
64 * will be set the the limit offset of the text which can be
65 * rendered using the returned font.
66 * @param limit - the limit offset for the input text.
67 * @param script - the script hint.
68 * @param success - set to an error code if the arguments are illegal, or no font
69 * can be returned for some reason. May also be set to
70 * <code>LE_NO_SUBFONT_WARNING</code> if the subfont which
71 * was returned cannot render all of the text.
72 *
73 * @return an <code>LEFontInstance</code> for the sub font which can render the characters, or
74 * <code>NULL</code> if there is an error.
75 *
76 * @see LEScripts.h
77 */
78 virtual const LEFontInstance *getSubFont(const LEUnicode chars[], le_int32 *offset, le_int32 limit, le_int32 script, LEErrorCode &success) const;
79
80 /**
81 * This method maps a single character to a glyph index, using the
82 * font's charcter to glyph map.
83 *
84 * @param ch - the character
85 *
86 * @return the glyph index
87 */
88 virtual LEGlyphID mapCharToGlyph(LEUnicode32 ch) const;
89
90 virtual const void *getFontTable(LETag tableTag) const;
91
92 virtual le_int32 getUnitsPerEM() const;
93
94 virtual le_int32 getAscent() const;
95
96 virtual le_int32 getDescent() const;
97
98 virtual le_int32 getLeading() const;
99
100 virtual void getGlyphAdvance(LEGlyphID glyph, LEPoint &advance) const;
101
102 virtual le_bool getGlyphPoint(LEGlyphID glyph, le_int32 pointNumber, LEPoint &point) const;
103
104 float getXPixelsPerEm() const;
105
106 float getYPixelsPerEm() const;
107
108 float getScaleFactorX() const;
109
110 float getScaleFactorY() const;
111
112 /**
113 * ICU "poor man's RTTI", returns a UClassID for the actual class.
114 */
getDynamicClassID()115 virtual inline UClassID getDynamicClassID() const { return getStaticClassID(); }
116
117 /**
118 * ICU "poor man's RTTI", returns a UClassID for this class.
119 */
getStaticClassID()120 static inline UClassID getStaticClassID() { return (UClassID)&fgClassID; }
121
122 protected:
123 FontMap *fFontMap;
124
125 private:
126
127 /**
128 * The address of this static class variable serves as this class's ID
129 * for ICU "poor man's RTTI".
130 */
131 static const char fgClassID;
132 };
133
getFontTable(LETag)134 inline const void *ScriptCompositeFontInstance::getFontTable(LETag /*tableTag*/) const
135 {
136 return NULL;
137 }
138
139 // Can't get units per EM without knowing which sub-font, so
140 // return a value that will make units == points
getUnitsPerEM()141 inline le_int32 ScriptCompositeFontInstance::getUnitsPerEM() const
142 {
143 return 1;
144 }
145
getAscent()146 inline le_int32 ScriptCompositeFontInstance::getAscent() const
147 {
148 return fFontMap->getAscent();
149 }
150
getDescent()151 inline le_int32 ScriptCompositeFontInstance::getDescent() const
152 {
153 return fFontMap->getDescent();
154 }
155
getLeading()156 inline le_int32 ScriptCompositeFontInstance::getLeading() const
157 {
158 return fFontMap->getLeading();
159 }
160
getXPixelsPerEm()161 inline float ScriptCompositeFontInstance::getXPixelsPerEm() const
162 {
163 return fFontMap->getPointSize();
164 }
165
getYPixelsPerEm()166 inline float ScriptCompositeFontInstance::getYPixelsPerEm() const
167 {
168 return fFontMap->getPointSize();
169 }
170
171 // Can't get a scale factor without knowing the sub-font, so
172 // return 1.0.
getScaleFactorX()173 inline float ScriptCompositeFontInstance::getScaleFactorX() const
174 {
175 return 1.0;
176 }
177
178 // Can't get a scale factor without knowing the sub-font, so
179 // return 1.0
getScaleFactorY()180 inline float ScriptCompositeFontInstance::getScaleFactorY() const
181 {
182 return 1.0;
183 }
184
185 // U_NAMESPACE_END
186 #endif
187