1 
2 /*
3  *
4  * (C) Copyright IBM Corp. 1998-2015 - All Rights Reserved
5  *
6  */
7 
8 #ifndef __LEFONTINSTANCE_H
9 #define __LEFONTINSTANCE_H
10 
11 #include "LETypes.h"
12 /**
13  * \file
14  * \brief C++ API: Layout Engine Font Instance object
15  */
16 
17 U_NAMESPACE_BEGIN
18 
19 /**
20  * Instances of this class are used by <code>LEFontInstance::mapCharsToGlyphs</code> and
21  * <code>LEFontInstance::mapCharToGlyph</code> to adjust character codes before the character
22  * to glyph mapping process. Examples of this are filtering out control characters
23  * and character mirroring - replacing a character which has both a left and a right
24  * hand form with the opposite form.
25  *
26  * @deprecated ICU 54. See {@link icu::LayoutEngine}
27  */
28 class LECharMapper /* not : public UObject because this is an interface/mixin class */
29 {
30 public:
31     /**
32      * Destructor.
33      * @deprecated ICU 54. See {@link icu::LayoutEngine}
34      */
35     virtual ~LECharMapper();
36 
37     /**
38      * This method does the adjustments.
39      *
40      * @param ch - the input character
41      *
42      * @return the adjusted character
43      *
44      * @deprecated ICU 54. See {@link icu::LayoutEngine}
45      */
46     virtual LEUnicode32 mapChar(LEUnicode32 ch) const = 0;
47 };
48 
49 /**
50  * This is a forward reference to the class which holds the per-glyph
51  * storage.
52  *
53  * @deprecated ICU 54. See {@link icu::LayoutEngine}
54  */
55 class LEGlyphStorage;
56 
57 /**
58  * This is a virtual base class that serves as the interface between a LayoutEngine
59  * and the platform font environment. It allows a LayoutEngine to access font tables, do
60  * character to glyph mapping, and obtain metrics information without knowing any platform
61  * specific details. There are also a few utility methods for converting between points,
62  * pixels and funits. (font design units)
63  *
64  * An instance of an <code>LEFontInstance</code> represents a font at a particular point
65  * size. Each instance can represent either a single physical font, or a composite font.
66  * A composite font is a collection of physical fonts, each of which contains a subset of
67  * the characters contained in the composite font.
68  *
69  * Note: with the exception of <code>getSubFont</code>, the methods in this class only
70  * make sense for a physical font. If you have an <code>LEFontInstance</code> which
71  * represents a composite font you should only call the methods below which have
72  * an <code>LEGlyphID</code>, an <code>LEUnicode</code> or an <code>LEUnicode32</code>
73  * as one of the arguments because these can be used to select a particular subfont.
74  *
75  * Subclasses which implement composite fonts should supply an implementation of these
76  * methods with some default behavior such as returning constant values, or using the
77  * values from the first subfont.
78  *
79  * @deprecated ICU 54. See {@link icu::LayoutEngine}
80  */
81 class U_LAYOUT_API LEFontInstance : public UObject
82 {
83 public:
84 
85     /**
86      * This virtual destructor is here so that the subclass
87      * destructors can be invoked through the base class.
88      *
89      * @deprecated ICU 54. See {@link icu::LayoutEngine}
90      */
91     virtual ~LEFontInstance();
92 
93     /**
94      * Get a physical font which can render the given text. For composite fonts,
95      * if there is no single physical font which can render all of the text,
96      * return a physical font which can render an initial substring of the text,
97      * and set the <code>offset</code> parameter to the end of that substring.
98      *
99      * Internally, the LayoutEngine works with runs of text all in the same
100      * font and script, so it is best to call this method with text which is
101      * in a single script, passing the script code in as a hint. If you don't
102      * know the script of the text, you can use zero, which is the script code
103      * for characters used in more than one script.
104      *
105      * The default implementation of this method is intended for instances of
106      * <code>LEFontInstance</code> which represent a physical font. It returns
107      * <code>this</code> and indicates that the entire string can be rendered.
108      *
109      * This method will return a valid <code>LEFontInstance</code> unless you
110      * have passed illegal parameters, or an internal error has been encountered.
111      * For composite fonts, it may return the warning <code>LE_NO_SUBFONT_WARNING</code>
112      * to indicate that the returned font may not be able to render all of
113      * the text. Whenever a valid font is returned, the <code>offset</code> parameter
114      * will be advanced by at least one.
115      *
116      * Subclasses which implement composite fonts must override this method.
117      * Where it makes sense, they should use the script code as a hint to render
118      * characters from the COMMON script in the font which is used for the given
119      * script. For example, if the input text is a series of Arabic words separated
120      * by spaces, and the script code passed in is <code>arabScriptCode</code> you
121      * should return the font used for Arabic characters for all of the input text,
122      * including the spaces. If, on the other hand, the input text contains characters
123      * which cannot be rendered by the font used for Arabic characters, but which can
124      * be rendered by another font, you should return that font for those characters.
125      *
126      * @param chars   - the array of Unicode characters.
127      * @param offset  - a pointer to the starting offset in the text. On exit this
128      *                  will be set the the limit offset of the text which can be
129      *                  rendered using the returned font.
130      * @param limit   - the limit offset for the input text.
131      * @param script  - the script hint.
132      * @param success - set to an error code if the arguments are illegal, or no font
133      *                  can be returned for some reason. May also be set to
134      *                  <code>LE_NO_SUBFONT_WARNING</code> if the subfont which
135      *                  was returned cannot render all of the text.
136      *
137      * @return an <code>LEFontInstance</code> for the sub font which can render the characters, or
138      *         <code>NULL</code> if there is an error.
139      *
140      * @see LEScripts.h
141      *
142      * @deprecated ICU 54. See {@link icu::LayoutEngine}
143      */
144     virtual const LEFontInstance *getSubFont(const LEUnicode chars[], le_int32 *offset, le_int32 limit, le_int32 script, LEErrorCode &success) const;
145 
146     //
147     // Font file access
148     //
149 
150     /**
151      * This method reads a table from the font. Note that in general,
152      * it only makes sense to call this method on an <code>LEFontInstance</code>
153      * which represents a physical font - i.e. one which has been returned by
154      * <code>getSubFont()</code>. This is because each subfont in a composite font
155      * will have different tables, and there's no way to know which subfont to access.
156      *
157      * Subclasses which represent composite fonts should always return <code>NULL</code>.
158      *
159      * @param tableTag - the four byte table tag. (e.g. 'cmap')
160      * @param length - ignored on entry, on exit will be the length of the table if known, or -1 if unknown.
161      * @return the address of the table in memory, or <code>NULL</code>
162      *         if the table doesn't exist.
163      * @deprecated ICU 54. See {@link LayoutEngine}
164      */
165     virtual const void* getFontTable(LETag tableTag, size_t &length) const = 0;
166 
167     /**
168      * This method is used to determine if the font can
169      * render the given character. This can usually be done
170      * by looking the character up in the font's character
171      * to glyph mapping.
172      *
173      * The default implementation of this method will return
174      * <code>TRUE</code> if <code>mapCharToGlyph(ch)</code>
175      * returns a non-zero value.
176      *
177      * @param ch - the character to be tested
178      *
179      * @return <code>TRUE</code> if the font can render ch.
180      *
181      * @deprecated ICU 54. See {@link icu::LayoutEngine}
182      */
183     virtual le_bool canDisplay(LEUnicode32 ch) const;
184 
185     /**
186      * This method returns the number of design units in
187      * the font's EM square.
188      *
189      * @return the number of design units pre EM.
190      *
191      * @deprecated ICU 54. See {@link icu::LayoutEngine}
192      */
193     virtual le_int32 getUnitsPerEM() const = 0;
194 
195     /**
196      * This method maps an array of character codes to an array of glyph
197      * indices, using the font's character to glyph map.
198      *
199      * The default implementation iterates over all of the characters and calls
200      * <code>mapCharToGlyph(ch, mapper)</code> on each one. It also handles surrogate
201      * characters, storing the glyph ID for the high surrogate, and a deleted glyph (0xFFFF)
202      * for the low surrogate.
203      *
204      * Most sublcasses will not need to implement this method.
205      *
206      * @param chars - the character array
207      * @param offset - the index of the first character
208      * @param count - the number of characters
209      * @param reverse - if <code>TRUE</code>, store the glyph indices in reverse order.
210      * @param mapper - the character mapper.
211      * @param filterZeroWidth - <code>TRUE</code> if ZWJ / ZWNJ characters should map to a glyph w/ no contours.
212      * @param glyphStorage - the object which contains the output glyph array
213      *
214      * @see LECharMapper
215      *
216      * @deprecated ICU 54. See {@link icu::LayoutEngine}
217      */
218     virtual void mapCharsToGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, const LECharMapper *mapper, le_bool filterZeroWidth, LEGlyphStorage &glyphStorage) const;
219 
220     /**
221      * This method maps a single character to a glyph index, using the
222      * font's character to glyph map. The default implementation of this
223      * method calls the mapper, and then calls <code>mapCharToGlyph(mappedCh)</code>.
224      *
225      * @param ch - the character
226      * @param mapper - the character mapper
227      * @param filterZeroWidth - <code>TRUE</code> if ZWJ / ZWNJ characters should map to a glyph w/ no contours.
228      *
229      * @return the glyph index
230      *
231      * @see LECharMapper
232      *
233      * @deprecated ICU 54. See {@link icu::LayoutEngine}
234      */
235     virtual LEGlyphID mapCharToGlyph(LEUnicode32 ch, const LECharMapper *mapper, le_bool filterZeroWidth) const;
236 
237     /**
238      * This method maps a single character to a glyph index, using the
239      * font's character to glyph map. The default implementation of this
240      * method calls the mapper, and then calls <code>mapCharToGlyph(mappedCh)</code>.
241      *
242      * @param ch - the character
243      * @param mapper - the character mapper
244      *
245      * @return the glyph index
246      *
247      * @see LECharMapper
248      *
249      * @deprecated ICU 54. See {@link icu::LayoutEngine}
250      */
251     virtual LEGlyphID mapCharToGlyph(LEUnicode32 ch, const LECharMapper *mapper) const;
252 
253     /**
254      * This method maps a single character to a glyph index, using the
255      * font's character to glyph map. There is no default implementation
256      * of this method because it requires information about the platform
257      * font implementation.
258      *
259      * @param ch - the character
260      *
261      * @return the glyph index
262      *
263      * @deprecated ICU 54. See {@link icu::LayoutEngine}
264      */
265     virtual LEGlyphID mapCharToGlyph(LEUnicode32 ch) const = 0;
266 
267     //
268     // Metrics
269     //
270 
271     /**
272      * This method gets the X and Y advance of a particular glyph, in pixels.
273      *
274      * @param glyph - the glyph index
275      * @param advance - the X and Y pixel values will be stored here
276      *
277      * @deprecated ICU 54. See {@link icu::LayoutEngine}
278      */
279     virtual void getGlyphAdvance(LEGlyphID glyph, LEPoint &advance) const = 0;
280 
281     /**
282      * This method gets the hinted X and Y pixel coordinates of a particular
283      * point in the outline of the given glyph.
284      *
285      * @param glyph - the glyph index
286      * @param pointNumber - the number of the point
287      * @param point - the point's X and Y pixel values will be stored here
288      *
289      * @return <code>TRUE</code> if the point coordinates could be stored.
290      *
291      * @deprecated ICU 54. See {@link icu::LayoutEngine}
292      */
293     virtual le_bool getGlyphPoint(LEGlyphID glyph, le_int32 pointNumber, LEPoint &point) const = 0;
294 
295     /**
296      * This method returns the width of the font's EM square
297      * in pixels.
298      *
299      * @return the pixel width of the EM square
300      *
301      * @deprecated ICU 54. See {@link icu::LayoutEngine}
302      */
303     virtual float getXPixelsPerEm() const = 0;
304 
305     /**
306      * This method returns the height of the font's EM square
307      * in pixels.
308      *
309      * @return the pixel height of the EM square
310      *
311      * @deprecated ICU 54. See {@link icu::LayoutEngine}
312      */
313     virtual float getYPixelsPerEm() const = 0;
314 
315     /**
316      * This method converts font design units in the
317      * X direction to points.
318      *
319      * @param xUnits - design units in the X direction
320      *
321      * @return points in the X direction
322      *
323      * @deprecated ICU 54. See {@link icu::LayoutEngine}
324      */
325     virtual float xUnitsToPoints(float xUnits) const;
326 
327     /**
328      * This method converts font design units in the
329      * Y direction to points.
330      *
331      * @param yUnits - design units in the Y direction
332      *
333      * @return points in the Y direction
334      *
335      * @deprecated ICU 54. See {@link icu::LayoutEngine}
336      */
337     virtual float yUnitsToPoints(float yUnits) const;
338 
339     /**
340      * This method converts font design units to points.
341      *
342      * @param units - X and Y design units
343      * @param points - set to X and Y points
344      *
345      * @deprecated ICU 54. See {@link icu::LayoutEngine}
346      */
347     virtual void unitsToPoints(LEPoint &units, LEPoint &points) const;
348 
349     /**
350      * This method converts pixels in the
351      * X direction to font design units.
352      *
353      * @param xPixels - pixels in the X direction
354      *
355      * @return font design units in the X direction
356      *
357      * @deprecated ICU 54. See {@link icu::LayoutEngine}
358      */
359     virtual float xPixelsToUnits(float xPixels) const;
360 
361     /**
362      * This method converts pixels in the
363      * Y direction to font design units.
364      *
365      * @param yPixels - pixels in the Y direction
366      *
367      * @return font design units in the Y direction
368      *
369      * @deprecated ICU 54. See {@link icu::LayoutEngine}
370      */
371     virtual float yPixelsToUnits(float yPixels) const;
372 
373     /**
374      * This method converts pixels to font design units.
375      *
376      * @param pixels - X and Y pixel
377      * @param units - set to X and Y font design units
378      *
379      * @deprecated ICU 54. See {@link icu::LayoutEngine}
380      */
381     virtual void pixelsToUnits(LEPoint &pixels, LEPoint &units) const;
382 
383     /**
384      * Get the X scale factor from the font's transform. The default
385      * implementation of <code>transformFunits()</code> will call this method.
386      *
387      * @return the X scale factor.
388      *
389      *
390      * @see transformFunits
391      *
392      * @deprecated ICU 54. See {@link icu::LayoutEngine}
393      */
394     virtual float getScaleFactorX() const = 0;
395 
396     /**
397      * Get the Y scale factor from the font's transform. The default
398      * implementation of <code>transformFunits()</code> will call this method.
399      *
400      * @return the Yscale factor.
401      *
402      * @see transformFunits
403      *
404      * @deprecated ICU 54. See {@link icu::LayoutEngine}
405      */
406     virtual float getScaleFactorY() const = 0;
407 
408     /**
409      * This method transforms an X, Y point in font design units to a
410      * pixel coordinate, applying the font's transform. The default
411      * implementation of this method calls <code>getScaleFactorX()</code>
412      * and <code>getScaleFactorY()</code>.
413      *
414      * @param xFunits - the X coordinate in font design units
415      * @param yFunits - the Y coordinate in font design units
416      * @param pixels - the tranformed co-ordinate in pixels
417      *
418      * @see getScaleFactorX
419      * @see getScaleFactorY
420      *
421      * @deprecated ICU 54. See {@link icu::LayoutEngine}
422      */
423     virtual void transformFunits(float xFunits, float yFunits, LEPoint &pixels) const;
424 
425     /**
426      * This is a convenience method used to convert
427      * values in a 16.16 fixed point format to floating point.
428      *
429      * @param fixed - the fixed point value
430      *
431      * @return the floating point value
432      *
433      * @deprecated ICU 54. See {@link icu::LayoutEngine}
434      */
435     static inline float fixedToFloat(le_int32 fixed);
436 
437     /**
438      * This is a convenience method used to convert
439      * floating point values to 16.16 fixed point format.
440      *
441      * @param theFloat - the floating point value
442      *
443      * @return the fixed point value
444      *
445      * @deprecated ICU 54. See {@link icu::LayoutEngine}
446      */
447     static inline le_int32 floatToFixed(float theFloat);
448 
449     //
450     // These methods won't ever be called by the LayoutEngine,
451     // but are useful for clients of <code>LEFontInstance</code> who
452     // need to render text.
453     //
454 
455     /**
456      * Get the font's ascent.
457      *
458      * @return the font's ascent, in points. This value
459      * will always be positive.
460      *
461      * @deprecated ICU 54. See {@link icu::LayoutEngine}
462      */
463     virtual le_int32 getAscent() const = 0;
464 
465     /**
466      * Get the font's descent.
467      *
468      * @return the font's descent, in points. This value
469      * will always be positive.
470      *
471      * @deprecated ICU 54. See {@link icu::LayoutEngine}
472      */
473     virtual le_int32 getDescent() const = 0;
474 
475     /**
476      * Get the font's leading.
477      *
478      * @return the font's leading, in points. This value
479      * will always be positive.
480      *
481      * @deprecated ICU 54. See {@link icu::LayoutEngine}
482      */
483     virtual le_int32 getLeading() const = 0;
484 
485     /**
486      * Get the line height required to display text in
487      * this font. The default implementation of this method
488      * returns the sum of the ascent, descent, and leading.
489      *
490      * @return the line height, in points. This vaule will
491      * always be positive.
492      *
493      * @deprecated ICU 54. See {@link icu::LayoutEngine}
494      */
495     virtual le_int32 getLineHeight() const;
496 
497     /**
498      * ICU "poor man's RTTI", returns a UClassID for the actual class.
499      *
500      * @deprecated ICU 54. See {@link icu::LayoutEngine}
501      */
502     virtual UClassID getDynamicClassID() const;
503 
504     /**
505      * ICU "poor man's RTTI", returns a UClassID for this class.
506      *
507      * @deprecated ICU 54. See {@link icu::LayoutEngine}
508      */
509     static UClassID getStaticClassID();
510 
511 };
512 
fixedToFloat(le_int32 fixed)513 inline float LEFontInstance::fixedToFloat(le_int32 fixed)
514 {
515     return (float) (fixed / 65536.0);
516 }
517 
floatToFixed(float theFloat)518 inline le_int32 LEFontInstance::floatToFixed(float theFloat)
519 {
520     return (le_int32) (theFloat * 65536.0);
521 }
522 
523 U_NAMESPACE_END
524 #endif
525