icuSources/layout/LEFontInstance.h

   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
 513 inline float LEFontInstance::fixedToFloat(le_int32 fixed)
 514 {
 515     return (float) (fixed / 65536.0);
 516 }
 517
 518 inline le_int32 LEFontInstance::floatToFixed(float theFloat)
 519 {
 520     return (le_int32) (theFloat * 65536.0);
 521 }
 522
 523 U_NAMESPACE_END
 524 #endif