/* * * (C) Copyright IBM Corp. 1998-2004 - All Rights Reserved * */ #ifndef __LEFONTINSTANCE_H #define __LEFONTINSTANCE_H #include "LETypes.h" U_NAMESPACE_BEGIN /** * Instances of this class are used by LEFontInstance::mapCharsToGlyphs and * LEFontInstance::mapCharToGlyph to adjust character codes before the character * to glyph mapping process. Examples of this are filtering out control characters * and character mirroring - replacing a character which has both a left and a right * hand form with the opposite form. * * @stable ICU 3.2 */ class LECharMapper /* not : public UObject because this is an interface/mixin class */ { public: /** * Destructor. * @stable ICU 3.2 */ virtual inline ~LECharMapper() {}; /** * This method does the adjustments. * * @param ch - the input character * * @return the adjusted character * * @stable ICU 2.8 */ virtual LEUnicode32 mapChar(LEUnicode32 ch) const = 0; }; /** * This is a forward reference to the class which holds the per-glyph * storage. * * @draft ICU 3.0 */ class LEGlyphStorage; /** * This is a virtual base class that serves as the interface between a LayoutEngine * and the platform font environment. It allows a LayoutEngine to access font tables, do * character to glyph mapping, and obtain metrics information without knowing any platform * specific details. There are also a few utility methods for converting between points, * pixels and funits. (font design units) * * An instance of an LEFontInstance represents a font at a particular point * size. Each instance can represent either a single physical font, or a composite font. * A composite font is a collection of physical fonts, each of which contains a subset of * the characters contained in the composite font. * * Note: with the exception of getSubFont, the methods in this class only * make sense for a physical font. If you have an LEFontInstance which * represents a composite font you should only call the methods below which have * an LEGlyphID, an LEUnicode or an LEUnicode32 * as one of the arguments because these can be used to select a particular subfont. * * Subclasses which implement composite fonts should supply an implementation of these * methods with some default behavior such as returning constant values, or using the * values from the first subfont. * * @draft ICU 3.0 */ class U_LAYOUT_API LEFontInstance : public UObject { public: /** * This virtual destructor is here so that the subclass * destructors can be invoked through the base class. * * @stable ICU 2.8 */ virtual inline ~LEFontInstance() {}; /** * Get a physical font which can render the given text. For composite fonts, * if there is no single physical font which can render all of the text, * return a physical font which can render an initial substring of the text, * and set the offset parameter to the end of that substring. * * Internally, the LayoutEngine works with runs of text all in the same * font and script, so it is best to call this method with text which is * in a single script, passing the script code in as a hint. If you don't * know the script of the text, you can use zero, which is the script code * for characters used in more than one script. * * The default implementation of this method is intended for instances of * LEFontInstance which represent a physical font. It returns * this and indicates that the entire string can be rendered. * * This method will return a valid LEFontInstance unless you * have passed illegal parameters, or an internal error has been encountered. * For composite fonts, it may return the warning LE_NO_SUBFONT_WARNING * to indicate that the returned font may not be able to render all of * the text. Whenever a valid font is returned, the offset parameter * will be advanced by at least one. * * Subclasses which implement composite fonts must override this method. * Where it makes sense, they should use the script code as a hint to render * characters from the COMMON script in the font which is used for the given * script. For example, if the input text is a series of Arabic words separated * by spaces, and the script code passed in is arabScriptCode you * should return the font used for Arabic characters for all of the input text, * including the spaces. If, on the other hand, the input text contains characters * which cannot be rendered by the font used for Arabic characters, but which can * be rendered by another font, you should return that font for those characters. * * @param chars - the array of Unicode characters. * @param offset - a pointer to the starting offset in the text. On exit this * will be set the the limit offset of the text which can be * rendered using the returned font. * @param limit - the limit offset for the input text. * @param script - the script hint. * @param success - set to an error code if the arguments are illegal, or no font * can be returned for some reason. May also be set to * LE_NO_SUBFONT_WARNING if the subfont which * was returned cannot render all of the text. * * @return an LEFontInstance for the sub font which can render the characters, or * NULL if there is an error. * * @see LEScripts.h * * @stable ICU 3.2 */ virtual const LEFontInstance *getSubFont(const LEUnicode chars[], le_int32 *offset, le_int32 limit, le_int32 script, LEErrorCode &success) const; // // Font file access // /** * This method reads a table from the font. Note that in general, * it only makes sense to call this method on an LEFontInstance * which represents a physical font - i.e. one which has been returned by * getSubFont(). This is because each subfont in a composite font * will have different tables, and there's no way to know which subfont to access. * * Subclasses which represent composite fonts should always return NULL. * * @param tableTag - the four byte table tag. (e.g. 'cmap') * * @return the address of the table in memory, or NULL * if the table doesn't exist. * * @stable ICU 2.8 */ virtual const void *getFontTable(LETag tableTag) const = 0; /** * This method is used to determine if the font can * render the given character. This can usually be done * by looking the character up in the font's character * to glyph mapping. * * The default implementation of this method will return * TRUE if mapCharToGlyph(ch) * returns a non-zero value. * * @param ch - the character to be tested * * @return TRUE if the font can render ch. * * @stable ICU 3.2 */ virtual le_bool canDisplay(LEUnicode32 ch) const; /** * This method returns the number of design units in * the font's EM square. * * @return the number of design units pre EM. * * @stable ICU 2.8 */ virtual le_int32 getUnitsPerEM() const = 0; /** * This method maps an array of character codes to an array of glyph * indices, using the font's character to glyph map. * * The default implementation iterates over all of the characters and calls * mapCharToGlyph(ch, mapper) on each one. It also handles surrogate * characters, storing the glyph ID for the high surrogate, and a deleted glyph (0xFFFF) * for the low surrogate. * * Most sublcasses will not need to implement this method. * * @param chars - the character array * @param offset - the index of the first character * @param count - the number of characters * @param reverse - if TRUE, store the glyph indices in reverse order. * @param mapper - the character mapper. * @param glyphStorage - the object which contains the output glyph array * * @see LECharMapper * * @draft ICU 3.0 */ virtual void mapCharsToGlyphs(const LEUnicode chars[], le_int32 offset, le_int32 count, le_bool reverse, const LECharMapper *mapper, LEGlyphStorage &glyphStorage) const; /** * This method maps a single character to a glyph index, using the * font's character to glyph map. The default implementation of this * method calls the mapper, and then calls mapCharToGlyph(mappedCh). * * @param ch - the character * @param mapper - the character mapper * * @return the glyph index * * @see LECharMapper * * @stable ICU 3.2 */ virtual LEGlyphID mapCharToGlyph(LEUnicode32 ch, const LECharMapper *mapper) const; /** * This method maps a single character to a glyph index, using the * font's character to glyph map. There is no default implementation * of this method because it requires information about the platform * font implementation. * * @param ch - the character * * @return the glyph index * * @stable ICU 3.2 */ virtual LEGlyphID mapCharToGlyph(LEUnicode32 ch) const = 0; // // Metrics // /** * This method gets the X and Y advance of a particular glyph, in pixels. * * @param glyph - the glyph index * @param advance - the X and Y pixel values will be stored here * * @stable ICU 3.2 */ virtual void getGlyphAdvance(LEGlyphID glyph, LEPoint &advance) const = 0; /** * This method gets the hinted X and Y pixel coordinates of a particular * point in the outline of the given glyph. * * @param glyph - the glyph index * @param pointNumber - the number of the point * @param point - the point's X and Y pixel values will be stored here * * @return TRUE if the point coordinates could be stored. * * @stable ICU 2.8 */ virtual le_bool getGlyphPoint(LEGlyphID glyph, le_int32 pointNumber, LEPoint &point) const = 0; /** * This method returns the width of the font's EM square * in pixels. * * @return the pixel width of the EM square * * @stable ICU 2.8 */ virtual float getXPixelsPerEm() const = 0; /** * This method returns the height of the font's EM square * in pixels. * * @return the pixel height of the EM square * * @stable ICU 2.8 */ virtual float getYPixelsPerEm() const = 0; /** * This method converts font design units in the * X direction to points. * * @param xUnits - design units in the X direction * * @return points in the X direction * * @stable ICU 3.2 */ virtual float xUnitsToPoints(float xUnits) const; /** * This method converts font design units in the * Y direction to points. * * @param yUnits - design units in the Y direction * * @return points in the Y direction * * @stable ICU 3.2 */ virtual float yUnitsToPoints(float yUnits) const; /** * This method converts font design units to points. * * @param units - X and Y design units * @param points - set to X and Y points * * @stable ICU 3.2 */ virtual void unitsToPoints(LEPoint &units, LEPoint &points) const; /** * This method converts pixels in the * X direction to font design units. * * @param xPixels - pixels in the X direction * * @return font design units in the X direction * * @stable ICU 3.2 */ virtual float xPixelsToUnits(float xPixels) const; /** * This method converts pixels in the * Y direction to font design units. * * @param yPixels - pixels in the Y direction * * @return font design units in the Y direction * * @stable ICU 3.2 */ virtual float yPixelsToUnits(float yPixels) const; /** * This method converts pixels to font design units. * * @param pixels - X and Y pixel * @param units - set to X and Y font design units * * @stable ICU 3.2 */ virtual void pixelsToUnits(LEPoint &pixels, LEPoint &units) const; /** * Get the X scale factor from the font's transform. The default * implementation of transformFunits() will call this method. * * @return the X scale factor. * * * @see transformFunits * * @stable ICU 3.2 */ virtual float getScaleFactorX() const = 0; /** * Get the Y scale factor from the font's transform. The default * implementation of transformFunits() will call this method. * * @return the Yscale factor. * * @see transformFunits * * @stable ICU 3.2 */ virtual float getScaleFactorY() const = 0; /** * This method transforms an X, Y point in font design units to a * pixel coordinate, applying the font's transform. The default * implementation of this method calls getScaleFactorX() * and getScaleFactorY(). * * @param xFunits - the X coordinate in font design units * @param yFunits - the Y coordinate in font design units * @param pixels - the tranformed co-ordinate in pixels * * @see getScaleFactorX * @see getScaleFactorY * * @stable ICU 3.2 */ virtual void transformFunits(float xFunits, float yFunits, LEPoint &pixels) const; /** * This is a convenience method used to convert * values in a 16.16 fixed point format to floating point. * * @param fixed - the fixed point value * * @return the floating point value * * @stable ICU 2.8 */ static float fixedToFloat(le_int32 fixed); /** * This is a convenience method used to convert * floating point values to 16.16 fixed point format. * * @param theFloat - the floating point value * * @return the fixed point value * * @stable ICU 2.8 */ static le_int32 floatToFixed(float theFloat); // // These methods won't ever be called by the LayoutEngine, // but are useful for clients of LEFontInstance who // need to render text. // /** * Get the font's ascent. * * @return the font's ascent, in points. This value * will always be positive. * * @stable ICU 3.2 */ virtual le_int32 getAscent() const = 0; /** * Get the font's descent. * * @return the font's descent, in points. This value * will always be positive. * * @stable ICU 3.2 */ virtual le_int32 getDescent() const = 0; /** * Get the font's leading. * * @return the font's leading, in points. This value * will always be positive. * * @stable ICU 3.2 */ virtual le_int32 getLeading() const = 0; /** * Get the line height required to display text in * this font. The default implementation of this method * returns the sum of the ascent, descent, and leading. * * @return the line height, in points. This vaule will * always be positive. * * @stable ICU 3.2 */ virtual le_int32 getLineHeight() const; /** * ICU "poor man's RTTI", returns a UClassID for the actual class. * * @stable ICU 3.2 */ virtual UClassID getDynamicClassID() const; /** * ICU "poor man's RTTI", returns a UClassID for this class. * * @stable ICU 3.2 */ static UClassID getStaticClassID(); }; inline le_bool LEFontInstance::canDisplay(LEUnicode32 ch) const { return LE_GET_GLYPH(mapCharToGlyph(ch)) != 0; } inline float LEFontInstance::xUnitsToPoints(float xUnits) const { return (xUnits * getXPixelsPerEm()) / (float) getUnitsPerEM(); } inline float LEFontInstance::yUnitsToPoints(float yUnits) const { return (yUnits * getYPixelsPerEm()) / (float) getUnitsPerEM(); } inline void LEFontInstance::unitsToPoints(LEPoint &units, LEPoint &points) const { points.fX = xUnitsToPoints(units.fX); points.fY = yUnitsToPoints(units.fY); } inline float LEFontInstance::xPixelsToUnits(float xPixels) const { return (xPixels * getUnitsPerEM()) / (float) getXPixelsPerEm(); } inline float LEFontInstance::yPixelsToUnits(float yPixels) const { return (yPixels * getUnitsPerEM()) / (float) getYPixelsPerEm(); } inline void LEFontInstance::pixelsToUnits(LEPoint &pixels, LEPoint &units) const { units.fX = xPixelsToUnits(pixels.fX); units.fY = yPixelsToUnits(pixels.fY); } inline void LEFontInstance::transformFunits(float xFunits, float yFunits, LEPoint &pixels) const { pixels.fX = xUnitsToPoints(xFunits) * getScaleFactorX(); pixels.fY = yUnitsToPoints(yFunits) * getScaleFactorY(); } inline float LEFontInstance::fixedToFloat(le_int32 fixed) { return (float) (fixed / 65536.0); } inline le_int32 LEFontInstance::floatToFixed(float theFloat) { return (le_int32) (theFloat * 65536.0); } inline le_int32 LEFontInstance::getLineHeight() const { return getAscent() + getDescent() + getLeading(); } U_NAMESPACE_END #endif