nsISVGRendererGlyphMetrics Interface

 \addtogroup renderer_interfaces Rendering Engine Interfaces
 @{


 One of a number of interfaces (all starting with nsISVGRenderer*)
 to be implemented by an SVG rendering engine. See nsISVGRenderer
 for more details.

 The SVG rendering backend uses this interface to communicate to the
 rendering engine-native glyph metrics objects.

 A glyph metrics object is instantiated by the backend for a given
 nsISVGGlyphMetricsSource object with a call to
 nsISVGRenderer::createGlyphMetrics(). The glyph metrics object is
 assumed to store a reference to its associated source object and
 provide metrics information about the (composite) glyph described
 by nsISVGGlyphMetricsSource::characterData,
 nsISVGGlyphMetricsSource::font, nsISVGGlyphMetricsSource::canvasTM, and
 other relevant style such as nsISVGGlyphMetricsSource::strokeWidth.

[uuid(2cdc98a4-594f-42a7-970c-e4dcb7a72aa0)]

Constants

 @name Baseline offset constants for getBaselineOffset()
 @{

const unsigned short BASELINE_ALPHABETIC = 0

const unsigned short BASELINE_HANGING = 1

const unsigned short BASELINE_IDEOGRAPHC = 2

const unsigned short BASELINE_MATHEMATICAL = 3

const unsigned short BASELINE_CENTRAL = 4

const unsigned short BASELINE_MIDDLE = 5

const unsigned short BASELINE_TEXT_BEFORE_EDGE = 6

const unsigned short BASELINE_TEXT_AFTER_EDGE = 7

Attributes

 Untransformed width of the composite glyph in pixels.

readonly attribute float advance

Methods

 Get the advance of an individual glyph.

float getAdvanceOfChar(in unsigned long charnum)

 @} */

 Retrieve the (y-axis) offset of the given baseline.
 
 @param baselineIdentifier One of the BASELINE_* constants defined
 in this interface.
 @return Y-axis offset in pixels relative to top of bounding box.

float getBaselineOffset(in unsigned short baselineIdentifier)

 Get the untransformed bounding box of an individual glyph.

 @param charnum The index of the character in
 nsISVGGlyphMetricsSource::characterData whose glyph bounding box
 is to be determined
 @return The untransformed bounding box in pixel coordinates

nsIDOMSVGRect getExtentOfChar(in unsigned long charnum)

 Called by this object's corresponding nsISVGGlyphMetricsSource as
 a notification that some of the source's data (identified by
 paramter 'updatemask') has changed.

 @param updatemask An OR-ed combination of the UPDATEMASK_*
 constants defined in nsISVGGlyphMetricsSource.
 @return PR_TRUE if the metrics have changed as a result of the
 source update, PR_FALSE otherwise.

boolean update(in unsigned long updatemask)