Mozilla2:GFXTextRun
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Class gfxTextRun
/**
* A class representing a single span of text with a uniform style.
* It treats the text is laid out along a straight horizontal line
* with the glyphs oriented normally with respect to the baseline. Of course,
* the text can be rotated or otherwise transformed by imposing a
* transformation in the drawing context before drawing.
*
* When determining glyph geometry, the text should be hinted
* assuming it will be drawn with the current transformation in the
* referenceContext used to construct the gfxTextRun. The caller guarantees not
* to change the state of referenceContext during the lifetime of the
* gfxTextRun object.
* The actual transformation or even context used in Draw() or AddToPath()
* may be different.
*/
class gfxTextRun {
// these do not copy the text. it is the caller's responsibility to keep
// the text alive during the lifetime of the text run.
gfxTextRun(const char* ASCII, int length, nsFontMetrics* font, PRBool RTL, nsIAtom* language, gfxContext* referenceContext);
gfxTextRun(const PRUnichar* unicode, int length, nsFontMetrics* font, PRBool RTL, nsIAtom* language, gfxContext* referenceContext);
enum { ClusterStart = 0x1 } CharFlags;
// ClusterStart: character is the first character of a cluster
// Get the flags for each character in a substring. 'flags' is an array
// of length 'len'
void GetCharacterFlags(int pos, int len, CharFlags* flags);
struct RunFlags {
PRPackedBool startsWord;
PRPackedBool endsWord;
PRPackedBool startsLine;
PRPackedBool endsLine;
};
// Set whether or not this text run starts/ends a word.
// This must NOT change the character flags but it can change the geometry.
void SetRunFlags(RunFlags flags);
RunFlags GetRunFlags();
// Set the spacing between clusters. For each character index i that is
// the start of a cluster, spacingArray[i] is the amount of space to insert
// before that cluster (possibly negative) (i.e. between this cluster
// and the cluster containing the previous character in the string).
// For each character index i that is not the start of a cluster,
// spacingArray[i] must be zero. spacingArray[0] must be zero.
// This must NOT change the character flags but it can change the geometry.
void SetSpacing(gfxFloat* spacingArray);
// The substring must not contain any partial clusters. 'pt' is the
// the baseline of the visually left edge of the visually leftmost cluster.
void Draw(gfxContext* ctx, gfxPoint& pt, int pos, int len);
// The substring must not contain any partial clusters. 'pt' is the
// the baseline of the visually left edge of the visually leftmost cluster.
// The outlines of the characters are added to the current path.
void AddToPath(gfxContext* ctx, gfxPoint& pt, int pos, int len);
struct Dimensions {
// advance of substring start from the origin of the whole string,
// always positive regardless of RTL
gfxFloat xOffset;
// advance of the substring, always positive regardless of RTL
gfxFloat advance;
// font ascent and descent for this substring, both always positive
gfxFloat ascent, descent;
// the bounding box of area actually rendered by the glyphs in the
// substring, relative to the origin of the whole string; if this can't
// be accurately determined, then at least this must contain the true
// bounding box
gfxRect boundingBox;
};
// The substring must not contain any partial clusters.
Dimensions MeasureText(int pos, int len);
// Compute how many characters from this string starting at
// character 'pos' and up to length 'len' fit
// into the given width. 'breaks' is an array of length len.
// A break is allowed before character i wherever breaks[i] is nonzero,
// i.e., if the result of GetCharsFit is i then breaks[i] is nonzero.
// If none of the chars fit then this will return zero, so breaks[0] must be
// nonzero. If all of the chars fit, return 'len'. Breaks are only allowed
// at cluster boundaries so if character i is not the start of a cluster,
// then breaks[i] must be zero.
// We will usually want to call MeasureText right afterwards,
// the implementor could optimize for that.
// The substring must not contain any partial clusters.
int GetCharsFit(int pos, int len, gfxFloat width, PRUint8* breaks);
// Return the index of the character selected if the user clicks the
// mouse at point pt. If the point is exactly between two characters,
// if preferLeft is true then return the character visually to the left
// (as if pt.x had been smaller) if there is one, otherwise return the
// character visually to the right. If the point is before the start of
// the string, return -1. If the point is beyond the end of the string,
// return the full string length.
int GetPositionInString(gfxPoint& pt, PRBool preferLeft);
};