73 lines
3.3 KiB
C
73 lines
3.3 KiB
C
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typedef struct uiDrawTextLayoutLineMetrics uiDrawTextLayoutLineMetrics;
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// Height will equal ParagraphSpacingBefore + LineHeightSpace + Ascent + Descent + Leading + LineSpacing + ParagraphSpacing.
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// The above values are listed in vertical order, from top to bottom.
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// Ascent + Descent + Leading will give you the typographic bounds
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// of the text. BaselineY is the boundary between Ascent and Descent.
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// X, Y, and BaselineY are all in the layout's coordinate system, so the
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// start point of the baseline will be at (X, BaselineY). All values are
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// nonnegative.
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struct uiDrawTextLayoutLineMetrics {
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// This describes the overall bounding box of the line.
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double X;
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double Y;
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double Width;
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double Height;
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// This describes the typographic bounds of the line.
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double BaselineY;
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double Ascent;
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double Descent;
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double Leading;
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// This describes any additional whitespace.
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// TODO come up with better names for these.
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double ParagraphSpacingBefore;
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double LineHeightSpace;
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double LineSpacing;
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double ParagraphSpacing;
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// TODO trailing whitespace?
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};
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// uiDrawTextLayoutNumLines() returns the number of lines in tl.
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// This number will always be greater than or equal to 1; a text
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// layout with no text only has one line.
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_UI_EXTERN int uiDrawTextLayoutNumLines(uiDrawTextLayout *tl);
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// uiDrawTextLayoutLineByteRange() returns the byte indices of the
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// text that falls into the given line of tl as [start, end).
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_UI_EXTERN void uiDrawTextLayoutLineByteRange(uiDrawTextLayout *tl, int line, size_t *start, size_t *end);
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_UI_EXTERN void uiDrawTextLayoutLineGetMetrics(uiDrawTextLayout *tl, int line, uiDrawTextLayoutLineMetrics *m);
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// TODO rewrite this documentation
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// uiDrawTextLayoutHitTest() returns the byte offset and line closest
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// to the given point. The point is relative to the top-left of the layout.
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// If the point is outside the layout itself, the closest point is chosen;
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// this allows the function to be used for cursor positioning with the
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// mouse. Do keep the returned line in mind if used in this way; the
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// user might click on the end of a line, at which point the cursor
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// might be at the trailing edge of the last grapheme on the line
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// (subject to the operating system's APIs).
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_UI_EXTERN void uiDrawTextLayoutHitTest(uiDrawTextLayout *tl, double x, double y, size_t *pos, int *line);
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// uiDrawTextLayoutByteLocationInLine() returns the point offset
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// into the given line that the given byte position stands. This is
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// relative to the line's X position (as returned by
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// uiDrawTextLayoutLineGetMetrics()), which in turn is relative to
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// the top-left of the layout. This function can be used for cursor
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// positioning: if start and end are the start and end of the line
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// (as returned by uiDrawTextLayoutLineByteRange()), you will get
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// the correct offset, even if pos is at the end of the line. If pos is not
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// in the range [start, end], a negative value will be returned,
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// indicating you need to move the cursor to another line.
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// TODO make sure this works right for right-aligned and center-aligned lines and justified lines and RTL text
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_UI_EXTERN double uiDrawTextLayoutByteLocationInLine(uiDrawTextLayout *tl, size_t pos, int line);
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_UI_EXTERN void uiDrawCaret(uiDrawContext *c, double x, double y, uiDrawTextLayout *layout, size_t pos, int *line);
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// TODO allow blinking
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// TODO allow secondary carets
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