First Commit

libui-ng/old/_wip/attrstr_metrics/old_ui_attrstr.h

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