Added the uiDrawCaret() function for drawing text carets. Now to write the backend-specific code and test it out.

common/CMakeLists.txt

@@ -6,6 +6,7 @@ list(APPEND _LIBUI_SOURCES
 	common/areaevents.c
 	common/control.c
 	common/debug.c
+	common/drawtext.c
 	common/matrix.c
 	common/shouldquit.c
 	common/userbugs.c

common/drawtext.c

@@ -0,0 +1,53 @@
+// 10 february 2017
+#include "../ui.h"
+#include "uipriv.h"
+
+void uiDrawCaret(uiDrawContext *c, double x, double y, uiDrawTextLayout *layout, size_t pos, int *line)
+{
+	double xoff;
+	uiDrawTextLayoutLineMetrics m;
+	struct caretDrawParams cdp;
+	uiDrawPath *path;
+	uiDrawBrush brush;
+
+	caretDrawParams(c, &cdp);
+
+	xoff = uiDrawTextLayoutByteLocationInLine(layout, pos, *line);
+	if (xoff < 0) {
+		size_t start, end;
+		int incr;
+
+		if (*line > (uiDrawTextLayoutNumLines(layout) - 1)) {
+			*line = (uiDrawTextLayoutNumLines(layout) - 1);
+			incr = -1;
+		} else {
+			uiDrawTextLayoutLineByteRange(layout, *line, &start, &end);
+			incr = 1;
+			if (end < pos)
+				incr = -1;
+		}
+		while (xoff < 0) {
+			*line += incr;
+			xoff = uiDrawTextLayoutByteLocationInLine(layout, pos, *line);
+		}
+	}
+	uiDrawTextLayoutLineGetMetrics(layout, *line, &m);
+
+	uiDrawSave(c);
+
+	path = uiDrawNewPath(uiDrawFillModeWinding);
+	uiDrawPathAddRectangle(path,
+		// TODO add m.X?
+		x + xoff, y + m.Y,
+		cdp.width, m.Height);
+	uiDrawPathEnd(path);
+	brush.Type = uiDrawBrushTypeSolid;
+	brush.R = cdp.r;
+	brush.G = cdp.g;
+	brush.B = cdp.b;
+	brush.A = cdp.a;
+	uiDrawFill(c, path, &brush);
+	uiDrawFreePath(path);
+
+	uiDrawRestore(c);
+}

common/uipriv.h

@@ -89,6 +89,16 @@ extern void attrlistForEach(struct attrlist *alist, uiAttributedString *s, uiAtt
 extern struct attrlist *attrlistNew(void);
 extern void attrlistFree(struct attrlist *alist);
 
+// drawtext.c
+struct caretDrawParams {
+	double r;
+	double g;
+	double b;
+	double a;
+	double width;
+};
+extern void caretDrawParams(uiDrawContext *c, struct caretDrawParams *p);
+
 #ifdef __cplusplus
 }
 #endif

ui_attrstr.h

@@ -161,3 +161,5 @@ _UI_EXTERN void uiDrawTextLayoutHitTest(uiDrawTextLayout *tl, double x, double y
 // 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);