Started a new drawtext.m with a different way to handle the empty-string crash problem.

darwin/attrstr.m

@@ -449,6 +449,7 @@ static CTParagraphStyleRef mkParagraphStyle(uiDrawTextLayoutParams *p)
 	return ps;
 }
 
+// TODO either rename this to uiprivDrawTextLayoutParams... or rename this file or both or split the struct or something else...
 CFAttributedStringRef uiprivAttributedStringToCFAttributedString(uiDrawTextLayoutParams *p, NSArray **backgroundBlocks)
 {
 	CFStringRef cfstr;

darwin/drawtext.m

@@ -0,0 +1,127 @@
+// 7 march 2018
+#import "uipriv_darwin.h"
+#import "draw.h"
+#import "attrstr.h"
+
+// problem: for a CTFrame made from an empty string, the CTLine array will be empty, and we will crash when gathering metrics or hit-testing
+// solution: for those cases, maintain a separate framesetter just for computing those things
+// in the usual case, the separate copy will just be identical to the regular one, with extra references to everything within
+struct frame {
+	CFAttributedStringRef attrstr;
+	NSArray *backgroundBlocks;
+	CTFramesetterRef framesetter;
+	CGSize size;
+	CGPathRef path;
+	CTFrameRef frame;
+};
+
+struct uiDrawTextLayout {
+	struct frame forDrawing;
+	struct frame forMetrics;
+};
+
+static void paramsToFrame(uiDrawTextLayoutParams *params, struct frame *frame)
+{
+	CFRange range;
+	CGFloat width;
+	CFRange unused;
+	CGRect rect;
+
+	frame->attrstr = uiprivAttributedStringToCFAttributedString(p, &(frame->backgroundBlocks));
+	// TODO kCTParagraphStyleSpecifierMaximumLineSpacing, kCTParagraphStyleSpecifierMinimumLineSpacing, kCTParagraphStyleSpecifierLineSpacingAdjustment for line spacing
+	frame->framesetter = CTFramesetterCreateWithAttributedString(tl->attrstr);
+	if (frame->framesetter == NULL) {
+		// TODO
+	}
+
+	range.location = 0;
+	range.length = CFAttributedStringGetLength(tl->attrstr);
+
+	cgwidth = (CGFloat) (frame->width);
+	if (cgwidth < 0)
+		cgwidth = CGFLOAT_MAX;
+	frame->size = CTFramesetterSuggestFrameSizeWithConstraints(frame->framesetter,
+		range,
+		// TODO kCTFramePathWidthAttributeName?
+		NULL,
+		CGSizeMake(cgwidth, CGFLOAT_MAX),
+		&unused);			// not documented as accepting NULL (TODO really?)
+
+	rect.origin = CGPointZero;
+	rect.size = frame->size;
+	frame->path = CGPathCreateWithRect(rect, NULL);
+	frame->frame = CTFramesetterCreateFrame(tl->framesetter,
+		range,
+		tl->path,
+		// TODO kCTFramePathWidthAttributeName?
+		NULL);
+	if (frame->frame == NULL) {
+		// TODO
+	}
+}
+
+static void freeFrame(struct frame *frame)
+{
+	CFRelease(frame->frame);
+	CFRelease(frame->path);
+	CFRelease(frame->framesetter);
+	[frame->backgroundBlocks release];
+	CFRelease(frame->attrstr);
+}
+
+static void retainFrameCopy(struct frame *out, const struct frame *frame)
+{
+	memcpy(out, frame, sizeof (struct frame));
+	CFRetain(out->attrstr);
+	[out->backgroundBlocks retain];
+	CFRetain(out->framesetter);
+	CFRetain(out->path);
+	CFRetain(out->frame);
+}
+
+uiDrawTextLayout *uiDrawNewTextLayout(uiDrawTextLayoutParams *p)
+{
+	uiDrawTextLayout *tl;
+
+	tl = uiprivNew(uiDrawTextLayout);
+	paramsToFrame(p, &(tl->forDrawing));
+	if (uiAttributedStringLength(p->String) != 0)
+		retainFrameCopy(&(tl->forMetrics), &(tl->forDrawing));
+	else {
+		uiAttributedString *space;
+		uiDrawTextLayoutParams p2;
+
+		space = uiNewAttributedString(" ");
+		p2 = *p;
+		p2.String = space;
+		paramsToFrame(&p2, &(tl->forMetrics));
+		uiFreeAttributedString(space);
+	}
+	return tl;
+}
+
+void uiDrawFreeTextLayout(uiDrawTextLayout *tl)
+{
+	freeFrame(&(tl->forMetrics));
+	freeFrame(&(tl->forDrawing));
+	uiprivFree(tl);
+}
+
+// uiDrawText() draws tl in c with the top-left point of tl at (x, y).
+_UI_EXTERN void uiDrawText(uiDrawContext *c, uiDrawTextLayout *tl, double x, double y);
+
+// uiDrawTextLayoutExtents() returns the width and height of tl
+// in width and height. The returned width may be smaller than
+// the width passed into uiDrawNewTextLayout() depending on
+// how the text in tl is wrapped. Therefore, you can use this
+// function to get the actual size of the text layout.
+_UI_EXTERN void uiDrawTextLayoutExtents(uiDrawTextLayout *tl, double *width, double *height);
+
+// 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);