From 1bd2ca22c234b8e6d56cdffd0e741871a4e08364 Mon Sep 17 00:00:00 2001
From: Pietro Gagliardi <pietro10@mac.com>
Date: Fri, 6 Jan 2017 23:53:23 -0500
Subject: [PATCH] Some more work on the new Cocoa text drawing code.

---
 darwin/CMakeLists.txt  |  1 +
 darwin/_old_drawtext.m | 48 ------------------------------------------
 darwin/draw.h          |  6 ++++++
 darwin/draw.m          |  6 +-----
 darwin/drawtext.m      | 25 +++++++++++++++++++++-
 5 files changed, 32 insertions(+), 54 deletions(-)
 create mode 100644 darwin/draw.h

diff --git a/darwin/CMakeLists.txt b/darwin/CMakeLists.txt
index 385a4a53..32d1b45e 100644
--- a/darwin/CMakeLists.txt
+++ b/darwin/CMakeLists.txt
@@ -44,6 +44,7 @@ list(APPEND _LIBUI_SOURCES
 )
 set(_LIBUI_SOURCES ${_LIBUI_SOURCES} PARENT_SCOPE)
 
+// TODO is this correct?
 list(APPEND _LIBUI_INCLUDEDIRS
 	darwin
 )
diff --git a/darwin/_old_drawtext.m b/darwin/_old_drawtext.m
index 14346784..72a8d2e6 100644
--- a/darwin/_old_drawtext.m
+++ b/darwin/_old_drawtext.m
@@ -227,54 +227,6 @@ void uiDrawTextLayoutExtents(uiDrawTextLayout *layout, double *width, double *he
 	freeFramesetter(&fs);
 }
 
-// Core Text doesn't draw onto a flipped view correctly; we have to do this
-// see the iOS bits of the first example at https://developer.apple.com/library/mac/documentation/StringsTextFonts/Conceptual/CoreText_Programming/LayoutOperations/LayoutOperations.html#//apple_ref/doc/uid/TP40005533-CH12-SW1 (iOS is naturally flipped)
-// TODO how is this affected by the CTM?
-static void prepareContextForText(CGContextRef c, CGFloat cheight, double *y)
-{
-	CGContextSaveGState(c);
-	CGContextTranslateCTM(c, 0, cheight);
-	CGContextScaleCTM(c, 1.0, -1.0);
-	CGContextSetTextMatrix(c, CGAffineTransformIdentity);
-
-	// wait, that's not enough; we need to offset y values to account for our new flipping
-	*y = cheight - *y;
-}
-
-// TODO placement is incorrect for Helvetica
-void doDrawText(CGContextRef c, CGFloat cheight, double x, double y, uiDrawTextLayout *layout)
-{
-	struct framesetter fs;
-	CGRect rect;
-	CGPathRef path;
-	CTFrameRef frame;
-
-	prepareContextForText(c, cheight, &y);
-	mkFramesetter(layout, &fs);
-
-	// oh, and since we're flipped, y is the bottom-left coordinate of the rectangle, not the top-left
-	// since we are flipped, we subtract
-	y -= fs.extents.height;
-
-	rect.origin = CGPointMake(x, y);
-	rect.size = fs.extents;
-	path = CGPathCreateWithRect(rect, NULL);
-
-	frame = CTFramesetterCreateFrame(fs.fs,
-		CFRangeMake(0, 0),
-		path,
-		fs.frameAttrib);
-	if (frame == NULL)
-		complain("error creating CTFrame object in doDrawText()");
-	CTFrameDraw(frame, c);
-	CFRelease(frame);
-
-	CFRelease(path);
-
-	freeFramesetter(&fs);
-	CGContextRestoreGState(c);
-}
-
 // LONGTERM provide an equivalent to CTLineGetTypographicBounds() on uiDrawTextLayout?
 
 // LONGTERM keep this for later features and documentation purposes
diff --git a/darwin/draw.h b/darwin/draw.h
new file mode 100644
index 00000000..41629809
--- /dev/null
+++ b/darwin/draw.h
@@ -0,0 +1,6 @@
+// 6 january 2017
+
+struct uiDrawContext {
+	CGContextRef c;
+	CGFloat height;				// needed for text; see below
+};
diff --git a/darwin/draw.m b/darwin/draw.m
index 262ad3e2..231b4dfd 100644
--- a/darwin/draw.m
+++ b/darwin/draw.m
@@ -1,5 +1,6 @@
 // 6 september 2015
 #import "uipriv_darwin.h"
+#import "draw.h"
 
 struct uiDrawPath {
 	CGMutablePathRef path;
@@ -103,11 +104,6 @@ void uiDrawPathEnd(uiDrawPath *p)
 	p->ended = TRUE;
 }
 
-struct uiDrawContext {
-	CGContextRef c;
-	CGFloat height;				// needed for text; see below
-};
-
 uiDrawContext *newContext(CGContextRef ctxt, CGFloat height)
 {
 	uiDrawContext *c;
diff --git a/darwin/drawtext.m b/darwin/drawtext.m
index cdf766f5..a7a400f7 100644
--- a/darwin/drawtext.m
+++ b/darwin/drawtext.m
@@ -1,5 +1,6 @@
 // 2 january 2017
 #import "uipriv_darwin.h"
+#import "draw.h"
 
 struct uiDrawTextLayout {
 	CFAttributedStringRef attrstr;
@@ -124,9 +125,31 @@ void uiDrawFreeTextLayout(uiDrawTextLayout *tl)
 	uiFree(tl);
 }
 
-// TODO what is y, the top-left corner, bottom-left corner, topmost baseline, or bottommost baseline?
+// TODO double-check helvetica
+// TODO document that (x,y) is the top-left corner of the *entire frame*
 void uiDrawText(uiDrawContext *c, uiDrawTextLayout *tl, double x, double y)
 {
+	CGContextSaveGState(c->c);
+
+	// Core Text doesn't draw onto a flipped view correctly; we have to pretend it was unflipped
+	// see the iOS bits of the first example at https://developer.apple.com/library/mac/documentation/StringsTextFonts/Conceptual/CoreText_Programming/LayoutOperations/LayoutOperations.html#//apple_ref/doc/uid/TP40005533-CH12-SW1 (iOS is naturally flipped)
+	// TODO how is this affected by a non-identity CTM?
+	CGContextTranslateCTM(c->c, 0, cheight);
+	CGContextScaleCTM(c->c, 1.0, -1.0);
+	CGContextSetTextMatrix(c->c, CGAffineTransformIdentity);
+
+	// wait, that's not enough; we need to offset y values to account for our new flipping
+	y = c->height - y;
+
+	// CTFrameDraw() draws in the path we specified when creating the frame
+	// this means that in our usage, CTFrameDraw() will draw at (0,0)
+	// so move the origin to be at (x,y) instead
+	// TODO are the signs correct?
+	CGContextTranslateCTM(c->c, x, y);
+
+	CTFrameDraw(tl->frame, c->c);
+
+	CGContextRestoreGState(c->c);
 }
 
 // TODO document that the width and height of a layout is not necessarily the sum of the widths and heights of its constituent lines; this is definitely untrue on OS X, where lines are placed in such a way that the distance between baselines is always integral