Support any angle in CPGradient drawInRect:angle:.

AppKit/CPGradient.j

@@ -68,16 +68,43 @@ CPGradientDrawsAfterEndingLocation      = kCGGradientDrawsAfterEndLocation;
 
 - (void)drawInRect:(CGRect)rect angle:(float)angle
 {
-    if (angle !== 0)
-        [CPException raise:CPInvalidArgumentException reason:@"angle != 0 not yet implemented"];
-
     var ctx = [[CPGraphicsContext currentContext] graphicsPort];
 
     CGContextSaveGState(ctx);
     CGContextClipToRect(ctx, rect);
     CGContextAddRect(ctx, rect);
 
-    [self drawFromPoint:rect.origin toPoint:CGPointMake(CGRectGetMaxX(rect), CGRectGetMinY(rect)) options:CPGradientDrawsBeforeStartingLocation | CPGradientDrawsAfterEndingLocation];
+    var startPoint,
+        endPoint;
+
+    // Modulo of negative values doesn't work as expected in JS.
+    angle = ((angle % 360.0) + 360.0) % 360.0;
+
+    if (angle < 90.0)
+        startPoint = CGPointMake(CGRectGetMinX(rect), CGRectGetMinY(rect));
+    else if (angle < 180.0)
+        startPoint = CGPointMake(CGRectGetMaxX(rect), CGRectGetMinY(rect));
+    else if (angle < 270.0)
+        startPoint = CGPointMake(CGRectGetMaxX(rect), CGRectGetMaxY(rect));
+    else
+        startPoint = CGPointMake(CGRectGetMinX(rect), CGRectGetMaxY(rect));
+
+    // A line segment comes out of the starting point at the given angle, with the first colour
+    // at the starting point and the last at the end. To do what drawInRect: is supposed to do
+    // we want the opposite corner of the starting corner to just reach the final colour stop.
+    // So when the angle isn't a right angle, the segment has to extend beyond the edge of the
+    // rectangle just far enough. This is hard to describe without a picture but if we place
+    // another line through the opposite corner at -90 degrees, it'll cross through our
+    // gradient segment just where it should end and form a right triangle with the right edge.
+    // of the rect. One leg of this triangle is how far the gradient line should stick out,
+    // and the length of that leg is (in the first quadrant) width * cos(a) + height * sin(a).
+    var radians = PI * angle / 180.0,
+        length = ABS(CGRectGetWidth(rect) * COS(radians)) + ABS(CGRectGetHeight(rect) * SIN(radians));
+
+    endPoint = CGPointMake(startPoint.x + length * COS(radians),
+                           startPoint.y + length * SIN(radians));
+
+    [self drawFromPoint:startPoint toPoint:endPoint options:CPGradientDrawsBeforeStartingLocation | CPGradientDrawsAfterEndingLocation];
     CGContextRestoreGState(ctx);
 }
 

Tests/Manual/CPGraphicsTest/AppController.j

@@ -18,6 +18,8 @@
 
     @outlet CustomDrawView  gradientView0;
     @outlet CustomDrawView  gradientView1;
+    @outlet CustomDrawView  gradientView2;
+    @outlet CustomDrawView  gradientView3;
 }
 
 - (void)awakeFromCib
@@ -29,6 +31,12 @@
     var context = [[CPGraphicsContext currentContext] graphicsPort],
         innerRect;
 
+    var grad0 = aView == gradientView0,
+        grad1 = aView == gradientView1,
+        grad2 = aView == gradientView2,
+        grad3 = aView == gradientView3,
+        isGradient = (grad0 || grad1 || grad2 || grad3);
+
     if (aView === view1 || aView === view2)
     {
         var bounds = [aView bounds],
@@ -64,29 +72,49 @@
 
         innerRect = CPDrawColorTiledRects(bounds, bounds, sides, colors);
     }
-    else if (aView === gradientView0 || aView === gradientView1)
+    else if (isGradient)
     {
         var bounds = [aView bounds],
-            locations,
-            colors;
+            colors,
+            gradient;
 
-        if (aView === gradientView0)
+        if (grad1 || grad3)
         {
-            locations = [0.0, 0.25, 0.50, 0.75, 1.0];
-            colors = [[CPColor blackColor], [CPColor redColor], [CPColor greenColor], [CPColor blueColor], [CPColor whiteColor]];
+            // Draw a pattern for the gradient to blend with.
+            strokeGrid(bounds);
+        }
+
+        if (grad0)
+        {
+            var locationsGrad0 = [ 0.0, 0.25, 0.50, 0.75, 1.0 ];
+            colors = [CPArray arrayWithObjects:[CPColor blackColor], [CPColor redColor], [CPColor greenColor], [CPColor blueColor], [CPColor whiteColor]];
+            gradient = [[CPGradient alloc] initWithColors:colors atLocations:locationsGrad0 colorSpace:[CPColorSpace sRGBColorSpace]];
+            [gradient drawInRect:bounds angle:0];
+        }
+        else if (grad1)
+        {
+            var mainColor = [CPColor orangeColor],
+                locationsGrad1 = [ 0.0, 0.45, 0.56, 1.0 ];
+            colors = [CPArray arrayWithObjects:[mainColor colorWithAlphaComponent:0.0], mainColor, mainColor, [mainColor colorWithAlphaComponent:0.0]];
+            gradient = [[CPGradient alloc] initWithColors:colors atLocations:locationsGrad1 colorSpace:[CPColorSpace sRGBColorSpace]];
+            [gradient drawInRect:bounds angle:90];
+        }
+        else if (grad2)
+        {
+            colors = [CPArray arrayWithObjects:[CPColor cyanColor], [CPColor magentaColor], [CPColor yellowColor], [CPColor blackColor]];
+            gradient = [[CPGradient alloc] initWithColors:colors];
+            [gradient drawInRect:bounds angle:225];
         }
         else
         {
-            locations = [0.0, 0.35, 0.66, 1.0];
-            var mainColor = [CPColor blackColor];
-            colors = [[mainColor colorWithAlphaComponent:0.0], mainColor, mainColor, [mainColor colorWithAlphaComponent:0.0]];
-        }
 
-        var gradient = [[CPGradient alloc] initWithColors:colors atLocations:locations colorSpace:[CPColorSpace sRGBColorSpace]];
-        [gradient drawInRect:bounds angle:0];
+            colors = [CPArray arrayWithObjects:[[CPColor cyanColor] colorWithAlphaComponent:0.5], [CPColor magentaColor], [CPColor clearColor], [CPColor whiteColor]];
+            gradient = [[CPGradient alloc] initWithColors:colors];
+            [gradient drawInRect:bounds angle:-20];
+        }
     }
 
-    if (!(aView === gradientView0 || aView === gradientView1))
+    if (!isGradient)
     {
         CGContextSetFillColor(context, [CPColor colorWithHexString:@"E1EAFF"]);
         CGContextFillRect(context, innerRect);
@@ -108,3 +136,22 @@
 }
 
 @end
+
+
+function strokeGrid(/* CGRect */ rect)
+{
+    [CPBezierPath setDefaultLineWidth:1];
+    [[CPColor whiteColor] setFill];
+    [[[CPColor blueColor] colorWithAlphaComponent:0.5] setStroke];
+
+    var mx = CGRectGetMaxX(rect),
+        my = CGRectGetMaxY(rect);
+
+    [CPBezierPath fillRect:rect];
+
+    for (var x = rect.origin.x; x < mx; x += 6)
+        [CPBezierPath strokeLineFromPoint:CGPointMake(x + 0.5, rect.origin.y + 0.5) toPoint:CGPointMake(x + 0.5, my - 0.5)];
+
+    for (var y = rect.origin.y; y < my; y += 6)
+        [CPBezierPath strokeLineFromPoint:CGPointMake(rect.origin.x + 0.5, y + 0.5) toPoint:CGPointMake(mx - 0.5, y + 0.5)];
+}