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(fixes issue #438) by Steve Nicholson, NSGradient drawInRect:angle: fix

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This commit is contained in:
Christopher Lloyd 2009-11-05 14:21:18 +00:00
parent 9bd79ee55e
commit e60f746331
1 changed files with 25 additions and 18 deletions
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43
AppKit/NSGradient.m
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@ -149,47 +149,54 @@ void _NSGradientInterpolator(void *info, float const *inData, float *outData)
- (void)drawInRect:(NSRect)rect angle:(CGFloat)angle
{
if ([_colors count] < 2)
if ([_colors count] < 2 || 0 == rect.size.width)
return;
CGPoint start;
CGPoint end;
CGPoint start; //start coordinate of gradient
CGPoint end; //end coordinate of gradient
//tanSize is the rectangle size for atan2 operation. It is the size of the rect in relation to the offset start point
CGPoint tanSize;
float width = rect.size.width;
float height = rect.size.height;
angle = (CGFloat)fmod(angle, 360);
CGFloat radAngleToEndFromCenter;
if (angle < 90)
{
start = CGPointMake(0, 0);
radAngleToEndFromCenter = (angle * 2 - 45) / 180 * M_PI;
start = CGPointMake(rect.origin.x, rect.origin.y);
tanSize = CGPointMake(rect.size.width, rect.size.height);
}
else if (angle < 180)
{
start = CGPointMake(width, 0);
radAngleToEndFromCenter = ((angle - 90) * 2 + 45) / 180 * M_PI;
start = CGPointMake(rect.origin.x + rect.size.width, rect.origin.y);
tanSize = CGPointMake(-rect.size.width, rect.size.height);
}
else if (angle < 270)
{
start = CGPointMake(width, height);
radAngleToEndFromCenter = ((angle - 180) * 2 + 135) / 180 * M_PI;
start = CGPointMake(rect.origin.x + rect.size.width, rect.origin.y + rect.size.height);
tanSize = CGPointMake(-rect.size.width, -rect.size.height);
}
else
{
start = CGPointMake(0, height);
radAngleToEndFromCenter = ((angle - 270) * 2 + 225) / 180 * M_PI;
start = CGPointMake(rect.origin.x, rect.origin.y + rect.size.height);
tanSize = CGPointMake(rect.size.width, -rect.size.height);
}
end.x = (0.5f + cos(radAngleToEndFromCenter) / sqrt(2)) * width;
end.y = (0.5f + sin(radAngleToEndFromCenter) / sqrt(2)) * height;
CGFloat radAngle = angle / 180 * M_PI; //Angle in radians
//The trig for this is difficult to describe without an illustration, so I'm attaching an illustration
//to Cocotron issue number 438 along with this patch
CGFloat distanceToEnd = cos(atan2(tanSize.y,tanSize.x) - radAngle) *
sqrt(rect.size.width * rect.size.width + rect.size.height * rect.size.height);
end = CGPointMake(cos(radAngle) * distanceToEnd + start.x, sin(radAngle) * distanceToEnd + start.y);
CGFunctionCallbacks callbacks = { 0, &_NSGradientInterpolator, NULL };
CGFunctionRef function = CGFunctionCreate(self, 1, NULL, 4, NULL, &callbacks);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGShadingRef shading = CGShadingCreateAxial(colorSpace, start, end, function, NO, YES);
CGShadingRef shading = CGShadingCreateAxial(colorSpace, start, end, function, NO, NO);
CGContextRef context = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
CGContextSaveGState(context);
CGContextClipToRect(context, rect);
CGContextDrawShading(context, shading);
CGContextRestoreGState(context);
CGFunctionRelease(function);
CGColorSpaceRelease(colorSpace);