Hi I have draw a gradient in core graphic using drawRect function..
but I don't know how to draw a border to surround this view?
this is my code, could anyone help?
- (void)drawRect:(CGRect)rect {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = UIGraphicsGetCurrentContext();
NSArray *gradientColors = [NSArray arrayWithObjects:(id)[UIColor blackColor].CGColor, [UIColor colorWithRed:90/255.0 green:0 blue:0 alpha:1].CGColor, nil];
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef) gradientColors, NULL);
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
CGGradientRelease(gradient);
CGColorSpaceRelease(colorSpace);
}
If you just want to draw a border around the view, try this:
UIBezierPath *border = [UIBezierPath bezierPathWithRect:rect];
[[UIColor redColor] setStroke];
[border setLineWidth:4.0];
[border stroke];
Use it at the end of drawRect: method.
Related
I have a view in storyboard controller which extends my custom UIView and when I try to draw a gradient in drawRect it displays fine when loading on to device/sim via XCode but when I install via TestFlight after uploading to ITunes Connect the gradient isn't present at first (displays black background) - it needs a rotation of the device and the gradient displays fine again. What could be causing this behaviour?
- (void)drawRect:(CGRect)rect {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = UIGraphicsGetCurrentContext();
NSArray *gradientColors = [NSArray arrayWithObjects:
(id)[[self colorWithHexString:#"FF7542"]CGColor],
(id)[[self colorWithHexString:#"FF7542"]CGColor],
(id)[[self colorWithHexString:#"FFC0A1"]CGColor],
nil];
CGFloat gradientLocations[] = {0, 1};
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef) gradientColors, gradientLocations);
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
CGGradientRelease(gradient);
CGColorSpaceRelease(colorSpace);
NSShadow *shadow = [[NSShadow alloc] init];
[shadow setShadowColor : BLACK_SHADOW];
[shadow setShadowOffset : CGSizeMake (1.0, 1.0)];
}
I solved this by creating my gradient another way and strangely it shows first time when loaded without the need for a rotation.
CGContextRef current_context = UIGraphicsGetCurrentContext();
CGContextSaveGState(current_context);
// Gradient
CGFloat locations[2] = {0.0, 1.0};
CGFloat components[8] = {1.00,0.75,0.63,1.0,1.00,0.46,0.26,1.0};
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents(colorspace, components, locations, 2);
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextDrawLinearGradient(current_context, gradient, startPoint, endPoint, 0);
CGGradientRelease(gradient);
CGColorSpaceRelease(colorspace);
I am overriding drawRect method in order to draw ellipse
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, [UIColor mainColorYellow].CGColor);
CGRect rectangle = CGRectMake(0.0, 2.0, rect.size.width , rect.size.height - 4.0);
CGContextAddEllipseInRect(context, rectangle);
CGContextStrokePath(context);
}
How can I change fill color on ellipse? I tried using CGContextSetFillColorWithColor(CGContextRef c, CGColorRef color) but without result.
There is two different operations, fill and stroke. Stroke es the border, fill is the inside. You are only doing the border. You can control the fill and border color independently. You have, however, to render both explicitly. For example:
[[UIColor yellowColor] setFill];
[[UIColor blackColor] setStroke];
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0.0, 2.0, rect.size.width , rect.size.height - 4.0)];
path.lineWidth = 2.0;
[path fill];
[path stroke];
Notice I wrote the code in a more modern quartz. The context is implicit. Hope it helps.
Just add below:
CGContextFillEllipseInRect(context, rectangle);
My goal is
1. add gradient for my view (done)
2. add drop shadow for the bottom edge of my view ( issue at here )
What I am doing is :
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
UIColor *whiteColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:1.0];
UIColor *lightGrayColor = [UIColor colorWithRed:230.0/255.0 green:230.0/255.0 blue:230.0/255.0 alpha:1.0];
CGRect paperRect = self.bounds;
// Fill with gradient
[self drawLinearGradient:context for:paperRect start:whiteColor.CGColor end:lightGrayColor.CGColor];
CGContextSetStrokeColorWithColor(context, [UIColor lightGrayColor].CGColor);
CGContextSetLineWidth(context, .9);
CGContextStrokeRect(context, paperRect);
// Add shadow
CGContextSetShadowWithColor(context, CGSizeMake(0, self.frame.size.height), 9.0, [UIColor blueColor].CGColor);
}
-(void)drawLinearGradient:(CGContextRef)context for:(CGRect)rect start:(CGColorRef)startColor end:(CGColorRef)endColor {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGFloat locations[] = { 0.0, 1.0 };
NSArray *colors = [NSArray arrayWithObjects:(__bridge id)startColor, (__bridge id)endColor, nil];
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef) colors, locations);
CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));
CGContextSaveGState(context);
CGContextAddRect(context, rect);
CGContextClip(context);
CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
CGContextRestoreGState(context);
CGGradientRelease(gradient);
CGColorSpaceRelease(colorSpace);
}
However, what I am getting is the picture below without shadow at all
Am I on the right track but missing something in the middle ? Please help if you have any ideas..
You need to set the shadow properties before drawing whatever it is that's supposed to have the shadow. Put your call to CGContextSetShadowWithColor before the call to CGContextStrokeRect.
Also, the offset should probably not be as large as you're making it. The shadow offset controls how much the shadow is offset from the pixels that were drawn with that shadow, so unless you want the shadow to actually start very far away from your rect you probably want an offset of just a pixel or so, like CGSizeMake(0.0, 1.0).
I have a camera app to load photo into a device with mask. Everything is OK. When I try to use renderInContext to save the view to an image, I only see the image without any mask.
UIGraphicsBeginImageContext(contentView.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[contentView.layer renderInContext:context];
UIImage *outImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(outImage, self, #selector(image: didFinishSavingWithError: contextInfo:), context);
I have read some paper from Apple to say that renderInContext don't support mask and composition. I've made some search on the internet to get the information that UIView needed to draw as a context first and then use renderInContext to save the image.
Now my question is what method to do the job? What about drawRect, drawInRect, drawLayer, drawInContent, or other method. Can anyone give me a hint. Thanks a lots.
I started from here: http://chinkisingh.com/2013/03/03/draw-on-iphoneipad-screen-using-bezier-paths-core-graphics-ios-app-development/
I have a UIBezierPath and I wanted to apply a gradient to it and apply to an existing image, see if the following code helps
CGRect r = CGRectMake(0, 0, HEART_SIZE, HEART_SIZE);
UIBezierPath *heart = [Bezier heartShape:r]; //this is only in my case
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
UIColor *darkPink = [UIColor colorWithHue:0.915 saturation:1.000 brightness:0.941 alpha:1.000];
UIColor *lightPink = [UIColor colorWithHue:0.917 saturation:0.647 brightness:1.000 alpha:1.000];
NSArray *gradientColors = [NSArray arrayWithObjects:
(id)darkPink.CGColor,
(id)lightPink.CGColor,
(id)darkPink.CGColor, nil];
CGFloat gradientLocations[] = {0, 0.5, 1};
CGGradientRef gradient = CGGradientCreateWithColors(colorSpace, (__bridge CFArrayRef)gradientColors, gradientLocations);
CGColorSpaceRelease(colorSpace);
UIGraphicsBeginImageContext(r.size);
heart.lineCapStyle = kCGLineCapRound;
heart.lineWidth = 10.0f;
[[UIColor blackColor] setStroke];
[[UIColor redColor] setFill];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
[heart stroke]; //removed the black stroke around
[heart fill];
CGContextAddPath(context, heart.CGPath);
CGContextClip(context);
CGContextDrawLinearGradient(context, gradient, CGPointMake(10, 10), CGPointMake(210, 210), kCGGradientDrawsAfterEndLocation); //check that gradient is drawn in the right place
CGGradientRelease(gradient);
UIImage *theRightImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
i have just a problem with my MKPolyLineView. I simply try to make a color gradient to the Polyline, but with CAGradient it doenst work. I subclasses MKPolylineView and redrawing in
- (void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:(CGContextRef)context
UIColor *darker = [UIColor blackColor];
CGFloat baseWidth = self.lineWidth / zoomScale;
// draw the dark colour thicker
CGContextAddPath(context, self.path);
CGContextSetStrokeColorWithColor(context, darker.CGColor);
CGContextSetLineWidth(context, baseWidth * 1.5);
CGContextSetLineCap(context, self.lineCap);
CGContextStrokePath(context);
// now draw the stroke color with the regular width
CGContextAddPath(context, self.path);
CGContextSetStrokeColorWithColor(context, self.strokeColor.CGColor);
CGContextSetLineWidth(context, baseWidth);
CGContextSetLineCap(context, self.lineCap);
CGContextStrokePath(context);
[super drawMapRect:mapRect zoomScale:zoomScale inContext:context];
}
but even that is not working (StrokeColor = red). Any ideas how to get a gradient into
the Polyline? (Highcolor, centercolor, lowcolor)
Thanks everyone.
To paint a MKPolyline with a gradient, you can use a custom subclass of MKPolylineView. As CoreGraphics does not support stroking a path with a gradient, we have to
convert the path to a shape that traces the paths edge using CGPathCreateCopyByStrokingPath
clip the context to that shape
fill using CGContextDrawLinearGradient
Here is a subclass to get you started:
#interface TWOGradientPolylineView : MKPolylineView
#end
#implementation TWOGradientPolylineView
- (void)strokePath:(CGPathRef)path inContext:(CGContextRef)context
{
CGFloat lineWidth = CGContextConvertSizeToUserSpace(context, (CGSize){self.lineWidth, self.lineWidth}).width;
CGPathRef pathToFill = CGPathCreateCopyByStrokingPath(path, NULL, lineWidth, self.lineCap, self.lineJoin, self.miterLimit);
CGRect rect = CGPathGetBoundingBox(pathToFill);
CGContextAddPath(context, pathToFill);
CGPathRelease(pathToFill);
CGContextClip(context);
CGFloat gradientLocations[2] = {0.0f, 1.0f};
CGFloat gradientColors[8] = {1.0f, 0.0f, 0.0f, 0.75f, 1.0f, 1.0f, 0.0f, 0.75f};
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace, gradientColors, gradientLocations, 2);
CGColorSpaceRelease(colorSpace);
CGPoint gradientStart = rect.origin;
CGPoint gradientEnd = {CGRectGetMaxX(rect), CGRectGetMaxY(rect)};
CGContextDrawLinearGradient(context, gradient, gradientStart, gradientEnd, kCGGradientDrawsAfterEndLocation);
CGGradientRelease(gradient);
}
#end
Here is a screenshot of a path drawn with the class above: