I've been trying to do this but never succeeded. I have a CAShapelayer which has a shape that's defined by a UIBezierpath. I want to render it as a retina image so when I submask an UIImageview with it, I get correct proportions. The Image in my UIImageview is indeed a retina image.
Here is my CAShapelayer code
CAShapeLayer*shapeLayer = [CAShapeLayer layer];
shapeLayer.path=forgroungPath.CGPath;
shapeLayer.bounds = pathRect;
CGFloat xRect =(CGPathGetBoundingBox(shapeLayer.path).origin.x)* -1;
CGFloat yRect =(CGPathGetBoundingBox(shapeLayer.path).origin.y)* -1;
[shapeLayer setAffineTransform:CGAffineTransformMakeTranslation(xRect, yRect)];
shapeLayer.position = CGPointMake(CGRectGetMidX(pathRect), CGRectGetMidY(pathRect));
[shapeLayer setFillColor:[UIColor redColor].CGColor];
[shapeLayer fillColor];
I've tried both
UIGraphicsImageRenderer*renderer = [[UIGraphicsImageRenderer
alloc]initWithBounds:rectForMainview];
UIImage*shapeImage=[renderer imageWithActions:
^(UIGraphicsImageRendererContext*_Nonnull context){
[shapeLayer renderInContext: context.CGContext];
}];
and
UIGraphicsBeginImageContextWithOptions(rectForMainview.size, NO, 0.0);
CGContextRef ctx = UIGraphicsGetCurrentContext();
[shapeLayer renderInContext:ctx];
UIImage * shapeImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
even though I've put 0.0 as scale, shapeImage will not get rendered as a retina image.
Any help is much appreciate.
Related
I am trying to draw circles on an image view for an ios application and there will be many circles and I want them to be in the same layer. My circle drawing code is;
UIBezierPath *circle = [UIBezierPath bezierPathWithArcCenter:center
radius:radius
startAngle:0
endAngle:2.0*M_PI
clockwise:YES];
CAShapeLayer *circleLayer = [CAShapeLayer layer];
circleLayer.bounds = CGRectMake(0, 0, 2.0*radius, 2.0*radius);
circleLayer.path = circle.CGPath;
circleLayer.backgroundColor = [UIColor orangeColor].CGColor;
and I need some thing different than the code below;
[imageView.layer addSublayer:circleLayer];
thanks.
From this site: http://www.cocoanetics.com/2010/07/drawing-on-uiimages/
- (UIImage *)imageByDrawingCircleOnImage:(UIImage *)image
{
// begin a graphics context of sufficient size
UIGraphicsBeginImageContext(image.size);
// draw original image into the context
[image drawAtPoint:CGPointZero];
// get the context for CoreGraphics
CGContextRef ctx = UIGraphicsGetCurrentContext();
// set stroking color and draw circle
[[UIColor redColor] setStroke];
// make circle rect 5 px from border
CGRect circleRect = CGRectMake(0, 0,
image.size.width,
image.size.height);
circleRect = CGRectInset(circleRect, 5, 5);
// draw circle
CGContextStrokeEllipseInRect(ctx, circleRect);
// make image out of bitmap context
UIImage *retImage = UIGraphicsGetImageFromCurrentImageContext();
// free the context
UIGraphicsEndImageContext();
return retImage;
}
I'm currently dealing with an iOS app asset generation in code ( creating CAShapeLayer and rendering it as an UIImage ).
I'm having a problem with rounded corners getting distorted when drawing a bezier path for my layer and was wondering if someone has had the same issue?
Screenshot to visualize the problem :
http://i.stack.imgur.com/I8Jre.png
( Generated UIImage is used as a backgroundImage for UIButton )
Code used to create a layer :
CAShapeLayer * layer = [CAShapeLayer new];
[layer setBackgroundColor:[UIColor clearColor].CGColor];
[layer setFrame:CGRectMake(.0, .0, size.width, size.height)];
[layer setFillColor:[UIColor colorForKey:#"colour_1"].CGColor];
[layer setStrokeColor:[UIColor colorForKey:#"colour_4"].CGColor];
[layer setLineWidth:2.0];
[layer setPath:[UIBezierPath bezierPathWithRoundedRect:layer.frame byRoundingCorners:UIRectCornerBottomLeft|UIRectCornerBottomRight cornerRadii:CGSizeMake(10.0, 10.0)].CGPath];
Turn it into an UIImage :
UIImage * imageFromCALayer(CALayer * layer) {
UIGraphicsBeginImageContextWithOptions([layer frame].size, NO, [UIScreen mainScreen].scale);
[layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return outputImage;
}
Why are you taking a CAShapeLayer and rasterizing it to an image? Just draw the path directly! Not only is that the correct way to generate an image, but it will give you more control over the drawing process.
Since your CAShapeLayer and the image have the same dimensions and you apply an outline (which is half inside and half outside the shapes path) the resulting image is cropped. So all you need to do is to add the width of the outline to the width and height of your resulting image.
How can I fill the non-transparent areas of a PNG UIImage with a linear gradient? I'd like to reuse a PNG shape for MKAnnotationViews, but change the gradient per annotation's properties.
To use an image as a mask for a gradient (i.e. to have a gradient in the shape of the non-transparent pixels of your image), you can:
create a simple view with a gradient (you can either create a simple UIView and use the addGradientLayerToView shown below to give it a gradient or you can create the gradient PNG in advance and add it to your bundle).
apply your PNG as a mask to that gradient view:
UIImage *mask = [UIImage imageNamed:#"mask.png"];
CALayer *maskLayer = [CALayer layer];
maskLayer.frame = CGRectMake(0, 0, mask.size.width, mask.size.height);
maskLayer.contents = (id)[mask CGImage];
gradientViewToMask.layer.mask = maskLayer;
To apply a gradient to the transparent pixels, you can either:
Create a new image with a gradient:
- (UIImage *)imageWithGradient:(UIImage *)image
{
UIGraphicsBeginImageContextWithOptions(image.size, NO, 1.0);
CGContextRef context = UIGraphicsGetCurrentContext();
size_t locationCount = 2;
CGFloat locations[2] = { 0.0, 1.0 };
CGFloat components[8] = { 0.0, 0.8, 0.8, 1.0, // Start color
0.9, 0.9, 0.9, 1.0 }; // End color
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGGradientRef gradient = CGGradientCreateWithColorComponents (colorspace, components, locations, locationCount):
CGPoint startPoint = CGPointMake(0.0, 0.0);
CGPoint endPoint = CGPointMake(0.0, image.size.height);
CGContextDrawLinearGradient (context, gradient, startPoint, endPoint, 0);
CGContextTranslateCTM(context, 0, image.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, CGRectMake(0.0, 0.0, image.size.width, image.size.height), [image CGImage]);
UIImage *gradientImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGGradientRelease(gradient);
CGColorSpaceRelease(colorspace);
return gradientImage;
}
You can also add a CAGradientLayer to a view and then add the UIImageView as a subview of that view.
- (void)addGradientLayerToView:(UIView *)view
{
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = view.bounds;
gradient.colors = #[(id)[[UIColor colorWithRed:0.0 green:0.8 blue:0.8 alpha:1.0] CGColor],
(id)[[UIColor colorWithRed:0.9 green:0.9 blue:0.9 alpha:1.0] CGColor]];
[view.layer insertSublayer:gradient atIndex:0];
}
Note, you have to #import <QuartzCore/QuartzCore.h> as well as add the QuartzCore framework to your project.
I ended up hacking together some bits of Rob's code and an extension to UIImage I found at http://coffeeshopped.com/2010/09/iphone-how-to-dynamically-color-a-uiimage
+ (UIImage *)imageNamed:(NSString *)name withGradient:(CGGradientRef)gradient
{
// load the image
UIImage *img = [UIImage imageNamed:name];
// begin a new image context, to draw our colored image onto
UIGraphicsBeginImageContextWithOptions(img.size, NO, [[UIScreen mainScreen] scale]);
// get a reference to that context we created
CGContextRef context = UIGraphicsGetCurrentContext();
// translate/flip the graphics context (for transforming from CG* coords to UI* coords
CGContextTranslateCTM(context, 0, img.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// set the blend mode to overlay, and the original image
CGContextSetBlendMode(context, kCGBlendModeOverlay);
CGRect rect = CGRectMake(0, 0, img.size.width, img.size.height);
// set a mask that matches the shape of the image, then draw (overlay) a colored rectangle
CGContextClipToMask(context, rect, img.CGImage);
CGContextAddRect(context, rect);
//gradient
CGPoint startPoint = CGPointMake(0.0, img.size.height);
CGPoint endPoint = CGPointMake(0.0, 0.0);
CGContextDrawLinearGradient (context, gradient, startPoint, endPoint, 0);
// generate a new UIImage from the graphics context we drew onto
UIImage *coloredImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGGradientRelease(gradient);
//return the color-burned image
return coloredImg;
}
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 am trying to draw some circles inside a UIImageView with a specific image. This is what I was trying to do:
UIGraphicsBeginImageContext(self.view.bounds.size);
CGContextRef contextRef = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(contextRef, 2.0);
CGContextSetStrokeColorWithColor(contextRef, [color CGColor]);
CGRect circlePoint = (CGRectMake(coordsFinal.x, coordsFinal.y, 50.0, 50.0));
CGContextStrokeEllipseInRect(contextRef, circlePoint);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[photoView addSubview:image];
The circle is drawn fine, but I would like the PhotoView to act as a mask to it. So if for example I move the UIImageView out of the UIView using an animation, I would like the circle to move with it. Important is the fact that the coordinates are relative to the whole screen.
Use Core Animation's shape layer instead.
CAShapeLayer *circleLayer = [CAShapeLayer layer];
// Give the layer the same bounds as your image view
[circleLayer setBounds:CGRectMake(0.0f, 0.0f, [photoView bounds].size.width,
[photoView bounds].size.height)];
// Position the circle anywhere you like, but this will center it
// In the parent layer, which will be your image view's root layer
[circleLayer setPosition:CGPointMake([photoView bounds].size.width/2.0f,
[photoView bounds].size.height/2.0f)];
// Create a circle path.
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:
CGRectMake(0.0f, 0.0f, 50.0f, 50.0f)];
// Set the path on the layer
[circleLayer setPath:[path CGPath]];
// Set the stroke color
[circleLayer setStrokeColor:[[UIColor redColor] CGColor]];
// Set the stroke line width
[circleLayer setLineWidth:2.0f];
// Add the sublayer to the image view's layer tree
[[photoView layer] addSublayer:circleLayer];
Now, if you animate the UIImageView that contains this layer, the layer will move with it since it is a child layer. And there is now no need to override drawRect:.