I have this code and it's not adding anything to the view, can you help me figure out what is wrong?
also I will apply a filer to image, but that will be later, when I get this done, but tell me if this is a wrong approach if Im going to add filters.
UIGraphicsPushContext(context);
CALayer *layer = [CALayer layer];
CGColorRef bgColor = [UIColor colorWithHue:0.6 saturation:1.0 brightness:1.0 alpha:1.0].CGColor;
layer.frame = CGRectMake(0, 0, 200, 200);
CGContextSetFillColorWithColor(context, bgColor);
CGContextFillRect(context, layer.bounds);
CGContextSaveGState(context);
CGColorSpaceRef patternSpace = CGColorSpaceCreatePattern(NULL);
CGContextSetFillColorSpace(context, patternSpace);
CGColorSpaceRelease(patternSpace);
CGContextFillRect(context, layer.bounds);
CGContextRestoreGState(context);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageView *borrar = [[UIImageView alloc]initWithImage:image];
[self.view addSubview:borrar];
You never open an image context. Use UIGraphicsBeginImageContextWithOptions.
Related
In objective-c, I make a circle shape programmatically by following codes:
+(UIImage *)makeRoundedImage:(CGSize) size backgroundColor:(UIColor *) backgroundColor cornerRadius:(int) cornerRadius
{
UIImage* bgImage = [self imageWithColor:backgroundColor andSize:size];;
CALayer *imageLayer = [CALayer layer];
imageLayer.frame = CGRectMake(0, 0, size.width, size.height);
imageLayer.contents = (id) bgImage.CGImage;
imageLayer.masksToBounds = YES;
imageLayer.cornerRadius = cornerRadius;
UIGraphicsBeginImageContext(bgImage.size);
[imageLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *roundedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return roundedImage;
}
The imageWithColor method is as following:
+(UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)size
{
//quick fix, or pop up CG invalid context 0x0 bug
if(size.width == 0) size.width = 1;
if(size.height == 0) size.height = 1;
//---quick fix
UIImage *img = nil;
CGRect rect = CGRectMake(0, 0, size.width, size.height);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context,
color.CGColor);
CGContextFillRect(context, rect);
img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
Then I used it to create a pure color circle shape image, but what I found is the circle image is not perfect rounded. As an example, please see following code:
CGSize size = CGSizeMake(diameter, diameter);
int r = ceil((float)diameter/2.0);
UIImage *imageNormal = [self makeRoundedImage:size backgroundColor:backgroundColor cornerRadius:r];
[slider setThumbImage:imageNormal forState:UIControlStateNormal];
First I created a circle image, then I set the image as the thumb to a UISlider. But what shown is as the picture shown below:
You can see the circle is not an exact circle. I'm thinking probably it caused by the screen resolution issue? Because if I use an image resource for the thumb, I need add #2x. Anybody know the reason? Thanx in advance.
updated on 8th Aug 2015.
Further to this question and the answer from #Noah Witherspoon, I found the blurry edge issue has been solved. But still, the circle looks like being cut. I used the code as following:
CGRect rect = CGRectMake(0.0f, 0.0f, radius*2.0f, radius*2.0f);
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillEllipseInRect(context, rect);
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
And the circle looks like:
You can see the edge has been cut.
I changed the code as following:
CGRect rect = CGRectMake(0.0f, 0.0f, radius*2.0f+4, radius*2.0f+4);
CGRect rectmin = CGRectMake(2.0f, 2.0f, radius*2, radius*2);
UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, color.CGColor);
CGContextFillEllipseInRect(context, rectmin);
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
You can see the circle looks better(The top edge and the bottom edge):
I made the fill rect size smaller, and the edge looks better, but I don't think it's a nice solution. Still, does anybody know why this happen?
From your screenshot it looks like you do actually have a circular image, but its scale is wrong—it’s not Retina—so it looks blurry and not-circular. The key thing is that instead of using UIGraphicsBeginImageContext which defaults to a scale of 1.0 (as compared to your screen, which is at a scale of 2.0 or 3.0), you should be using UIGraphicsBeginImageContextWithOptions. Also, you don’t need to make a layer or a view to draw a circle in an image context.
+ (UIImage *)makeCircleImageWithDiameter:(CGFloat)diameter color:(UIColor *)color {
UIGraphicsBeginImageContextWithOptions(CGSizeMake(diameter, diameter), NO, 0 /* scale (0 means “use the current screen’s scale”) */);
[color setFill];
CGContextFillEllipseInRect(UIGraphicsGetCurrentContext(), CGRectMake(0, 0, diameter, diameter));
UIImage *image = UIGraphicsGetImageFromCurrentContext();
UIGraphicsEndImageContext();
return image;
}
If you want to get a circle every time try this:
- (UIImage *)makeCircularImage:(CGSize)size backgroundColor:(UIColor *)backgroundColor {
CGSize squareSize = CGSizeMake((size.width > size.height) ? size.width : size.height,
(size.width > size.height) ? size.width : size.height);
UIView *circleView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, squareSize.width, squareSize.height)];
circleView.layer.cornerRadius = circleView.frame.size.height * 0.5f;
circleView.backgroundColor = backgroundColor;
circleView.opaque = NO;
UIGraphicsBeginImageContextWithOptions(circleView.bounds.size, circleView.opaque, 0.0);
[circleView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
I know how to create a UIImage programatically, with the following code:
CGRect rect = CGRectMake(0.0f, 0.0f, 300.0f, 60.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
What I want to do is, to fill it with multiple colors. like the following
You know how to paint one rectangle, just extrapolate for painting multiple rectangles as below. Usse your own colors. I have used inbuilt color, if need any custom colors then set the color using RGB value.
CGRect rect = CGRectMake(0.0f, 0.0f, 300.0f, 60.0f);
NSArray *colorArray = [NSArray arrayWithObjects:[UIColor redColor],[UIColor yellowColor],[UIColor greenColor],[UIColor brownColor],
[UIColor lightGrayColor],nil];
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
for (int i = 0; i < colorArray.count; i++)
{
CGRect smallRect = CGRectMake((300.0f /colorArray.count) * i,0.0f,(300.0f /colorArray.count) ,60.0f);
CGContextSetFillColorWithColor(context, [colorArray[i] CGColor]);
CGContextFillRect(context, smallRect);
}
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Hi i want to covert my UIView to UIImage in particular frame size kindly help me.
I have 'UITableView` which is added as subview of 'UIScrollView' for horizontal scroll, my table view frame size is (0, 0, 12000, 768).
I want to convert the current visible are of my UITableView as UIImage after scrolling.
Example:
if i scrolled my table view horizontally some distance means that current visible are is (150,0,1200,768) that means full device screen.
if i use the following code:
UIGraphicsBeginImageContext(self.frame.size);
[self.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *backgroundImage = UIGraphicsGetImageFromCurrentImageContext();
its capturing always the frame size of (0, 0, 1200, 768) only.
so, how can i set the origin of image capturing.
Kindly help me out.... Thanks in advance....
- (UIImage *)rasterizedImageInView:(UIView *)view atRect:(CGRect)rect {
UIGraphicsBeginImageContextWithOptions(rect.size, view.opaque, 0.0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(context, -rect.origin.x, -rect.origin.y);
[view.layer renderInContext:context];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
This will allow you to capture a UIImage from a particular region within a UIView as defined by a CGRect.
CGRect rect = [self.view bounds];
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[self.view.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Try this.
UIView *viewprint=[[UIView alloc] initWithFrame:CGRectMake(0, 0, width, height)];
viewprint.backgroundColor=[UIColor whiteColor];
tableView.frame = CGRectMake(0, 0, width, height);
[viewprint addSubview:tableView];
UIGraphicsBeginImageContext(viewprint.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[view.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Trying to get an image with rounded corners and stroke,
but there is something I do wrong, because app hangs during this:
- (UIImage *)roundedCornerImage:(NSInteger)radius{
UIGraphicsBeginImageContextWithOptions(self.size, NO, 0);
CGRect box = CGRectInset((CGRect){CGPointZero, self.size}, self.size.width * 0.9f, self.size.height * 0.9f);
UIBezierPath *ballBezierPath = [UIBezierPath bezierPathWithOvalInRect:box];
[[UIColor blackColor] setStroke];
[ballBezierPath setLineWidth:4.0];
[ballBezierPath stroke];
[[UIBezierPath bezierPathWithRoundedRect:(CGRect){CGPointZero, self.size}
cornerRadius:radius]addClip];
[self drawInRect:(CGRect){CGPointZero, self.size}];
UIImage* result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
Forget messing with the layer, it's a performance killer in scroll views. Just generate a new image instead:
+(UIImage *)makeRoundedImage:(UIImage *)image withRadius:(CGFloat)radius
{
CGRect itemFrame = CGRectMake(0, 0, radius*2, radius*2);
// The source image
UIImageView *imageView = [UIImageView new];
imageView.frame = itemFrame;
imageView.contentMode = UIViewContentModeScaleToFill;
[imageView setImage:image];
imageView.layer.cornerRadius = radius;
imageView.layer.masksToBounds = YES;
// Make an image of our client item
UIGraphicsBeginImageContextWithOptions(itemFrame.size, NO, 0.0);
[imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *returnImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Fini
return returnImage;
}
Just use
[imageView.layer setCornerRadius:5.0f];
[imageView.layer setBorderWidth:5.0f];
Don;t forget to #import Quartzcore;
Is there any way of accessing the preset UIColor Textures, then setting them as a background? Sort of like this:
UIColor *mytexture = [UIColor scrollViewTexturedBackgroundColor];
UIImage *myimage = [UIImage imageWithData:mytexture];
[outletWallpaper setImage:myimage];
Thanks in advance,
Declan
Just set the backgroundColor of the view to the texture colour you require.
outletWallpaper.backgroundColor = [UIColor scrollViewTexturedBackgroundColor];
In addition you can load your own images and use them as a UIColour by using the [UIColour -colorWithPatternImage:] API:
UIImage *myImage = [UIImage imageNamed:#"anImageFile"];
UIColour colourPattern = [UIColor colorWithPatternImage: myImage];
outletWallpaper.backgroundColor = colourPattern;
You can create category of UIImage with method like this:
+ (UIImage *)imageWithColor:(UIColor *)color
{
CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetFillColorWithColor(context, [color CGColor]);
CGContextFillRect(context, rect);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}