So I have a spritesheet in png format, and have already worked out the coordinates for what I want to display. I'm trying to create a method that will return a UIImage when passed the location information on the spritesheet. I'm just not sure how to use the CGContext stuff along with the the coordinates to return an UIImage.
I was looking to CGContextClipToRect because I think that is the way to do it, but I just can't seem to get it to work.
Something like this
CGSize size = CGSizeMake(xSize, ySize);
UIGraphicsBeginImageContext(size);
//CGContextClipToRect(spriteSheet.size, imageRect);
[spriteSheet drawAtPoint:CGPointMake(xPos, yPos)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
returns only what is in the size Context. I need to be able to "move" this size window around the spritesheet if that makes sense.
Any help would be appreciated.
Thanks,
Mike
I think the call you want to use is CGImageCreateWithImageInRect
newImage = [UIImage imageWithCGImage:CGImageCreateWithImageInRect( [spriteSheet CGImage] , imageRect )];
you need to think of your co-ordinates backwards. The CGSize is fixed. Translate your xPos,yPos so that your sprite appears under the window.
Related
I've been having issues rendering images with the UIImageView class. The pixelation seems to occur mostly on the edges of the image I am trying to show.
I have tried changing the property 'Render with edge antialiasing' to no avail.
The image files contain images that are larger than what will appear on the screen.
It seems to be royally messing with the quality of the image and then displaying it. I tried to post images here, but StackOverflow is denying me that privilege. So here's a link to what's going on.
http://i.imgur.com/QpUOTOF.png
The sun in this image is the problem I'm speaking of. Any ideas?
On-the-fly image resizing is quick and of low quality. For bundled images, it is worth the extra bundle space to include downsized versions. For downloaded images, you can achieve better results by resizing with Core Graphics into a new UIImage before you set the image property.
CGSize newSize = CGSizeMake(newWidth, newHeight);
UIGraphicsBeginImageContextWithOptions(newSize, // context size
NO, // opaque?
0); // image scale. 0 means "device screen scale"
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
[bigImage drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Use following method use for get specific hight and width with image
+ (UIImage*)resizeImage:(UIImage*)image withWidth:(int)width withHeight:(int)height
{
CGSize newSize = CGSizeMake(width, height);
float widthRatio = newSize.width/image.size.width;
float heightRatio = newSize.height/image.size.height;
if(widthRatio > heightRatio)
{
newSize=CGSizeMake(image.size.width*heightRatio,image.size.height*heightRatio);
}
else
{
newSize=CGSizeMake(image.size.width*widthRatio,image.size.height*widthRatio);
}
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
This method return NewImage, with specific size that you specified.
How big is your image and what is the size of the imageView? Don't rely on UIImageView to scale it down for you. You probably need to resize it manually. This would also be a bit more memory efficient.
I use categories like these:
>>>github link <<<
to do image resizing.
This also gives you some other nice function for rounded corners etc.
Also keep in mind, that you need a transparent border at the edge of an image if you want to rotate it to avoid aliasing.
I'm trying to save the image after manipulating it with move, pinch and rotate gestoures.
All I get is the real image no matter what I tried,
I tried with UIGraphicsBeginImageContextWithOptions on the UIView container and on the UIIMageView without success.
Hope someone can help on this one.
Thanks,
Itay
You could try with this:
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
CGContextConcatCTM(UIGraphicsGetCurrentContext(), imageView.transform);
[imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
This is assuming your imageView is transformed by means of a CGAffineTransform applied to it.
I have found the following code to resize an UIImage:
CGSize newSize = CGSizeMake(self.image.size.width*0.25, self.image.size.height*0.25);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[self.image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
self.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
but there are some couple of things I don't understand.
First I'm trying to resize the original image to 25% of the original size - but this method resizes it to 50% of the original size. Why?
What is the connection between drawInRect and UIGraphicsGetImageFromCurrentImageContext. As I see it, the UIGraphicsGetImageFromCurrentImageContext is overwriting the current image making the call to drawInRect redundant.
I would be grateful if someone could help me understand what's going on in details.
Thanks in advance.
first , because it's retina screen, you should set the scale to 1.0 , or it just x2
UIGraphicsBeginImageContextWithOptions(newSize, NO, 1.0);
if you call UIGraphicsBeginImageContext , any paint work will result in the Context you specific
the drawInRect in your code paint the image to the context, it's not redundant
or you can remove it, you get a empty image
finally, you can get a merged UIImage from the context
UIGraphicsGetImageFromCurrentImageContext();
just get a UIImage From What you have done(on context)
if you don't set the image back , it's won't change anything
self.image = UIGraphicsGetImageFromCurrentImageContext();
I am adding 2 images to each other and wanted to know if this is a good way to do this? This code works and looked to be powerful.
So, my question really is, It this good or is there a better way?
PS: Warning code written by a designer.
Call the function:
- (IBAction) {
UIImage *MyFirstImage = UIImage imageNamed: #"Image.png"];
UIImage *MyTopImage = UIImage imageNamed: #"Image2.png"];
CGFloat yFloat = 50;
CGFloat xFloat = 50;
UIImage *newImage = [self placeImageOnImage:MyFirstImage imageOver:MyTopImage x:&xFloat y:&yFloat];
}
The Function:
- (UIImage*) placeImageOnImage:(UIImage *)image topImage:(UIImage *)topImage x:(CGFloat *)x y:(CGFloat *)y {
// if you want the image to be added next to the image make this CGSize bigger.
CGSize newSize = CGSizeMake(image.size.width,image.size.height);
UIGraphicsBeginImageContext( newSize );
[topImage drawInRect:CGRectMake(*x,*y,topImage.size.width,topImage.size.height)];
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height) blendMode:kCGBlendModeDestinationOver alpha:1];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
Looks OK. Perhaps you don't really need the CGFloat pointers, but that's fine, too.
The main idea is correct. There is no better way to do what you want.
Minuses:
1) Consider UIGraphicsBeginImageContextWithOptions method. UIGraphicsBeginImageContext isn't good for retina.
2) Don't pass floats as pointers. Use x:(CGFloat)x y:(CGFloat)y instead
You should use the begin context version, UIGraphicsBeginImageContextWithOptions, that allows you to specify options for scale (and pass 0 as the scale) do you don't lose any quality on retina displays.
If you want one image drawn on top of another image, just draw the one in back, then the one in front, exactly as if you were using paint. There is no need to use blend modes.
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
[topImage drawInRect:CGRectMake(*x,*y,topImage.size.width,topImage.size.height)];
I have put a UILabel that the user has chosen over a UIImageView that was also chosen by the user. I would like to put these two into a picture, kind of like a screenshot of a small part of the screen. I have absolutely no idea how to do this and have no experience in this. Any help is appreciated!!
You could setup a Bitmap context with a clipping mask of the area you want to save. Then you use the backing layer's renderInContext method to draw onto that context.
CGSize imageSize = CGSizeMake(960, 580);
UIGraphicsBeginImageContext(imageSize);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClipToRect(context, CGRectMake(10,10,200,200); // whatever rect you want
[self.layer renderInContext:context];
UIImage *myImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Save to camera roll
UIImageWriteToSavedPhotosAlbum(myImage, self, #selector(didSaveImage), null);