In objective-C, I was able to render the EAGLContext to UIImage using glReadPixels to read the pixel data from the framebuffer, creating a CGImage using the pixel data, and then retrieving a UIImage from the context.
I am trying a new method in Swift, but it is returning an empty image. I would like to create a GLKView from the EAGLContext, and then use 'snapshot' to get the UIImage. The “myEaglContext” passed into the GLKView constructor has data on it.
let glkView = GLKView(frame: CGRect(x: 0,y: 0,width: self.frame.size.width,height: self.frame.size.height),context: myEaglContext)
glkView.bindDrawable()
glkView.display()
let image : UIImage = glkView.snapshot
Does anyone know why this approach is not working?
Related
I load a image and create a mirror in this way:
originalImg = [UIImage imageNamed:#"ms06.png"];
mirrorImg = [UIImage imageWithCGImage:[originalImg CGImage] scale:1.0 orientation:UIImageOrientationUpMirrored];
Then I set the above UIImage object to a subclass of UIView, and override the drawRect:
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
CGAffineTransform t0 = CGContextGetCTM(context);
CGContextConcatCTM(context, t0);
CGContextDrawImage(context, self.bounds, [image CGImage]);
CGContextRestoreGState(context);
}
No matter which image I draw, the displayed image always be the original one, mirrored image was never displayed when set to the UIView subclass.
I'm sure that the mirrored image was set to the UIView correctly because the debug info showed that the orientation member variable equals to 4, which means "UIImageOrientationUpMirrored", while the original image equals to 0.
Does anyone could help me with this problem, thanks.
I also tried to display the mirrored image in UIImageView with setImage: and it works correctly. By the way I found that the breakpoint in drawRect was never hit when call the setImage of UIImageView, how can we define the drawing behavior(such as draw a line above the image) when loading image to the UIImageView?
You mirrow the image on UI-Level. This returns a new UIImage, but the CGImage stays the same. If you do some NSLogs, you will notice this.
You can also do transformations on UI-Level. If you use this approach, I would suggest to use originalImg.scale instead of 1.0. Then the code would work for retina and non-retina displays.
[UIImage imageWithCGImage:[originalImg CGImage] scale:originalImg.scale orientation:UIImageOrientationUpMirrored];
If you really need to mirror the CGImage, take a look at NYXImagesKit on GitHub (see UIImage+Rotating.m)
Is there a way to load a picture from the library or take a new one, resize it to a smaller size to be able to edit it and then save it at the original size? I'm struggling with this and can't make it to work. I have the resize code setup like this :
firstImage = [firstImage resizedImageWithContentMode:UIViewContentModeScaleAspectFit bounds:CGSizeMake(960, 640) interpolationQuality:kCGInterpolationHigh];
and then i have an UIImageView :
[finalImage setFrame:CGRectMake(10, 100, 300, 232)];
finalImage.image = firstImage;
if I setup the CGSizeMake at the original size of the picture it is a very slow process. I saw in other apps that they work on a smaller image and the editing process is fairly quick even for effects. What's the approach on this?
You can refer to Move and Scale Demo. This is a custom control which implements Moving and scaling and cropping image which can be really helpful to you.
Also this is the most simple code for scaling images to given size. Refer to it here: Resize/Scale of an Image
You can refer to it's code here
// UIImage+Scale.h
#interface UIImage (scale)
-(UIImage*)scaleToSize:(CGSize)size;
#end
Implementation UIImage Scale Category
With the interface in place, let’s write the code for the method that will be added to the UIImage class.
// UIImage+Scale.h
#import "UIImage+Scale.h"
#implementation UIImage (scale)
-(UIImage*)scaleToSize:(CGSize)size
{
// Create a bitmap graphics context
// This will also set it as the current context
UIGraphicsBeginImageContext(size);
// Draw the scaled image in the current context
[self drawInRect:CGRectMake(0, 0, size.width, size.height)];
// Create a new image from current context
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
// Pop the current context from the stack
UIGraphicsEndImageContext();
// Return our new scaled image
return scaledImage;
}
#end
Using the UIImage Scale Method
Calling the new scale method we added to UIImage is as simple as this:
#import "UIImage+Scale.h"
...
// Create an image
UIImage *image = [UIImage imageNamed:#"myImage.png"];
// Scale the image
UIImage *scaledImage = [image scaleToSize:CGSizeMake(25.0f, 35.0f)];
Let me know if you want more help.
Hope this helps you.
I am using some CoreImage filters to process an image. Applying the filter to my input image results in an output image called filterOutputImage of type CIImage.
I now wish to display that image, and tried doing:
self.modifiedPhoto = [UIImage imageWithCIImage:filterOutputImage];
self.photoImageView.image = self.modifiedPhoto;
The view however is blank - nothing is being displayed.
If I add logging statements that print out details about both filterOutputImage and self.modifiedPhoto, those logging statements are showing me that both those vars appear to contain legitimate image data: their size is being reported and the objects are not nil.
So after doing some Googling, I found a solution that requires going through a CGImage stage; vis:
CGImageRef outputImageRef = [context createCGImage:filterOutputImage fromRect:[filterOutputImage extent]];
self.modifiedPhoto = [UIImage imageWithCGImage:outputImageRef scale:self.originalPhoto.scale orientation:self.originalPhoto.imageOrientation];
self.photoImageView.image = self.modifiedPhoto;
CGImageRelease(outputImageRef);
This second approach works: I am getting the correct image displayed in the view.
Can someone please explain to me why my first attempt failed? What am I doing wrong with the imageWithCIImage method that is resulting in an image that seems to exist but can't be displayed? Is it always necessary to "pass through" a CGImage stage in order to generate a UIImage from a CIImage?
Hoping someone can clear up my confusion :)
H.
This should do it!
-(UIImage*)makeUIImageFromCIImage:(CIImage*)ciImage
{
self.cicontext = [CIContext contextWithOptions:nil];
// finally!
UIImage * returnImage;
CGImageRef processedCGImage = [self.cicontext createCGImage:ciImage
fromRect:[ciImage extent]];
returnImage = [UIImage imageWithCGImage:processedCGImage];
CGImageRelease(processedCGImage);
return returnImage;
}
I assume that self.photoImageView is a UIImageView? If so, ultimately, it is going to call -[UIImage CGImage] on the UIImage and then pass that CGImage as the contents property of a CALayer.
(See comments: my details were wrong)
Per the UIImage documentation for -[UIImage CGImage]:
If the UIImage object was initialized using a CIImage object, the
value of the property is NULL.
So the UIImageView calls -CGImage, but that results in NULL, so nothing is displayed.
I haven't tried this, but you could try making a custom UIView and then using UIImage's -draw... methods in -[UIView drawRect:] to draw the CIImage.
i have a question that suppose i have 1 png which background is transparent and all the custom design are their suppose this: http://www.creativetechs.com/iq/tip_images/iPhoneElements-Yahoo.png
i want that i have add the png in my code and how could i get the cordinate and implement those images cordinate into UIImageView and when its run the it can grab those cordinate from the png and map the design.
I know its possible their is some software which can give the plist of those cordinate and then map it please any one guide me. Thanks.
This question/answer explains how to create the subimage:
Return a subimage from a UIImage
I would suggest storing the coordinates in a plist (as you suggested) and using the above method to create each subimage from you sprite sheet.
(code from the above post)
CGRect fromRect = CGRectMake(0, 0, 320, 480); // or whatever rectangle
CGImageRef drawImage = CGImageCreateWithImageInRect(image.CGImage, fromRect);
UIImage *newImage = [UIImage imageWithCGImage:drawImage];
CGImageRelease(drawImage);
Actually, I wanted a custom cell which contains 2 image objects and 1 text object, and I decided to make a container for those objects.
So is it possible to hold a image in object and insert that object in any of the collection objects, and later use that object to display inside cell?
NSArray and NSDictionary both hold objects. These are most likely the collections you'll use with a table view.
The best way to implement what you are trying to do is to use the UIImage class. UIImages wrap a CGImage and do all the memory management for you (if your app is running low on memory, the image data is purged and automatically reloaded when you draw it- pretty cool, huh?) You can also read images from files very easily using this class (a whole bunch of formats supported).
Look at the documentation for NSArray, NSMutableArray, and UIImage for more information.
//create a UIImage from a jpeg image
UIImage *myImage = [UIImage imageWithContentsOfFile:#"myImage.jpg"];
NSArray *myArray = [NSMutableArray array]; // this will autorelease, so if you need to keep it around, retain it
[myArray addObject:myImage];
//to draw this image in a UIView's drawRect method
CGContextRef context = UIGraphicsGetCurrentContext(); // you need to find the context to draw into
UIImage *myImage = [myArray lastObject]; // this gets the last object from an array, use the objectAtIndex: method to get a an object with a specific index
CGImageRef *myCGImage = [myImage CGImage];
CGContextDrawImage(context, rect, myCGImage); //rect is passed to drawRect
There should be no problem with that. Just make sure you are properly retaining it and what not in your class.