I have a simple app with a tabbar. The view size is 480 x 320. The tabbar is 49 x 320. However when i try to take a screenshot using UIgraphicsbeginimagecontext(self.view.frame.size) I get an image of 411 x 320..
My background image is 480 x 320 and shows properly in the ios simulator.
When I use UIgraphicsbeginimagecontext(480x320) I get empty space in the bottom of the screenshot..
However when the screen is captured the background image is cut by the 69 height pixels.
Anyone knows why my background image displays properly in simulator but is cropped when taking a screenshot.. Or how to capture all the screenshot if I increase the imagecontext size?
Many Thanks
Is the status bar showing? It sounds like the status bar (20px) and the UITabBar (49px) is where the extra space is being cropped. I imagine that self.view is returning a UIViewControllers view which is smaller than the shot you want.
If you want just the background image, try reducing the size of the screen shot, or if you want the whole screen, try targeting the apps main window, something like this
UIGraphicsBeginImageContext(self.window.bounds.size);
[self.window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Related
I am creating an Ipad app and no matter what height I set my ImageView to be it is always too big.
For example I have an ImageView that's about 20 pixels tall and has all of the constraints that I need to keep it where I want it to be. When I play this 20 pixel tall ImageView on the Ipad simulator the ImageView covers about half of the Ipad screen.
How can I work with Ipad images if even a 1x1 pixel image view takes up a signifiant amount of the screen? (Yes, I made the 1x1 image just to see if it would still be insanely large)
Under Auto Layout, if you don't set the size of the image view absolutely, it will size itself to match the size of the image assigned to it. That is probably what is happening to you.
I have taken a photo, and then I'm initializing a UIImageView object with this photo. The only problem is, when I take the photo, the photo is being taken using the full iPhone screen (portrait).
The UIImageView that is being initialized with this photo is only set to take up the top 50% of the iphone's screen. So you can imagine the image looks distorted.
I have been able to make it look a lot better by using the following code:
UIImageView *halfView = [[UIImageView alloc]initWithImage:image];
[self.view addSubview:halfView];
halfView.frame = CGRectMake(0, 0, self.view.bounds.size.width, self.view.frame.size.height/2);
halfView.contentMode = UIViewContentModeScaleAspectFill;
The only problem is, the final UIImageView called "halfView" is still slightly distorted.
I have a feeling that this is impossible to fix, because the original photo is being taken with the full iphone screen and can never perfectly scale to fit a UIImageView that only takes up the top 50% of the iphone screen.
I was basically trying to copy the frontback app. Here is what it looks like when you are taking the original image in their app:
This is what my app's screen looks like when you are taking the picture:
And then right after you take the picture, my app's screen changes to look like the frontback screen and takes the picture you just took and places it in the top half and tries to scale it.
I hope that makes sense. I know it is a long question, but I just really wanted to let the user use the full screen while taking the photo and then just scale it to half the screen.
Am I going about this all wrong? Am I crazy to think I could ever properly scale the image to half the screen when it was originally captured as a "full screen" image?
Thanks for the help.
For the sake of argument let's say your captured image size is 640x1136 (twice the size of an iPhone 5 screen) and you are trying to display it in a UIImageView with of size 320x284 (half the size of an iPhone 5 screen).
As you can already see from these dimensions the captured image's width is smaller than its height whereas the UIImageView's width is larger than its height - the proportions are different.
Therefore, scaling the captured image to fit the UIImageView's width (scale by 0.5) means the captured image will be of size 320x568 - its height is larger than the UIImageView's height.
Scaling the captured image to fit the UIImageView's height (scale by 0.25) means the captured image will be of size 160x284 - its width is smaller the the UIImageView's width.
The image can't scale exactly like you want it to scale. However, you can use UIViewContentModeScaleAspectFill to fill the entire UIImageView but lose some of the image (image's height is too big to fit). You can also choose to use UIViewContentModeScaleAspectFit which will show the entire image but will leave some space on the sides (image's width is too small).
Another option you have is to actually capture the image in the proportions of your UIImageView in the first place but that means you won't be able to capture a full screen image.
Try this function, pass your UIImage in this function along with the new size, in turn it will return you the UIImage with size specified by you.
- (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
I guess this is what you want.
Hope this helps.
You mention the image takes up the full size of the screen. If it's to display the UIImageView taking up half the screen, then you'll need to add this code to clip the frame
halfView.clipToBounds = YES;
Despite making the size of the imageview half the screen, the actual image will show outside the boundaries of the imageview if it's original size is bigger with the aspectFit property. clipToBounds will fix this.
I hope this is what you're looking for. Thanks, Jim.
I'm taking a photo with UIImagePickerController. Everything works fine on iPad and on iPhone 5. The problem comes with an iPhone4: the photo that I get from the picker is "bigger" than what I saw on the screen when I took the photo.
What do I mean with bigger? I mean that at both sides of the photo, and at the bottom, I see parts of the scene that the camera didn't show when I was taking the photo. This is a problem for my app. I need to capture exactly the same scene that the user sees through the camera when he takes the photo. Not a bigger scene. As I said, on iPhone5 and iPad4 everything works fine. I don't understand this different behaviour. How can I solve this?
PD: I'm not applying any transformation to the image on the picker.
-(void)imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info
{
UIImage* originalImage = [info valueForKey:#"UIImagePickerControllerOriginalImage"];
NSLog(#"Image Size Width %f Height %f",originalImage.size.width,originalImage.size.height);
UIGraphicsBeginImageContext(CGSizeMake(320, 480));
[originalImage drawInRect:CGRectMake(0,0,320,480)];
UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSLog(#"image Size h %f Width %f",[image size].height, [image size].width);
}
Here you can see that What is original image size and after than you can change size as your wish..
It was a problem with the preview on the iPhone4... the preview on the iPhone4 is 16:9, but the final image is 4:3. On the iPhone5 and the iPad, both the preview and the final image are 4:3.
I didn't realize it before because my overlay was hiding part of the preview on the iPhone4, so I thought the preview was 4:3 too (and I think that the preview with iOS6 is 4:3, I'm not sure, I've got to find an iPhone4 with iOS6).
I made my overlay (a UIToolbar) translucent, and now I get what I want.
The following code block is used in my application to take a screenshot of the current screen of an iPad mini(768 x 1024):
UIImage *img;
UIGraphicsBeginImageContext(self.view.bounds.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
In a different viewcontroller, I present a UIScrollView with a width of 540 and a height of 290. I display the screencapture UIImage in a UIImageView which I create programmatically initWithFrame with a rectangle width of 250 and height of 250. The content size of the scrollview is 768 by 250.
Now running the application, I display four rectangles and screenshot the screen using the above block of code. Transitioning to the UIScrollView, the image is not clear (and by not clear, some rectangles are missing sides while some are thicker than others). Is there a way to display the image clearer? I know the image has to be scaled down from the original 768 by 1024 to 250 by 250. Could this be the problem? If so, what would be the best fix?
Edit:
Above a screenshot of the image I want to capture.
Below is the UIImage in UIImageView within a UIScrollView:
Cast each coordinate to int, or use CGRectIntegral, to do that directly on a CGRect, decimal point requires AA and makes images blurry.
Try changing the content mode of your UIImageViews. If you use UIViewContentModeScaleAspectFill, you shouldn't see any extra space around the edges.
Update: From the screenshots you posted, it looks like this is just an effect of the built-in downscaling in UIKit. Try manually downscaling the image to fit using Core Graphics first. Alternatively, you might want to use something like the CILanczosScaleTransform Core Image filter (iOS 6+).
I have a simple app with a tabbar. The view size is 480 x 320. The tabbar is 49 x 320. However when i try to take a screenshot using UIgraphicsbeginimagecontext(self.view.frame.size) I get an image of 411 x 320..
My background image is 480 x 320 and shows properly in the ios simulator.
However when the screen is captured the background image is cut by the 69 height pixels.
Anyone knows:
1) Where the 20 missing pixels are going (480-49) = 431 while im getting 411
2) Why my background image displays properly in simulator but is cropped when taking a screenshot..
Many Thanks
Try using self.view.bounds for the context size.
Also, are you taking the screenshot before the view has been properly initialized? If you are, this may result in an incorrect size.
The missing 20 pixels are the size of the status bar on the top. Actually your view size height is 460 pixels if you are displaying a status bar on the top. When you take a screen shot using UIgraphicsbeginimagecontext(self.view.frame.size) your size parameter is 320x460, and NOT 320x480 as you expected, resulting in a "cropped" image. (sorry about my english...)