I'm using Xcode 4.5.2, the app is targeting iOS 6.0.
In my application, I am having trouble with showing iPad Retina images. I know I have to use the #2x~ipad.png extension in order to get them to properly show and I do that. My images are named according so they are all named the same besides the extension for each device.
Here is how I named it.
However,
NSString *name=#"appearanceConnection.png";
//NSString *name=#"appearanceConnection"; //I did check this
//I did check the target
UIImage *image = [UIImage imageNamed:name];
NSLog(#"%f",image.size.width);
shows me the width of #1x image.
If i try to set proper image name manually:
if ([[UIScreen mainScreen] respondsToSelector:#selector(displayLinkWithTarget:selector:)] &&
([UIScreen mainScreen].scale == 2.0)) {
// Retina display
name=#"appearanceConnection#2x~ipad.png";
NSLog(#"retina");
}
else
{
name=#"appearanceConnection.png";
NSLog(#"non-retina");
}
UIImage *image = [UIImage imageNamed:name];
NSLog(#"%f",image.size.width);
proper #2x picked and then it scaled by 2.0 when I'm adding it to view.
I cleaned/rebuild my project many times, I reset IOS simulator settings, no result.
What am I doing wrong?
update:
non-retina
retina:
NSLog(#"%f", image.scale)
after imageNamed method gives me 1.0
UPDATE 2:
I'm trying to optimize my animation appearance, so I want to load one big image once and cut it by frames.
Firstly, I load big image (#2x or 1#x), then using cycle
for (int i = 0; i<numberOfFrames; i++)
{
CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage,
CGRectMake(i*width, 0.0f, width, height));
UIImage *animationImage = [UIImage imageWithCGImage:imageRef];
if (isFlip)
{
[animationImages insertObject:animationImage atIndex:0];
}
else
{
[animationImages addObject:animationImage];
}
CGImageRelease(imageRef);
}
i cut this big image and create animation.
width and height are multiplied by 2 if it is retina display.
Maybe here is a caveat?
UIImage *animationImage = [UIImage imageWithCGImage:imageRef];
returns me image scaled twice?
however, if I scale (0.5,0.5) UIImageView which is initialized by this image it fits. Have any idea why scaled twice?
the retina and non retina images will have the same width and height when used as a UIImage or something similar, think of it as on retina displays the DPI of the image is doubled, and not the width or height.
this is to keep things transparent when coding for retina and non retina.
Related
I have collection view with some videos and images
Using AVFoundation able to capture video from iPhone and generated thumbnail using AVAssetImageGenerator. When shown in gallery image should distinguish it's of video thumbnail. So i need to transform exact image by drawing video symbol(like play icon) over it.
Is it possible?
You could use CoreGraphics to edit the image.
First, create a UIImage with the image you would like to edit. Then, do something like this:
UIImage *oldThumbnail; //set this to the original thumbnail image
UIGraphicsBeginImageContext(oldThumbnail.size);
[oldThumbnail drawInRect:CGRectMake(0, 0, oldThumbnail.size.width, oldThumbnail.size.height)];
/*Now there are two ways to draw the play symbol.
One would be to have a pre-rendered play symbol that you load into a UIImage and draw with drawInRect */
UIImage *playSymbol = [UIImage imageNamed:"PlaySymbol.png"];
CGRect playSymbolRect; //I'll let you figure out calculating where you should draw the play symbol
[playSymbol drawInRect: playSymbolRect];
//The other way would be to draw the play symbol directly using CoreGraphics calls. Start with this:
CGContextRef context = UIGraphicsGetCurrentContext();
//now use CoreGraphics calls. I won't go over it here, butthe second answer to this questionmay be helpful.
//Once you have finished drawing your image, you can put it in a UIImage.
UIImage *newThumbnail = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext(); //make sure you remember to do this :)
Now you can use the newly generated thumbnail in a UIImageView, cache it so you don't need to re-render it every time, etc.
This should work (you may have to play with positions and sizes):
-(UIImage*)drawPlayButton:(UIImage*)image
{
UIImage *playButton = [UIImage imageNamed:#"playbutton.png"];
UIGraphicsBeginImageContext(image.size);
[image drawInRect:CGRectMake(0, 0, image.size.width, image.size.height)];
[playButton drawInRect:CGRectMake(image.size.width/2-playButton.size.width/2, image.size.height/2-playButton.size.height/2, playButton.size.width, playButton.size.height)];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return result;
}
I am building a note editor using the Text Kit in ios7. Earlier I had trouble in rendering of custom size NSTextAttachment's as it was slowing down the rendering to a great extent.I solved the issue by scaling the images and then adding them to textview.You can find my answer in
iOS 7.0 UITextView gettings terribly slow after adding images to it
After scaling the images the textview rendering runs fine without any lag.The attributed text of textview is stored in core data.During a running session of application the textview displays the images correctly.Even after saving the attributed text in the core data and retrieving it again to display on textview,the images look fine.But after killing the app and again running the application.The images get enlarged to 2x size.while scaling the images I used the following function and used [[UIScreen bounds] scale] to maintain the image quality.
- (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
UIGraphicsBeginImageContextWithOptions(newSize, NO, [UIScreen mainScreen].scale);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
If I scale the images to 1.0 the images doesn't expand but the image quality is very bad.
What I Think where the problem lies?
The problem lies in the layout manager.
What I have Tried
I have tried subclassing the NSLayoutManager and overriding the
- (void)drawGlyphsForGlyphRange:(NSRange)glyphsToShow atPoint:(CGPoint)origin
What I see is the attachment size is doubling when running a new session of the application.If I try to check the size of attachment and resize it.The lag starts coming again.
I am stucked with this problem from a quite time.Any suggestions would be much appreciated.
Could the reason due to retina display? If it is retina, you might need to reduce the size by 50% before storing. How about trying this:-
//Original Size that you want to store
CGSize imageSize = CGSizeMake(320.0f, 320.0f);
//Make the image 50% of the size for retina
if ([[UIScreen mainScreen] respondsToSelector:#selector(displayLinkWithTarget:selector:)] &&([UIScreen mainScreen].scale == 2.0)) {
// Retina display
imageSize = CGSizeMake(160.0f, 160.0f);
}
UIImage * storeImage = [self imageWithImage:self.image scaledToSize:imageSize]
//TODO: Store this image locally or whatever you want to do.
#interface MMTextAttachment : NSTextAttachment
{
}
#end
#implementation MMTextAttachment
//I want my emoticon has the same size with line's height
- (CGRect)attachmentBoundsForTextContainer:(NSTextContainer *)textContainer proposedLineFragment:(CGRect)lineFrag glyphPosition:(CGPoint)position characterIndex:(NSUInteger)charIndex NS_AVAILABLE_IOS(7_0)
{
return CGRectMake( 0 , 0 , lineFrag.size.height , lineFrag.size.height );
}
#end
I think you can try this.
I have some images I need to get from the web. Just using data from a URL.
They need to show correctly on Retina Display.
When I get the images from the web, they still look pixelated. I need to set the images' scale to retina display (2.0), but I must be missing something.
Here's what I did so far.
UIImage *img = [UIImage imageWithData:[NSData dataWithContentsOfURL:#"http://www.msdomains.com/tmp/test.png"];
CGRect labelFrame = CGRectMake(0,0,64,64);
UIImageView *imageView = [[UIImageView alloc] initWithFrame:labelFrame];
imageView.contentScaleFactor = [UIScreen mainScreen].scale;
[imageView setImage:img];
[self addSubview:imageView];
[imageView release];
Try adding ##2x.png at the end of your URL. That wont change the URL, but the image will be recognized as a retina #2x image. It worked for me, but I used this method with SDWebImage.
e.g. using http://www.msdomains.com/tmp/test.png##2x.png.
Your code should work pretty much as-is. I don't know what the original dimensions of your image were, but I'd guess they were 64x64 px. In order to scale down correctly, the original image would need to be 128x128 px.
As a test, the following code correctly displayed my photo in Retina resolution on the Simulator, and on my iPhone 4:
UIImage *img = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:#"http://www.seenobjects.org/images/mediumlarge/2006-08-19-native-lilac.jpg"]]];
CGRect labelFrame = CGRectMake(0, 0, 375, 249.5);
UIImageView *imageView = [[UIImageView alloc] initWithFrame:labelFrame];
[imageView setImage:img];
[self.view addSubview:imageView];
Note that the UIImageView is 375x249.5 points, which is half of the original (pixel) dimensions of the photo. Also, setting the contentScaleFactor didn't seem to be necessary.
(As an aside, I can't see that specifying #2x on the URL will help, in this case, as the call to dataWithContentsOfURL: will return an opaque blob of data, with no trace of the filename left. It's that opaque data that's then passed to imageWithData: to load the image.)
when you directly assign the image URL to imageView, it will not take it as retina.
imageView.imageURL = [NSURL URLWithString:#"http://example.com/image.png"];
will not give you a retina image.
So, inspite your image is 200x200 but if your imageView is 100x100 then it will take 100x100 from the downloaded image and show pixelated image on retina devices.
Solution would be to use the image property of imageView instead of imageURL.
imageView.image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:#"http://example.com/image.png"]]];
This will assign 200x200 image to the imageView of 100x100 and hence the image will not be pixelated.
For retina display, add the same image with the resolution which is exactly the double of the original image. dont forget to add "#2x"at the end of this image name... e.g. "image_header.png" is an image 320x100 then another image with name "image_header#2x.png" (dimension 640x200) will be selected for the retina display automatically by the OS...
hope it helps
I have a set of buttons and different sized images. I want to scale each image in order that it fits the button in the correct aspect ratio. Once I've scaled the image, I set the button's image property to the scaled version.
UIImage *scaledImage = [image scaledForButton:pickerButton];
[pickerButton setImage:scaledImage forState:UIControlStateNormal];
my scaledForButton method is defined in a class extension for UIImage. It looks like this:
- (UIImage *)scaledForButton:(UIButton *)button
{
// Check which dimension (width or height) to pay respect to and
// calculate the scale factor
CGFloat imageRatio = self.size.width / self.size.height;
CGFloat buttonRatio = button.frame.size.width / button.frame.size.height;
CGFloat scaleFactor = (imageRatio > buttonRatio ? self.size.width/button.frame.size.width : self.size.height/button.frame.size.height);
// Create image using scale factor
UIImage *scaledimage = [UIImage imageWithCGImage:[self CGImage]
scale:scaleFactor
orientation:UIImageOrientationUp];
return scaledimage;
}
When I run this on an iPad2 it works fine and the images are scaled correctly. However if I run it on a retina display (both in the simulator and on a device) the image does not scale correctly and is squished into the button.
Any ideas why this would happen on retina only? I've been scratching my head for a couple of days but can't figure it out. They're both running the same iOS and I've checked the scale and ratio outputs, which are always the same, regardless of device. Many thanks.
Found the answer here: UIButton doesn't listen to content mode setting?
If you're setting the .contentMode, it seems you have to set the imageView property of the UIButton, not just the UIButton, then it worked properly.
The problem on iPad 3 was as Herman suggested - the CGImage was still a lot larger than the UIButton, so even though it was scaled down, it still had to be resized to fit the button.
I am downloading images from a webserver for display in a table view in my iOS application using the following code:
NSURL *url = [NSURL URLWithString:[imageArray objectAtIndex:indexPath.row]];
UIImage *myImage = [UIImage imageWithData:[NSData dataWithContentsOfURL:url]];
cell.imageView.image = myImage;
The image view is a 60x60 placeholder and 120x120 for the retina display. I am going to assume the user has an iPhone 4. However, if I size the image to 120x120 it does not correct the issue, it just becomes too big for the the imageview. If I size the image to 60x60, on the webserver that is, then the image fits fine but its a little fuzzy. Anyone know how to fix this issue?
Thanks!
Let's first agree that your UIImageView is 60x60 points, meaning 60x60 pixels for a standard display and 120x120 pixels for a retina display.
For a UIImageView at 60x60 points, the image should be 60x60 pixels at scale 1.0 for a standard display and 120x120 pixels at scale 2.0 for a retina display. This means that your UIImage should always have a size of 60x60 points, but should have a different scale depending on the display resolution.
When getting the image data from your server, you should first check the scale of the device's screen and then request the appropriate image size (in pixels), like so:
if ([UIScreen mainScreen].scale == 1.0) {
// Build URL for 60x60 pixels image
}
else {
// Build URL for 120x120 pixels image
}
Then you should put the image data in a UIImage of size 60x60 points, at the appropriate scale:
NSData *imageData = [NSData dataWithContentsOfURL:url];
CFDataRef cfdata = CFDataCreate(NULL, [imageData bytes], [imageData length]);
CGDataProviderRef imageDataProvider = CGDataProviderCreateWithCFData (cfdata);
CGImageRef imageRef = CGImageCreateWithJPEGDataProvider(imageDataProvider, NULL, true, kCGRenderingIntentDefault);
UIImage *image = [[UIImage alloc] initWithCGImage:imageRef
scale:[UIScreen mainScreen].scale
orientation:UIImageOrientationUp];
CFRelease (imageRef);
CFRelease (imageDataProvider);
CFRelease(cfdata);
Hope this helps.
If your downloaded image have a size 2X from your UIImageView dimension size. It's look fine for retina display in iPhone4.
see also there: http://mobile.tutsplus.com/tutorials/iphone/preparing-your-iphone-app-for-higher-resolutions/
Images downloaded from the web are not formatted for Retina Display the same way images bundled with your app (using the "#2x" suffix) are.
You can get/set the scale of any UIView with the aptly named scale: and setScale: methods to help you better display content from the web if you know it's intended for Retina Display devices.
Well the answer is as simple as it can be:
I would recommend always downloading the double density images from the server (as users with non retina display are very few) and setting in the imageview.
What you didn't do correctly is you didn't set the imageView to automatically fit the content.
You can do this either in IB by selecting the ImageView and setting the contentMode (mode) to scale to Fill, or by code:
imageView.contentMode = UIViewContentModeScaleToFill;