Suppose I want an image to be 320x100 points for a retina screen, I would have to make an image 640x200 pixel and named it #2x. The problem is when I download an image from a web service of size 640x200 pixel. Normally a #2x image would be translate to size 320x100 points in the phone, but the image from the web service is still 640x200 points.
Note - the web service is my own, so I can fix it if it's the web service's problem.
Sorry If might have not worded the problem well, but this is what I meant(similar):
Retina display and [UIImage initWithData]
You'll have to set the height and width of the control in points manually and it will automatically display the image with a higher DPI without unnecesarily downscaling.
An #2x image will always be twice the dimensions of a non-retina image if it wasn't loaded through imageNamed.
Create an image like so on a retina and non-retina device:
UIImage *anImage = [UIImage imageNamed: #"anImageName"];
NSLog(#"%#: scale: %f", NSStringFromCGSize(anImage.size), anImage.scale);
The CGSize object printed on the retina device will be the same size of the non-retina image, but will have the scale set to 2.0.
Creating an image using the explicit retina suffix will reveal that the image is actually twice as big - so imageNamed does its own image scaling.
For the case where you want to display this in an already created and sized image view, you still don't need to do anything - just load it straight in and the image view will adjust the image to the correct size.
If, however, you want to create a new image view, then you'll need to create a frame paying attention to the UIScreen's resolution like so (unfortunately, you can't just set the scale property as its read only):
CGRect newFrame = CGRectZero;
newFrame.size.width = (anImage.size.width / [UIScreen mainScreen].scale);
newFrame.size.height = (anImage.size.height / [UIScreen mainScreen].scale);
This assumes that your web service is aware of wether the screen of the device is retina or not; some services will pick this up automatically, some will require you to tell them this up front. YMMV.
Related
I am just confused about the image sizes that I need to use for buttons, image views etc.
I want to adjust images for all iphones.
What should be ratio between the screen height/width and different iphones.
Like i have a button. I have created in following way-
UIButton *takePicButton = [UIButton buttonWithType:UIButtonTypeCustom];
takePicButton.frame = CGRectMake(0, SCREEN_HEIGHT-UI_ITEM_HEIGHT, SCREEN_WIDTH, UI_ITEM_HEIGHT);
[takePicButton setBackgroundImage:[UIImage imageNamed:#"take_photo.png"] forState:UIControlStateNormal];
[self.view addSubview:takePicButton];
[takePicButton addTarget:self action:#selector(takePicture:) forControlEvents:UIControlEventTouchUpInside];
for this button what size of images I need to add on xcode to support iPhone 4 - iPhone 7.
Thanks in advance.
Here is description about how image can set in iPhone:
• 1x images are for the original iPhone through the 3GS - 'standard' resolution devices (3.5" screens)
• 2x images are for the iPhone 4 and 4S (3.5" Retina screens) and are also used for the iPhone 5, 5s,6,6s,7
• 3x images are for the new iPhone 6+,7+ (5.5" super-Retina [3x] screen)
You have to keep three different types of image into your Assets.xcassets and just provide image name at where you want to display it. It will automatically take relevant image and display it.
You can check attached screenshots. You just have to write “bgImag” and it will take relevant image from assist.
About image ration, just create image for highest resolution of iPhone (i.e iPhone 6+), and just use iConify to get rest of image assest.
Try this, u can ask for two sizes. One is SCREEN_WIDTH * 2, UI_ITEM_HEIGHT * 2, the other is SCREEN_WIDTH * 3, UI_ITEM_HEIGHT * 3.Then put two sizes pics in your Images.xcassets named xxx#2x, xxx#3x.
I want to adjust images for all iPhones.
The easy way to do that is to use layout constraints. Your code tries to do what the constraints system would, given an appropriate set of constraints, but it's less flexible because it doesn't provide for changing geometry such as when the user rotates the device.
What should be ratio between the screen height/width and different iphones[?]
Different devices have different aspect ratios. There are lots of web sites (like this one) that list the screen sizes. When possible, though, it's best not to make any assumptions about screen size. New devices may be introduced with different aspect ratios, and even a single device may appear to have different screen sizes depending on how the user chooses to use it -- things like rotation and split screen affect the size and shape of the screen real estate that your device gets to use.
for this button what size of images I need to add on xcode to support iPhone 4 - iPhone 7[?]
We can't say without knowing what your UI_ITEM_HEIGHT constant is or what relative proportions you want for your button, but you should be able to calculate that yourself if you know the various screen sizes. You can use the reference I linked above, or this one, or one of the many others out there.
Read guide line for 1x, 2x, 3x
You should simply use:
UIImage *imButton = [UIImage imageNamed:#"image.png"];
[YOURBUTTON setImage:imButton forState:UIControlStateNormal];
Xcode will automatically use the available image with scales ex: #2x or #3x
From my example your images would be:
image.png (20x20 px),
image#2x.png, (40x40 px)
image#3x.png, (60x60 px)
respectively.
Quoting from apple:
Image Size and Resolution
iOS uses a coordinate system to place content onscreen. This
coordinate system is based on measurements in points, which map to
pixels in the display. On a standard-resolution screen, one point
(1/72 of an inch) is equal to one pixel. High-resolution screens have
a higher pixel density. Because there are more pixels in the same
amount of physical space, there are more pixels per point. As a
result, high-resolution displays require images with more pixels.
Refer here
Guys
You can try below code:
if (IS_IPHONE4) {
imgHeight.constant = 150;
}
else if (IS_IPAD) {
imgHeight.constant = 300;
}
else if (IS_IPHONE5) {
imgHeight.constant = 170;
}
else {
imgHeight.constant = 200;
}
Thanks.
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 new to iOS Development, I'm using a UIImageView to display an image. I've made a 320x480 and a 640x960 image called "red.png" and "red#2x.png".
No matter how I scale or align the UIImageView, the image always chops off half way at the top.
Is there something I'm meant to do to combat this, as I thought those resolutions were correct?
The UIImageView is sized at 320x568 to fill the storyboard.
Thanks :)
My comment above is hard to read, and it's probably an answer:
myImageView.contentMode = UIViewContentModeScaleAspectFit;
Try changing to image name as follows:
self.colourImage.image = [UIImage imageNamed: #"red.png"];
You should not directly specify '#2x' in image names.
It is automatically used if a device supports retina display.
That is why you need to create 2 sets of images; one for non-retina and one for retina (using #2x) and the OS selects the correct one for you.
I'm working with UIImage and like everyone else have to deal with retina and non-retina display adaptability. As for as I know, retina display requires double pixels.
I'm wondering if I could simply use a large image with the same width/height ratio, just resize it smaller to adapt all device?
For example, I made a original image with size of 200*200 pixel. Now I want to use it in application as 20*20 pixel, and 80*80 pixel (two situations). Then I have to make four copies like img2020.png, img2020#2x.png, img8080.png and img8080#2x.png
So if I want to use it in three situations with difference size, I have to store 6 copies. Can I just use UIImage's resize function to do this? I've tried a bit but cannot figure out it's quality and performance.
Any ideas? Thanks a lot :)
All native API suppose you to use image.png and image#2x.png, so it may be difficult sometimes to use just one image and scale it depending on retina/non-retina. Moreover using retina graphics on non-retina devices lead to more extensive use of these devices' resource causing battery drain. And, of course, if you have many images, that will decrease performance of your application. In other words there are reasons to use double set of images and you should better use it instead of one large image being scaled.
You don't need to make 6 copies. You should use the size 200*200 pixel. And set the property contentMode of imageview to aspectFit. Or you can also use below function and change the size of images at run time.
-(UIImage *)Resize_Image:(UIImage *)image requiredHeight:(float)requiredheight andWidth:(float)requiredwidth
{
float actualHeight = image.size.height;
float actualWidth = image.size.width;
if (actualWidth*requiredheight <actualHeight*requiredwidth)
{
actualWidth=requiredheight*(actualWidth/actualHeight);
actualHeight=requiredheight;
}
else
{
actualHeight=requiredwidth*(actualWidth/actualHeight); actualWidth=requiredwidth;
}
CGRect rect = CGRectMake(0.0, 0.0, actualWidth, actualHeight);
UIGraphicsBeginImageContext(rect.size);
[image drawInRect:rect];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
I made some comparisons before. Leaving iOS handle the resizing causes lower quality, and really unacceptable sometimes.
I feel lazy sometimes, my approach is to run it with the retina version, and if it looks bad, I will create a low-res version.
If you're writing an iPhone-only app, most of iPhones on the market has retina, so I don't think you should worry about non-retina version. Just my opinion though.
I have developed an small iOS app, where i have image named bg.png which is of dimension
1024 * 768 for iPad.
Now i have many images which has been created for iPad size. Now i need to make support of this app in iPhone, for that weather i need to create same set of images agian for iPhone size,
568 * 300 for iPhone.
or there is another way to do this?
Scaling down the iPad image assets will destroy UX on iPhone. Also images like icon, splash screen usually contain company logo. Scaling down will tamper the look of the logo and overall image. Better way is to create separate images for iPhone form factor. Trim the png files using http://tinypng.org/ to keep binary size low.
Cheers!Amar.
You can use this code to re-size the image by following code,
CGSize newSize = CGSizeMake(568, 300);
UIGraphicsBeginImageContext(newSize);
[yourIpadImage drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
newIphoneImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
//UIGraphicsBeginImageContext(newSize);
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
You have option to change the Size of Your Image
sathiamoorthys solution is a difficult way or rescaling your image. You can do that by simply creating a UIImageView, initialize it with a UIImage and then change its frame.
Note that your image will look scaled/distorted that way.
follow this:
open the image in preview.
go to tools > adjust size
put in whatever size you want.
save the image as a different name.
yes
you should create duplicate and resize them for iphone. Using same images for iphone will bring memory issues because the images are unnecessarily big for iphone.
Use any software to resize them or you can do this using preview also as Nikita described above
If you are doing this to create universal app then you must postfix ~ipad in the name of the image file.
Please visit this link, May help you and solve your issue.
There is the some tips like:
Propotional scale,
Resize
If you want your images to show up unscaled, you are going to need an additional image with the correct size.
So supporting both iPad with and without retina screens would require one image of 768x1024 and one of 1536 x 2048. For iPhone 3.5" you would need 960 x 640 when it is a retina screen or 480 x 320 when it is non-retina. For iPhone 5 (4" screen) you would need 568 x 320.
If you use UIImages method imageNamed: there is help from Apple. It loads on retina devices that method looks for the the image you specified with the postfix '#2x'. So you can simply code:
UIImage * myImage = [UIImage imageNamed: #"myImage"]
If you make sure you project contains myImage.png for non-retina devices and myImage#2x.png for retina devices the right image gets loaded at runtime.