I am working on an iPad UI and a button on that UI needs to have this image:
http://imgur.com/tVkP8wd
(as a PNG). The button is being declared like this:
CGRect newNoteButtonRect = CGRectMake(0, 0, 69, 43);
UIButton* newNoteButton = [[UIButton alloc] initWithFrame:newNoteButtonRect];
newNoteButton.imageView.contentMode = UIViewContentModeScaleToFill;
[newNoteButton setImage:self.fNewNoteIcon forState:UIControlStateNormal];
where 'fNewNoteIcon' is a UIImage. When the UI comes up, the image is tiny and squished, and almost nothing I do can change that. Any ideas?
The icon is initialized like this:
self.fNewNoteIcon = [UIImage imageNamed:#"New_Note.png"];
In that provided code you haven't specified a UIButton type? Creating a button with a custom image
// Create image
self.fNewNoteIcon = [UIImage imageNamed:#"buttomImage.png"];
// Create rect for button. 0, 0 and size it from image
CGRect newNoteButtonRect = CGRectMake:(0, 0, _fNewNoteIcon.size.width, _fNewNoteIcon.size.height);
// Alloc and init UIButton with type
// Pass in image. Add to subview of view.
UIButton *newNoteButton = [UIButton buttonWithType: UIButtonTypeCustom];
[newNoteButton setImage: _fNewNoteIcon forState: UIControlStateNormal];
[self.view addSubview: newNoteButton];
I type all of this out in SO without compiling so check over but that should get you a UIButton, with the required image at the correct size.
So it looks like if your PNG doesn't have an Alpha channel, then you'll have size issues. I opened the PNG in Photoshop and added an Alpha channel. The image is now properly sized in the iPad!
Related
This is the first time I have ever designed an iOS app so I want to make sure I understand this behavior correctly.
I designed a custom bar button icon for a navigation bar in Photoshop. The final image that I saved in Photoshop was 102 x 45, and yes I realize that these dimensions are bigger than the recommended 44x44 in the iOS 7 design guidelines.
Anyways, I placed my image into the asset folder, and then programmatically set the bar button item with the following code:
UIImage* firstButtonImage = [UIImage imageNamed:#"loginbutton1"];
CGRect frame = CGRectMake(0, 0, 102, 45);
UIButton * someButton = [[UIButton alloc] initWithFrame:frame];
[someButton setBackgroundImage:firstButtonImage forState:UIControlStateNormal];
[someButton addTarget:self action:#selector(didTapLoginButton:)
forControlEvents:UIControlEventTouchUpInside];
self.rightBarButton = [[UIBarButtonItem alloc] initWithCustomView:someButton];
self.navItem.rightBarButtonItem = self.rightBarButton;
As you can see I set the frame's width and height to the exact size of the image. When I first ran the app, I didn't like the image and thought it was too big. So I changed the width and height parameters in this statement:
CGRect frame = CGRectMake(0, 0, 70, 30);
And now the image looks perfect on the iPhone screen. This is on an iPhone 4s.
So my main question is, what is actually happening when I change the frame size? Since the frame is now smaller than the actual image size, does the image just get scaled down automatically to fit inside the frame?
Yes the image get scaled because you are using backgroundImage (not Image). Both images have different behaviors.
Check the Xcode Interface Builder, you can see there, that you can set two images: Image and Background. Background is the UIImage that get scaled for the whole frame of the UIButton.
The UIButton Class Reference allows you to access the imageView of the image (not theimageView of the backgroundImage)
Because you have access to the imageView, you can change the mode of the image with:
[[someButton imageView] setContentMode:UIViewContentModeBottomLeft];
In UIView Class Reference you can check all the UIViewContentModes provided by Apple.
You can check that changing a little bit your code:
[someButton setImage:firstButtonImage forState:UIControlStateNormal];
[[someButton imageView] setContentMode:UIViewContentModeBottomRight];
I have created a custom button using a .png image that has transparency. However, when I implement it as a UIImage, the transparency is lost. Here's the code that I'm using:
- (void)setMyCustomBackButton;
{
UIImage *backButtonImage = [UIImage imageNamed:#"Back Button.png"];
UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];
[backButton setBackgroundImage:backButtonImage forState:UIControlStateNormal];
[backButton addTarget:self action:#selector(popCurrentViewController) forControlEvents:UIControlEventTouchUpInside];
backButton.frame = CGRectMake(0, 0, backButtonImage.size.width, backButtonImage.size.height);
UIView *backButtonView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 63, 33)];
backButtonView.bounds = CGRectOffset(backButtonView.bounds, -12, -2);
[backButtonView addSubview:backButton];
UIBarButtonItem *finalBackButton = [[UIBarButtonItem alloc] initWithCustomView:backButtonView];
self.navigationItem.leftBarButtonItem = finalBackButton;
}
Is there a UIImage property for transparency? Does it have to do with opacity?
If you're creating the PNG in an image editing software, please make sure you've encoded the transparency while creating the image. Sometimes some image editors have an option for 'saving transparency' that's unchecked by default, when you're exporting something as a PNG.
Other than that, any transparency on a PNG will show up on a UIButtonTypeCustom. You don't need to do anything special to preserve transparency on a UIImage that's loading up a PNG.
Before you use the image in the code, please open it in Preview to make sure the transparency is present.
Oh and to answer your other question, UIImage does not have any properties relating to transparency. The closest thing you have is the alpha property for a UIView but even that simply changes the overall opacity of your UIView.
EDIT: Missed this the first time I read your question. Try:
UIBarButtonItem *finalBackButton = [[UIBarButtonItem alloc] initWithCustomView:backButton];
No need to have the backButtonView. You can pass in the UIButton as the custom view. I use this to create custom bar button items. This should fix your problem.
EDIT 2: The UIBarButtonItem class does not have an alpha property you can set. Also, modifying the alpha property of the UIButton that you set as the UIBarButtonItem's custom view won't affect the transparency of the UIBarButtonItem.
The only way you can do this is to modify the transparency of the source image being used for the UIButton.
Modify your original PNG to have the desired transparency you want (and based on your comments, you need a very low transparency). Use an image editing software / preview to fine tune the transparency before you export the PNG.
I have the following image representing my button:
I want to use that image to create a button that uses that as the background, but that is much wider than the image I supplied.
Here are the two methods that I have tried:
UIButton *emailSupportButton = [[UIButton alloc] initWithFrame:CGRectMake(25, 315, 200, 60)];
[emailSupportButton setTitle:#"Email Support" forState:UIControlStateNormal];
[emailSupportButton setImage:[UIImage imageNamed:#"toolbar-button"] forState:UIControlStateNormal];
This method results in the button image not being stretched and displaying exactly how the .png would display normally.
The other method I have tried is setting the background image, like so...
UIButton *emailSupportButton = [[UIButton alloc] initWithFrame:CGRectMake(25, 315, 200, 60)];
[emailSupportButton setTitle:#"Email Support" forState:UIControlStateNormal];
[emailSupportButton setBackgroundImage:[UIImage imageNamed:#"toolbar-button"] forState:UIControlStateNormal];
This method stretches the image in a really ugly fashion instead of achieving the desired effect, causing the button to be almost elliptical with a really ugly border.
Is the problem that I am not using the right method of creating a custom button, or that my image is not suitable for the task I am trying to accomplish? Is my image supposed to be rectangular and not include the button's border, letting UIButton take care of the border/rounding for me? Is my image supposed to already be the size of the button (this seems a bit limiting)?
The second method you listed (code-wise) is what you want. What you are missing is the stretchable image. Try this:
UIButton *emailSupportButton = [[UIButton alloc] initWithFrame:CGRectMake(25, 315, 200, 60)];
[emailSupportButton setTitle:#"Email Support" forState:UIControlStateNormal];
UIImage *backgroundImage = [UIImage imageNamed:#"toolbar-button"];
CGSize size = backgroundImage.size;
backgroundImage = [backgroundImage stretchableImageWithLeftCapWidth:size.width/2.0 topCapWidth:size.height/2.0];
[emailSupportButton setBackgroundImage:backgroundImage forState:UIControlStateNormal];
If you are deploying on iOS 5 and greater only, then you will want to use the new -[UIImage resizableImageWithCapInsets:(UIEdgeInsets)capInsets]; iOS 6 also adds -[UIImage resizableImageWithCapInsets:(UIEdgeInsets)capInsets resizingMode:(UIImageResizingMode)resizingMode];
I'm allocating a UIButtonTypeCustom to a UIView with a background image that is smaller than the button's frame.
Reason why the image is smaller is because I'm trying to add more of a "target area" for the UIButton. However, the image is being scaled to the full size of the frame, rather than just being the image's size.
I have tried setting the UIButton and UIButton's imageView's contentMode property to UIViewContentModeScaleAspectFit, but no luck, the image still gets stretched out.
Is there a way to do what I'm trying to do programmatically?
Thanks in advance!
A lot of people make the same mistake you do in regards to button images and then jump through hoops trying to make the button behave as they expect it to. Let's clear this up once and for all:
A UIButton has two types of images it can display -- a foreground image and a background image. The background image for a button is expected to replace the button's background texture. As such, it makes sense that it stretches to fill the entire background. However, the button's foreground image is expected to be an icon that may or may not display alongside text; it will not stretch. It may shrink if the frame is smaller than the image, but it will not stretch. You can even set the alignment of the foreground image using the Control alignment properties in Interface Builder.
A button's foreground and background image can be set in code like this:
// stretchy
[self setBackgroundImage:backgroundImage forState:UIControlStateNormal];
// not stretchy
[self setImage:forgroundImage forState:UIControlStateNormal];
You don't have access to the background imageView, but there is fully working workaround:
EDIT: There is an even better workaround then what I posted originally.
You can create a UIImage from any color, and call -setBackgroundImage:forState.
See bradley's answer, here:
https://stackoverflow.com/a/20303841/1147286
Original answer:
Instead of calling -setBackgroundImage:forState:, create a new UIImageView and add it as a subview of the button.
UIImageView *bgImageView = [[UIImageView alloc] initWithImage:img];
bgImageView.contentMode = UIViewContentModeScaleAspectFit;
[bgImageView setFrame:CGRectMake(0, 0, videoButton.frame.size.width, videoButton.frame.size.height)];
bgImageView.tag = 99;
[yourButton addSubview:bgImageView];
[yourButton bringSubviewToFront:yourButton.imageView];
Create the imageview
Set the content mode and frame
I also set a recognizable tag, so that when the screen rotates I can easily find my custom imageView in the button's subviews and reset its frame
Add it as a subview to the button
Bring the frontal imageView of the button to the front so our custom imageView doesn't overlap it
When the button needs to rotate just find the imageView by its tag and reset its frame:
UIImageView *bgImageView = (UIImageView *)[button viewWithTag:99];
[bgImageView setFrame:CGRectMake(0, 0, newWidth, newHeight)];
The cleanest and easiest way it probably to use the title insets of the button.
You set your image as the button image, and then you change the left title inset to match minus the width of your image:
myButton.titleEdgeInsets = UIEdgeInsetsMake(0, -myImage.width, 0, 0)
This will move the text back where it was before the image was added to its left. You can also use this value to add some padding to you button.
Stumbled on this problem too.
Adding image programmatically, as memmons thoroughly explained, did not help:(
I had a button 100x40 and image 100x100, it would appear squeezed, not fitted, as one would infer from "Aspect Fit" option. Actually, non of those view options had an effect.
I just had to rescale it so it would fit on a button, then use setImage:
UIImage *img=[UIImage imageNamed:#"myimage.png"];
CGImageRef imgRef = [img CGImage];
CGFloat imgW = CGImageGetWidth(imgRef);
CGFloat imgH = CGImageGetHeight(imgRef);
CGFloat btnW = myBttn.frame.size.width;
CGFloat btnH = myBttn.frame.size.height;
//get lesser button dimension
CGFloat minBtn=btnW;
if (btnW>btnH) {
minBtn=btnH;
}
//calculate scale using greater image dimension
CGFloat scl=imgH/minBtn;
if (imgW>imgH) {
scl=imgW/minBtn;
}
//scale image
UIImage *scaledImage = [UIImage imageWithCGImage:[img CGImage] scale:(img.scale * scl) orientation:(img.imageOrientation)];
//clean up
UIGraphicsEndImageContext();
//set it on a button
[myBttn setImage:scaledImage forState:UIControlStateNormal];
It is simple as:
ImageBtn.imageView?.contentMode = .scaleAspectFit
ImageBtn.setImage(chosenImage, for: .normal)
Another consideration is the BaseLine constraint. If your buttons have this constraint set (depicted as a horizontal or vertical line through multiple controls on your layout), it will cause your images to stretch without stretching the underlying button control. If your button is otherwise properly constrained (leading/trailing and top/bottom spaces, and etc...) removing the BaseLine constraint should have no impact on the layout, while allowing the foreground image to scale properly to the underlying button shape.
Answerbot answers the question with what is proper and correct to do. Don't fight the OS and use things as intended is always good advice. However, sometimes you need to break the rules.
I was able to mask the enlarged background image (not prevent it) by overlaying it with a black CAlayer then overlaying again with a properly resized image CAlayer. This was all done by creating a subclass of UIButton and overwriting the setHighlighted method.
NEED CODE?
- (void)setHighlighted:(BOOL)highlighted
{
super.highlighted = highlighted;
//
//Whenever an image needs to be highlighted, create a dimmed new image that is correctly sized. Below it is a englarged stretched image.
//
if (highlighted != _previousHighlightedSate)
{
_previousHighlightedSate = highlighted;
if (highlighted)
{
//Create a black layer so image can dim
_blackLayer = [CALayer layer];
_blackLayer.bounds = self.bounds;
CGRect rect = _blackLayer.bounds;
rect.size.width = rect.size.width*2;
rect.size.height = rect.size.height*2;
_blackLayer.bounds = rect;
_blackLayer.backgroundColor = [[UIColor blackColor] CGColor];
//create image layer
_nonStretchImageLayer = [CALayer layer];
_nonStretchImageLayer.backgroundColor = [UIColor blackColor].CGColor;
_nonStretchImageLayer.bounds = CGRectMake(0 , 0, self.bounds.size.width, self.bounds.size.height);
_nonStretchImageLayer.frame = CGRectMake(0 , 0, self.bounds.size.width, self.bounds.size.height);
_nonStretchImageLayer.contentsGravity = kCAGravityResizeAspect;//default is to resize
_nonStretchImageLayer.contents = (id)self.imageView.image.CGImage;
_nonStretchImageLayer.opacity = 0.5;
//add layers to image view
[self.imageView.layer addSublayer:_blackLayer];
[self.imageView.layer addSublayer:_nonStretchImageLayer];
}
else
{
//remove from image view
[_blackLayer removeFromSuperlayer];
[_nonStretchImageLayer removeFromSuperlayer];
//nil them out.
_blackLayer = nil;
_nonStretchImageLayer = nil;
}
}
Inspiration for this work around came from here
I guess the easiest solution is to use UIImage's resizableImageWithCapInsets method. Use UIEdgeInsetsMake to configure the free spaces.
might help someone
button.subviews.first?.contentMode = .scaleAspectFit
Swift version of Zoltán Matók answer
Just a copy of my code using SnapKit to do auto layout and syntatic sugar Then library for initilizations, it should work similar for normal Apples way of programatic layout.
let backButton = UIButton(type: .custom).then { (button) in
let image = UIImage(named: "backButtonIcon")?.withRenderingMode(.alwaysOriginal)
let imageView = UIImageView(image: image)
button.addSubview(imageView)
imageView.snp.makeConstraints { (make) in
make.center.equalTo(button.snp.center)
}
button.bringSubviewToFront(imageView)
button.contentMode = .scaleAspectFit
button.backgroundColor = .clear
button.isUserInteractionEnabled = true
button.isEnabled = true
button.imageView?.contentMode = .scaleAspectFit
button.imageView?.snp.makeConstraints({ (make) in
make.height.width.equalTo(24)
})
button.snp.makeConstraints { (make) in
make.height.width.equalTo(24)
}
}
You can use uibutton.imageView.contentMode for no stretching:
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(posX, posY, widthButton, heightButton);
[button setTitle:#"" forState:UIControlStateNormal];
[button setImage:[UIImage imageNamed:#"imageNamed"] forState:UIControlStateNormal];
[button setImage:[UIImage imageNamed:#"imageNamedHighlighted"] forState:UIControlStateHighlighted];
button.imageView.contentMode = UIViewContentModeScaleAspectFit;
[button addTarget:self action:#selector(functionMenu:) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview: button];
What you need to do is add your image as a UIImageView.
Than add a button with transperent background (UIColor ClearColor) on top of it with your desired width and height.
Behold:
//UIImageView* stretchTest = [[UIImageView alloc] initWithImage:[UIImage imageNamed:#"image.png"]];
//[self addSubview:stretchTest];
UIButton *stretchTest = [UIButton buttonWithType:UIButtonTypeCustom];
[stretchTest setFrame:CGRectMake(0, 0, 400, 100)];
[stretchTest setBackgroundImage:[UIImage imageNamed:#"image.png"] forState:UIControlStateNormal];
[self addSubview:stretchTest];
stretchTest.contentStretch = CGRectMake(0.5, 0.5, 0, 0);
stretchTest.contentMode = UIViewContentModeScaleToFill;
CGRect frame = stretchTest.frame;
frame.size.height = 300;
stretchTest.frame = frame;
Using the UIImageView (commented out above), the image stretches appropriately - rounded corners maintain the correct radius, because only the center pixel of the image gets stretched.
Using the UIButton, the image gets stretched incorrectly. The corner radii are not maintained and it gets ugly.
Both UIImageView and UIButton are subclasses of UIView. Why does the button resize differently than the imageView?
You're making assumptions about the way UIButton works. It's not implemented the same way as UIImageView. UIImageView is just a view, with no subviews, and its contents is the image. UIButton is different, and the way it works is a private implementation detail.
If you're trying to stretch an image appropriately on a button, you should use -[UIImage stretchableImageWithLeftCapWidth:topCapHeight:] to get a UIImage that knows how it should be stretched. If you want to stretch just the middle pixel, you can use something like
UIImage *image = [UIImage imageNamed:#"image.png"];
image = [image stretchableImageWithLeftCapWidth:floorf(image.size.width/2) topCapHeight:floorf(image.size.height/2)];
A UIButton has two types of images it can display -- a foreground image and a background image. The background image for a button is expected to replace the button's background texture. As such, it will stretch to fill the entire background. The button's foreground image is expected to be an icon that may or may not display alongside text; it will not stretch. It may shrink if the frame is smaller than the image, but it will not stretch.
A button's foreground and background image can be set in code like this:
// stretchy
[self setBackgroundImage:backgroundImage forState:UIControlStateNormal];
// not stretchy
[self setImage:forgroundImage forState:UIControlStateNormal];
By default, the backgroundImage of a button will use scaleToFill to stretch the image. If you need the image to stretch using cap insets though, you should set them on the image before assigning it to the backgroundImage, like this:
UIImage *image = [UIImage imageNamed:#"bg_image.png"];
/* This assumes your image will have a 1px column and 1px row of pixels
in the horizontal and vertical middle of the image that should be
stretchable. If that's not the case (such as asymetrical buttons)
you need to adjust the caps */
image = [image stretchableImageWithLeftCapWidth:floorf(image.size.width/2)
topCapHeight:floorf(image.size.height/2)];
[self setBackgroundImage:image forState:UIControlStateNormal];