I'm trying to reuse a small chunk of code inside a custom button class. For this to work I need to pass in non stretchable images (an icon) or a stretchable image (a 'swoosh'). Within the code I need to set the rect to draw the height so I'd like, ideally, to simply determine if the image is stretchable or not? If it isn't I draw it at the size of the image, if not I draw at the bounds of the containing rect.
From my investigation so far capInsets (iOS 5) or leftCapWidth/topCapHeight (pre iOS 5) are not useful for this.
Is there something buried in the core or quartz information I can use?
Just curious, for now I'm coding around it with an extra parameter.
** I've since read through CGImageRef and the CI equivalent **
As far as I can tell there is no such information that we can access to identify such images, which begs the question how does the OS know?
There is no way to detect this unless you have some intense image analysis (which won't be 100% correct). UIImage is essentially some pixels with meta-information, all obtained from the file that you loaded it from. No file formats would have that information.
However, you can encode some information into the file name of the image. If you have an image called foo.png that is stretchable, why not call it foo.stretch.png? Your loading routines can analyse the file name and extract meta-information that you can associate with the UIImage (see http://labs.vectorform.com/2011/07/objective-c-associated-objects/ for associated objects) or by creating your own class that composites a UIImage with meta-information.
Good luck in your research.
When u create UIImage*, its .size property is absolute.
If u mean stretchable to your button view. just check scale for example.
- (BOOL) stretchableImage:(UIImage*)aImage toView:(UIView*)aView{
CGFloat scaleW = aView.size.width/aImage.size.width;
CGFloat scaleH = aView.size.height/aImage.size.height;
if (scaleW == scaleH){
if (scaleW < 1)
return YES;
}
return NO;
}
You can check it's class.
UIImage *img = [UIImage imageNamed:#"back"];
NSString *imgClass = NSStringFromClass(img.class);
UIImage *imgStretch = [img stretchableImageWithLeftCapWidth:10 topCapHeight:10];
NSString *imgStrClass = NSStringFromClass(imgStretch.class);
NSLog(#"Normal class:\t%#\nStretchable class:\t%#",imgClass,imgStrClass);
Console:
Normal class: UIImage
Stretchable class: _UIResizableImage
Related
I am using a UITableViewCellStyleSubTitle. I am trying to add thumbnails to my table cells.
UIViewContentModeScaleAspectFit does not seem to work for reasons unknown. I have seen a lot of answers in stack overflow for similar kind of questions. If i crop the image using drawInRect it works, like this
[thumbnail drawInRect:thumbnailRect];
UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
But what i am trying to achieve should not need me to do this. I am only trying to scale the image and not crop it.
So setting the content mode to "UIViewContentModeScaleAspectFit" for the imageview of the default cell should work.. but it does not.
cell.imageView.contentMode = UIViewContentModeScaleAspectFit;
Complete logic for setting thumbnails.. fPath is the path to image
UIImage *thumbnail = [UIImage imageWithContentsOfFile:fPath];
[cell.imageView setImage:thumbnail];
cell.imageView.contentMode = UIViewContentModeScaleAspectFit;
cell.imageView.clipsToBounds = YES;
I found out that drawInRect stretches the original image if the size is lower or croppes it if it is bigger.
This article will help you to prepare a thumbnail of your image
http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way/
It has several useful UIImage classes extentions:
* UIImage+Resize
* UIImage+Alpha
* UIImage+RoundedCorner
Example Usage:
UIImage *imageThumb = [YourImage thumbnailImage:70 transparentBorder:0 cornerRadius:10 interpolationQuality:kCGInterpolationHigh];
and then you can use drawInRect method. If the image is not rectangle - the image will crop the bigger side and take the middle of the image
Hope this answer will guide you.
I have two ImageViews and I am merging two images. First image is a bodyImage and second Image is a tattooImage. I already done merging, but I wants ask
1)I can drag tattooImage over bodyImage. I wants on doubleTap tattooImage mergeWith bodyImage on the tap coordinates. Hope you understand question
Thanks
+ =
and here is my code : here imageView1 is my bodyImage and imageView2 is my tattooImage
- (void)tapDetected:(UITapGestureRecognizer *)tapRecognizer
{
int width=500;
int height=500;
NSLog(#"takephoto from twitter");
CGSize newSize = CGSizeMake(width, height);
UIGraphicsBeginImageContext( newSize );
// Use existing opacity as is
[imageView1.image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
// Apply supplied opacity if applicable
[imageView2.image drawInRect:CGRectMake(180,200,200,200) blendMode:kCGBlendModeDarken alpha:0.4];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
imageView1.image=newImage;
UIGraphicsEndImageContext();
}
mask image http://www.developers-life.com/resize-and-mask-an-image.html
You need image masking for that. I wrote a tutorial on how to use it, and how I've used it in my own application. From the Apple documentation:
Masking techniques can produce many interesting effects by controlling which parts of an image are painted. You can:
Apply an image mask to an image. You can also use an image as a mask
to achieve an effect that’s opposite from applying an image mask.
Use color to mask parts of an image, which includes the technique
referred to as chroma key masking.
Clip a graphics context to an
image or image mask, which effectively masks an image (or any kind of
drawing) when Quartz draws the content to the clipped context.
I have an image which I use to frame a tweet. It consists of two rounded rects, with a twitter icon a the top left. The important part is that it is repeatable, as you could copy any part of the middle section vertically, and it would be the same, just longer. Here is the image I created:
My question is how, in code, do I extend (or shrink) that dependent on how many lines are in my UITextView? Something like this to get the size:
float requiredHeight = lines * 14;
I know this is possible, because apple do it with their SMS app :)
UPDATE: Here is the complete code for doing this:
UIImage *loadImage = [UIImage imageNamed:#"TwitPost.png"];
float w2 = loadImage.size.width/2;
float h2 = loadImage.size.height/2;
// I have now reduced the image size so the height must be offset a little (otherwise it stretches the bird!):
loadImage = [loadImage stretchableImageWithLeftCapWidth:w2 topCapHeight:h2+15];
imageView.image = loadImage;
Thanks for both answers.
By using
- (UIImage *)stretchableImageWithLeftCapWidth:(NSInteger)leftCapWidth topCapHeight:(NSInteger)topCapHeight
Where you set leftCapWidth and topCapHeight as half the width and height of your image. This image you can stretch in a UIImageView by changing its bounds/frame.
Look at the documentation for UIImage. Specifically:
- (UIImage *)stretchableImageWithLeftCapWidth:(NSInteger)leftCapWidth topCapHeight:(NSInteger)topCapHeight
This allows you to use an image which repeats the portion at the leftCapWidth or topCapHeight to stretch it horizontally or vertically.
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);
Hopefully a quick one? I am creating a custom uitableviewcell and have added an imageview.
I have some PNG images which are around 200x200 in size. I want to create a thumbnail to put in the tableview, but when I resize the image, it results in a poor quality image.
I use UIViewContentModeScaleAspectFit to resize it to a 50x50 frame.
Should I be calling a better draw resize on each image before I Put it to the table cell? There will be around 20-40 images in each table, so I don't want to over work the device!!
Thanks for any help.
Rescaling the images yourself with CoreGraphics will give you more control over the quality, but your best bet is to size the images appropriately for your table in the first place -- less work the software has to do and complete control over the image's appearance.
If you still want to resize them in Quartz, here's one way you might go about it:
UIImage* originalThumbnail = [UIImage imageWithContentsOfFile:<PATH_TO_IMAGE>];
CGSize originalSize = [originalThumbnail size];
CGSize cropSize = { 50, 50 };
CGRect cropRect = CGRectMake(abs(cropSize.width - originalSize.width)/2.0, abs(cropSize.height - originalSize.height)/2.0, cropSize.width, cropSize.height);
CGImageRef imageRef = CGImageCreateWithImageInRect([originalThumbnail CGImage], cropRect);
// here's your cropped UIImage
UIImage* croppedThumbnail = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
You'd want to do this once if possible, i.e. not every time you construct your UITableViewCell.