I have a issue with masking images. I do game "puzzle" and have to make custom images. I found and tried 2 way of custom cropping:
Using CALayer.mask property.
Using UIImage.mask property.
In first option i create my custom path, then assign it to CAShapeLayer.path property, then assign CAShapeLayer to CALayer.mask property. At the end i have custom cropped image.
In second option i use firstly use CGImageMaskCreate() method (i use previously created black mask images of puzzle), then CGContextClipToMask().
In either options i have problem with performance (mostly when i crop image into 16 puzzles and drag in over the screen).
Is there any other approaches to crop image in custom way.
(I don't know how to solve performance problem).
Thanks in advance.
There are lots of UIImage-categories out there you can use for this. Give me a moment and I'll post some links here:
Cropping an UIImage (not really a category though, but it'll fit)
UIImage: Resize, then Crop
https://sites.google.com/a/injoit.com/knowledge-base/for-developers/graphics/uiimage-routines-scaling-cropping-rotating-etc
http://www.hive05.com/2008/11/crop-an-image-using-the-iphone-sdk/
http://maybelost.com/2010/11/cropping-a-uiimage-on-iphone/
Try this:
-(UIImage *)imageByCropping:(UIImage *)imageToCrop toRect:(CGRect)rect
{
CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return cropped;
}
...
UIImage *temp_image = [self imageByCropping:original_image toRect:clipping_rectangle];
Maybe you should consider about drawing the image in a new image with an alpha background an overdrawing the current background. I mean: All pixel which are inside the jigsaw piece: normal colour, all pixels outside the jigsaw piece = transparent. And then try to blend it to the new background or overdrawing it.
Just my 2 cents. :)
Related
In my app i have one transparent image, now when user selects one image from photo library, that image have to be display over transparent image and make as an one uiiimage so that user can mail or share with it. I have used the following code, however image is not coming correct over transparent image
UIImage *backgroundImage = [UIImage imageNamed:#"iPhoneOverLay.png"];
UIGraphicsBeginImageContext(backgroundImage.size);
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[testImage drawInRect:CGRectMake(backgroundImage.size.width - testImage.size.width, backgroundImage.size.height - testImage.size.height, testImage.size.width, testImage.size.height)];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Here testImage is selected from Photo Library or taken from camera
You draw the 2 images in the wrong order. Transparency is a property that makes things shine through that have been painted previously. Therefore you have to draw the (opaque) photo first and the (transparent) overlay second.
Hi am a noob at PDF generation and currently am displaying a 3d bar charts in my application in glview which is in side a uiview. Now i want to generate a PDF document from the uiview which contains a text view and a glview. Am able to generate a PDF from text but where as GL View am unable to proceed.even i tried for a possibility over the net but unable to get any info regarding this.Can someone help me by providing the solution whether this can be possible or not.Thanks in Advance
You can ask any UIView to give you an image (which might be a start) via something like:
- (UIImage *) imageRepresentation {
// render myself (or more correctly, my layer) to an image
UIGraphicsBeginImageContext(self.bounds.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetShouldSmoothFonts(context, false);
CGContextSetShouldAntialias(context, false);
[self drawLayer:self.layer inContext:context];
[self.layer renderInContext:context];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
After that, you might be able to get a PDF representation of it, or investigate calls like CGPDFDocumentCreateWithURL to construct one yourself from the image.
You can use CoreGraphic's PDF-APIs to creating and drawing to a PDF.
See Apple's guide for more details.
Current I am trying to show a simple table in my iPhone application where I use UITableViewCell's with the style UITableViewCellStyleValue1 (image to the left, detail-label right-alligned). The cells all have the default height (50.0f). Before I add an image to the cell, I resize the image to be 40x40, so that it is not the total height of the cell (I think that looks ugly).
I do this with this code:
cell.imageView.image = [UIImage imageNamed:#"icon.png"];
cell.imageView.image = [RootViewController imageWithImage:cell.imageView.image scaledToSize:CGSizeMake(40, 40)];
This is all very nice and works flawlessly. But I want to accomplish this also on the iPhone 4 (with the higher resolution screen). The problem is, that everything is scaled without problems on the iPhone 4 but the images appear very pixelated.
The reason for this is ofcourse that everything on the screen is blown up to scale to the new resolution, also the images, so the images should probably be something like 80x80. But when I resize them to 80x80 (originals are 120x120) they appear way to big, because of the scaling thing.
Is there a way to actually make my images not the complete height of a tablecell, but I want them in the higher resolution on the iPhone 4. Should I create a complete new View for this?
Oops, after the first reply I realised that my own written function was missing:
+ (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;
}
As you can see, after the first reply, I tried to get this to work with the method UIGraphicsBeginImageContextWithOptions but somehow this results in an empty image.
I assume you wrote "imageWithImage:scaledToSize:", right?
I further assume you use "UIGraphicsBeginImageContext(yourSize)" within this call. Replace that with "UIGraphicsBeginImageContextWithOptions(yourSize, NO, 2.0)" in case your platform is iPhone 4.
The "2.0" defines the scale factor for points (you define the size in points not in pixels). On pre-retina-display a point is 1x1 pixel. On retina display a point is 2x2 pixels.
Edit:
Make sure you have a high-res version of "icon.png" in your resources called "icon#2x.png". This is automatically loaded in case it is a retina display.
How can I save a stretched image?
I have a small(50 X 50) image, that I have stretched while displaying it on a UIImageView (by choosing scaletofit mode.) Now I need to fetch & save that stretched image.
I have tried by using UIImageView's image property, but it gives me original image not that stretched image.
So, do you have any idea how to solve this problem? If then please help me or guide me or at-least give me a hint.
Hoping for your reply.........
Thanks
You have to create an image by copying the bit map of the view's CGContext (core graphic context). This has been asked on stackoverflow before but I can't find the answer right now.
You need to render your UIImageView into a graphic context you create :
UIGraphicsBeginImageContext(yourUIImageView.frame.size);
yourUIImageView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
//get the PNG representation of the UIImage (but you could do the same with JPEG
NSData *myData = UIImagePNGRepresentation(screenshot);
//then save it to a file
[myData writeToFile:thePathToWriteYourFileAsNSString atomically:YES];
I'd like to get the image that is being displayed on the UIImagePickerController when user uses the camera. And when I get I want to process the image and display instead of regular camera view.
But the problem is when I want to get the camera view, the image is just a black rectangle.
Here's my code:
UIView *cameraView = [[[[[[imagePicker.view subviews] objectAtIndex:0]
subviews] objectAtIndex: 0]
subviews] objectAtIndex: 0];
UIGraphicsBeginImageContext( CGSizeMake(320, 427) );
[cameraView.layer renderInContext: UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
imageToDisplay.image = [PixelProcessing processImage: viewImage]; //In this case the image is black
//imageToDisplay.image = viewImage; //In this case the image is black too
//imageToDisplay.image = [UIImage imageNamed: #"icon.png"]; //In this case image is being displayed properly
What am I doing wrong?
Thanks.
This one is also working quite good. Use it when the camera preview is open:
UIImage *viewImage = [[(id)objc_getClass("PLCameraController")
performSelector:#selector(sharedInstance)]
performSelector:#selector(_createPreviewImage)];
But as far as I found out it brings the same results than the following solution which takes a 'screenshot' of the current screen:
extern CGImageRef UIGetScreenImage();
CGImageRef cgoriginal = UIGetScreenImage();
CGImageRef cgimg = CGImageCreateWithImageInRect(cgoriginal, rect);
UIImage *viewImage = [UIImage imageWithCGImage:cgimg];
CGImageRelease(cgoriginal);
CGImageRelease(cgimg);
A problem I didn't still find a fix for is, how can one get the camera image very fast without any overlays?
The unofficial call is:
UIGetScreenImage()
which you declare above the #implementation as:
extern CGImageRef UIGetScreenImage();
There may be a documented way to do this in 3.1, but I'm not sure. If not, please please file a Radar with Apple asking them to make some kind of screen grab access public!!!
That uses your same AppleID you log in to the iPhone development portal with.
Update: This call is not yet documented, but Apple explicitly has given the OK to use it with App Store apps.
at least for now, there's no way to do this. (certainly no official documented way, and as far as I know nobody's figured out an unofficial way either.)
the camera preview data is being drawn by the OS in some way that bypasses the normal graphics methods.