I am stuck with a strange problem that,
I have a image view which has to shown at some angle approx 5 degree.For that I rotate my UIImageView to 5 degree but the image in UIImageView not coming proper as it was before transformation.
For more understanding see images
You can see the second image is looking like clipped from corners and looks some blur also.
My code for rotation:-
myimageView.transform = CGAffineTransformMakeRotation(radians(5));
Please suggest me how to solve this problem.
Thanks in advance.
Looks like there are several solutions located in this similar SO Q&A:
Any quick and dirty anti-aliasing techniques for a rotated UIImageView?
If it is, in fact, just the edges that are jagged, try adding a 1px transparent border around in image content (this is a suggestion in the above link).
Have you tried using CGContextRotateCTM(context, radians); and [sourceImage drawInRect:rect];?
Related
I'm trying to achieve a sort of dynamic UIView masking effect. Here is a sketch:
So as you can see, I'm trying to create a UIView that can effectively cut through an image to reveal the image behind it. I already know how to return an image with a mask statically, however I would like the "revealer" to be draggable (I'll use pan gesture) and live.
Does anyone have any ideas or starting points on how to achieve this? Thanks
(NOTE: My demo says White layer, but I'd actually like to show another image or photo).
masking an image is not that difficult.
This link shows the basics.
http://iosdevelopertips.com/cocoa/how-to-mask-an-image.html
But personally I think i would make 2 UIImage views and crop the content of the draggable UIView. I'm not sure but I would expect that clipping and panning the second image will be less computationally expensive then applying the mask and will get you a better frame rate.
So I would do: UIImageView of the full image. A UIView on top of it with a white and some transparency setting to make it look white, then a UIImageView with the image either places or cropped so that only the correct section is showing.
An iPhone SDK question: I'm drawing a UIImageView on the screen. I've rotated it in 3D and provided a bit of perspective, so the image looks like it's pointing into the screen at an angle. That all works fine. Now the problem is the edges of the resulting picture don't seem to be antialiased at all. Anybody know how to make it so?
Essentially, I'm implementing my own version of CoverFlow (yeah yeah, design patent blah blah) using quartz 3d transformations to do everything. It works fine, except that each cover isn't antialiased, and Apples version is.
I've tried messing around with the edgeAntialisingMask of the CALayer, but that didn't help - the defaults are that every edge should be antialiased...
thanks!
If you rotate only one image, than one trick will resolve the problem. Try to set
layer.shadowOpacity = 0.01;
After that picture will look smoother after 3D Rotation
The Gloomcore answer give a really neat result.
however this sometime make things really LAGGY !
Adding rasterization help a little bit:
.layer.shadowOpacity = 0.01;
.layer.shouldRasterize = YES;
I know the question/answer is old, but hey i just found it.
You could try adding some transparent pixels around the edge of the image, either by putting the UIImageView in a slightly larger empty view that you apply rotation to, or by changing the source images.
I had a similar issue that was solved by only setting shouldRasterize = YES, however because I was re-using my views (and layers), the shouldRasterize = YES killed the performance.
Fortunately I found a solution by turning shouldRasterize = NO at the right time to restore performance in my app's case.
I posted a solution here: Antialiasing edges of UIView after transformation using CALayer's transform
You can try this
Method: Using layer.shouldRasterize
Create a superlayer/superview which is 1 pixel bigger in all 4 directions
Do the transform on the superlayer/superview
Enable layer.shouldRasterize on the original layer/view
Method: Drawing to a UIImage
Draw your content to a UIImage
Make sure that you have a transparent border of 1 pixel around the content
Display the image
Reference: http://darknoon.com/2012/05/18/the-transparent-border-trick/
I'm using the UIGraphicsGetImageFromCurrentImageContext() function to capture the screen contents into an UIImage object (previously rendered into an Image context). This works great for both the simulator and a real device, however in the latter the resulting image has a few pixels with distorted colors, as seen here:
http://img300.imageshack.us/img300/2788/screencap.png
Please notice the few fucsia pixels at the top navigation bar, at both sides of the search field and to the right of the button. There are also such pixels at the right of the bottom-left button.
The code I'm using to capture the screen view into an UIImage object is pretty straightforward:
UIGraphicsBeginImageContext(self.view.window.frame.size);
[self.view.window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *anImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
One thing to note is that all the graphics that get distorted belong to custom PNG files, used to draw the search field background as well as the buttons background.
Does anyone knows what could be possible causing this strange color distortion?
Best regards,
Just checked my own code that is doing the same thing you are. Yours is nearly identical to mine, except that I am asking the view's layer to render instead of the window's, i.e.:
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
I don't know why that would make a difference, but it's worth a try.
Solved it by using the just-approved private function UIGetScreenImage().
For more info, please check http://www.tuaw.com/2009/12/15/apple-relents-and-is-now-allowing-uigetscreenimage-for-app-st/ and https://devforums.apple.com/message/149553
Regards,
This article explains the issue with image corruption (caused by partially transparent pixels) and provides a workaround which corroborates Chris's comment:
http://www.kaoma.net/iphone/?p=9
UIGetScreenImage() is quite annoying when you just want to capture a view.
I found a nice trick, just re-save all your PNG images into TIFF format using Preview.app :)
I need to mask a "texture" image with a rotated greyscale image.
I found out, that I have to do it with CGImages or CGlayers (if there is a simplier way using UIImageViews only, please let me know about it).
My problem is simple:
The antialias of any
rotation-transformed CG stuff is quiet
jaggy...
... but the antialias of a rotation-transformed UIImageView is kinda perfect. How can I produce that beautiful antialiased rotations?
I've uploaded a "proof" involving actual iPhone Simulator screenshots, to see what am I talkin' about: http://gotoandplay.freeblog.hu/files/Proof.png
I've tried to use CGImages, CGLayers, UIImageViews "captured" with renderInContext, I've tried to CGContextSetInterpolationQuality to high, and also tried to set CGContextSetAllowsAntialiasing - CGContextSetShouldAntialias, but every case returned the same jaggy result.
I'm planning to learn using OpenGL next year, but this development should released using CoreGraphics only. Please let me know how to get a perfectly rendered rotated image, I just can't accept it's impossible.
To add 1px transparent border to your image use this
CGRect imageRect = CGRectMake(0, 0, image.size.width, image.size.height);
UIGraphicsBeginImageContext( imageRect.size );
[image drawInRect:CGRectMake(1,1,image.size.width-2,image.size.height-2)];
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Have you tried adding a clear, 1 pixel border around your image? I've heard of that recommended as a trick to avoid aliasing, by giving CoreGraphics some room to work with when blending the edges.
I am having a similar problem, looks like I'm going to move it over to OpenGL ES as well. I can't nail down an effective solution that doesn't hurt performance.
For reference of future CoreGraphics explorers, putting a 1-pixel transparent border did make for a noticeable improvement in my experiments, but it appears that as Eonil mentioned, you end up with multiple stages of antialiasing/smoothing/interpolation working against each other. IE: CGLayer does some interpolation for it's rotation, then context it's being drawn to will do some interpolation/antialiasing, so on so forth until it ends up looking pretty rough.
I actually ended up with better results by disabling interpolation and antialiasing on the destination context, though it was still obviously jaggy (less artifacts overall though). I was able to achieve the best overall appearance by enabling interpolation and antialiasing when constructing the CGLayer, and disabling it for the destination context when re-drawing it. This approach, obviously, is fraught with other problems.
I am developing one game where I want to magnify the image where magnifier image is placed.
For that I am using the concept of masking. After masking I am zooming the image but looks blur. And I want image should be clearer like we r looking through rifle magnifier. So if any one have solution then kindly reply
are you sure that the problem is the masking?
perhaps your resources are too low resolution? high resolution images scaled down always look better than low resolution images scaled up.
Maybe you need to look at the problem backwards... so that your image when looking through the rifle magnifier [scope?] is viewed at a 1:1 resolution and when not viewed through the scope it is zoomed out (1:2 resolution?). so this way your 'normal' mode is the zoomed out mode and the "magnified view" is actually just the image at 1:1.
If you have A UIImage whose size is 293x184 but you create a UIImageView with an initial size of 40x30, the iPhone SCALES the UIImage to fit according to the property: contentMode. Default contentMode is: UIViewContentModeScaleToFill, which scales your image.
So even though you started with a large image, it is now only 40x30 and rendered at 40x30. When you zoom it is STILL 40x30, but rendered at some larger size which is causing the blur.
One solution would be to replace the image after the zoom, then you would have a completely new UIImage at full resolution.
[self.view setFrame:reallyBigFrame];
[self.view setImage:newUIImage];
Another would be initially place the UIImage in a full size 293x184 UIImageView, then use an AffineTransform to scale it down:
view.transform = CGAffineTransformScale(view.transform, 0.25, 0.25);