I have built a zoomable scrollview with a pattern image background.
cntView.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:#"patternStripe.png"]];
the scrollview is very long and zoomable.
and of coure: i recieve memory warnings (lvl 1 & 2)
is there a workaround to have pattern images in large zoomable views?
Either find a way to reduce the size of the pattern. Does it really need to be 1800px in height, is there no repetition in that pattern already ?
Or you will have to split the pattern background up into smaller images and create a view that draws them as needed and use that view as background/parent view for your content. See for example this question and this question.
Apple says to avoid images larger than 1024x1024, and while this doesn't exactly fit your image, the fact that you use it as a pattern where it is copied a lot in whole before getting cropped likely breaks the barrier.
Related
I am trying to save the view with its subview, but the saved image is little bit blurry (especially the label's text)
I tried all the solutions given in stackoverflow - no use.
Can anyone help me on the same?
I am using the below code
UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, 0);
[view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
And getting the blurred text, also the picture quality is low.
You could try a higher resolution image. It should be fine if you compress a high resolution image to down, but scaling up a low resolution image to a larger size will generally blur the image contents, as it stretches everything.
The preferred approach is [UIView snapshotViewAfterScreenUpdates:]. You should only use drawViewHierarchyInRect:afterScreenUpdates: if you plan to apply additional effects.
That said, there are several likely causes, depending on how you're manipulating or saving the image. For example, saving text in JPEG format will cause blurriness. Rotating or scaling the image without great care can make the text blurry. Drawing the image incorrectly (for instance, failing to pixel-align it) can make the text blurry. You should simplify your problem if you're making multiple steps, and validate the quality at each step. To discuss it further on StackOverflow, you need to provide details on how you're manipulating and displaying the image, not just how you generate it.
Text is extremely susceptible to artifacts. If you must take pictures of it (something you generally should avoid if at all possible), you should make sure to manipulate it as little as possible. It is always better to manipulate the text before it's drawn rather than after.
I understand that i can't adapt GLPainter example from apple to retina due to a bug mentioned here: Problems displaying full-screen CAEAGLLayer on Retina iPad
Any one knows a good starting point to creating an Open-GL basic painter with brushes, that will work on Retina?
or - creating an openGL painter without CAEAGLLayer
I think that the starting point can still be GLPaint, only you need to set to NO hte value of kEAGLDrawablePropertyRetainedBacking and change the way you draw in your GL view.
GLPaint will only render to the gl buffer the strokes you draw by touching the screen, relying on kEAGLDrawablePropertyRetainedBacking to make the full buffer content retained. An alternative might be redrawing at each step the full content of the buffer. This would require keeping track of all the strokes that were drawn and kind-of "replay" them.
I suspect that in any serious painting app you would not rely on kEAGLDrawablePropertyRetainedBacking to retain the buffer content due both to performance and the need for managing you own data structure representing the painting (for anything like storing, sending the painting etc.) and would therefore implement your own solution for it.
I have been looking for the solution on the web for a long time. Most tutorials are fairly simple about adding shadow to a UIView. I also noticed that if we add a shadow to an UIImageView. The shadow shape could perfectly fit the shape of the content image if the image itself has alpha channel in it. Say for example, if the image is an animal with transparent background, the shadow shape is also the same as that animal (not a rectangle shadow as same as UIImageView frame).
But these are not enough. What I need to do is to add some changes to the shadow so it may have some rotation angle and compressed (squeezed or shift) effect so that looks like the sunlight comes from a certain spot.
To demonstrate what I need, I upload 2 images below, which I captured from the Google Map App created by Apple. You can imagine the Annotation Pin is an image which has the Pin shape, so the shadow is also "pin shaped", but it is not simply "offset" with a CGSize, you can see the top of the shadow is shifted right about 35 degrees and slightly squeezed the height.
When we tap and hold and pin, the shadow is also animated away from the pin, so I believe that such shadow can be made programmably.
The best shadow tutorial I can found so far is http://nachbaur.com/blog/fun-shadow-effects-using-custom-calayer-shadowpaths But unfortunately, that cannot make this effect.
If anyone know the answer or know any better words to search for, please let me know. Thank you.
(Please note that the shape of the image is dynamic in the App, so using any tool like Photoshop to pre-render the shadow is not an option.)
In order to create dynamic effects like this, you have to use Core Graphics. It's incredibly powerful once you know how to use it. Basically you need to set a skew transform on the context, set up a shadow and draw the image. You will probably have to use transparency layers as well.
It doesn't sound like you can use CALayer shadows, since that is meant to solve a specific use-case. The approach Apple takes with the pin marks on the map is to have two separate images that are created ahead of time (e.g. in Photoshop) and they position them within the map relative to a reference point.
If you really do need to do this at run-time, it should still be possible by using either Core Graphics or ImageKit. To get a blurred shadow appearance, you can use the kCICategoryBlur CIFilter. You can then convert the image to grayscale. And to get that compressed look you just need to resize and skew the image.
Once you have two separate images, you can either take the CGImageRef for the shadow image and can set that as the content of another sublayer, or you can add it as a separate view.
If you know what all the shapes are, you could just render a shadow image in Photoshop or something.
I'm making a game using UIView.
I use a large (8192x8192) UIView as the map area, (the game is birds-eye-view) with a UIImageView stretched across it displaying a grass texture.
This uses heaps of memory, doesn't run on older devices and nearly crashes Xcode whenever I try to edit it...
Is there an alternate method of creating a 8192x8192 map, but without being laggy?
If it's possible to tile your graphics, something involving CATiledLayer would probably be a good fit. CATiledLayer allows you to provide only the images that are necessary to display the currently viewable area of the view (just like Maps does).
Here is some example code for displaying a large PDF.
I'm developing an iPhone Cocos2D game and reading about optimization. some say use spritesheet whenever possible. others say use atlassprite whenever possible and others say sprite is fine.
I don't get the "whenever possible", when each one can and can't be used?
Also what is the best case for each type?
My game will typically use 100 sprites in a grid, with about 5 types of sprites and some other single sprites. What is the best setup for that? guidelines for deciding for general cases will help too.
Here's what you need to know about spritesheets vs. sprites, generally.
A spritesheet is just a bunch of images put together onto one big image, and then there will be a separate file for image location data (i.e. image 1 starts at coordinate 0,0 with a size of 100,100, image 2 starts at coordinate 100,0, etc).
The advantage here is that loading textures (sprites) is a pretty I/O and memory-alloc intensive operation. If you're trying to do this continually in your game, you may get lags.
The second advantage is memory optimization. If you're using transparent PNGs for your images, there may be a lot of blank pixels -- and you can remove those and "pack" your texture sizes way down than if you used individual images. Good for both space & memory concerns. (TexturePacker is the tool I use for the latter).
So, generally, I'd say it's always a good idea to use a sprite sheet, unless you have non-transparent sprites.