I'm trying to display a series of images in a animation where the duration between the images changes frame to frame. I can successfully animate images where the duration is the same. I've looked into subclassing UIImageView but it doesn't seem to allow you access anything that could be helpful.
I've also looked into subclassing UIView directly but it seems like I'd have to write a lot of the stuff that UIImageView already does for me.
Is there a way to do this with UIImageView? Or if I am going to have to build my own UIView animation can someone point me the right direction to get started? Thanks.
You could have many UIImageViews next to one another, each representing one image, and animate them inside a UIView or UIScrollView, depending on what exactly you need to do. Animations with the help of UIView are very straightforward to implement.
Related
I want to use a UIProgressView but I want the background to be an image to make things a bit more good looking. I'm not sure how to lay one over the other. It would be important for the background image to encompass the UIProgressView.
Any help appreciated.
You can simply create a UIImageView for your background image, then add a UIProgressView as a sub view.
You can do this in either Interface Builder or in code such as [myBackgroundImageView addSubView:myProgressView];
Obviously you will need to setup the correct frame for both to ensure they are in the correct position.
Check out addSubview: in the Apple reference.
I've been working on a Crosswords app for a while and this problem keep returning no mater what i try.
The actual game runs in an UIScrollView because the player should be able to zoom, pan etc.
To the UIScrollview i have added a UIView. First i tried to add multiple UIImageViews and UILabels to the UIView but it resulted in very bad scrolling performance.
Now I've tried to create 3 subclassed UIViews where i wrote a custom drawRect method for each of them. I need 3 UIVIews because only two of the them needs to be redrawn, but not at the same time. The third one contains the clue numbers which are constant.
My UIScrollView hierarchy look like this:
UIScrollView
UIView
UIImageView (show the game board image)
UIView (shows the marked row/column)
UIView (shows the text the user writes)
UIView (shows the clue numbers)
I think the problem is that i have the UIImageView + 3 UIViews in one UIView. When I try to make this hierarchy it doesn't lag, but I'm not able to zoom, pan, scroll etc.:
UIScrollView
UIImageView (show the game board image)
UIView (shows the marked row/column)
UIView (shows the text the user writes)
UIView (shows the clue numbers)
Can you please try do guide me in the right direction. I will appreciate if I do not have to change too much, because the code in the three UIVIews are pretty long.
Thanks in advance :)
EDIT
Screenshot: http://crosswords-plus.com/puzzles/screen.png
First off, I'd recommend shrinking your UIScrollView and pulling the UIView containing the clues out of it. It sounds like it doesn't need to pan/zoom, so you're just adding to the overhead by having it contained inside the UIScrollView.
Secondly, it's hard to give much of an answer without seeing your implementation, but it seems to me that it's possible to turn the UIImageView/UIView/UIView hierarchy into 1 subclass that draws empty, blacked out or filled-in squares plus row/column numbering as necessary. That way, you only have 1 UIView in the UIScrollView and all of this is probably much simpler.
Is that helpful? Is there a reason you're using a UIImageView for the background? Is there a reason you're separating the row/column numbering from the text the user has entered?
I've got a pretty big UIScrollView (contentSize 8000 x 960) with a lot of small labels.
The labels are only added if you scroll to the area where the label belongs to. So, at first, the scrooling is smooth, but as more and more labels are loaded, the performance suffers more and more.
What's the best solution to keep the scrolling smooth? Is CATiledLayer the way to go? Or should the labels off the view should be hidden or something like that?
Thanks a lot for your help!
Stefan
EDIT:
I got a huge performance boost when drawing some objects instead of using views; but now, I've got another problem; if I draw directly onto the UIScrollView, everything performs great. But if I lay a UIView on the UIScrollView and draw on that, performance goes down again (both times calling setNeedsDisplayInRect: in scrollViewDidScroll:).
So hierarchy:
UIWindow
UIView
UIScrollView <== drawing here
works fine.
But hierarchy:
UIWindow
UIView
UIScrollView (size 8000x960)
UIView (size 8000 x 960) <== drawing here
performs bad.
Any ideas why? I need the UIView above because the drawing should be ABOVE some UIViews; so I place the UIViews in the scrollView and draw in the view above...
The label reuse is one of possible solutions. Sometimes it doesn't help a lot. When a new UIView appears the drawRect method will be called and that may cause problems with animation.
Sometimes the best solution is to draw your labels (I mean text) directly using Core Graphics without creating UILabel object or something else. The CALayer will increase performance, but there is a possibility that it will not help you a lot.
But first of all you should remember that views with alpha = 0 or hidden = YES will not be drawn at all, so there is no penalty for using them. Maybe you should try to hide unused ones before using Core Graphics.
The best way would be to have just a few UILabels and reuse them. But you'll have to implement - (void)scrollViewDidScroll:(UIScrollView *)scrollView and do some reusable logic there. Depending on case it might be easier to use a UITableView and transform it 90 degrees, so it looks like a scrollview. That way you can the build-in reusable logic of the TableView.
For others seeing this post, I was able to drastically improve performance and keep UIViews in a scroller without using a table by enabling each view's "shouldRasterize" property. This property renders the view as an image while the view is in motion, causing it to not need to be reprocess for each pixel it moves. So, if I have a UIButton called button, it gets enabled like this:
button.layer.shouldRasterize = YES;
Did u try something similar to UITableViewCell
dequeueReusableCellWithIdentifier
Using a reuseIdentifer to reuse the once allocated labels..
How do I animate a UIImageView from UITableview with the flying effect?
Without knowing what you mean by the 'flying effect', pretty much any animation is possible using CoreAnimation.
Grab the UIImageView instance's layer and animate it as you wish.
Info on CoreAnimation can be found here.
I need to play frame based animations. I tried the UIImageView with animationImages but it doesn't give me any control over my animation. I can't pause it, I can't mask it, I can't know the current frame etc.
So I subclassed UIView and created something I called AnimationView which takes the array of images and does the animation using an NSTimer. In the drawRect: I can then do all the masking and everything else I want.
However this method is way too slow. I can't run an animation at 30fps, maybe not even at 10fps and I am testing on a 3GS. (I am only doing masking and blending on every frame :) - and using the same images plays fine at 30fps on a UIImageView).
So, what is the most efficient way to achieve this? Is the NSTimer a bad choice? Is there a better way around it?
Thanks :)
In this answer to this question Mo DeJong provides a link to a source code implementation of a class that manually animates PNG image frames. He claims to get 15 FPS for 480x320 images animating on a non-3GS iPhone.
The NSTimer is fine. The problem is that you're touching a lot of pixels using the CPU in every frame using Quartz (the drawRect:). What you want to do is either use OpenGL if you have to compose images using a mask or cache your images in CALayers or CGImages.