I am trying to integrate a zoom/pan capability into an image gallery for iPad (implemented with Flash builder 4.5 and Air mobile sdk), which is pretty simple on the paper, using gesturezoom handling and scale on the displayed image.
My problem is that I have some medium & high resolution images (about 4096*3072, 5Mo photo), and that zoom/unzoom seems to freeze a lot on the iPad upon the first initial gestures. After a while, everything goes smooth (or kind of smooth :-).
Does anybody know what is the reason of these freezes, and how to solve this?
Thanks a lot,
Antoine
I would suggest working with the BitmapData of the image and blit to a container the size of the screen. The Matrix class can help you to scale the BitmapData you are drawing to your container and you can change the size of a Rectangle as your scaling gesture events occur to bring in more pixels from the source image. That way you're never displaying more than the amount of pixels that fit into your container at any given time.
Related
I'm currently using AVCaptureSessionpresetPhoto to take my pictures and I'm adding filters to them. Problem is that the resolution is so big that I have memory warnings ringing all over the place. The picture is simply way to large to process. It crashes my app every single time. Is there anyway I can specify the resolution to shoot at?
EDIT**
Photography apps like Instagram or the Facebook Camera app for example can do this without any problems. These applications can take pictures at high resolutions, scale them down and process them without any delay. I did a comparison check, the native iOS camera maintains a much higher quality resolution when compared to pictures taken by other applications. The extreme level of quality isn't really needed required for a mobile platform so it seems as if these images are being taken at lower resolution to allow for faster processing and quick upload times. Thus there must be a way to shoot at a lower resolution. If anyone has a solution to this problem, it would greatly be appreciated!
You need to re-size image after capture image using AVCaptureSession and store it's image after resizing.
You found lots of similar question in to StackOverlow i just putting some link bellow that makes help's you.
One More thing As my suggestion that using SDWebImage for Displaying Images asynchronously Becouse App working smoothly. There are also some other way for example(Grand Central Dispatch (GCD) Reference , NSOperationQueue etc) in iOS for asynchronous Tast
Re-size Image:-
How to resize an image in iOS?
UIImage resizing not working properly
How to ReSize Image with Good Quality in iPhone
How to resize the image programmatically in objective-c in iphone
I need to update an app which was written for the iPhone 4 screen size to work on the iPhone 5. I have read on SO about AutoLayout and so on, but the problem is that each screen in this app is made up of a background image, which then has touchable areas and such drawn on in code. These are positioned absolutely. This isn't the way I would have designed the app, but it's the task I am faced with.
I have two problems to solve:
1) How do I load the correct background image. Do I need to create a separate image size for each and them in code query the device size each time an image is loaded? To give some context, there are well over 100 images.
2) How do I maintain the touchable areas. Is it best to just add the required number of pixels to the bottom of the app? Would this then work, or will I need to query device size and change coords accordingly every time I draw something?
Thank you,
Sam
Autolayout will work in the device is running iOS 6 or higer.
1) Yes you will need a image larger image for all the images in your app. You could overload some methods in a base class to make this more easy to load the correct image.
An other option is to stretch the image, but this is up to you.
2) I would adjust my coordinates to the size of the device.
If Apple would add an other screen size you will run in the same problem again. You should try and create an interface that can grow with the screen.
I'm using a full screen UIWebView to house/render an HTML5 application under iOS. Very much like Cordova/phonegap although I'm not using those. I try to make my webview size match the underlying display. Unfortunately, on retina displays, the value returned by self.view.bounds relies on the UIScreen scaling factor. So I get 1024x768 instead of 2048x1536. Not a huge problem except I then instantiate the UIWebView using the smaller bounds (after adjusting for the status bar) and some things get a bit jaggy. In particular, I use canvas at a couple of points and also rounded borders appear thick. To be clear, this isn't a case of scaled raster resources.
I'm not getting the full resolution of the screen using that UIWebView. Ideally, I'd like to set the screen scale to 1.0 but that doesn't appear to be supported. Any suggestions on how best to get full advantage of the screen?
The problem is most noticeable on the iPhone 5 simulator. I don't have that hardware to test on. iPad/new iPad I think has the problem but the jaggies aren't as noticeable.
Update: The more I look at this, the more I think it may be restricted to canvas.
Solution: In case anyone else gets here. Based on the answer below, I created all of my canvas elements with width and height multiplied by window.devicePixelRatio and then set their style attribute to have the original (device independent) size.
See https://stackoverflow.com/a/7736803/341994. Basically you need to detect that you've got double resolution and effectively double the resolution of the canvas.
I've been working on an iPad app that has gone through fairly extensive testing on the iPad 2. I recently obtained a "New iPad" (iPad 3), and the app feels significantly slower. Animations / scolling behaviors that were silky smooth in the iPad 2 now feel extremely stuttery on the new iPad.
I do a lot of the standard UI performance tips: using shadowPaths, drawing UITableViewCells using CoreGraphics, rasterizing views that don't change often / don't need to animate.
Are there any pitfalls I should watch be watching out for in transitioning my app to the iPad 3?
Update
I swore that I tried this before but removing rounded corners from my UIViews views ended up speeding the app significantly. clipToBounds also seems to be a significant performance hit (although strangely... setting a view's layer's maskToBounds seems to be okay, which makes no sense to me). Some combination of this and other tweaks seems to have resolved the issue.
Once I do a second visual pass over the app, I'll figure out a way to reimplement rounded corners in a more performant way.
4x the pixels, only 2x the fill rate. The maths says it all.
I think that the biggest thing to watch out for is copies of graphics from system memory to the video card since they are 4X larger than previous iPad graphics with about the same CPU power as the iPad 2.
Maybe it's due to upscaling by iOS? After all it has to calculate a higher res version of everything before showing to screen. Since some things on the screen are hi-res already (font and default ui elements) it has to scale every other element individually.
Have you tried just scaling the images yourself and adding them as retina images to your project?
Good luck.
I'm currently working on an OpenGL game, and recently began refactoring it to support iPhone in addition to iPad. In an attempt to give myself as little work as possible, I simply resized the containing EAGLView to 480 x 360 (to preserve the iPad aspect ratio) and shifted the view up so it's y origin lay at -20 (in order to centre the content, and as the edges could be cropped).
I found this resulted in jerky performance on the device (despite the CADisplay link reporting a frame duration that equated to 59-61 fps) and was at least 20% slower when compared side by side with the iPad version.
I then tried resizing the view to the screen size 480 x 320 and the performance returned to normal (though the rendered content no longer has the correct aspect ratio).
Why is it that the 'off screen' rendering causes a performance hit and why does the displaylink still think it is running at 60fps?
Any ideas?
Thanks
This is mostly a wild guess, but what about clipping regions? There was this hardware functionality that made it possible to mix windows and hardware accelerated graphics. Maybe it is not implemented very well on mobile devices.
You could, however, avoid making the UIView offscreen and try to use glViewport() to shift the parts of the view offscreen. While it seems to be the same, it is handled by a different part of the pipeline (the rasterizer), and should be much faster.