I have to create a custom photolib like the default one, with animation etc. I had some doubts..
1. Doubt
Should I create 3 images (Thumbnail image, 320*480 image to display full image and original size image in case user share the image) (I am storing this all in app doc directory)
Or should I only store the original image and crop them wen required in 2 other images? In this case, if I use scroll view to display cropped images, how do I know what the user is seeing? And when do I crop next images to keep them ready to display?
(Can anything like reusable cells be created here like in tableview? If yes, can you give me some idea?)
Also, I am fetching images from doc directory. In this case should I load all images in Array or load in batches?
2. Problem Major:
Also need to compress original image and keep it of same size (I used uijpegrepresentation with compression ratio but with some jpegs after compression. It increases sizes even double the size).
You can use single image and for thumbnail you can Resize at run time else it increase size and performance issue. there is lots of open source library are there which do same what you needed. Please have a look below.
https://github.com/arturgrigor/AGImagePickerController
https://github.com/gdavis/FGallery-iPhone
Related
I'm loading images on a list from a server. The UIImageView size is very small (40 x 40), So ideally an image with a size of 40 x 40 or a little larger should be loaded in it. However, the server guy is sending an image of a much larger size (1920 x 1200).
When I diagnosed the view controller memory I noticed that it increases as the image is loading.
So my question is
Will the Kingfisher library download a smaller size version of the image?
Will it abort the image loading if the image size is too big?
Is there any way by which can I specifically achieve the above task.
Kingfisher: https://github.com/onevcat/Kingfisher
Will the Kingfisher library download a smaller size version of the
image?
Nor Kingfisher nor any other library will download a smaller version of an image. The server has to send you a smaller version of it. (different url, or same url with a parameter)
Will it abort the image loading if the image size is too big?
I don't know how the library implements the downloading but unless you are talking about unreasonably big files (way bigger than the resolution you expect (1920x1200)) it will not be aborted. And even then, it probably won't be aborted but instead the app might be killed by the system when displaying super high resolution images (again, way bigger than 1920 x 1200)
Is there any way by which can I specifically achieve the above task.
If you want to display many many images at once and are worried about their sizes, its better to create thumbnails of them.
You can use Kingfisher to
1) first download the image
2) then resize the image
3) then show and cache it if you need
Check this page to see a ton of code snippets for that library.
https://github.com/onevcat/Kingfisher/wiki/Cheat-Sheet
just want to see if I'm on the right track here is understanding the performance trade-offs of placing various image sizes into image views.
If I have a large image, will the image load faster if I place it in a correspondingly large imageView versus placing it in a smaller imageView?
No, the loading time depends on the file, and if the image is large, and its file Size is large, it will load slower than a small images on the same image View.
To make it clear, image view doesn't affect loading performance, image size (File size) does affect performance.
Answering you r question first, size of image is not directly proportional to imageview i.e. regardless of your imageview size, you image will take time based on the size of image.
Now, if you have a task in which you need to show user images & on click you need to share that image, you need to maintain 2 copies for showing take resized copy & while sharing pick image from original position. In this way, your loading will be fast & while sharing you will be able to share original image itself.
I am using the SDWebImage library in order to download and cache images. In my application, each user has an avatar which can be displayed in different shapes and sizes (circle, square ...).
Right now i am downloading the image, and when i get it i resize it according to the image view size.
But i think this approach is inefficient and specially when scrolling in a table view.
Is there a different approach (concerning SDWebImage) that allows me to get the image in the desired size without having to resize it my self ?
Thanks.
You can resize image once and store it in a cache (SDImageCache). Then load it from this cache. There is no way to get the image in the desired size without having to resize it yourself, unless such image of desired size exists on the server.
I'm building a camera application that saves the image data to a single JPEG file in the sandbox. The images average at about 2mb in size.
Problem : I cannot display the images in a photo viewer because having a few images in memory throws memory warnings and makes scrolling through the images very slow.
I cannot split the image into tiles and save them to disk because that's even more expensive than displaying the single image. I tried splitting the image up into tiles upon capture, but on the 5S it took, on average, 5 1/2 seconds to save all the tiles to disk. It will only get worse from there as the app is executed on older devices. This is very bad because what if the user exists the app in the middle of the save? I will have missing tiles and no uncompressed original file to find missing tiles later.
Question : what's the best way to show a full sized image without causing memory issues and keeping the scrolling fast? Tons of camera applications on the App Store do this and the Photos app does this, there has to be a good solution.
Note : I'm currently showing a thumbnail of the image and then loading the full size image from disk in another thread. Once the full size image loading has finished, I present the full size image on the main thread. This removes the memory issues because I only have one full size image in memory at once, with two thumbnails, but still causes lagging on the scrollview because drawing the full size image in the main thread is still pretty expensive.
I would greatly appreciate any input!
you could..
create a down sized thumb nail..
create a smaller image and save that in a different "sandbox" folder.. and read that for browsing.. then after that load the image if the user wants to look at it full size.
One way to deal with this is to tile the image.
You can save the large decompressed image to "disk" as a series of tiles, and as the user pans around pull out only the tiles you need to actually display. You only ever need 1 tile in memory at a time because you draw it to the screen, then throw it out and load the next tile. (You'll probably want to cache the visible tiles in memory, but that's an implementation detail. Even having the whole image as tiles may relieve memory pressure as you don't need one large contiguous block.)
This is how applications like Photoshop deal with this situation.
Second way which I suggest you is to
check the example from Apple for processing large images called PhotoScroller. The images have already been tiled. If you need an example of tiling an image in Cocoa check out cimgf.com
Hope this will helps you.
I am displaying image thumbnails from urls(which are in json file) into custom cells of a tableview.
The images loaded from url are not showing up properly- they are of a resolution much higher than need and some are of much lower resolution.
How do I manipulate these images so that they are scaled properly as per each screen(retina as well as normal) in iphone?
How do I scale and resize the thumbnail images from url?
Unless you care about other issues like memory or disk usage (for some caching) for the images, you don't have to resize them.
You can use UIViewContentModeScaleAspectFit as contentMode for an UIImageView and just set an image for the image view. It would be sufficient for you.