Question

I have an app that need to display image(in a folder) thumbnail list in UITableView.
My way is to create the thumbnail of an image when add the image to the folder.

CGSize itemSize = CGSizeMake(100, 100);
UIGraphicsBeginImageContext(itemSize);

[image drawInRect:CGRectMake(0, 0,100, 100)];
image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

NSData* imageData1 =[NSData dataWithData:UIImagePNGRepresentation (image)]; 

NSMutableString *sss1=[[NSMutableString  alloc] initWithString:folderPath];
[sss1 appendString: thumbnailIdString] ;
[sss1 appendString:fileName] ;
[imageData1 writeToFile:sss1 atomically:NO]; 
[sss1 release];

Then the app display the resized the thumbnail image in UITableView.

It DOES work. But the performance is not perfect.
It needs to load the large image and rewrites the thumbnails to the folder.
Is there any other better solution? I checked Three20, but I am not sure if it can do this.

Welcome any comment

Thanks

interdev

Answer 1

You can load and resize image in a worker thread, and when the image is ready, show this image in the main thread. In order to complete the above behaviors, you need to find a thread-safe way to resize image. The UIGraphicsBeginImageContext() and UIGraphicsEndImageContext() should only run in the main thread.