Asynchronous binding to a remote image
Asynchronous binding to a remote image
- Subject: Asynchronous binding to a remote image
- From: Dario Mèndez Musicò <email@hidden>
- Date: Tue, 27 Sep 2005 16:15:45 +0200
Hello everyone,
I've got a quick (?) question about how to bind an NSImageView to a
remote image by it's URL without "freezing" the interface during the
process.
I now managed to do it by using an helper method in my NSApp's
delegate which "brutally" changes the image.
Needles to say, I don't quite like the way it's done, so I'd like to
know if someone has a better idea.
My code is something like this...
ValueTransformer:
@implementation DownloadImageTransformer
+ (Class)transformedValueClass
{
return [NSImage class];
}
+ (BOOL)allowsReverseTransformation
{
return NO;
}
- (id)transformedValue:(id)value
{
if ([value isEqualToString: @"N/D"]) {
return [NSImage imageNamed: @"NotAvailable"];
} else {
NSURL *imageURL = [[NSURL alloc] initWithString: value];
[imageURL loadResourceDataNotifyingClient: self usingCache:
YES];
return [NSImage imageNamed: @"Wait"];
}
}
- (void)URLResourceDidFinishLoading:(NSURL*)sender
{
//NSLog(@"Image loaded");
[(AppController *)[NSApp delegate] displayGameIcon: [[NSImage
alloc] initWithContentsOfURL:sender]];
}
@end
Support method
- (void)displayGameIcon: (NSImage *)gameImage
{
[gameIcon setImage: gameImage];
}
So basically I take it's URL, check if it is "N/D" (Not Available)
and display a notAvailable Image.
If there is an URL I download it using
loadResourceDataNotifyingClient:usingCache: in order to keep the UI
active in the process.
In the meanwhile I return a "Waiting" image to display a placeholder
to inform the user the Image is being download.
After the image is available I put it into the ImageView using the
helper method.
It works OK, but I'd like to manage everything without having to use
that displayGameIcon: thing, does it sound possible to you?
Thanks in advance
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