To Convert HTML doc to image in cocoa

Question

is it possible to convert the HTML page to image in cocoa?

Actually i have created the complete view in the HTML and now i want to convert the whole html preview to the image (any jpeg or png etc.).

I couldn't find any resource or sample on the web, which provides some sort of help on my above queries.It's highly appreciated if someone could share his wisdom on how I can achieve this.

Thanks in advance..

Answer 1

First off, I'd like to thank sergio... his answer got me started but I thought I'd share some of the code that I didn't find obvious that I had to write to make it work:

Here's how to make a thumbnail for a page without ever having it displayed:

// Your width and height can be whatever you like, but if you want this to render
// off screen, you need an x and y bigger than the superview's width and height
UIWebView* webView = [[UIWebView alloc] initWithFrame:CGRectMake(largerScreenDimension, largerScreenDimension, largerScreenDimension, largerScreenDimension)];
[self.view addSubview:webView]; // UIWebViews without an assigned superview don't load ever.
webView.delegate = self; // or whoever you have implement UIWebViewDelegate
webView.scalesToFit = YES; // This zooms the page appropriately to fill the entire thumbnail.
[webView loadRequest:[NSURLRequest requestWithURL:url]];

Then implement this in your delegate:

- (void)webViewDidFinishLoad:(UIWebView *)webView {
    UIGraphicsBeginImageContext(webView.bounds.size);
    [webView.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *webViewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    NSData *thumbnailData = UIImagePNGRepresentation(webViewImage);
    [webView removeFromSuperview];
}

Finally, to display this thumbnail you'll need something like:

thumbnailImageView.image = [UIImage imageWithData:thumbnailData];

As a bonus thing I'll mention, I wanted multiple thumbnails to be generated at once. I found using objc_setAssociatedObject() and objc_getAssociatedObject() to be very helpful with keeping track of which webView was loading which thumbnail. Going into detail on how that worked is beyond the scope of this question, though.