macos - cocoa: how to render view to image?

Question

I want to know is there any method to render a view to image? just like a screenshot, but I can specify any view to that method. I know how to do it in ios. Saving view content, but how can I do it in mac os ?

Answer 1

There are several ways, but non of them works perfect. Many problems are connected with Layer Backed views.

if you don't have layer backing or hosting views you can use this code:

    NSData* data = [mainView dataWithPDFInsideRect:[mainView bounds]];
    NSImage *img = [[NSImage alloc] initWithData:data];

if you work with layer based views:

till 10.8 the best way for me was

        NSSize mySize = mapImage.bounds.size;
        NSSize imgSize = NSMakeSize( mySize.width, mySize.height );
        NSBitmapImageRep *bir = [mapImage bitmapImageRepForCachingDisplayInRect:[mapImage bounds]];
        [bir setSize:imgSize];
        [mapImage cacheDisplayInRect:[mapImage bounds] toBitmapImageRep:bir];
        caheImg = [[NSImage alloc]initWithSize:imgSize];
        [caheImg addRepresentation:bir];

but in 10.8 bitmapImageRepForCachingDisplayInRect stopped working with Layer Backed views.

there is an option to make a screenshot of your screen and cut out your view:

+ (NSImage*) screenCacheImageForView:(NSView*)aView
{
    NSRect originRect = [aView convertRect:[aView bounds] toView:[[aView window] contentView]];

    NSRect rect = originRect;
    rect.origin.y = 0;
    rect.origin.x += [aView window].frame.origin.x;
    rect.origin.y += [[aView window] screen].frame.size.height - [aView window].frame.origin.y - [aView window].frame.size.height;
    rect.origin.y += [aView window].frame.size.height - originRect.origin.y - originRect.size.height;

    CGImageRef cgimg = CGWindowListCreateImage(rect,
                                           kCGWindowListOptionIncludingWindow,
                                           (CGWindowID)[[aView window] windowNumber],
                                           kCGWindowImageDefault);
    return [[NSImage alloc] initWithCGImage:cgimg size:[aView bounds].size];
}