Another newbie request.

Member

Posts: 22
Joined: 2007.05

Post: #1

Jun 8, 2007 — 08:57 PM

Can anyone point me to some sample code that illustrates:

1.) Drawing a partial segment of a source image (png) to an NSImageView
2.) Drawing a partial segment of a source image (png) to a Custom View

Here is a little of what I am trying to get to work (using the NSImageView approach):

Code:

- (NSImage *)drawCard

{

    NSImage * cardSheet = [[NSImage alloc] initWithContentsOfFile:@"cardSheet.png"];

    NSSize cardInSheetSize;

    cardInSheetSize.height = 70;

    cardInSheetSize.width = 50;

    NSRect srcRect;

    (srcRect.origin).x = 0.0;

    (srcRect.origin).y = 0.0;

    srcRect.size = cardInSheetSize;

    NSRect dstRect;

    dstRect.origin = NSZeroPoint;

    dstRect.size = cardInSheetSize;

    NSImage * card = [[NSImage alloc] initWithSize:cardInSheetSize];

    [card lockFocus];

    [cardSheet drawInRect:dstRect fromRect:srcRect operation:NSCompositeCopy fraction:1.0];

    [card unlockFocus];

    return card;

}

I am calling it with:

Code:

[nextCardImage setImage:[deck drawCard]];

nextCardImage is an NSImageView Outlet.

Thanks for any help.

Taxxodium

Moderator

Posts: 508
Joined: 2002.09

Post: #2

Jun 9, 2007 — 01:13 AM

You are leaking memory badly. Before returning, release cardSheet and at the end do return [card autorelease]

Maybe it's better to use drawAtPoint or one of the composite methods. drawInRect is good, but you'll need to:

a) read what the docs say
b) experiment to get it right

"When you dream, there are no rules..."

hypnotx

Member

Posts: 22
Joined: 2007.05

Post: #3

Jun 10, 2007 — 02:03 AM

Still playing around with it but now using a Custom View. Came up with this after looking at the Quartz tutorials on Dev Central but it is still a work in progress. I most certainly need to reread the sections on memory management. I'm guessing that I can define an NSRect for the portion of the source image and pass that as the fromRect variable to drawInRect instead of NSZeroRect. I think I am almost there.

Code:

- (void)drawRect:(NSRect)rect

{

    // lets put an image in there.

    [[NSGraphicsContext currentContext] setImageInterpolation: NSImageInterpolationHigh];

    NSRect desRect = NSMakeRect(52, 1, 50, 70);

//      Next line wont work because it loads the entire sheet into the card rect. 

//    Need to create a srcRect (see below) and pull the image from a portion of the source CardSheet.png.

//    NSString * file = @"/CardSheet.png";

    NSRect srcRect = NSMakeRect(0, 0, 50, 70);

    NSString * file = @"/singCard.png";

    NSImage * cardImage = [[NSImage alloc] initWithContentsOfFile:file];

    [cardImage drawInRect:desRect fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1.0];

    [cardImage release];

}

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