How Can You Use An Image As A Background For A Text Field In Cocoa?

Question

Is it possible to use an image as a background for a Text Field in Cocoa? If so, how?

Answer 1

I don't know if this is the "correct" way to do it, but the first thing that comes to mind would be to make a custom subclass of NSTextField, which might look roughly like this:

- (void)awakeFromNib
{
    [self setDrawsBackground:NO];
}

- (void)drawRect:(NSRect)rect
{
    [super drawRect:rect];

    [self lockFocus];
    [[NSImage imageNamed:@"<your image's filename>.png"] drawInRect:rect
        fromRect:rect
        operation:NSCompositeSourceOver
        fraction:1.0];
    [self unlockFocus];
}

Again, that's a just rough outline of the essential parts.

Anyways, like I said, I'm not sure if this really the "correct" way to do it (or if there is even a "correct" way, for that matter), but this will give you a background image for your NSTextField.

Edit in response to Joshua's comment (I'm not going to have enough room in that tiny little comment box):

To add the image into your project, you'd drag it from wherever it is into the project window (the main list of files in the middle of the project window, although depending on how you've set up your Xcode editing environment, this might be different for you).

In order to subclass NSTextField, you would want to create a new Objective-C class file (File -> New File…), but edit the header so that the class inherits from NSTextField instead of NSObject. In other words, your header file might look like this:

#import <Cocoa/Cocoa.h>

@interface BGImageTextField : NSTextField
{
}

@end

As for the rest of the code, you would want to add that in the main body of the implementation file (BGImageTextField.m, for example), specifically in between the @implementation and @end keywords.

I'd also like to mention two things. First, I'd recommend picking up a copy of Cocoa Programming for Mac OS X, by Aaron Hillegass—it covers most of the Cocoa basics that I just went over, and is one of the best ways to learn Cocoa in general. Secondly, although my approach works, it's probably not the best approach—especially since I just recently found this post, which seems to hint at a better way of extending NSTextField.

Answer 2

Instead of subclassing NSTextField, just make the background color transparent [NSColor clearColor] and put the image behind it.