FunWithNSCursor.m

FunWithNSCursor.m

- (void)cursorUpdate:(NSEvent *)theEvent {
  [self.cursor set];
}

- (void)resetCursorRects
{
  // ...
}

- (NSImage *)cursorImage
{
    if (! _cursorImage) {
        int pixelsWide = 100;
        int pixelsHigh = 100;
        
        CGContextRef    context = NULL;
        CGColorSpaceRef colorSpace;
        char *          bitmapData;
        int             bitmapByteCount;
        int             bitmapBytesPerRow;
        
        bitmapBytesPerRow = (pixelsWide * 4);
        bitmapByteCount = (bitmapBytesPerRow * pixelsHigh);
        colorSpace = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
        bitmapData = malloc(bitmapByteCount);
        
        if (bitmapData == NULL)
        {
            fprintf (stderr, "Memory not allocated!");
            return NULL;
        }
        context = CGBitmapContextCreate(bitmapData,// 4
                                        pixelsWide,
                                        pixelsHigh,
                                        8,      // bits per component
                                        bitmapBytesPerRow,
                                        colorSpace,
                                        (CGBitmapInfo)kCGImageAlphaPremultipliedFirst);
        if (context== NULL)
        {
            free (bitmapData);
            fprintf (stderr, "Context not created!");
            return NULL;
        }
        CGColorSpaceRelease( colorSpace );
        
        CGContextSetRGBFillColor (context, 1, 0, 0, 1);
        CGContextFillRect (context, CGRectMake (0, 0, 100, 50 ));
        CGContextSetRGBFillColor (context, 0, 0, 1, .5);
        CGContextFillRect (context, CGRectMake (0, 0, 100, 100 ));
        
        CGImageRef image = CGBitmapContextCreateImage (context);
        CGContextDrawImage(context, CGRectMake(0, 0, 100, 100), image);
        _cursorImage = [[NSImage alloc] initWithCGImage:image size:CGSizeMake(100, 100)];
        
#warning Oh no!
        // This needs to go somewhere else I am sure?
        
        CGContextRelease (context);
        if (bitmapData) free(bitmapData);
        CGImageRelease(image);
    }
    return _cursorImage;
}

- (NSCursor *)cursor {
    if (! _cursor) {
        _cursor = [[NSCursor alloc] initWithImage:self.cursorImage hotSpot:NSZeroPoint];
    }
    return _cursor;
}

This is some fun code for overwriting the current cursor with an updating image.