CODEWITHSUNDEEP
objective-ccocoa
Lupurus
Lupurus

Reputation: 4189

NSView draw permanently to background

I'm trying to draw some things on the background of my windows. Therefore I subclassed the NSView of the window and added some drawing code like this:

- (void)drawRect:(NSRect)dirtyRect {
    float color = 0.95;
    [[NSColor colorWithDeviceRed:color green:color blue:color alpha:1.0] set];
    NSRectFill(NSMakeRect(320, 0, 220, NSHeight(dirtyRect)-60));
}

This works great, but as soon as I open a NSComboBox or if I activate a checkbox, the background of these elements erases my just drawn rect.

I don't understand this, because checking for example the checkbox causes, that drawRect is called (I added a NSLog). Only resizing the window draws my rect again.

EDIT: here is a screenshot of the problem:

enter image description here

Upvotes: 2

Views: 176

Answers (1)

El Tomato
El Tomato

Reputation: 6707

I sometimes face the same problem. I think the following is what I use.

/// .h
@interface BackgroundView1 : NSView {
    NSImage *myImage;
}

// .m
- (void)awakeFromNib {
    [self setupBackgroundImage];
}

- (void)setupBackgroundImage {
    NSColor *c = [NSColor colorWithDeviceRed:0.0f/255.0f green:55.0f/255.0f blue:150.0f/255.0f alpha:1.0f];
    if (myImage == nil)
        myImage = [self createColorImage:NSMakeSize(1,1):c];
}

- (void)drawRect:(NSRect)rect { 
    [myImage drawInRect:NSMakeRect([self bounds].origin.x,[self bounds].origin.y,[self frame].size.width,[self frame].size.height)
               fromRect:NSMakeRect(0,0,[myImage size].width, [myImage size].height)
              operation:NSCompositeCopy
               fraction:1.0];
}

// Start Functions //
- (NSImage *)createColorImage:(NSSize)size :(NSColor *)color {
    NSImage *image = [[NSImage alloc] initWithSize:size];
    NSBitmapImageRep *rep = [[NSBitmapImageRep alloc]
                             initWithBitmapDataPlanes:NULL
                             pixelsWide:size.width
                             pixelsHigh:size.height
                             bitsPerSample:8
                             samplesPerPixel:4
                             hasAlpha:YES
                             isPlanar:NO
                             colorSpaceName:NSCalibratedRGBColorSpace
                             bytesPerRow:0
                             bitsPerPixel:0];

    [image addRepresentation:rep];
    [image lockFocus]; // Lock focus of image, making it a destination for drawing
    [color set];
    NSRectFill(NSMakeRect(0,0,size.width,size.height));
    [image unlockFocus];
    return image;
}
// End Functions //

Upvotes: 2

Related Questions