iTunes Visual Plugin Difficulties

Discussion in 'Mac Programming' started by IndigoFuzzy, Jun 9, 2008.

  1. macrumors newbie

    Jun 8, 2008
    DarkCity, Bay of Rainbows, Moon.
    I'm currently working on a visualizer plugin for iTunes.

    I have most of it working, but i need a way to draw a transparent black rectangle. (For a nice fade-out effect)

    I haven't been able to find what I need in any of the API references - That is, I'm not sure if I should have 2 large bitmaps (one all black, one light grey as an alpha channel) and call CopyMask, or wether I should do something with CoreGraphics (in which case I don't know where to start, I haven't used any of OSX's "Core" APIs yet.

    Any help would be greatly appreciated.
  2. thread starter macrumors newbie

    Jun 8, 2008
    DarkCity, Bay of Rainbows, Moon.
    Some good and bad news:
    1, i figured out how to use Quartz to do the fading, but it's slowing things down horribly.

    Here's the code I used:

    GrafPtr			oldPort;
    		GDHandle		oldDevice;
    		Rect			srcRect;
    		RGBColor		foreColor;
    		short			j;
    		long			vw, vh, hw, hh, hs, hd;
    		CGContextRef	cgc;
    		CGRect			fadeRect;
    		CGColorRef			chroma;
    		OSErr			err;
    		float			fadeColor[4];
    		srcRect		= *destRect;
    		GetGWorld(&oldPort, &oldDevice);
    		SetGWorld(destPort, nil);
    		vw = srcRect.right - srcRect.left;
    		vh = srcRect.bottom -;
    		hw = vw/2;
    		hh = vh/2;
    		hs = hw+hh;
    		hd = hw-hh;
    		err = CreateCGContextForPort(destPort,&cgc);
    		if (err == noErr)
    			fadeColor[0] = 0.0;
    			fadeColor[1] = 0.0;
    			fadeColor[2] = 0.0;
    			fadeColor[3] = 0.03;
    			chroma = CGColorCreate(CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB),fadeColor);
    			fadeRect = CGRectMake(0,0,vw,vh);
    		{ = = = 0;
    any reason why this would cause a slowdown, and any possible fixes?

    And I suppose I should ask: is calling CoreGraphics here before doing the rest of my drawing with QuickDraw a bad idea?

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