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  • quartz2d translating the origin

    - by qwertyp96
    My understanding of quartz2d is that the code CGContextTranslateCTM(context, x, y); translates the coordinate system. I have a quartz2d view with lots of shapes on it, and the user needs to be able to pan around and zoom it. However, when using the CGContextScaleCTM(context, scaleX, scaleY); code, everything scales around the origin, not the center of the viewpoint the user is viewing. My solution to this was to use the following code: CGContextRef context = UIGraphicsGetCurrentContext(); CGContextTranslateCTM(context, 512.0+offset.x, 384.0+offset.y); //(512, 384) is the center of the iPad screen CGContextScaleCTM(context, scale, scale); You can translate around fine, but things still scale into the corner. What's wrong? EDIT: Oh. Wow. Duh. If you move the origin, the shapes move too, so you can't move it relative to the shapes. Now I know what's wrong, but how do I do that?(move the origin independently of the shapes)

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