     
     public let height: Int
     
-    private var _image: CIImage {
-        didSet {
-            _image = _image.clamped(to: extent)
-            state.isDirty = true
-        }
-    }
+    private var _image: CIImage
     
     fileprivate var state: GPContextState = GPContextState()
     

        let filter = alpha_mask ? "CIBlendWithAlphaMask" : "CIBlendWithMask"
        
        let _color = CIImage(color: CIColor(cgColor: color))
        let image = _color.applyingFilter(filter, parameters: [kCIInputBackgroundImageKey: GPContext.clear, kCIInputMaskImageKey: mask])
        
        self.blend_layer(image)
    }

        
        if opacity < 1 {
            let mask = CIImage(color: CIColor(red: 1, green: 1, blue: 1, alpha: CGFloat(opacity)))
            image = image.applyingFilter("CIBlendWithAlphaMask", parameters: [kCIInputBackgroundImageKey: CIImage.empty(), kCIInputMaskImageKey: mask])
        }
        
        self.blend_layer(image)
