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copied!<p>You're trying to solve this problem using a view hierarchy like this:</p> <ul><li>Parent<ul><li>ListView</li><li>InverterView</li></ul></li></ul> <p>Problem is, in this position, <code>InverterView</code> has no control over how <code>ListView</code> is drawn. But you know who does have control over how <code>ListView</code> is drawn? <code>ListView</code>'s parent layout does. In other words, what you really want is a hierarchy like this:</p> <ul><li>Parent<ul><li>InverterLayout<ul><li>ListView</li></ul></li></ul></li></ul> <p>Now <code>InverterLayout</code> is responsible for drawing <code>ListView</code>, and can apply effects to it.</p> <pre><code>class InverterLayout extends FrameLayout { // structure to hold our color filter private Paint paint = new Paint(); // the color filter itself private ColorFilter cf; // the rectangle we want to invert private Rect inversion_rect = new Rect(100, 100, 300, 300); public InverterLayout(Context context) { super(context); // construct the inversion color matrix float[] mat = new float[] { -1, 0, 0, 0, 255, 0, -1, 0, 0, 255, 0, 0, -1, 0, 255, 0, 0, 0, 1, 0 }; cf = new ColorMatrixColorFilter(new ColorMatrix(mat)); } @Override protected void dispatchDraw(Canvas c) { // create a temporary bitmap to draw the child views Bitmap b = Bitmap.createBitmap(getWidth(), getHeight(), Config.ARGB_8888); Canvas cc = new Canvas(b); // draw them to that temporary bitmap super.dispatchDraw(cc); // copy the temporary bitmap to screen without the inversion filter paint.setColorFilter(null); c.drawBitmap(b, 0, 0, paint); // copy the inverted rectangle paint.setColorFilter(cf); c.drawBitmap(b, inversion_rect, inversion_rect, paint); } } </code></pre> <p>When using this, <strong>ensure your child view has its own background</strong>. If the view is transparent and the window background shows through, that window background will not be inverted, because the <code>InverterLayout</code> has no control over how the window is drawn.</p>

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