Question Detail

You can draw the background of every ViewGroup by yourself.

There are some key points in this solution:

1. You need to extend the desired ViewGroup:

   public class DiagonalLayout extends LinearLayout

2. Override the function:

   protected void dispatchDraw(Canvas canvas)

3. Fill the method above. Here is the sample code:

   @Override
   protected void dispatchDraw(Canvas canvas) {
       int height = canvas.getHeight();
       int width = canvas.getWidth();
       Path path = new Path();
       path.moveTo(0, 0);
       path.lineTo(width / 3 + width / 10, 0);
       path.lineTo(width / 3 - width / 10, height);
       path.lineTo(0, height);
       path.close();
       canvas.save();
       canvas.clipPath(path, Region.Op.INTERSECT);
       canvas.drawColor(ContextCompat.getColor(getContext(), android.R.color.holo_red_dark));
       canvas.restore();
       path = new Path();
       path.moveTo(width / 3 + width / 10 + width / 10, 0);
       path.lineTo(width, 0);
       path.lineTo(width, height);
       path.lineTo(width / 3, height);
       path.close();
       canvas.save();
       canvas.clipPath(path, Region.Op.INTERSECT);
       Paint paint = new Paint();
       paint.setStrokeWidth(8);
       paint.setStyle(Paint.Style.STROKE);
       paint.setColor(ContextCompat.getColor(getContext(), android.R.color.black));
       canvas.drawPath(path, paint);
       canvas.restore();
       super.dispatchDraw(canvas);
   }

The effect of the code above is:

What the code above does is:

1. Draw the polygon on the left.
2. Save Canvas state, clip Canvas to the polygon and fill it with color
3. Restore Canvas to original size, draw second polygon

To draw a bitmap, use drawBitmap (Bitmap bitmap, Matrix matrix, Paint paint) method instead of filling it with red color.

You can draw the background of every ViewGroup by yourself.

There are some key points in this solution:

1. You need to extend the desired ViewGroup:

   public class DiagonalLayout extends LinearLayout

2. Override the function:

   protected void dispatchDraw(Canvas canvas)

3. Fill the method above. Here is the sample code:

   @Override
   protected void dispatchDraw(Canvas canvas) {
       int height = canvas.getHeight();
       int width = canvas.getWidth();
       Path path = new Path();
       path.moveTo(0, 0);
       path.lineTo(width / 3 + width / 10, 0);
       path.lineTo(width / 3 - width / 10, height);
       path.lineTo(0, height);
       path.close();
       canvas.save();
       canvas.clipPath(path, Region.Op.INTERSECT);
       canvas.drawColor(ContextCompat.getColor(getContext(), android.R.color.holo_red_dark));
       canvas.restore();
       path = new Path();
       path.moveTo(width / 3 + width / 10 + width / 10, 0);
       path.lineTo(width, 0);
       path.lineTo(width, height);
       path.lineTo(width / 3, height);
       path.close();
       canvas.save();
       canvas.clipPath(path, Region.Op.INTERSECT);
       Paint paint = new Paint();
       paint.setStrokeWidth(8);
       paint.setStyle(Paint.Style.STROKE);
       paint.setColor(ContextCompat.getColor(getContext(), android.R.color.black));
       canvas.drawPath(path, paint);
       canvas.restore();
       super.dispatchDraw(canvas);
   }

The effect of the code above is:

What the code above does is:

1. Draw the polygon on the left.
2. Save Canvas state, clip Canvas to the polygon and fill it with color
3. Restore Canvas to original size, draw second polygon

To draw a bitmap, use drawBitmap (Bitmap bitmap, Matrix matrix, Paint paint) method instead of filling it with red color.