Get size of 9-patch content area

Question

In my app, I have a feature where you can put a frame around an image.

I use setBackground(Drawable) to apply the image of the frame to an ImageView. When the ImageView is clicked, I want to blow the content area (the image contained in the frame) up to the size of the screen. For this, I need to know the difference between the entire view and the content area, i.e. the thickness of the border.

Is there a way to get the size of the content area? (Accessing View.getWidth() for the ImageView gives content + border. I'm trying to get the border / padding.)

Answer 1

You can use:

Rect padding = new Rect();
view.getBackground().getPadding(padding);
int contentWidth = view.getWidth() - padding.left - padding.right;
int contentHeight = view.getHeight() - padding.top - padding.bottom;

If your background is a nine patch, the getPadding method will return the insets of the drawable

Answer 2

Here's an alternative approach:

The horizontal and vertical borders of the 9patch frame should not be stretched vertically and horizontally, respectively. Therefore you have constant width of the vertical border and height of the horizontal border. You can open the 9patch with any image editor that supports measuring and measure those lengths.

Use those values as margin or padding of the content view. Providing a single 9patch for all DPIs should work as the system would stretch it for higher DPIs but your padding/margin would be in DPs, so it should be the same size as the frame.