How do I modify TouchImageView with double tap to zoom in and out?

Question

I am modifying the TouchImageView (https://github.com/MikeOrtiz/TouchImageView/issues) to have zoom in and out for when you double tap. I have started as per this post - How

Answer 1

Doubles the current zoom to zoom in, then returns to original zoom level:

float oldScale = 1.0f;
public void zoomIn() {
    LogUtil.i(TAG, "Zooming in");
    oldScale = saveScale;
    saveScale *= 2;
    matrix.setScale(saveScale, saveScale);
    setImageMatrix(matrix);
    invalidate();
}

public void zoomOut() {
    LogUtil.i(TAG, "Zooming out");
    saveScale = oldScale;
    matrix.setScale(saveScale, saveScale);
    setImageMatrix(matrix);
    invalidate();
}

You might want to translate the matrix to centre on the point the user double clicked.