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javaandroidareageometry-path

Android: How to get the area size of a drawn path?


My problem is to measure the surface area of a path.
I generate a random Path and draw it on a canvas. After touching on this closen path, i want to get the area size of this drawn path.

How can i get the real area size of this path?

The pathes (shapes) looks like this here:
link to the image


Solution

  • I found a solution. I generate a Region from the path and use a RegionIterator to get Rects inside the Region. With this Rects i can calculate the whole area of the path.

    private void calculateArea(Region region) {
    
            RegionIterator regionIterator = new RegionIterator(region);
    
            int size = 0; // amount of Rects
            float area = 0; // units of area
    
            Rect tmpRect= new Rect(); 
    
            while (regionIterator.next(tmpRect)) {
                size++;
                area += tmpRect.width() * tmpRect.height();
            }
    
            log.d("Rect amount=" + size);
            log.d("Area Size / units of area=" + area);
    }