Calculating the dimensions of a flat figure

The application can be used to roughly calculate the area and perimeter of a figure, as well as the length of a curve on a flat surface. The area of ​​the figure must be bounded by a closed curve. The dimensions of the shape are scaled. You can transfer to paper, for example, the boundaries of a land plot, set the scale and calculate its area and perimeter. Shapes should be drawn in a dark color on a white background (ballpoint pen, pencil or printer). You can first take a snapshot of the figure and save it in JPG format, you can use any suitable snapshot. It is also possible to use the phone's camera directly. There can be several disjoint shapes in one frame.