Android XML| Understanding the pathData syntax

Question

So i am trying to understand the pathData syntax in order to create some vector drawables via xml...

I am able to create any square shapes, but i just can't understand how to create circular shapes (such as oval or a circle).

could anyone give some examples of circular shapes:

1. Circle.
2. Oval.
3. Empty Circle/Oval (putting it on another shape will cause this part to be transparent).

with explanation to what each pathData attribute does?

Thanks!

Answer 1

Notes on Paths (SVG notation used in anroid-vectordrawable) : Paths have a compact coding. For example M (for 'move to') precedes initial numeric x and y coordinates and L (line to) precedes a point to which a line should be drawn. Further command letters (C, S, Q, T and A) precede data that is used to draw various Bézier and elliptical curves. Q is quadratic Bézier, Z is used to close a path. In all cases, absolute coordinates follow capital letter commands and relative coordinates are used after the equivalent lower-case letters. SVG path notation.
Command :A (absolute)a (relative)
Name :elliptical arc
Parameters :(rx ry x-axis-rotation large-arc-flag sweep-flag x y)+
Description:Draws an elliptical arc from the current point to (x, y). The size and orientation of the ellipse are defined by two radii (rx, ry) and an x-axis-rotation, which indicates how the ellipse as a whole is rotated relative to the current coordinate system. The center (cx, cy) of the ellipse is calculated automatically to satisfy the constraints imposed by the other parameters. large-arc-flag and sweep-flag contribute to the automatic calculations and help determine how the arc is drawn.

Use this (circle.xml), in your res/drawable folder:

<?xml version="1.0" encoding="utf-8"?>
<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="200dp"
    android:height="200dp"
    android:viewportHeight="64"
    android:viewportWidth="64">

    <path
        android:fillColor="#ff0000"
        android:pathData="M22,32
        A10,10 0 1,1 42,32
        A10,10 0 1,1 22,32 Z" />
</vector>

Parameters :(rx, ry x-axis-rotation large-arc-flag, sweep-flag x,  y )

            (10, 10       0               1,            1     42, 32 )
            (10, 10       0               1,            1     22, 32 )

NOTE:Superfluous white space and separators such as commas can be eliminated.
Two arc's make a circle.
Circle is a special case of oval, android:fillColor="@color/transparent".