How to get the matrix in which I translated, then rotate, and then translate, and then rotate a second time?

In an Android app, I want to draw a running foot. To output the upper leg, I do something like:

// legCX,legCY is the location on screen about which the leg rotates.
Matrix m = new Matrix();
m.postTranslate(-legCX,-legCY);
m.postRotate(legRot);
m.postTranslate(legCX,legCY);

Then I set the matrix on the canvas and draw the leg.

How to make the second part of the leg below the knee? It rotates at a different speed than the leg above it, and has a central point that moves with its legs above it. I tried the following, but it turns out that the end result is a rotation around a single point that does not match the leg above.

Matrix m = new Matrix();
m.postTranslate(-legCX,-legCY);
m.postRotate(legRot);
m.postTranslate(0,-legLength);
m.postRotate(footRot);
m.postTranslate(0,legLength);
m.postTranslate(legCX,legCY);

I suspect that it is probably necessary to make two rotations in two different Matrix objects, and then somehow combine them, but I cannot figure out exactly how to do this.

EDIT: , -, " ". . , .

, , , , .

, , .