Example 4 As shown in Figure 4, connect the midpoints of each side of a square with side length 1, and connect the diagonals of the square. Then the total number of isosceles right triangles in the figure is ( ).
(A) 16
(B) 32
(C) 22
(D) 44
(2009, National Junior High School Mathematics League, Nanchang City Competition)
Explanation: Obviously, the number is large, so the exhaustive method cannot be used. If we classify and count the shapes of isosceles right triangles based on the "hypotenuse length" or "leg length," it is easy to obtain the correct result.

Notice that, there are 4 isosceles right triangles with a hypotenuse of $\sqrt{2}$, 16 isosceles right triangles with a hypotenuse of $\frac{\sqrt{2}}{2}$, 8 isosceles right triangles with a hypotenuse of 1, and 16 isosceles right triangles with a hypotenuse of $\frac{1}{2}$. Therefore, the answer is (D).