Reference: pmScale
pmScale(pm, x, y) returns the pixmap pm scaled with factors x and y in the horizontal and vertical directions, respectively. Thus, pmScale(pm, 1, 1) is the identity transformation. If x = y, the transformation preserves the shapes of object. pmScale(pm, 2, 2) magnifies all lengths by a factor 2, and the total area by a factor 2^2 = 4. pmScale(pm, 2, 1) doubles the width of the pixmap, preserving the height, thus distorting shapes.