TextureUs
Vec2 = [0, 1] The left and the right of the sprite, in pixels of the source resolution.
A vertical three-slice atlas provider: the sprite is cut into a top cap, a middle and a bottom cap. The caps keep their height and the middle stretches, so a panel can be any height. All three pieces stretch to the icon's full width.
Slicing and the scaling of the edge sizes are described on IUiTextureDataProvider.
Vec2 = [0, 1] The left and the right of the sprite, in pixels of the source resolution.
Vec4 = [0, 0.25, 0.75, 1] The four row boundaries, top to bottom, in pixels of the source resolution: the top edge of the sprite, the two cuts, and the bottom edge.
Vec2 = [0.25, 0.25] Height of the top and of the bottom cap on screen, in pixels of the icon's layout.