iOS off-screen rendering

Why use off-screen rendering

When using fillets, shadows, and masks, the blend of layer properties is specified to not be drawn directly to the screen before being pre-synthesized, so an off-screen rendering is required.

Out-of-screen rendering does not imply software drawing, but it means that the layer must be rendered in an out-of-screen context (whether CPU or GPU) before it is displayed.

Therefore, when using off-screen rendering, it is very easy to cause performance consumption, because in OpenGL, off-screen rendering will create an out-of-screen buffer in memory and render, while the off-screen buffer and the current screen buffer context switch is very performance.

iOS off-screen rendering