窗口服务器为客户提供了一块共用内存区域用来绘图，然后(用gpu)将其混合为帧缓冲。

The window server provides a region of Shared memory to clients for drawing and then composites this into the frame buffer (on the GPU).

youdao

随后，主循环在每次循环时都检查事件、重置绘图状态、绘出圆形的“门户”窗口，然后以动画形式将其失真返回当前时帧。

Then, each pass of the main loop checks for events, resets the draw state, draws the circular "portal" windows, then animates their distortion back to the current time frame.

youdao

第一眼看上去，Pencil呈现在你面前的就是一个绘图工具，有一个文档窗口在里面工作，还有用来工作的工具、图形、挂件等。

Pencil is, at first glance, a drawing tool that presents you with a document to work within, and tools, shapes and widgets to work with.

youdao