direct2d - Direct2D 是否使用后台缓冲区？

Question

阅读 https://learn.microsoft.com/en-us/windows/win32/direct2d/comparing-direct2d-and-gdi :

Presentation Model

When Windows wasfirst designed, there was insufficientmemory to allow every window to bestored in its own bitmap. As a result,GDI always rendered logically directlyto the screen, with various clippingregions applied to ensure that it didnot render outside of its window. Incontract, Direct2D follows a modelwhere the application renders to aback-buffer and the result isatomically “flipped” when theapplication is done drawing. Thisallows Direct2D to handle animationscenarios much more fluidly that GDIcan.

作者说 Direct2D 使用后台缓冲区，我猜他所说的“翻转”指的是交换链。我创建了一个简单的演示，可以在鼠标单击时在随机位置绘制一个矩形。但是之前的矩形没有被清除，所以看起来它是直接绘制到屏幕上的，不使用任何后台缓冲区。

Answer 1

当您为 Direct2D 操作初始化 RenderTarget 时，您可以在第二个参数中指定 D2D1_PRESENT_OPTIONS 选项。

我认为让您感到困惑的是 D2D1_PRESENT_OPTIONS_RETAIN_CONTENTS 以及缓冲区不是交换而是复制的事实。