跪求ID2D1RenderTarget::CreateBitmap method中对pitch的描述是什么意思

[huihui_54321]

msdn描述如下：
pitch
Type: UINT32

The byte count of each scanline, which is equal to (the image width in pixels × the number of bytes per pixel) + memory padding. If srcData is NULL, this value is ignored. (Note that pitch is also sometimes called stride.)

pitch值该怎么求，其中的memory padding怎么求？举个例子最好？谢谢大家

[e3internet]

在线翻译