为什么BITMAPS负荷＆QUOT;向上＆QUOT;？
如果你有一个真的很大JPG和嵌入在HTML和在加载到Firefox中BMP，你会发现，JPG将加载向下（漆由左到右，再向下）和BMP将加载向上（漆由右至左，然后向上）。
If you have a really really large JPG and a BMP embedded on HTML and you load it into Firefox, you will notice that the JPG will load "downwards" (paint from left to right, then down) and the BMP will load "upwards" (paint from right to left, then up).
只是好奇。 ：）
我写了一个位图分析器而回，如果我没有记错，位图存储图像倒退。即，第一存储的下行和较高的行持续。数据到达有序您的浏览器，所以这就是为什么你可以看它从下往上加载。
I wrote a bitmap parser a while back, and if I remember correctly, bitmaps store the image backwards. That is, it stores the lower rows first and the higher rows last. The data arrives to your browser in-order, so that's why you can watch it load from the bottom up.
编辑：这里有一个更好的链接，pretty多告诉你，你会永远想了解一个位图文件的一切：http://en.wikipedia.org/wiki/BMP_file_format
Here's a better link that pretty much tells you everything you would ever want to know about a bitmap file: http://en.wikipedia.org/wiki/BMP_file_format