在安装程序和许多游戏、屏幕保护程序中，经常有背景渐变的效果（一幅图象渐渐的消失，同时另一幅图象渐渐显示出来）。如何实现这种效果呢？在windows(GDI)环境下，实现位图的淡入淡出的方法有三种：

1． 调色板动画：该方法速度很快，但只能用于256色的图形，而且不易实现渐隐效果，不推荐使用；

2． 模式画刷：该方法实现比较简单，但是效果不如其余两种；

3． 动画法：该方法效果很好，但是速度要稍慢一些。

本例采用“动画法”以两幅位图为例进行讲解，实现从黑色背景中逐渐显现第一幅图片，之后

第一幅图片逐渐消隐、第二幅图片逐渐显现的渐变效果。

-Installer and many games, screen savers, often have the effect of background gradient (an image gradually disappear, while the other one image is gradually displayed). How to achieve this effect? Windows (GDI) environment, bitmap fade in three ways: 1. The palette animation: This method is fast, but can only be used for 256-color graphics, but not easy to achieve fade effect, is not recommended　2. The pattern brush: This method is relatively simple, but the effect is not as good as the other two　3. Animation method: This method works well, but the speed is slightly slower. This example uses " animation"　example to explain the two bitmaps, the first picture is gradually emerging from the black background, gradually blanking after the first picture, the second picture is gradually emerging gradient effect.