说明：  VFP应用程式色彩的渐变算法-体现一个色彩到另一个色彩的渐变主要和三个因素有关: 1、起始色彩,2、终止色彩,3、渐变的深度（也就是从起始色彩到到终止色彩的宽度).这里有具体的设计方法及例程.
(VFP application of color gradient algorithm- reflects the gradation of a color to another color primarily to three factors: 1, a starting color, 2 terminate color 3, the depth of the gradient (i.e. from the starting color to terminate the width of color). specific design methods and routines.)