绘制渐变色

循环改变图片的像素值，请注意每一行使用一个颜色。

int []data = new int[fontImage.getWidth() * fontImage.getHeight()];
fontImage.getRGB(data, 0, fontImage.getWidth(), 0, 0, fontImage.getWidth(), fontImage.getHeight());
int newColor = fontColor;
int r = (fontColor & 0x00FF0000)>>16;
int g = (fontColor & 0x0000FF00)>>8;
int b = (fontColor & 0x000000FF);

int offsetR = r/fontImage.getHeight();
int offsetG = g/fontImage.getHeight();
int offsetB = b/fontImage.getHeight();
for(int i=0; i<data.length; i++){
    if(data[i] != backgroundColor){
        data[i] = newColor;
    }
    if(i%imageWidth == 0){ // subtract each color on every row.
        if(r>offsetR)
            r -= offsetR;
        if(g>offsetG)
            g -= offsetG;
        if(b>offsetB)
            b -= offsetB;

        newColor = 0xFF000000; // make the pixel opaque.
        newColor += (r<<16);
        newColor += (g<<8);
        newColor += b;
    }
}