方法一:直接将原来的putimage函数替换成下面这个函数
void drawAlpha(IMAGE* picture, int picture_x, int picture_y) //x为载入图片的X坐标,y为Y坐标
{
// 变量初始化
DWORD *dst = GetImageBuffer(); // GetImageBuffer()函数,用于获取绘图设备的显存指针,EASYX自带
DWORD *draw = GetImageBuffer();
DWORD *src = GetImageBuffer(picture); //获取picture的显存指针
int picture_width = picture->getwidth(); //获取picture的宽度,EASYX自带
int picture_height = picture->getheight(); //获取picture的高度,EASYX自带
int graphWidth = getwidth(); //获取绘图区的宽度,EASYX自带
int graphHeight = getheight(); //获取绘图区的高度,EASYX自带
int dstX = 0; //在显存里像素的角标
// 实现透明贴图 公式: Cp=αp*FP+(1-αp)*BP , 贝叶斯定理来进行点颜色的概率计算
for (int iy = 0; iy < picture_height; iy++)
{
for (int ix = 0; ix < picture_width; ix++)
{
int srcX = ix + iy * picture_width; //在显存里像素的角标
int sa = ((src[srcX] & 0xff000000) >> 24); //0xAArrggbb;AA是透明度
int sr = ((src[srcX] & 0xff0000) >> 16); //获取RGB里的R
int sg = ((src[srcX] & 0xff00) >> 8); //G
int sb = src[srcX] & 0xff; //B
if (ix >= 0 && ix <= graphWidth && iy >= 0 && iy <= graphHeight && dstX <= graphWidth * graphHeight)
{
dstX = (ix + picture_x) + (iy + picture_y) * graphWidth; //在显存里像素的角标
int dr = ((dst[dstX] & 0xff0000) >> 16);
int dg = ((dst[dstX] & 0xff00) >> 8);
int db = dst[dstX] & 0xff;
draw[dstX] = ((sr * sa / 255 + dr * (255 - sa) / 255) << 16) //公式: Cp=αp*FP+(1-αp)*BP ; αp=sa/255 , FP=sr , BP=dr
| ((sg * sa / 255 + dg * (255 - sa) / 255) << 8) //αp=sa/255 , FP=sg , BP=dg
| (sb * sa / 255 + db * (255 - sa) / 255); //αp=sa/255 , FP=sb , BP=db
}
}
}
}
方法二:先链接一个库,再将原来的putimage函数替换成下面这个函数
#pragma comment(lib,"MSIMG32.LIB")
inline void putimage_alpha(int x, int y, IMAGE* img)
{
int w = img->getwidth();
int h = img->getheight();
AlphaBlend(GetImageHDC(NULL), x, y, w, h,
GetImageHDC(img), 0, 0, w, h, { AC_SRC_OVER,0,255,AC_SRC_ALPHA });
}