Linux XRender如何处理透明效果

<code>#include <x11>
#include <x11>
<p>int main() {
Display *display = XOpenDisplay(NULL);
if (!display) {
fprintf(stderr, "无法打开显示\n");
return 1;
}</p><pre class="brush:php;toolbar:false;"><code>int event_base, error_base;
if (!XRenderQueryExtension(display, &event_base, &error_base)) {
    fprintf(stderr, "XRender扩展不可用\n");
    XCloseDisplay(display);
    return 1;
}

// 接下来处理透明效果</code>

<code>XImage <em>image = XOpenImage(display, XCreateImage(display, ZPixmap, 32, ZRGB, 0, (char </em>)image_data, width, height, 32, 0));
if (!image) {
fprintf(stderr, "无法打开图像\n");
XCloseDisplay(display);
return 1;
}</code>

<code>XImage *mask = XCreateImage(display, ZPixmap, 32, ZRGB, 0, NULL, width, height, 32, 0);
if (!mask) {
fprintf(stderr, "无法创建遮罩图像\n");
XDestroyImage(image);
XCloseDisplay(display);
return 1;
}</p><p>// 设定遮罩的透明度
unsigned char <em>p = (unsigned char </em>)mask->data;
for (int y = 0; y bytes_per_line + x <em> 4;
p[index + 3] = (desired_opacity) ? 255 : 0; // 设置alpha通道
}
}</code>

<code>Pixmap pixmap;
XImage </em>background_image = ...; // 载入背景图像</p><p>pixmap = XCreatePixmap(display, DefaultRootWindow(display), width, height, 32);
XPutImage(display, pixmap, XCreateGC(display, pixmap, 0, NULL), image, 0, 0, 0, 0, width, height);</p><p>XImage *result_image = XCreateImage(display, ZPixmap, 32, ZRGB, 0, NULL, width, height, 32, 0);
XRenderComposite(display, PictOpOver, background_image, None, pixmap, 0, 0, 0, 0, 0, 0, width, height);</p><p>// 将最终图像展示在窗口内或保存至文件</code>

<code>XDestroyImage(image);
XDestroyImage(mask);
XDestroyImage(background_image);
XDestroyPixmap(pixmap);
XCloseDisplay(display);</code>