int i; FILE * out; gdImagePtr im; gdImagePtr prev =NULL; int black; im = gdImageCreate(100, 100); if (!im) { fprintf(stderr, "can't create image"); return 1; ...-Go服务器开发

要生成不透明的图片，只需将颜色分配函数gdImageColorAllocate()中的透明度参数设置为255。修改后的代码如下：

#include <stdio.h>
#include <stdlib.h>
#include "gd.h"

int main() {
    int i;
    FILE *out;

    gdImagePtr im;
    gdImagePtr prev = NULL;
    int black;

    im = gdImageCreate(100, 100);
    if (!im) {
        fprintf(stderr, "can't create image");
        return 1;
    }

    out = fopen("anim.gif", "wb");
    if (!out) {
        fprintf(stderr, "can't create file %s", "anim.gif");
        return 1;
    }

    gdImageColorAllocate(im, 255, 255, 255); /* allocate white as side effect */
    gdImageGifAnimBegin(im, out, 1, -1);

    for (i = 0; i < 20; i++) {
        int r,g,b;
        im = gdImageCreate(100, 100);
        r = rand() % 255;
        g = rand() % 255;
        b = rand() % 255;

        gdImageColorAllocate(im, 255, 255, 255); /* allocate white as side effect */
        black = gdImageColorAllocateAlpha(im, r, g, b, 0xFF); // 设置完全不透明（alpha值为0xFF）
        
        printf("(%i, %i, %i)\n", r, g ,b);
        
        gdImageFilledRectangle(im,
                               rand() % 100,
                               rand() % 100,
                               rand() % 100,
                               rand() % 100,
                               black);

        gdImageGifAnimAdd(im, out, 1, 0, 0, 10, 1, prev);

        if (prev) {
            gdImageDestroy(prev);
        }
        prev = im;
    }

    gdImageGifAnimEnd(out);
    fclose(out);

    return 0;
}

这样，生成的图片将是不透明的。注意，修改后的代码使用了gdImageColorAllocateAlpha()函数来分配带有完全不透明度（alpha值为0xFF）的颜色。

内容由零声教学AI助手提供，问题来源于学员提问