有名管道后 && gtk_window_set_opacity

http://www.cnblogs.com/hicjiajia/archive/2011/01/20/1940154.html

方式一：mkfifo("myfifo","rw");

　　方式二：mknod myfifo p

　　生成了有名管道后，就可以使用一般的文件I/O函数如open、close、read、write等来对它进行操作。下面即是一个简单的例子，假设我们已经创建了一个名为myfifo的有名管道。

 1/* 进程一：读有名管道*/
 2#include <stdio.h>
 3#include <unistd.h>
 4void main() {
 5    FILE * in_file;
 6    int count = 1;
 7    char buf[80];
 8    in_file = fopen("mypipe", "r");
 9    if (in_file == NULL) {
10        printf("Error in fdopen.\n");
11        exit(1);
12    }
13    while ((count = fread(buf, 1, 80, in_file)) > 0)
14        printf("received from pipe: %s\n", buf);
15    fclose(in_file);
16}
17/* 进程二：写有名管道*/
18#include <stdio.h>
19#include <unistd.h>
20void main() {
21    FILE * out_file;
22    int count = 1;
23    char buf[80];
24    out_file = fopen("mypipe", "w");
25    if (out_file == NULL) {
26        printf("Error opening pipe.");
27        exit(1);
28    }
29    sprintf(buf,"this is test data for the named pipe example\n");
30    fwrite(buf, 1, 80, out_file);
31    fclose(out_file);
32}
33

gtk_window_set_opacity

void gtk_window_set_opacity (GtkWindow *self,
gdouble opacity);

Request the windowing system to make @window partially transparent,with opacity 0 being fully transparent and 1 fully opaque. (Valuesof the opacity parameter are clamped to the [0,1] range.) On X11this has any effect only on X screens with a compositing managerrunning. See gtk_widget_is_composited(). On Windows it should workalways.Note that setting a window's opacity after the window has beenshown causes it to flicker once on Windows.

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