本文演示使用imlib2函数库实现截屏功能程序运行后，截屏图像保存为jpeg格式文件到当前目录下，起名为“screen.jpeg”
在Debian 5.02系统下，安装libimlib2-dev软件包imlib2的API文档在 /usr/share/doc/libimlib2-dev/html/index.html
用cvs获取笔者本机screen项目的源代码如下：$ cvs co -p screencvs checkout: Updating screen===================================================================Checking out screen/MakefileRCS: /home/c-aries/cvs/screen/Makefile,vVERS: 1.2***************CC = gccCFLAGS = -Wall -Werror -Wcast-align -gLDFLAGS =
SCREENOBJECT = screen.o
GIBLIBCFLAGS = `giblib-config –cflags`GIBLIBLIBS = `giblib-config –libs`
all: screen
screen: $(SCREENOBJECT) $(CC) $(LDFLAGS) $(GIBLIBLIBS) $(SCREENOBJECT) -o $@
screen.o: screen.c screen.h $(CC) $(CFLAGS) $(GIBLIBCFLAGS) -c $<
clean: rm -f screen *~ *.o a.out
clean-media: rm -f *~ *.jpeg
.PHONY: all clean===================================================================Checking out screen/screen.cRCS: /home/c-aries/cvs/screen/screen.c,vVERS: 1.2***************#include <stdio.h>#include <stdlib.h>#include <errno.h>#include <giblib/giblib.h>#include “screen.h”
voidscreen_init(struct screen *screen){ screen->display = XOpenDisplay(NULL); if (!screen->display) { perror(“XOpenDisplay”); exit(EXIT_FAILURE); } screen->screen = ScreenOfDisplay(screen->display, DefaultScreen(screen->display)); screen->visual = DefaultVisual(screen->display, DefaultScreen(screen->display)); screen->colormap = DefaultColormap(screen->display, DefaultScreen(screen->display)); screen->root = RootWindow(screen->display, DefaultScreen(screen->display)); imlib_context_set_display(screen->display); imlib_context_set_visual(screen->visual); imlib_context_set_colormap(screen->colormap);}
intmain(int argc, char *argv[]){ struct screen screen; Imlib_Image image;
screen_init(&screen); image = gib_imlib_create_image_from_drawable(screen.root, 0, 0, 0, screen.screen->width, screen.screen->height, 1); imlib_context_set_image(image); imlib_image_set_format(“jpeg”); imlib_save_image(“screen.jpeg”); imlib_free_image(); exit(EXIT_SUCCESS);}===================================================================Checking out screen/screen.hRCS: /home/c-aries/cvs/screen/screen.h,vVERS: 1.1.1.1***************#ifndef SCREEN_H#define SCREEN_H
#include <X11/Xlib.h>
struct screen { Display *display; Screen *screen; Visual *visual; Colormap colormap; Window root;};
void screen_init(struct screen *screen);
#endif$
该程序参考了scrot项目的源代码和imlib2的编程文档
上周的文章 video4linux2编程实例 使用video4linux2编程接口获得摄像头数据流，再将YUYV数据流转换成RGB数据流。然后想添加截取图片功能，将摄像头的RGB数据流保存成JPEG图片。找来平时一直在使用的自由软件scrot，阅读其源代码，，即找到将RGB保存成JPEG图片的方法:“将用于SDL的像素格式RGBA转换成用于imlib2的像素格式ARGB，再用imlib2的imlib_create_image_using_data()函数保存成JPEG图片”这部分的代码下周再介绍吧：）
实现截取图片功能的期间，学会了截屏功能……于是顺便把实现截屏的代码贴出来，作为编程实例。
人生的大部份时间里，承诺同义词是束缚，奈何我们向往束缚。
