使用imagemagick API截屏 [英] Taking a screenshot using imagemagick API

问题描述

我正在使用GCC 4.7.2，C89和ImageMagick-6.8.0-4.

I'm using GCC 4.7.2, C89, and ImageMagick-6.8.0-4.

我正在尝试使用ImageMagick API进行屏幕截图.我已经下载，编译并安装了标头和库.

I am trying to take a screen shot using the ImageMagick API. I have downloaded, compiled, and installed the headers and libraries.

但是，我在文档中看不到API调用来进行截屏.我将链接并包括标头，以便可以从C程序调用API.我只想要执行此操作所要使用的函数的名称.

However, I can't see in the documentation the API calls to do the screen shot. I will be linking and including the headers so that I can call the API from my C program. I just want the name of the function I will have to use to do this.

有人能指出我正确的方向吗?ImageMagick可以截屏吗?

Can anyone point me in the right direction? Can ImageMagick take screenshots?

推荐答案

使用'x:'特殊文件格式

如果您不想要刺激性的屏幕抓取；您可以通过在 MagickReadImage 中将" x:root "作为源参数传递来调用ImageMagick的import命令. x:格式通过传递 pid 或窗口标签.其他修饰符可以捕获区域&分页.

Using 'x:' Special File Format

If you want a no-thrill screen grab; you can invoke ImageMagick's import command by passing "x:root" as the source argument in MagickReadImage. The x: format allows for a full screenshot or a single window by passing a pid or window label. Additional modifiers can capture regions & paging.

#include <wand/MagickWand.h>

int main(int argc, char **argv) 
{
    MagickWandGenesis();
    MagickWand *wand = NULL;
    wand = NewMagickWand();
    MagickReadImage(wand,"x:root"); // <-- Invoke ImportImageCommand
    MagickWriteImage(wand,"screen_shot.png");
    if(wand)wand = DestroyMagickWand(wand);
    MagickWandTerminus();
    return 0;
}

使用其他魔术"库

在 wand 库之外， magick/xwindow.h 允许您使用 XImportImage ， XImportInfo 导入图像代码>& XGetImportInfo 方法.您可以在ImageMagick的源文件中检查这些方法的工作方式 wand/import.c

Use Additional 'magick' Libraries

Outside of wand libraries, magick/xwindow.h allows you to import images by use of XImportImage, XImportInfo & XGetImportInfo methods. You can examine how these methods work in ImageMagick's source files wand/import.c.

MagickWand还包括PixelWand；可以迭代内存中的图像指针.要做更多的工作，但更大的灵活性.

MagickWand also includes PixelWand; which, can iterate over an image-pointer in memory. A little more work, but greater flexibility.

#include <stdio.h>
#include <wand/MagickWand.h>
#include <X11/Xlib.h>

int main(int argc, char **argv) {
    int x,y;
    unsigned long pixel;
    char hex[128];

    // X11 items
    Display *display = XOpenDisplay(NULL);
    Window root = DefaultRootWindow(display);
    XWindowAttributes attr;
    XGetWindowAttributes(display, root, &attr);

    // MagickWand items
    MagickWand *wand = NULL;
    PixelWand *pwand = NULL;
    PixelIterator *pitr = NULL;
    PixelWand **wand_pixels = NULL;

    // Set-up Wand
    MagickWandGenesis();
    pwand = NewPixelWand();
    PixelSetColor(pwand,"white"); // Set default;
    wand = NewMagickWand();
    MagickNewImage(wand,attr.width,attr.height,pwand);
    pitr = NewPixelIterator(wand);

    // Get image from display server
    XImage *image = XGetImage(display,root, 0,0 , 
                                attr.width, attr.height,
                                XAllPlanes(), ZPixmap);

    unsigned long nwands; // May also be size_t

    for (y=0; y < image->height; y++) {
        wand_pixels=PixelGetNextIteratorRow(pitr,&nwands);
            for ( x=0; x < image->width; x++) {
                pixel = XGetPixel(image,x,y);
                sprintf(hex, "#%02x%02x%02x",
                                pixel>>16,           // Red
                                (pixel&0x00ff00)>>8, // Green
                                pixel&0x0000ff       // Blue
                                );
                PixelSetColor(wand_pixels[x],hex);
            }
            (void) PixelSyncIterator(pitr);
    }

    // Write to disk
    MagickWriteImages(wand,"screen_test.png");

    // Clean-Up
    XDestroyImage(image);
    pitr=DestroyPixelIterator(pitr);
    wand=DestroyMagickWand(wand);
    MagickWandTerminus();
    XCloseDisplay(display);
    return 0;
}

有用的提示

确保ImageMagick能够连接到您的显示系统.尝试使用几个 import CLI命令来验证本地安装是否正常.这个问题是一个很好的例子.

Helpful Hints

Ensure that ImageMagick is able to connect to your display system. Try a few import CLI commands to verify your local install is working. This question is a good example.

import -display localhost:0.0 -window root test_out.png
import -display ::0 -window root test_out.png
import -display :0.0 -window root test_out.png
import -display :0 -window root test_out.png

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