Java - 窗口图像

Question

有谁知道如何捕捉在Java中的屏幕截图(不是它自己的屏幕,但在桌面上的任何其他窗口,他们并不一定是积极的窗口)在Windows？这个类似的主题有很多线索,但我还没有找到答案.

我尝试过使用JNA,但经过几次尝试后卡住了.例如...

public class Main {

    public static void main(String[] args) {
        Main m = new Main();

        List<WindowInfo> list = m.getWindows();

        for (int i=0;i<list.size();i++) 
        {
            WindowInfo info = list.get(i);
            System.out.println(info.getTitle());
        }

        WindowInfo wi = list.get(0);

        W32API.HDC hdcSrc = User32.instance.GetWindowDC(wi.getHwnd());

        W32API.HDC hdcMemory = Gdi32.instance.CreateCompatibleDC(hdcSrc);

        //W32API.HBITMAP hBitmapMemory = Gdi32.instance.CreateCompatibleBitmap(hdcSrc, int width, int height);
        int width = wi.getRect().right - wi.getRect().left;
        int height = wi.getRect().bottom - wi.getRect().top;

        W32API.HBITMAP hBitmapMemory  = Gdi32.instance.CreateCompatibleBitmap(hdcSrc, width, height);

        W32API.HANDLE hOld  = Gdi32.instance.SelectObject(hdcMemory, hBitmapMemory);


        Gdi32.instance.BitBlt(hdcMemory, 0, 0, width, height, hdcSrc, width+2, height+2, 0x00CC0020);


        /* # now how do we convert to a BufferedImage???  */

        // clean up
        Gdi32.instance.SelectObject(hdcMemory, hOld);
        Gdi32.instance.DeleteDC(hdcMemory);
        Gdi32.instance.DeleteObject(hBitmapMemory);
        User32.instance.ReleaseDC(wi.getHwnd(), hdcSrc);


    }


    /**
     *
     * @return
     */
    private List<WindowInfo> getWindows() {

        final List<WindowInfo> list = new ArrayList<WindowInfo>();


        User32.instance.EnumWindows(new WndEnumProc() {
            public boolean callback(int hWnd, int lParam) {
                if (User32.instance.IsWindowVisible(hWnd)) {
                    RECT r = new RECT();
                    User32.instance.GetWindowRect(hWnd, r);
                    byte[] buffer = new byte[1024];
                    User32.instance.GetWindowTextA(hWnd, buffer, buffer.length);
                    String title = Native.toString(buffer);
                    if (title!=null&&title.length()>0) {
                        list.add(new WindowInfo(hWnd, r, title));
                    }
                }
                return true;
            }
        }, 0);

        Collections.sort(list, new Comparator<WindowInfo>() {
            public int compare(WindowInfo o1, WindowInfo o2) {
                int i1 = (o1.getTitle()!=null&&o1.getTitle().length()>0?o1.getTitle():" ").charAt(0);
                int i2 = (o2.getTitle()!=null&&o2.getTitle().length()>0?o2.getTitle():" ").charAt(0);
                return i1 - i2;
            }
        });

        return list;
    }
}

我也试过相当于"PrintWindow()"的API ......

Graphics g = form.CreateGraphics();
Bitmap bmp = new Bitmap(form.Size.Width, form.Size.Height, g);
Graphics memoryGraphics = Graphics.FromImage(bmp);
IntPtr dc = memoryGraphics.GetHdc();
bool success = PrintWindow(form.Handle, dc, 0);
memoryGraphics.ReleaseHdc(dc);
// bmp now contains the screenshot

或者我是否必须使用JNI或任何其他工具？

Answer 1

这是一个有效的例子.

被捕获的应用程序无法最小化,但它不需要具有焦点或位于顶部(即可见).

相关C#线程中提供的代码,MSDN文章捕获图像和jmemoryeditorw提供了必要的部分.

该代码使用GetDC和GetClientRect来捕获窗口的客户区域.如果要捕获包括窗口装饰在内的整个窗口,可以用GetWindowDC和GetWindowRect替换它们.

import java.awt.Graphics;
import java.awt.image.BufferedImage;

import javax.swing.JFrame;

import jna.extra.GDI32Extra;
import jna.extra.User32Extra;
import jna.extra.WinGDIExtra;

import com.sun.jna.Memory;
import com.sun.jna.platform.win32.GDI32;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinDef.HBITMAP;
import com.sun.jna.platform.win32.WinDef.HDC;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinDef.RECT;
import com.sun.jna.platform.win32.WinGDI;
import com.sun.jna.platform.win32.WinGDI.BITMAPINFO;
import com.sun.jna.platform.win32.WinNT.HANDLE;

public class Paint extends JFrame {

    public BufferedImage capture(HWND hWnd) {

        HDC hdcWindow = User32.INSTANCE.GetDC(hWnd);
        HDC hdcMemDC = GDI32.INSTANCE.CreateCompatibleDC(hdcWindow);

        RECT bounds = new RECT();
        User32Extra.INSTANCE.GetClientRect(hWnd, bounds);

        int width = bounds.right - bounds.left;
        int height = bounds.bottom - bounds.top;

        HBITMAP hBitmap = GDI32.INSTANCE.CreateCompatibleBitmap(hdcWindow, width, height);

        HANDLE hOld = GDI32.INSTANCE.SelectObject(hdcMemDC, hBitmap);
        GDI32Extra.INSTANCE.BitBlt(hdcMemDC, 0, 0, width, height, hdcWindow, 0, 0, WinGDIExtra.SRCCOPY);

        GDI32.INSTANCE.SelectObject(hdcMemDC, hOld);
        GDI32.INSTANCE.DeleteDC(hdcMemDC);

        BITMAPINFO bmi = new BITMAPINFO();
        bmi.bmiHeader.biWidth = width;
        bmi.bmiHeader.biHeight = -height;
        bmi.bmiHeader.biPlanes = 1;
        bmi.bmiHeader.biBitCount = 32;
        bmi.bmiHeader.biCompression = WinGDI.BI_RGB;

        Memory buffer = new Memory(width * height * 4);
        GDI32.INSTANCE.GetDIBits(hdcWindow, hBitmap, 0, height, buffer, bmi, WinGDI.DIB_RGB_COLORS);

        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        image.setRGB(0, 0, width, height, buffer.getIntArray(0, width * height), 0, width);

        GDI32.INSTANCE.DeleteObject(hBitmap);
        User32.INSTANCE.ReleaseDC(hWnd, hdcWindow);

        return image;

    }

    public static void main(String[] args) {
        new Paint();
    }

    BufferedImage image;

    public Paint() {
        HWND hWnd = User32.INSTANCE.FindWindow(null, "Untitled - Notepad");
        this.image = capture(hWnd);

        setDefaultCloseOperation(EXIT_ON_CLOSE);
        pack();
        setExtendedState(MAXIMIZED_BOTH);
        setVisible(true);
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        g.drawImage(image, 20, 40, null);
    }



}

我必须定义一些未包含在platform.jar中的额外函数(可以在JNA网站上找到).

package jna.extra;

import com.sun.jna.Native;
import com.sun.jna.platform.win32.GDI32;
import com.sun.jna.platform.win32.WinDef.DWORD;
import com.sun.jna.platform.win32.WinDef.HDC;
import com.sun.jna.win32.W32APIOptions;

public interface GDI32Extra extends GDI32 {

    GDI32Extra INSTANCE = (GDI32Extra) Native.loadLibrary("gdi32", GDI32Extra.class, W32APIOptions.DEFAULT_OPTIONS);

    public boolean BitBlt(HDC hObject, int nXDest, int nYDest, int nWidth, int nHeight, HDC hObjectSource, int nXSrc, int nYSrc, DWORD dwRop);

}



package jna.extra;

import com.sun.jna.Native;
import com.sun.jna.platform.win32.User32;
import com.sun.jna.platform.win32.WinDef.HDC;
import com.sun.jna.platform.win32.WinDef.HWND;
import com.sun.jna.platform.win32.WinDef.RECT;
import com.sun.jna.win32.W32APIOptions;

public interface User32Extra extends User32 {

    User32Extra INSTANCE = (User32Extra) Native.loadLibrary("user32", User32Extra.class, W32APIOptions.DEFAULT_OPTIONS);

    public HDC GetWindowDC(HWND hWnd);

    public boolean GetClientRect(HWND hWnd, RECT rect);

}



package jna.extra;

import com.sun.jna.platform.win32.WinDef.DWORD;
import com.sun.jna.platform.win32.WinGDI;

public interface WinGDIExtra extends WinGDI {

    public DWORD SRCCOPY = new DWORD(0x00CC0020);

}

Answer 2

使用java.awt.Robot.createScreenCapture().

这是一个例子:

    try {
        Robot robot = new Robot();
        Rectangle size = new Rectangle(Toolkit.getDefaultToolkit()
                .getScreenSize());
        BufferedImage buf = robot.createScreenCapture(size);
        ImageIO.write(buf, "png", new File("d:/test.png"));
    } catch (AWTException ae) {
        throw new RuntimeException("something went wrong");
    }

代码最初是从这里偷来的.