如何在 Java 中快速截取屏幕截图？
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How to take screenshots fast in Java?
提问by lyuba
I am implementing a simple eye tracker, which requires fast screenshoting of what is happening on the screen simultaneously with capturing the video from webcam.
我正在实现一个简单的眼动追踪器，它需要在从网络摄像头捕获视频的同时快速截取屏幕上正在发生的事情。
The thing is that the way of doing it with Robot, mentioned here: https://stackoverflow.com/questions/2475303/java-library-for-capturing-active-window-screenshotis extremely slow.
问题是这里提到的使用 Robot 进行操作的方式：https: //stackoverflow.com/questions/2475303/java-library-for-capturing-active-window-screenshot非常慢。
By the way, retrieving the video from a webcam works much faster and returns the byte array, which is very fast to be processed.
顺便说一句，从网络摄像头检索视频的速度要快得多，并返回字节数组，处理速度非常快。
Does anybody know a faster solution? C++ libraries, which can be linked to Java for doing this may help as well.
有人知道更快的解决方案吗？可以链接到 Java 的 C++ 库也可能有所帮助。
Thank you!
谢谢！
UPDATE: Decided to switch to OpenCV, now looking for the way to make screenshot with it :)
更新：决定切换到 OpenCV，现在正在寻找用它制作屏幕截图的方法:)
回答by finnw
Here's a Windows-specific version using JNA that I am using in one of my projects.
这是我在我的一个项目中使用的使用 JNA 的特定于 Windows 的版本。
I have found it to be an order-of-magnitude faster than Robot, even with the native call overhead.
我发现它比 快一个数量级Robot，即使有本机调用开销也是如此。
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.awt.image.DataBuffer;
import java.awt.image.DataBufferInt;
import java.awt.image.DataBufferUShort;
import java.awt.image.DirectColorModel;
import java.awt.image.Raster;
import java.awt.image.WritableRaster;
import com.sun.jna.Native;
import com.sun.jna.platform.win32.W32API;
import com.sun.jna.win32.W32APIOptions;
public class JNAScreenShot {
public static BufferedImage getScreenshot(Rectangle bounds) {
W32API.HDC windowDC = GDI.GetDC(USER.GetDesktopWindow());
W32API.HBITMAP outputBitmap =
GDI.CreateCompatibleBitmap(windowDC,
bounds.width, bounds.height);
try {
W32API.HDC blitDC = GDI.CreateCompatibleDC(windowDC);
try {
W32API.HANDLE oldBitmap =
GDI.SelectObject(blitDC, outputBitmap);
try {
GDI.BitBlt(blitDC,
0, 0, bounds.width, bounds.height,
windowDC,
bounds.x, bounds.y,
GDI32.SRCCOPY);
} finally {
GDI.SelectObject(blitDC, oldBitmap);
}
GDI32.BITMAPINFO bi = new GDI32.BITMAPINFO(40);
bi.bmiHeader.biSize = 40;
boolean ok =
GDI.GetDIBits(blitDC, outputBitmap, 0, bounds.height,
(byte[]) null, bi, GDI32.DIB_RGB_COLORS);
if (ok) {
GDI32.BITMAPINFOHEADER bih = bi.bmiHeader;
bih.biHeight = - Math.abs(bih.biHeight);
bi.bmiHeader.biCompression = 0;
return bufferedImageFromBitmap(blitDC, outputBitmap, bi);
} else {
return null;
}
} finally {
GDI.DeleteObject(blitDC);
}
} finally {
GDI.DeleteObject(outputBitmap);
}
}
private static BufferedImage
bufferedImageFromBitmap(GDI32.HDC blitDC,
GDI32.HBITMAP outputBitmap,
GDI32.BITMAPINFO bi) {
GDI32.BITMAPINFOHEADER bih = bi.bmiHeader;
int height = Math.abs(bih.biHeight);
final ColorModel cm;
final DataBuffer buffer;
final WritableRaster raster;
int strideBits =
(bih.biWidth * bih.biBitCount);
int strideBytesAligned =
(((strideBits - 1) | 0x1F) + 1) >> 3;
final int strideElementsAligned;
switch (bih.biBitCount) {
case 16:
strideElementsAligned = strideBytesAligned / 2;
cm = new DirectColorModel(16, 0x7C00, 0x3E0, 0x1F);
buffer =
new DataBufferUShort(strideElementsAligned * height);
raster =
Raster.createPackedRaster(buffer,
bih.biWidth, height,
strideElementsAligned,
((DirectColorModel) cm).getMasks(),
null);
break;
case 32:
strideElementsAligned = strideBytesAligned / 4;
cm = new DirectColorModel(32, 0xFF0000, 0xFF00, 0xFF);
buffer =
new DataBufferInt(strideElementsAligned * height);
raster =
Raster.createPackedRaster(buffer,
bih.biWidth, height,
strideElementsAligned,
((DirectColorModel) cm).getMasks(),
null);
break;
default:
throw new IllegalArgumentException("Unsupported bit count: " + bih.biBitCount);
}
final boolean ok;
switch (buffer.getDataType()) {
case DataBuffer.TYPE_INT:
{
int[] pixels = ((DataBufferInt) buffer).getData();
ok = GDI.GetDIBits(blitDC, outputBitmap, 0, raster.getHeight(), pixels, bi, 0);
}
break;
case DataBuffer.TYPE_USHORT:
{
short[] pixels = ((DataBufferUShort) buffer).getData();
ok = GDI.GetDIBits(blitDC, outputBitmap, 0, raster.getHeight(), pixels, bi, 0);
}
break;
default:
throw new AssertionError("Unexpected buffer element type: " + buffer.getDataType());
}
if (ok) {
return new BufferedImage(cm, raster, false, null);
} else {
return null;
}
}
private static final User32 USER = User32.INSTANCE;
private static final GDI32 GDI = GDI32.INSTANCE;
}
interface GDI32 extends com.sun.jna.platform.win32.GDI32 {
GDI32 INSTANCE =
(GDI32) Native.loadLibrary(GDI32.class);
boolean BitBlt(HDC hdcDest,
int nXDest,
int nYDest,
int nWidth,
int nHeight,
HDC hdcSrc,
int nXSrc,
int nYSrc,
int dwRop);
HDC GetDC(HWND hWnd);
boolean GetDIBits(HDC dc, HBITMAP bmp, int startScan, int scanLines,
byte[] pixels, BITMAPINFO bi, int usage);
boolean GetDIBits(HDC dc, HBITMAP bmp, int startScan, int scanLines,
short[] pixels, BITMAPINFO bi, int usage);
boolean GetDIBits(HDC dc, HBITMAP bmp, int startScan, int scanLines,
int[] pixels, BITMAPINFO bi, int usage);
int SRCCOPY = 0xCC0020;
}
interface User32 extends com.sun.jna.platform.win32.User32 {
User32 INSTANCE =
(User32) Native.loadLibrary(User32.class,
W32APIOptions.UNICODE_OPTIONS);
HWND GetDesktopWindow();
}
回答by Stephen Denne
The robot.createScreenCapture(captureSize);call takes about 20ms for me.
的robot.createScreenCapture(captureSize);通话时间约20毫秒我。
回答by Abdel Raoof
May be you can make use of JMF.. Checkout the Screen Grabber code @ Oracle's site. I think it will help you solve your problem.
也许你可以使用 JMF .. 签出屏幕抓取器代码@ Oracle 的网站。我认为它会帮助你解决你的问题。
回答by Hari Krishna
To capture full screen.
捕捉全屏。
Robot robot = new Robot();
Rectangle screenRect = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
BufferedImage screenFullImage = robot.createScreenCapture(screenRect);
ImageIO.write(screenFullImage, format, new File(destination));
To capture partial screen.
捕获部分屏幕。
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
Rectangle rect = new Rectangle(0, 0, screenSize.width / 2, screenSize.height / 2);
Robot robot = new Robot();
BufferedImage screenFullImage = robot.createScreenCapture(rect);
ImageIO.write(screenFullImage, format, new File(destination));
Reference : link
参考：链接
