Is there a way to take a screenshot using Java and save it to some sort of image?
Believe it or not, you can actually use java.awt.Robot
to "create an image containing pixels read from the screen." You can then write that image to a file on disk.
I just tried it, and the whole thing ends up like:
Rectangle screenRect = new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
BufferedImage capture = new Robot().createScreenCapture(screenRect);
ImageIO.write(capture, "bmp", new File(args[0]));
NOTE: This will only capture the primary monitor. See GraphicsConfiguration for multi-monitor support.
How to take a screenshot in Java?
Use Robot#createScreenCapture()
.
BufferedImage image = new Robot().createScreenCapture(new Rectangle(Toolkit.getDefaultToolkit().getScreenSize()));
ImageIO.write(image, "png", new File("/screenshot.png"));
How can I capture image of desktop screen in java?
Copy and paste following code in your Java class and invoke the method
captureScreen() with file name as argument. The screen shot will be
stored in the file that you specified in argument.import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import java.io.File;
...
public void captureScreen(String fileName) throws Exception {
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
Rectangle screenRectangle = new Rectangle(screenSize);
Robot robot = new Robot();
BufferedImage image = robot.createScreenCapture(screenRectangle);
ImageIO.write(image, "png", new File(fileName));
}
...
Explained in the following link
how-to-take-screen-shots-in-java-taking-screenshots-jav
Java Full Screenshot
Maybe using something like this:
//get the screen size
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
BufferedImage image = robot.createScreenCapture (dim);
//other code
//...
I see you have some errors, I don't know if your code even compiles, 'cause references seems not to be declared, but a code similar to this one will caputure a screenshoot of your desktop:
import java.awt.geom.*;
import java.awt.*;
import java.awt.image.*;
import javax.imageio.*;
import java.io.*;
public class ScreenCapturer
{
public static void main(String[] args)throws Exception
{
Dimension resolution = Toolkit.getDefaultToolkit().getScreenSize();
Rectangle rectangle = new Rectangle(resolution);
Robot robot = new Robot();
BufferedImage bufferedImage = robot.createScreenCapture(rectangle);
Graphics g = bufferedImage.getGraphics();
//g.drawImage(bufferedImage.getScaledInstance(bufferedImage.getWidth(), bufferedImage.getHeight(), Image.SCALE_DEFAULT), 0, 0, null);
File out = new File("image.png");
ImageIO.write(bufferedImage,"png",out);
}
}
I saved to an png image file instead of drawing it on the screen or the frame.
How to take a screenshot of desktop fast with Java in Windows (ffmpeg, etc.)?
Using the built-in Robots class is way easier than other Java libraries and should probably fit your needs.
If you need a smooth video with >= 30fps (more than 30 screenshots per second), you should first try the Robots approach plus performance improvements there using asynchronous storing of the screenshots.
If it doesn't work for you, try using JNA and that is (even though it's more complex) almost guaranteed to work for smooth screen capturing.
Approach with Robots
The robots class is indeed capable of doing what you want, the problem most screen capturing approaches with Robots have is the saving of the screenshots. An approach could look like that: Looping over the captureScreen() method, grabbing the screen into a BufferedImage, convert it to a byte array and save it with an asynchronous file writer to a target file after adding the future reference of your image to the ArrayList to be able to keep going while storing the image data.
// Pseudo code
while (capturing)
{
grab bufferedImage (screenCapture) from screen
convert bufferImage to byte array
start asynchronous file channel to write to the output file
and add the future reference (return value) to the ArrayList
}
Approach with JNA
Original Question:
How to take screenshots fast in Java?
As it is bad practice to just link, I will post the example here:
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();
}
More information and approaches
Increasing screen capture speed when using Java and awt.Robot
http://www.dreamincode.net/forums/topic/234896-faster-screen-capture/
How to get over 30FPS using Java in a Screen Capture Program?
http://ffmpeg.org
See also
http://www.thepcwizard.in/2012/12/java-screen-capturing-tutorial.html
How to develop screen capture to video application
http://www.javalobby.org/forums/thread.jspa?threadID=16400&tstart=0
http://hiddensciencex.blogspot.co.at/2014/01/fast-screen-capture-in-java-example.html
http://www.coderanch.com/t/340180/GUI/java/efficient-screenshot-Java
http://www.javaworld.com/article/2071755/learn-java/capture-the-screen.html
ffmpeg for screen capture?
Java applet screen capture to a video
Screen Capture of DirectX programs with Java
Take a screenshot of a web page in Java
To build on two of the answers above:
Rendering the HTML in Java then saving to an image - A few Java based HTML renders exist, all with different sets of drawbacks. The most common is the one built in. This is quite simple and can only render fairly basic HTML. The most intresting I know of is The Flying Saucer Project. This can render fairly complex XHTML but you will have to convert HTML before you can use it (JTindy may be able to help here). Taking a Swing component and creating a image is fairly simple, you just pass an BufferedImage
s graphics object and pass it to the Swing components paint method. Then splat that out with ImageIO.
A big advantage to this would be that the renderer would be headless. The disadvantage is that it would not be a perfect rendering and it would lack any plugins.
The second option requires you to start a web browser, work out where it is and then take a screen shot. Optionally you may also wish to strip out all the Firefox/IE/Opera/etc menus leaving you with just image. To get the dimensions of the web browser the simplest option would be to start it full screen. The other option would be to use something like JDICs browser component to include it as part of the Java application. It would then be able to specify where the HTML is being rendered on screen and then simply use Robot to create a screen shot of that area.
The big advantage to this is that it will give a perfect rendering (for a given browser). The two disadvantages is that it would require native code (or at least using a native component) and it could not be headless¹.
1) You could use a virtual frame buffer. But that is outside Java.
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