Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-7029560

On Linux java.awt.Robot cannot see through windows with transparent backgroung color

    Details

    • Subcomponent:
    • CPU:
      x86
    • OS:
      linux

      Description

      Platform: Linux - FAILS
                Windows - PASSES
      JDK: 7

      Problem:

          When a window has bg color with alpha component set to zero it is transparent visually, but java.awt.Robot on Linux considers it BLACK.

      Please see the following code sample:

      Two windows are created red on the front, green in background. Color of the foreground one is being set to new Color(123, 123, 123, 0) - it disappears visually but the robot considers it black. BTW, it is interesting to play with opacity as having zero opacity and NON-transparent background will let robot experience transparency.

      ---------------------------------------------------------------------------------------------------
      import javax.swing.*;
      import java.awt.*;

      public class BlindRobot {

          public static void main(String[] args) throws Exception {

              System.out.println("started");
              final Window[] window = new Window[1];
              final Window[] bgWindow = new Window[1];
              SwingUtilities.invokeAndWait(new Runnable() {
                  public void run() {
                      bgWindow[0] = new Window(null);
                      bgWindow[0].setSize(100, 100);
                      bgWindow[0].setLocationRelativeTo(null);
                      bgWindow[0].setBackground(Color.GREEN);
                      bgWindow[0].setVisible(true);
                      bgWindow[0].toFront();

                      window[0] = new Window(null);
                      window[0].setSize(100, 100);
                      // centering window on screen
                      window[0].setLocationRelativeTo(null);
                      window[0].setBackground(Color.RED);
                      window[0].setVisible(true);
                      window[0].setAlwaysOnTop(true);
                      window[0].toFront();

                  }
              });

              Thread.sleep(3000);

              SwingUtilities.invokeAndWait(new Runnable() {
                  public void run() {
                      GraphicsDevice device = window[0].getGraphicsConfiguration().getDevice();

                      System.out.println("PERPIXEL_TRANSLUCENT = " + device
                              .isWindowTranslucencySupported(GraphicsDevice
                                      .WindowTranslucency.PERPIXEL_TRANSLUCENT));
                      System.out.println("TRANSLUCENT = " + device
                              .isWindowTranslucencySupported(GraphicsDevice
                                      .WindowTranslucency.TRANSLUCENT));

                      window[0].setOpacity(0f);

                      final Color transparentColor = new Color(123, 123, 123, 0);
                      // COMMENT THIS TO GET GREEN ON LINUX
                      window[0].setBackground(transparentColor);

                  }
              });

              Thread.sleep(3000);


              int zeroX = window[0].getX();
              int zeroY = window[0].getY();

              java.awt.Robot robot = new java.awt.Robot(window[0].getGraphicsConfiguration().getDevice());

              System.out.println("createScreenCapture = " + new Color(robot.createScreenCapture
                      (new Rectangle(zeroX + 10, zeroY + 10, 1, 1)).getRGB(0, 0)));
              System.out.println("pixelColor = " + robot.getPixelColor(zeroX
                      + 10, zeroY + 10));

              Thread.sleep(3000);

              window[0].dispose();
              bgWindow[0].dispose();

          }

      }
      ---------------------------------------------------------------------------------------------------


      The result will be:

      [stt-robot@stt-119]$ /set/java/re/jdk/7/promoted/latest/binaries/linux-i586/bin/java -cp . BlindRobot
      started
      PERPIXEL_TRANSLUCENT = true
      TRANSLUCENT = true
      createScreenCapture = java.awt.Color[r=0,g=0,b=0]
      pixelColor = java.awt.Color[r=0,g=0,b=0]

        Attachments

          Issue Links

            Activity

              People

              • Assignee:
                denis Denis Fokin (Inactive)
                Reporter:
                dbessono Dmitry Bessonov
              • Votes:
                0 Vote for this issue
                Watchers:
                2 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved:
                  Imported:
                  Indexed: