JWindow
创建自定义UI,以选择要共享的屏幕区域。我已经扩展了JWindow
并添加了代码,使其可调整大小,并使用AWTUtilities.setWindowShape()
'剪切' 窗口中心。
运行代码时,当窗口向负x和y方向(即向上和向左)调整大小时,会出现闪烁。看起来是在更新组件之前调整大小并绘制窗口。下面是代码的简化版本。运行后,可以使用顶部面板将窗口向上和向左调整大小。窗口的背景设置为绿色,以清楚地显示不希望显示的像素。
编辑:通过ComponentListener
改进了代码以正确地形状化窗口,并在底部添加了虚拟组件以进一步说明闪烁(还更新了截图)。
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.geom.Area;
import javax.swing.JPanel;
import javax.swing.JWindow;
import javax.swing.border.CompoundBorder;
import javax.swing.border.EmptyBorder;
import javax.swing.border.EtchedBorder;
import javax.swing.border.LineBorder;
import com.sun.awt.AWTUtilities;
public class FlickerWindow extends JWindow implements MouseListener, MouseMotionListener{
JPanel controlPanel;
JPanel outlinePanel;
int mouseX, mouseY;
Rectangle windowRect;
Rectangle cutoutRect;
Area windowArea;
public static void main(String[] args) {
FlickerWindow fw = new FlickerWindow();
}
public FlickerWindow() {
super();
setLayout(new BorderLayout());
setBounds(500, 500, 200, 200);
setBackground(Color.GREEN);
controlPanel = new JPanel();
controlPanel.setBackground(Color.GRAY);
controlPanel.setBorder(new EtchedBorder(EtchedBorder.LOWERED));
controlPanel.addMouseListener(this);
controlPanel.addMouseMotionListener(this);
outlinePanel = new JPanel();
outlinePanel.setBackground(Color.BLUE);
outlinePanel.setBorder(new CompoundBorder(new EmptyBorder(2,2,2,2), new LineBorder(Color.RED, 1)));
add(outlinePanel, BorderLayout.CENTER);
add(controlPanel, BorderLayout.NORTH);
add(new JButton("Dummy button"), BorderLayout.SOUTH);
setVisible(true);
setShape();
addComponentListener(new ComponentAdapter() {
@Override
public void componentResized(ComponentEvent e) {
setShape();
}});
}
public void paint(Graphics g) {
// un-comment or breakpoint here to see window updates more clearly
//try {Thread.sleep(10);} catch (Exception e) {}
super.paint(g);
}
public void setShape() {
Rectangle bounds = getBounds();
Rectangle outlineBounds = outlinePanel.getBounds();
Area newShape = new Area (new Rectangle(0, 0, bounds.width, bounds.height));
newShape.subtract(new Area(new Rectangle(3, outlineBounds.y + 3, outlineBounds.width - 6, outlineBounds.height - 6)));
setSize(bounds.width, bounds.height);
AWTUtilities.setWindowShape(this, newShape);
}
public void mouseDragged(MouseEvent e) {
int dx = e.getXOnScreen() - mouseX;
int dy = e.getYOnScreen() - mouseY;
Rectangle newBounds = getBounds();
newBounds.translate(dx, dy);
newBounds.width -= dx;
newBounds.height -= dy;
mouseX = e.getXOnScreen();
mouseY = e.getYOnScreen();
setBounds(newBounds);
}
public void mousePressed(MouseEvent e) {
mouseX = e.getXOnScreen();
mouseY = e.getYOnScreen();
}
public void mouseMoved(MouseEvent e) {}
public void mouseClicked(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
}
重写的paint()
方法可以用作断点,或者可以取消注释Thread.sleep()
以提供更清晰的更新视图。
我的问题似乎源于setBounds()
方法在布局之前将窗口绘制到屏幕上。
窗口在调整大小之前,应该是这个样子:
窗口在调整大小时变大(向上和向左),这是在重写的
paint()
方法中看到的断点:
窗口在调整大小时变小(向下和向右),如在重写的paint()
方法中看到的断点:
这些屏幕截图是在鼠标拖动时拍摄的,但即使对于较为温和的鼠标拖动,闪烁也会变得非常令人讨厌。在调整大小到更大的屏幕截图上,绿色区域显示了在任何绘画/布局之前绘制的新背景,似乎发生在底层的ComponentPeer或本地窗口管理器中。在“调整大小到较小”的屏幕截图上,蓝色区域显示了JPanel的背景被推入视图,但现在已经过时。这在Linux(Ubuntu)和Windows XP下发生。
是否有人找到了一种方法,在对屏幕进行任何更改之前将Window或JWindow调整大小到后备缓冲区,从而避免这种闪烁效应?也许有一个java.awt....系统属性可以设置以避免这种情况,但我找不到。
编辑 #2: 将调用 AWTUtilities.setWindowShape()
的语句注释掉(如果需要,可以取消注释 paint()
中的 Thread.sleep(10)
行),然后激烈地拖动顶部面板,以清晰地看到闪烁的性质。
编辑 #3: 有人能在Windows 7或Mac OSX上测试这种行为吗?