我目前正在尝试使应用程序的 UI 变得轻量级，因此我尝试将重量级服务器调用移至它们自己的线程。然后，我使用 Display.getDefault.asyncExec() 更新小部件，效果非常好。
我想在服务器调用返回时向用户显示动画。到目前为止，我正在使用另一个线程，它在另一个 Display.getDefault.asyncExec() 中显示动画。这也有效......但以一种奇怪的方式。当我运行该应用程序时，小部件闪烁得非常厉害，有时屏幕保持未更新状态。问题是，当我运行原型(prototype)版本时，即没有主应用程序，只是一个简单的 SWT 应用程序，它运行得很好。有什么想法为什么会发生这种情况吗？
基本工作流程::
showAnimation = new Thread(new Runnable() {
@Override
public void run() {
while(true){
synchronized (this) {
try {
Thread.sleep(1000);
drawCircles(); // basically the animation, also called in a Display.getDefault().asyncExec()
}
catch (InterruptedException e)
{
// do nothing, because this thread is meant to be interrupted!
// and then, break out of the infinite loop
System.out.println("Interrupted");
break;
}
}
}
}
});
invokeLater = new Thread(new Runnable(){
@Override
public void run(){
// do the data base call here
System.out.println("Got data!");
if(showAnimation.isAlive())
{
showAnimation.interrupt();
}
}
});
在我看来 -->
showAnimation.start();
invokeLater.start();
我短暂地想知道是否应该增加动画线程的优先级，只是为了看看这是否有效。它没有(也没有意义增加线程的优先级，这不会成为应用程序的瓶颈)。
有什么想法吗？
P.S: drawCircles() 代码 -->
public void drawCircles(){
Display.getDefault().asyncExec(new Runnable() {
@Override
public void run(){
int radius = 100;
int maxX = radius ;
int maxY = radius ;
int direction=0;
int centerX = table.getBounds().width/2;
int centerY = table.getBounds().height/2;
System.out.println("Drawing");
Image image = new Image(Display.getDefault(),table.getBounds().width,table.getBounds().height);
GC gc = new GC(image);
gc.setAntialias(SWT.ON);
gc.setForeground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
//gc.drawLine(0, centerY, shell.getBounds().width, centerY);
//gc.drawLine(centerX, 0, centerX, shell.getBounds().height);
// 1st circle
gc.drawOval(centerX-radius/2, centerY-radius - radius/2, maxX, maxY);
// 2nd circle
gc.drawOval(centerX - 2*radius + radius/2, centerY - radius/2, maxX, maxY);
// 3rd circle
gc.drawOval(centerX+radius/2, centerY-radius/2, maxX, maxY);
// 4th circle
gc.drawOval(centerX-radius/2, centerY + radius/2, maxX, maxY);
direction++;
direction %= 4;
switch(direction){
case 0:
gc.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
gc.fillOval(centerX - 2*radius + radius/2, centerY - radius/2, maxX, maxY);
break;
case 1:
gc.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
gc.fillOval(centerX-radius/2, centerY-radius - radius/2, maxX, maxY);
break;
case 2:
gc.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
gc.fillOval(centerX+radius/2, centerY-radius/2, maxX, maxY);
break;
case 3 :
gc.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
gc.fillOval(centerX-radius/2, centerY + radius/2, maxX, maxY);
break;
}
table.setBackgroundImage(image);
table.redraw();
table.update();
image.dispose();
gc.dispose();
}
});
}
最佳答案
为了解决这个问题，我最终使用了双缓冲，在 GC 中绘制图像，然后稍后更新 PaintEvent gc。即使打开了抗锯齿功能，这也大大减少了闪烁。
基本上，创建一个 PaintListener::
final PaintListener paint = new PaintListener() {
@Override
public void paintControl(PaintEvent e) {
int radius = 100;
int maxX = radius ;
int maxY = radius ;
int centerX = e.width/2;
int centerY = e.height/2;
Image image = new Image(Display.getDefault(),e.width,e.height);
GC gc = new GC(image);
gc.setAntialias(SWT.ON);
gc.setForeground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
//gc.drawLine(0, centerY, shell.getBounds().width, centerY);
//gc.drawLine(centerX, 0, centerX, shell.getBounds().height);
// 1st circle
gc.drawOval(centerX-radius/2, centerY-radius - radius/2, maxX, maxY);
// 2nd circle
gc.drawOval(centerX - 2*radius + radius/2, centerY - radius/2, maxX, maxY);
// 3rd circle
gc.drawOval(centerX+radius/2, centerY-radius/2, maxX, maxY);
// 4th circle
gc.drawOval(centerX-radius/2, centerY + radius/2, maxX, maxY);
direction++;
direction %= 4;
switch(direction){
case 0:
gc.setAlpha(255);
gc.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
gc.fillOval(centerX - 2*radius + radius/2, centerY - radius/2, maxX, maxY);
break;
case 1:
gc.setAlpha(170);
gc.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
gc.fillOval(centerX-radius/2, centerY-radius - radius/2, maxX, maxY);
break;
case 2:
gc.setAlpha(80);
gc.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
gc.fillOval(centerX+radius/2, centerY-radius/2, maxX, maxY);
break;
case 3 :
gc.setAlpha(20);
gc.setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
gc.fillOval(centerX-radius/2, centerY + radius/2, maxX, maxY);
break;
}
e.gc.drawImage(image, 0, 0);
image.dispose();
gc.dispose();
}
};
动画线程可以写成::
showAnimation = new Thread(new Runnable() {
@Override
public void run() {
while(true){
synchronized (this) {
try {
Thread.sleep(100);
Display.getDefault().asyncExec(new Runnable() {
@Override
public void run() {
table.addPaintListener(paint);
table.redraw();
table.update();
table.removePaintListener(paint);
}
});
}
catch (InterruptedException e)
{
// do nothing, because this thread is meant to be interrupted!
// and then, break out of the infinite loop
break;
}
}
}
}
});
我添加和删除了监听器，因为通知出现了一些问题(绘制次数超出了要求!)。然后，可以在另一个线程中进行数据库调用，如下所示::
invokeLater = new Thread(new Runnable() {
@Override
public void run() {
//Fetching records from Service
try
{
// database call here
if(showAnimation.isAlive())
{
showAnimation.interrupt();
}
}
}
});
这最终对我有用如果有人可以对此进行改进，请告诉我:)
关于java - 正确刷新小部件吗？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21986575/