我正在寻找一种在 Java 中创建具有触摸滚动支持的触摸应用程序(不适用于移动设备)的方法。 到目前为止我一直在搜索,我正在研究如何做到这一点 - 我发现的是 MT4J ( http://www.mt4j.org/ ),但它似乎不支持这一点(如果我错了,请纠正我)。 所以我的问题是,如何模拟水平触摸/滑动的滚动事件?
感谢您的帮助! 亲切的问候, 亚历克斯
最佳答案
这通过子类化 JScrollPane 实现了触摸和拖动滚动条。
因为触摸和拖动本身是不够的,所以我添加了动力 这样当释放鼠标按钮时它会“抛出”滚动。
卷轴末端没有“弹跳”,因为我承受不起 对“bounce”所有者提起诉讼。
它没有完全封装,因为尽管如果 View 是一个jlist, View 上可能有需要的组件 如果当时正在拖动面板,则可以修改他们的响应。 还有一些组件,例如JRadioButton、JCheckBox等消耗 鼠标单击而不将它们传递到容器,因此您将 需要给它们添加TouchScroll的MouseListener和MouseMotionListener。
import java.awt.Component;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
public class TouchScroll extends JScrollPane implements MouseListener, MouseMotionListener {
private JScrollBar vbar = this.getVerticalScrollBar();
public TouchScroll(Component view){ // 1-arity CONSTRUCTOR
super(view);
view.addMouseListener(this);
view.addMouseMotionListener(this);
}
public TouchScroll() { super(); } // 0-arity CONSTRUCTOR
public void setViewportView(Component view) {
super.setViewportView(view);
view.addMouseListener(this);
view.addMouseMotionListener(this);
}
private static boolean wasdragged = false; // other MouseListeners may need to know this ...
public boolean wasDragged() { return wasdragged; } // ... this gives them safe access
static int lastY = 0, distY = 0;
double momentum = 0; // not really physical momentum but it will be used to 'throw' the scroll when the mouse button is released
static boolean lbdown = false;
@Override
public void mouseDragged(MouseEvent e) {
wasdragged = true;
distY = 0;
int currentY = e.getYOnScreen();
if(lbdown) {
distY = lastY - currentY;
vbar.setValue(distY + vbar.getValue());
if(Math.abs(distY) > 1)
momentum = distY + distY; // magnify and log the momentum for later use
}
lastY = currentY;
}
@Override
public void mousePressed(MouseEvent e) {
if (e.getButton() == MouseEvent.BUTTON1) {
lastY = e.getYOnScreen();
lbdown = true;
}
}
@Override
public void mouseReleased(MouseEvent e) {
if (e.getButton() == MouseEvent.BUTTON1)
lbdown = false;
if(wasdragged)
wasdragged = false;
if(Math.abs(momentum) <= 4.0) // then assume that the mouse wasn't moving (much) when the button was released
return;
// otherwise 'throw' the scroll
int max = vbar.getMaximum();
int count;
double brakingforce = 1.04; // set an initial braking force
for(count = 1000; count > 0; count--){ // don't allow it to accidentally go on forever
momentum = momentum / brakingforce; // apply the brake
if(Math.abs(momentum) < 1.5)
brakingforce = 1.02; // ease off the brake towards the end (gives a slight overrun ala iOS)
if(Math.abs(momentum) < 1.0) // bring it to a halt
break;
int val = vbar.getValue();
if(val < 0 || val > max) // prevent overrun
break;
vbar.setValue((int) momentum + val); // increment the scroll bar
try {
Thread.sleep(10); // slow the loop down so the user can see the scroll
} catch (InterruptedException e1) {
e1.printStackTrace();
}
}
}
public void mouseMoved(MouseEvent e) {}
public void mouseClicked(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
}
这是一个“简单的”示例,说明如何应用它:
panel = new JPanel();
jlist = new JList(list);
scroller = new TouchScroll(jlist);
panel.add(scroller);
任何响应鼠标释放的组件可能需要执行如下操作:
public void mouseReleased(MouseEvent e) {
if(scroller.wasDragged())
return;
actionENTER();
}
最后,如前所述,消耗鼠标事件的组件需要 像这样通知滚动条:
JCheckBox checkbox = new JCheckBox(text);
checkbox.addMouseMotionListener(scroller);
checkbox.addMouseListener(scroller);
关于java - 用Java模拟触摸滚动,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16470605/