如何在Java中按下鼠标按钮时监听鼠标的移动事件

Question

I have a problem with mouse events in my program. I'm trying to code a drawing program with a canvas.

The user should draw if he left-clicks and moves the mouse. So I defined a class Drawer with a boolean allow_draw in it, and I added a method draw .

draw is called with a mousemoved event in the canvas and allow_draw is set true and false with mousepressed and released .

However, mousemoved isn't firing while I press the mouse button...

My question is: how can I listen to mouse movements while a mouse button is pressed.

Hope you know what I'm looking for :)

Answer 1

Can you please post your source code? Please try adding a MouseMotionListener. Here is an example from a project I am working on.

addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {

        public void mouseDragged(java.awt.event.MouseEvent evt) {
            formMouseDragged(evt);
        }
        public void mouseMoved(java.awt.event.MouseEvent evt) {
            formMouseMoved(evt);
        }
    });`

Answer 2

You should consider,

• using a combination of MouseListener and MouseMotionListener, which is conveniently combined in the MouseAdapter class.
• Turn drawing on when mousePressed occurs.
• Turn drawing off when mouseReleased occurs
• Draw within mouseDragged if drawing is on (use an if block).
• Add your MouseAdapter object twice to the component, with the addMouseListener(...) method and the addMouseMotionListener(...) method.

Answer 3

A mouse move event with a pressed button would be a drag event. Simply listen to 'MouseListener#mouseDragged', it is what you're looking for.