java Android：似乎无法正确使用 MotionEvent.ACTION_MOVE
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Android: can't seem to use MotionEvent.ACTION_MOVE correctly
提问by Stijnn
I am quite new to Android programming and Java (though I have some experience with C#, so that helps).
我对 Android 编程和 Java 很陌生（尽管我对 C# 有一些经验，所以这有帮助）。
At this moment I'm goofing around with a couple of things to get to know how everything works. I've made an activity which implements onTouchListener. I've overridden onTouch and have a switch on event.getAction():
此时此刻，我正在忙着做一些事情来了解一切是如何运作的。我做了一个实现 onTouchListener 的活动。我已经覆盖了 onTouch 并且在 event.getAction() 上有一个开关：
public boolean onTouch(View v, MotionEvent event)
{
float x;
float y;
switch (event.getAction())
{
case MotionEvent.ACTION_DOWN: // gets called
{
x = event.getX();
y = event.getY();
circle c = new circle(this, x, y, 10, 0xFFFFFF);
_main.addView(c, tapCount++);
break;
}
case MotionEvent.ACTION_MOVE: // doesnt seem to do anything
{
x = event.getX();
y = event.getY();
circle c = new circle(this, x, y, 10, 0xFFFFFF);
_main.addView(c, tapCount++);
break;
}
}
return false;
}
Where "circle" is a class which draws a circle.
其中“circle”是一个绘制圆圈的类。
What I expected to see was a trail of circles as I dragged my finger over the screen. In stead, the circle is only being drawn when I start touching.
当我将手指拖过屏幕时，我期望看到的是一串圆圈。相反，只有当我开始触摸时才会绘制圆圈。
I have compared my code to examples (for example: this blogpost by Google: http://android-developers.blogspot.com/2010/06/making-sense-of-multitouch.html) and I can't find my mistake.
我将我的代码与示例进行了比较（例如：Google 的这篇博文：http: //android-developers.blogspot.com/2010/06/making-sense-of-multitouch.html），但我找不到我的错误.
EDIT: Link to the full class: http://pastebin.com/tVDQjQhu
编辑：完整课程的链接：http: //pastebin.com/tVDQjQhu
EDIT: Fixed. One has to return true in the onTouch() function. d'oh!
编辑：固定。必须在 onTouch() 函数中返回 true。哦！
回答by Saurabh Verma
I was having the same problem while using MotionEvent.ACTION_MOVE.
For MotionEvent.ACTION_MOVEto work, return true instead of false.
我在使用时遇到了同样的问题MotionEvent.ACTION_MOVE。为了MotionEvent.ACTION_MOVE工作，返回 true 而不是 false。
回答by QAMAR
For me Solution was
对我来说解决方案是
return true
in the onTouch function as you should use this
在 onTouch 功能中，因为您应该使用它
public boolean onTouch(View v, MotionEvent event){
float x;
float y;
switch (event.getAction())
{
case MotionEvent.ACTION_DOWN: // gets called
{
x = event.getX();
y = event.getY();
circle c = new circle(this, x, y, 10, 0xFFFFFF);
_main.addView(c, tapCount++);
break;
}
case MotionEvent.ACTION_MOVE: // doesnt seem to do anything
{
x = event.getX();
y = event.getY();
circle c = new circle(this, x, y, 10, 0xFFFFFF);
_main.addView(c, tapCount++);
break;
}
}
return true; //the problem was here
}
}
when you return false from onTouch(View v, MotionEvent event) then only MotionEvent.ACTION_DOWN will be called. so you should return true from this function
当您从 onTouch(View v, MotionEvent event) 返回 false 时，只会调用 MotionEvent.ACTION_DOWN 。所以你应该从这个函数返回 true
Hope this is helps
希望这有帮助
回答by ayinozendy
Had the same problems too, I don't know if it's a bug or not, but I managed to make it work by adding OnClickListenerto the implementation, and implementing public void onClick(View v)then also adding setOnClickListener(this)on the constructor.
也有同样的问题，我不知道这是否是一个错误，但我设法通过添加OnClickListener到实现中来使它工作，然后实现public void onClick(View v)然后添加setOnClickListener(this)到构造函数中。
