Android实现拖动效果的两种方法
时间：2020-12-14 14:37:39 | 栏目：Android代码 | 点击：次
因为最近项目的需要，需要实现一个拖动效果，看了一下网上刚好有这种拖动效果的demo,代码大概如下：
private void initListener(){
screenWidth = getScreenWidth(this);//获取屏幕宽度
screenHeight = getScreenHeight(this) - getStatusHeight(MainActivity.this);//屏幕高度-状态栏
testTv.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
int dx = (int) event.getRawX() - lastX;
int dy = (int) event.getRawY() - lastY;
int top = v.getTop() + dy;
int left = v.getLeft() + dx;
if (top <= 0) {
top = 0;
}
if (top >= screenHeight - testTv.getHeight() ) {
top = screenHeight - testTv.getHeight();
}
if (left >= screenWidth - testTv.getWidth()) {
left = screenWidth - testTv.getWidth();
}
if (left <= 0) {
left = 0;
}
v.layout(left, top, left+v.getWidth(), top+v.getHeight());
v.postInvalidate();
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
break;
case MotionEvent.ACTION_UP:
break;
}
return true;//这里根据项目需要选择false与true
}
});
}
可是我的项目本身是有涂鸦的界面，还有很多复杂的事件，发现会有很奇怪的效果，抖动很厉害，而且时不时回到原来的位置，后来发现这个v.layout(left, top, left+v.getWidth(), top+v.getHeight());可能不适合项目的需求，所以我想了另一种解法。代码如下：
private void initListener(){
screenWidth = getScreenWidth(this);//获取屏幕宽度
screenHeight = getScreenHeight(this) - getStatusHeight(MainActivity.this);//屏幕高度-状态栏
testTv.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
int dx = (int) event.getRawX() - lastX;
int dy = (int) event.getRawY() - lastY;
int top = v.getTop() + dy;
int left = v.getLeft() + dx;
if (top <= 0) {
top = 0;
}
if (top >= screenHeight - testTv.getHeight() ) {
top = screenHeight - testTv.getHeight();
}
if (left >= screenWidth - testTv.getWidth()) {
left = screenWidth - testTv.getWidth();
}
if (left <= 0) {
left = 0;
}
RelativeLayout.LayoutParams param = new RelativeLayout.LayoutParams(v.getWidth(), v.getHeight());
param.leftMargin = left;
param.topMargin = top;
v.setLayoutParams(param);
// v.layout(left, top, left+v.getWidth(), top+v.getHeight());
v.postInvalidate();
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
break;
case MotionEvent.ACTION_UP:
break;
}
return true;
}
});
}
效果如下图：
觉得可以了，不过要注意一些事项：键盘弹出需要自己处理一下（比如处理成弹出键盘就不能移动这些，不然会变形的），我觉得这种写法可以应用于各种复杂的场景。好了，今天一些项目问题总结就到这里了，希望对大家有帮助，代码也上传了，地址如下:Android实现拖动效果