控件的拖动,使用到一个监听事件
setOnTouchListener:
XML代码:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"> <ImageView
android:id="@+id/textview"
android:src="@drawable/ic_launcher_foreground"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="@color/colorPrimaryDark"
android:text="www.baidu.com"/> </LinearLayout>
JAVA代码
package com.example.a11658.textviewdrag; import android.annotation.SuppressLint;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView; public class MainActivity extends AppCompatActivity {
private ImageView tv;
private int x;
private int y; @SuppressLint("ClickableViewAccessibility")
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); tv = findViewById(R.id.textview);
tv.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
//手指按下
//获取第一次接触屏幕
x = (int) event.getRawX();
y = (int) event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
//手指拖动
//获取距离差
int dx = (int) event.getRawX() - x;
int dy = (int) event.getRawY() - y;
//更改Imageview在窗体的位置
v.layout(v.getLeft() + dx, v.getTop() + dy,
v.getRight() + dx, v.getBottom() + dy);
//获取移动后的位置
x = (int) event.getRawX();
y = (int) event.getRawY();
break;
case MotionEvent.ACTION_UP:
//手指弹起
x = (int) event.getRawX();
y = (int) event.getRawY();
break;
}
return true;
}
});
}
}
view.layout(left, top, right, bottom)实现拖动。
1.按下图搞懂几个坐标
视图宽度 view.getWidth();
视图高度 view.getHeight()
橘色线：view.getLeft()
蓝色线：view.getRight()
红色线：view.getTop()
粉色线：view.getBottom()
上下左右的偏移都是相对于（0.0）来说
