我想做一个简单的控件:一个里面有视图的容器。如果我触摸容器并移动手指，我想让视图跟着我的手指移动。
我应该使用什么样的容器(布局)?如何做到这一点?
我不需要使用一个表面，但一个简单的布局。
当前回答
触摸容器，视图将跟随您的手指。
xml代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="@+id/floating_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<ImageView
android:id="@+id/btn_chat"
android:layout_width="42dp"
android:layout_height="42dp"
/>
<LinearLayout>
Java代码
public class DashBoardActivity extends Activity implements View.OnClickListener, View.OnTouchListener {
float dX;
float dY;
int lastAction;
LinearLayout floatingLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dashboard);
floatingLayout = findViewById(R.id.floating_layout);
floatingLayout.setOnTouchListener(this);
@Override
public boolean onTouch(View view, MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
dX = view.getX() - event.getRawX();
dY = view.getY() - event.getRawY();
lastAction = MotionEvent.ACTION_DOWN;
break;
case MotionEvent.ACTION_MOVE:
view.setY(event.getRawY() + dY);
view.setX(event.getRawX() + dX);
lastAction = MotionEvent.ACTION_MOVE;
break;
case MotionEvent.ACTION_UP:
if (lastAction == MotionEvent.ACTION_DOWN)
Toast.makeText(DashBoardActivity.this, "Clicked!", Toast.LENGTH_SHORT).show();
break;
default:
return false;
}
return true;
}
}
其他回答
就像这样:
public class MyActivity extends Activity implements View.OnTouchListener {
TextView _view;
ViewGroup _root;
private int _xDelta;
private int _yDelta;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
_root = (ViewGroup)findViewById(R.id.root);
_view = new TextView(this);
_view.setText("TextView!!!!!!!!");
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(150, 50);
layoutParams.leftMargin = 50;
layoutParams.topMargin = 50;
layoutParams.bottomMargin = -250;
layoutParams.rightMargin = -250;
_view.setLayoutParams(layoutParams);
_view.setOnTouchListener(this);
_root.addView(_view);
}
public boolean onTouch(View view, MotionEvent event) {
final int X = (int) event.getRawX();
final int Y = (int) event.getRawY();
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
_xDelta = X - lParams.leftMargin;
_yDelta = Y - lParams.topMargin;
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_POINTER_DOWN:
break;
case MotionEvent.ACTION_POINTER_UP:
break;
case MotionEvent.ACTION_MOVE:
RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
layoutParams.leftMargin = X - _xDelta;
layoutParams.topMargin = Y - _yDelta;
layoutParams.rightMargin = -250;
layoutParams.bottomMargin = -250;
view.setLayoutParams(layoutParams);
break;
}
_root.invalidate();
return true;
}}
在main.xml中只需要RelativeLayout + @+id/root即可
改变了一点由@Vyacheslav Shylkin提供的解决方案，以删除手动输入数字的依赖性。
import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewTreeObserver;
import android.widget.ImageView;
import android.widget.RelativeLayout;
public class MainActivity extends Activity implements View.OnTouchListener
{
private int _xDelta;
private int _yDelta;
private int _rightMargin;
private int _bottomMargin;
private ImageView _floatingView;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this._floatingView = (ImageView) findViewById(R.id.textView);
this._floatingView.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener()
{
@Override
public boolean onPreDraw()
{
if (_floatingView.getViewTreeObserver().isAlive())
_floatingView.getViewTreeObserver().removeOnPreDrawListener(this);
updateLayoutParams(_floatingView);
return false;
}
});
this._floatingView.setOnTouchListener(this);
}
private void updateLayoutParams(View view)
{
this._rightMargin = -view.getMeasuredWidth();
this._bottomMargin = -view.getMeasuredHeight();
RelativeLayout.LayoutParams layoutParams = new RelativeLayout.LayoutParams(view.getMeasuredWidth(), view.getMeasuredHeight());
layoutParams.bottomMargin = this._bottomMargin;
layoutParams.rightMargin = this._rightMargin;
view.setLayoutParams(layoutParams);
}
@Override
public boolean onTouch(View view, MotionEvent event)
{
if (view == this._floatingView)
{
final int X = (int) event.getRawX();
final int Y = (int) event.getRawY();
switch (event.getAction() & MotionEvent.ACTION_MASK)
{
case MotionEvent.ACTION_DOWN:
RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
this._xDelta = X - lParams.leftMargin;
this._yDelta = Y - lParams.topMargin;
break;
case MotionEvent.ACTION_MOVE:
RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) view.getLayoutParams();
layoutParams.leftMargin = X - this._xDelta;
layoutParams.topMargin = Y - this._yDelta;
layoutParams.rightMargin = this._rightMargin;
layoutParams.bottomMargin = this._bottomMargin;
view.setLayoutParams(layoutParams);
break;
}
return true;
}
else
{
return false;
}
}
}
创建一个自定义的触摸监听器类(在Kotlin中):
(这段代码限制了视图从父视图中拖出)
class CustomTouchListener(
val screenWidth: Int,
val screenHeight: Int
) : View.OnTouchListener {
private var dX: Float = 0f
private var dY: Float = 0f
override fun onTouch(view: View, event: MotionEvent): Boolean {
val newX: Float
val newY: Float
when (event.action) {
MotionEvent.ACTION_DOWN -> {
dX = view.x - event.rawX
dY = view.y - event.rawY
}
MotionEvent.ACTION_MOVE -> {
newX = event.rawX + dX
newY = event.rawY + dY
if ((newX <= 0 || newX >= screenWidth - view.width) || (newY <= 0 || newY >= screenHeight - view.height)) {
return true
}
view.animate()
.x(newX)
.y(newY)
.setDuration(0)
.start()
}
}
return true
}
}
如何使用它?
parentView.viewTreeObserver.addOnGlobalLayoutListener { view.setOnTouchListener(CustomTouchListener(parentView.width, parentView.height)) }
parentView是视图的父视图。
我发现了一个简单的方法来做到这一点与ViewPropertyAnimator:
float dX, dY;
@Override
public boolean onTouch(View view, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
dX = view.getX() - event.getRawX();
dY = view.getY() - event.getRawY();
break;
case MotionEvent.ACTION_MOVE:
view.animate()
.x(event.getRawX() + dX)
.y(event.getRawY() + dY)
.setDuration(0)
.start();
break;
default:
return false;
}
return true;
}
触摸容器，视图将跟随您的手指。
xml代码
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="@+id/floating_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<ImageView
android:id="@+id/btn_chat"
android:layout_width="42dp"
android:layout_height="42dp"
/>
<LinearLayout>
Java代码
public class DashBoardActivity extends Activity implements View.OnClickListener, View.OnTouchListener {
float dX;
float dY;
int lastAction;
LinearLayout floatingLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_dashboard);
floatingLayout = findViewById(R.id.floating_layout);
floatingLayout.setOnTouchListener(this);
@Override
public boolean onTouch(View view, MotionEvent event) {
switch (event.getActionMasked()) {
case MotionEvent.ACTION_DOWN:
dX = view.getX() - event.getRawX();
dY = view.getY() - event.getRawY();
lastAction = MotionEvent.ACTION_DOWN;
break;
case MotionEvent.ACTION_MOVE:
view.setY(event.getRawY() + dY);
view.setX(event.getRawX() + dX);
lastAction = MotionEvent.ACTION_MOVE;
break;
case MotionEvent.ACTION_UP:
if (lastAction == MotionEvent.ACTION_DOWN)
Toast.makeText(DashBoardActivity.this, "Clicked!", Toast.LENGTH_SHORT).show();
break;
default:
return false;
}
return true;
}
}
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