1.前言

在开发中，会有需求实现控件在屏幕随意拖动，这就需要自定义View,然后在OnTouchEvent事件中，处理MotionEvent.ACTION_MOVE事件，然后通过坐标点传值给onlayout方法,来实现控件的任意拖动，具体代码如下：

import android.content.Context;import android.util.AttributeSet;import android.view.Display;import android.view.MotionEvent;import android.view.WindowManager;import android.widget.LinearLayout;public class DragLineLayout extends LinearLayout { private int mWidth; private int mHeight; private int mScreenWidth; private int mScreenHeight; private Context mContext; private onLocationListener mLocationListener; //是否拖动 private boolean isDrag = false; public boolean isDrag() { return isDrag; } public DragView(Context context, AttributeSet attrs) { super(context, attrs); this.mContext = context; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); mWidth = getMeasuredWidth(); mHeight = getMeasuredHeight(); mScreenWidth = getScreenWidth(mContext); mScreenHeight = getScreenHeight(mContext) - getStatusBarHeight(); } public int getStatusBarHeight() { int resourceId = mContext.getResources().getIdentifier("status_bar_height", "dimen", "android"); return mContext.getResources().getDimensionPixelSize(resourceId); } public int getScreenWidth(Context context) { WindowManager manager = (WindowManager) context .getSystemService(Context.WINDOW_SERVICE); Display display = manager.getDefaultDisplay(); return display.getWidth(); } public int getScreenHeight(Context context) { WindowManager manager = (WindowManager) context .getSystemService(Context.WINDOW_SERVICE); Display display = manager.getDefaultDisplay(); return display.getHeight(); } private float mDownX; private float mDownY; @Override public boolean onTouchEvent(MotionEvent event) { super.onTouchEvent(event); if (this.isEnabled()) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: isDrag = false; mDownX = event.getX(); mDownY = event.getY(); break; case MotionEvent.ACTION_MOVE: final float mXdistance = event.getX() - mDownX; final float mYdistance = event.getY() - mDownY; int l, r, t, b; //当水平或者垂直滑动距离大于10,才算是拖动事件 if (Math.abs(mXdistance) > 10 || Math.abs(mYdistance) > 10) { isDrag = true; l = (int) (getLeft() + mXdistance); r = l + mWidth; t = (int) (getTop() + mYdistance); b = t + mHeight; //边界判断,不让布局滑出界面 if (l < 0) { l = 0; r = l + mWidth; } else if (r > mScreenWidth) { r = mScreenWidth; l = r - mWidth; } if (t < 0) { t = 0; b = t + mHeight; } else if (b > mScreenHeight) { b = mScreenHeight; t = b - mHeight; } //回调移动后的坐标点 if(mLocationListener!=null){ mLocationListener.locationRect((l+r)/2,(t+b)/2); } this.layout(l, t, r, b); } break; case MotionEvent.ACTION_UP: setPressed(false); break; case MotionEvent.ACTION_CANCEL: setPressed(false); break; } return true; } return false; } public void setLocationListener(onLocationListener LocationListener) { this.mLocationListener = LocationListener; } public interface onLocationListener { void locationRect(float locationX, float locationY); }}

2.在代码中的运用

<com.xinrui.guestservice.view.DragLineLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="@dimen/dp_200" android:layout_height="@dimen/dp_110" android:orientation="vertical"> <RelativeLayout android:layout_width="match_parent" android:layout_height="@dimen/dp_50"> <EditText android:id="@+id/input_edt" android:layout_width="match_parent" android:layout_height="@dimen/dp_50" android:background="@drawable/edit_bg" /> </RelativeLayout> <RelativeLayout android:layout_width="match_parent" android:layout_height="@dimen/dp_55" android:layout_marginTop="@dimen/margin_5" android:background="@drawable/paint_bg"> <TextView android:id="@+id/paint_typeface" android:layout_width="@dimen/dp_50" android:layout_height="@dimen/dp_50" android:layout_alignParentLeft="true" android:layout_alignParentTop="true" android:layout_marginTop="@dimen/margin_5" android:background="@drawable/main_selector_write" android:clickable="true" /> <TextView android:id="@+id/paint_fontsize" android:layout_width="@dimen/dp_50" android:layout_height="@dimen/dp_50" android:layout_alignParentTop="true" android:layout_marginLeft="@dimen/dp_10" android:layout_marginTop="@dimen/margin_5" android:layout_toRightOf="@id/paint_typeface" android:background="@drawable/main_selector_write" android:clickable="true" /> </RelativeLayout></com.xinrui.guestservice.view.DragLineLayout>

3.这样就可以在Activity 加载这个xml 来实现任意拖动功能

总结

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