Android怎么实现可随意拖动的View效果

本篇内容主要讲解"Android怎么实现可随意拖动的View效果"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"Android怎么实现可随意拖动的View效果"吧!

自定义随意拖动View：

package com.dragdemo;import android.annotation.SuppressLint;import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.view.MotionEvent;import android.widget.ImageView;/** *随意拖动的view */@SuppressLint("AppCompatCustomView")public class DragView extends ImageView {  private int width;  private int height;  private int screenWidth;  private int screenHeight;  private Context context;  //是否拖动  private boolean isDrag=false;  public boolean isDrag() {    return isDrag;  }  public DragView(Context context, AttributeSet attrs) {    super(context, attrs);    this.context=context;  }  @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    super.onMeasure(widthMeasureSpec, heightMeasureSpec);    width=getMeasuredWidth();    height=getMeasuredHeight();    screenWidth= ScreenUtil.getScreenWidth(context);    screenHeight=ScreenUtil.getScreenHeight(context)-getStatusBarHeight();  }  public int getStatusBarHeight(){    int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android");    return getResources().getDimensionPixelSize(resourceId);  }  private float downX;  private float downY;  @Override  public boolean onTouchEvent(MotionEvent event) {    super.onTouchEvent(event);    if (this.isEnabled()) {      switch (event.getAction()) {        case MotionEvent.ACTION_DOWN:          isDrag=false;          downX = event.getX();          downY = event.getY();          break;        case MotionEvent.ACTION_MOVE:          Log.e("kid","ACTION_MOVE");          final float xDistance = event.getX() - downX;          final float yDistance = event.getY() - downY;          int l,r,t,b;          //当水平或者垂直滑动距离大于10,才算拖动事件          if (Math.abs(xDistance) >10 ||Math.abs(yDistance)>10) {            Log.e("kid","Drag");            isDrag=true;             l = (int) (getLeft() + xDistance);             r = l+width;             t = (int) (getTop() + yDistance);             b = t+height;            //不划出边界判断,此处应按照项目实际情况,因为本项目需求移动的位置是手机全屏,            // 所以才能这么写,如果是固定区域,要得到父控件的宽高位置后再做处理            if(l<0){              l=0;              r=l+width;            }else if(r>screenWidth){              r=screenWidth;              l=r-width;            }            if(t<0){              t=0;              b=t+height;            }else if(b>screenHeight){              b=screenHeight;              t=b-height;            }            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;  }}

用到的工具类：

package com.dragdemo;import android.content.Context;import android.util.DisplayMetrics;import android.view.Display;import android.view.View;import android.view.WindowManager;public class ScreenUtil {  private static int width = 0;  private static int height = 0;  private static int showHeight = 0;  private static int statusHeight = 0;  private static float density = 0;  public static int getScreenWidth(Context context) {    if (width == 0) {      WindowManager manager = (WindowManager) context          .getSystemService(Context.WINDOW_SERVICE);      Display display = manager.getDefaultDisplay();      width = display.getWidth();    }    return width;  }  public static int getScreenHeight(Context context) {    if (height == 0) {      WindowManager manager = (WindowManager) context          .getSystemService(Context.WINDOW_SERVICE);      Display display = manager.getDefaultDisplay();      height = display.getHeight();    }    return height;  }  public static int getScreenShowHeight(Context context) {    if (showHeight == 0) {      showHeight = getScreenHeight(context) - getStatusBarHeight(context);    }    return showHeight;  }  public static int getStatusBarHeight(Context context) {    if (statusHeight > 0) {      return statusHeight;    }    Class c = null;    Object obj = null;    java.lang.reflect.Field field = null;    int x = 0;    try {      c = Class.forName("com.android.internal.R$dimen");      obj = c.newInstance();      field = c.getField("status_bar_height");      x = Integer.parseInt(field.get(obj).toString());      statusHeight = context.getResources().getDimensionPixelSize(x);      return statusHeight;    } catch (Throwable e) {      e.printStackTrace();    }    return statusHeight;  }  public static float getScreenDensity(Context context) {    if (density == 0) {      try {        DisplayMetrics dm = new DisplayMetrics();        WindowManager manager = (WindowManager) context            .getSystemService(Context.WINDOW_SERVICE);        manager.getDefaultDisplay().getMetrics(dm);        density = dm.density;      } catch (Exception ex) {        ex.printStackTrace();        density = 1.0f;      }    }    return density;  }  public static float getScreentMinLength(Context context) {    return getScreenHeight(context) > getScreenWidth(context) ? getScreenWidth(context)        : getScreenHeight(context);  }  /**   * 根据指定k的系数获取屏幕在max范围内的最大长宽,默认宽比较小   *    * @param context   * @param k   * @return   */  public static DrawWrap getCutWrap(Context context, float k, float max) {    float tWidth = getScreenWidth(context);    float tHeight = getScreenHeight(context);    if (tWidth * max * k > tHeight) {      return new DrawWrap(tHeight * max / k, tHeight * max);    } else {      return new DrawWrap(tWidth * max, tWidth * max * k);    }  }  public static class DrawWrap {    public float width;    public float height;    public DrawWrap(float width, float height) {      this.width = width;      this.height = height;    }  }  public static int dip2px(Context context, float dipValue) {    return (int) (dipValue * getScreenDensity(context) + 0.5f);  }  /**   * 将sp值转换为px值，保证文字大小不变   *   * @param context   * @param spValue   *      （DisplayMetrics类中属性scaledDensity）   * @return   */  public static int sp2px(Context context, float spValue) {    final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;    return (int) (spValue * fontScale + 0.5f);  }  /**   * 根据手机的分辨率从 px(像素) 的单位 转成为 dp   */  public static int px2dip(Context context, float pxValue) {    final float scale = context.getResources().getDisplayMetrics().density;    return (int) (pxValue / scale + 0.5f);  }  /**   * 获取屏幕中控件顶部位置的高度--即控件顶部的Y点   *    * @return   */  public static int getScreenViewTopHeight(View view) {    return view.getTop();  }  /**   * 获取屏幕中控件底部位置的高度--即控件底部的Y点   *    * @return   */  public static int getScreenViewBottomHeight(View view) {    return view.getBottom();  }  /**   * 获取屏幕中控件左侧的位置--即控件左侧的X点   *    * @return   */  public static int getScreenViewLeftHeight(View view) {    return view.getLeft();  }  /**   * 获取屏幕中控件右侧的位置--即控件右侧的X点   *    * @return   */  public static int getScreenViewRightHeight(View view) {    return view.getRight();  }  /*   * 获取控件宽   */  public static int getWidth(View view) {    int w = View.MeasureSpec.makeMeasureSpec(0,        View.MeasureSpec.UNSPECIFIED);    int h = View.MeasureSpec.makeMeasureSpec(0,        View.MeasureSpec.UNSPECIFIED);    view.measure(w, h);    return (view.getMeasuredWidth());  }  /*   * 获取控件高   */  public static int getHeight(View view) {    int w = View.MeasureSpec.makeMeasureSpec(0,        View.MeasureSpec.UNSPECIFIED);    int h = View.MeasureSpec.makeMeasureSpec(0,        View.MeasureSpec.UNSPECIFIED);    view.measure(w, h);    return (view.getMeasuredHeight());  }}

XML文件：

MainActivity:package com.dragdemo;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.view.View;import android.widget.Toast;public class MainActivity extends AppCompatActivity {  DragView iv_drag;  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    iv_drag= (DragView) findViewById(R.id.iv_drag);    iv_drag.setOnClickListener(new View.OnClickListener() {      @Override      public void onClick(View v) {        if(!iv_drag.isDrag()){          Toast.makeText(MainActivity.this, "响应点击", Toast.LENGTH_SHORT).show();        }      }    });  }}

到此，相信大家对"Android怎么实现可随意拖动的View效果"有了更深的了解，不妨来实际操作一番吧！这里是网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！