image

项目需求：过程中要实现能在页面中随意的拖动，刚开始实现是用悬浮球的形式进行实现，因为之前项目中用过，实现后发现用户每次安装后，都有权限的限制，甚至有些用户关闭悬浮球权限之后，不知道怎么在手机上打开悬浮球的权限，这样的话用户体验很不好，所以自己重新自定义实现在页面中拖动，不需要请求权限。

第一步：废话少说效果图

image.png

image.png

第二步自定义view拖动的的实现：

    /**
   *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;
}

}

附录 工具包

 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());
}

    }

第三步xml：

   <com.dragdemo.DragView
   android:id="@+id/iv_drag"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_gravity="center"
   android:src="@mipmap/xue" />

第四步Mainactivity：

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();
            }

        }
    });
}
}