Android实现控件的缩放移动功能

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/**
 * 计算两个手指间的距离
 * @param event 触摸事件
 * @return 放回两个手指之间的距离
 */
 private float distance(MotionEvent event) {
 float x = event.getX(0) - event.getX(1);
 float y = event.getY(0) - event.getY(1);
 return (float) Math.sqrt(x * x + y * y);//两点间距离公式
 }

public class DragScaleView extends android.support.v7.widget.AppCompatImageView implements View.OnTouchListener {
 protected int screenWidth;
 protected int screenHeight;
 protected int lastX;
 protected int lastY;
 private int oriLeft;
 private int oriRight;
 private int oriTop;
 private int oriBottom;
 private int dragDirection;
 private static final int TOP = 0x15;
 private static final int LEFT = 0x16;
 private static final int BOTTOM = 0x17;
 private static final int RIGHT = 0x18;
 private static final int LEFT_TOP = 0x11;
 private static final int RIGHT_TOP = 0x12;
 private static final int LEFT_BOTTOM = 0x13;
 private static final int RIGHT_BOTTOM = 0x14;
 private static final int TOUCH_TWO = 0x21;
 private static final int CENTER = 0x19;
 private int offset = 0; //可超出其父控件的偏移量
 protected Paint paint = new Paint();
 private static final int touchDistance = 80; //触摸边界的有效距离
 // 初始的两个手指按下的触摸点的距离
 private float oriDis = 1f;
 /**
 * 初始化获取屏幕宽高
 */
 protected void initScreenW_H() {
 screenHeight = getResources().getDisplayMetrics().heightPixels - 40;
 screenWidth = getResources().getDisplayMetrics().widthPixels;
 }
 public DragScaleView(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 setOnTouchListener(this);
 initScreenW_H();
 }
 public DragScaleView(Context context, AttributeSet attrs) {
 super(context, attrs);
 setOnTouchListener(this);
 initScreenW_H();
 }
 public DragScaleView(Context context) {
 super(context);
 setOnTouchListener(this);
 initScreenW_H();
 }
 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 paint.setColor(Color.GRAY);
 paint.setStrokeWidth(4.0f);
 paint.setStyle(Paint.Style.STROKE);
 }
 @Override
 public boolean onTouch(View v, MotionEvent event) {
 setBackgroundResource(R.drawable.bg_dashgap);
 int action = event.getAction()& MotionEvent.ACTION_MASK;
 if (action == MotionEvent.ACTION_DOWN) {
 oriLeft = v.getLeft();
 oriRight = v.getRight();
 oriTop = v.getTop();
 oriBottom = v.getBottom();
 lastY = (int) event.getRawY();
 lastX = (int) event.getRawX();
 dragDirection = getDirection(v, (int) event.getX(),
  (int) event.getY());
 }
 if (action == MotionEvent.ACTION_POINTER_DOWN){
 oriLeft = v.getLeft();
 oriRight = v.getRight();
 oriTop = v.getTop();
 oriBottom = v.getBottom();
 lastY = (int) event.getRawY();
 lastX = (int) event.getRawX();
 dragDirection = TOUCH_TWO;
 oriDis = distance(event);
 }
 // 处理拖动事件
 delDrag(v, event, action);
 invalidate();
 return false;
 }
 /**
 * 处理拖动事件
 *
 * @param v
 * @param event
 * @param action
 */
 protected void delDrag(View v, MotionEvent event, int action) {
 switch (action) {
 case MotionEvent.ACTION_MOVE:
 int dx = (int) event.getRawX() - lastX;
 int dy = (int) event.getRawY() - lastY;
 switch (dragDirection) {
  case LEFT: // 左边缘
  left(v, dx);
  break;
  case RIGHT: // 右边缘
  right(v, dx);
  break;
  case BOTTOM: // 下边缘
  bottom(v, dy);
  break;
  case TOP: // 上边缘
  top(v, dy);
  break;
  case CENTER: // 点击中心-->>移动
  center(v, dx, dy);
  break;
  case LEFT_BOTTOM: // 左下
  left(v, dx);
  bottom(v, dy);
  break;
  case LEFT_TOP: // 左上
  left(v, dx);
  top(v, dy);
  break;
  case RIGHT_BOTTOM: // 右下
  right(v, dx);
  bottom(v, dy);
  break;
  case RIGHT_TOP: // 右上
  right(v, dx);
  top(v, dy);
  break;
  case TOUCH_TWO: //双指操控
  float newDist =distance(event);
  float scale = newDist / oriDis;
  //控制双指缩放的敏感度
  int distX = (int) (scale*(oriRight-oriLeft)-(oriRight-oriLeft))/50;
  int distY = (int) (scale*(oriBottom-oriTop)-(oriBottom-oriTop))/50;
  if (newDist>10f){//当双指的距离大于10时，开始相应处理
  left(v, -distX);
  top(v, -distY);
  right(v, distX);
  bottom(v, distY);
  }
  break;
 }
 if (dragDirection != CENTER) {
  v.layout(oriLeft, oriTop, oriRight, oriBottom);
 }
 lastX = (int) event.getRawX();
 lastY = (int) event.getRawY();
 break;
 case MotionEvent.ACTION_UP:
 case MotionEvent.ACTION_POINTER_UP:
 dragDirection = 0;
 break;
 }
 }
 /**
 * 触摸点为中心->>移动
 *
 * @param v
 * @param dx
 * @param dy
 */
 private void center(View v, int dx, int dy) {
 int left = v.getLeft() + dx;
 int top = v.getTop() + dy;
 int right = v.getRight() + dx;
 int bottom = v.getBottom() + dy;
 if (left <-offset) {
 left = -offset;
 right = left + v.getWidth();
 }
 if (right > screenWidth + offset) {
 right = screenWidth + offset;
 left = right - v.getWidth();
 }
 if (top <-offset) {
 top = -offset;
 bottom = top + v.getHeight();
 }
 if (bottom > screenHeight + offset) {
 bottom = screenHeight + offset;
 top = bottom - v.getHeight();
 }
 Log.d("raydrag", left+" "+top+" "+right+" "+bottom+" "+dx);
 v.layout(left, top, right, bottom);
 }
 /**
 * 触摸点为上边缘
 *
 * @param v
 * @param dy
 */
 private void top(View v, int dy) {
 oriTop += dy;
 if (oriTop <-offset) {
 //对view边界的处理，如果子view达到父控件的边界，offset代表允许超出父控件多少
 oriTop = -offset;
 }
 if (oriBottom - oriTop - 2 * offset <200) {
 oriTop = oriBottom - 2 * offset - 200;
 }
 }
 /**
 * 触摸点为下边缘
 *
 * @param v
 * @param dy
 */
 private void bottom(View v, int dy) {
 oriBottom += dy;
 if (oriBottom > screenHeight + offset) {
 oriBottom = screenHeight + offset;
 }
 if (oriBottom - oriTop - 2 * offset <200) {
 oriBottom = 200 + oriTop + 2 * offset;
 }
 }
 /**
 * 触摸点为右边缘
 *
 * @param v
 * @param dx
 */
 private void right(View v, int dx) {
 oriRight += dx;
 if (oriRight > screenWidth + offset) {
 oriRight = screenWidth + offset;
 }
 if (oriRight - oriLeft - 2 * offset <200) {
 oriRight = oriLeft + 2 * offset + 200;
 }
 }
 /**
 * 触摸点为左边缘
 *
 * @param v
 * @param dx
 */
 private void left(View v, int dx) {
 oriLeft += dx;
 if (oriLeft <-offset) {
 oriLeft = -offset;
 }
 if (oriRight - oriLeft - 2 * offset <200) {
 oriLeft = oriRight - 2 * offset - 200;
 }
 }
 /**
 * 获取触摸点flag
 *
 * @param v
 * @param x
 * @param y
 * @return
 */
 protected int getDirection(View v, int x, int y) {
 int left = v.getLeft();
 int right = v.getRight();
 int bottom = v.getBottom();
 int top = v.getTop();
 if (x