android可拖拽放缩ImageView

/**** * 这里你要明白几个方法执行的流程： 首先ImageView是继承自View的子类. * onLayout方法：是一个回调方法.该方法会在在View中的layout方法中执行，在执行layout方法前面会首先执行setFrame方法. * layout方法： * setFrame方法：判断我们的View是否发生变化，如果发生变化，那么将最新的l，t，r，b传递给View，然后刷新进行动态更新UI. * 并且返回ture.没有变化返回false. *  * invalidate方法：用于刷新当前控件, */public class DragImageView extends ImageView {private Activity mActivity;private int screen_W, screen_H;// 可见屏幕的宽高度private int bitmap_W, bitmap_H;// 当前图片宽高private int MAX_W, MAX_H, MIN_W, MIN_H;// 极限值private int current_Top, current_Right, current_Bottom, current_Left;// 当前图片上下左右坐标private int start_Top = -1, start_Right = -1, start_Bottom = -1,start_Left = -1;// 初始化默认位置.private int start_x, start_y, current_x, current_y;// 触摸位置private float beforeLenght, afterLenght;// 两触点距离private float scale_temp;// 缩放比例/** * 模式 NONE：无 DRAG：拖拽. ZOOM:缩放 *  * @author zhangjia *  */private enum MODE {NONE, DRAG, ZOOM};private MODE mode = MODE.NONE;// 默认模式private boolean isControl_V = false;// 垂直监控private boolean isControl_H = false;// 水平监控private ScaleAnimation scaleAnimation;// 缩放动画private boolean isScaleAnim = false;// 缩放动画private MyAsyncTask myAsyncTask;// 异步动画/** 构造方法 **/public DragImageView(Context context) {super(context);}public void setmActivity(Activity mActivity) {this.mActivity = mActivity;}/** 可见屏幕宽度 **/public void setScreen_W(int screen_W) {this.screen_W = screen_W;}/** 可见屏幕高度 **/public void setScreen_H(int screen_H) {this.screen_H = screen_H;}public DragImageView(Context context, AttributeSet attrs) {super(context, attrs);}/*** * 设置显示图片 */@Overridepublic void setImageBitmap(Bitmap bm) {super.setImageBitmap(bm);/** 获取图片宽高 **/bitmap_W = bm.getWidth();bitmap_H = bm.getHeight();MAX_W = bitmap_W * 3;MAX_H = bitmap_H * 3;MIN_W = bitmap_W / 2;MIN_H = bitmap_H / 2;}@Overrideprotected void onLayout(boolean changed, int left, int top, int right,int bottom) {super.onLayout(changed, left, top, right, bottom);if (start_Top == -1) {start_Top = top;start_Left = left;start_Bottom = bottom;start_Right = right;}}/*** * touch 事件 */@Overridepublic boolean onTouchEvent(MotionEvent event) {/** 处理单点、多点触摸 **/switch (event.getAction() & MotionEvent.ACTION_MASK) {case MotionEvent.ACTION_DOWN:onTouchDown(event);break;// 多点触摸case MotionEvent.ACTION_POINTER_DOWN:onPointerDown(event);break;case MotionEvent.ACTION_MOVE:onTouchMove(event);break;case MotionEvent.ACTION_UP:mode = MODE.NONE;break;// 多点松开case MotionEvent.ACTION_POINTER_UP:mode = MODE.NONE;/** 执行缩放还原 **/if (isScaleAnim) {doScaleAnim();}break;}return true;}/** 按下 **/void onTouchDown(MotionEvent event) {mode = MODE.DRAG;current_x = (int) event.getRawX();current_y = (int) event.getRawY();start_x = (int) event.getX();start_y = current_y - this.getTop();}/** 两个手指 只能放大缩小 **/void onPointerDown(MotionEvent event) {if (event.getPointerCount() == 2) {mode = MODE.ZOOM;beforeLenght = getDistance(event);// 获取两点的距离}}/** 移动的处理 **/void onTouchMove(MotionEvent event) {int left = 0, top = 0, right = 0, bottom = 0;/** 处理拖动 **/if (mode == MODE.DRAG) {/** 在这里要进行判断处理，防止在drag时候越界 **//** 获取相应的l，t,r ,b **/left = current_x - start_x;right = current_x + this.getWidth() - start_x;top = current_y - start_y;bottom = current_y - start_y + this.getHeight();/** 水平进行判断 **/if (isControl_H) {if (left >= 0) {left = 0;right = this.getWidth();}if (right <= screen_W) {left = screen_W - this.getWidth();right = screen_W;}} else {left = this.getLeft();right = this.getRight();}/** 垂直判断 **/if (isControl_V) {if (top >= 0) {top = 0;bottom = this.getHeight();}if (bottom <= screen_H) {top = screen_H - this.getHeight();bottom = screen_H;}} else {top = this.getTop();bottom = this.getBottom();}if (isControl_H || isControl_V)this.setPosition(left, top, right, bottom);current_x = (int) event.getRawX();current_y = (int) event.getRawY();}/** 处理缩放 **/else if (mode == MODE.ZOOM) {afterLenght = getDistance(event);// 获取两点的距离float gapLenght = afterLenght - beforeLenght;// 变化的长度if (Math.abs(gapLenght) > 5f) {scale_temp = afterLenght / beforeLenght;// 求的缩放的比例this.setScale(scale_temp);beforeLenght = afterLenght;}}}/** 获取两点的距离 **/float getDistance(MotionEvent event) {float x = event.getX(0) - event.getX(1);float y = event.getY(0) - event.getY(1);return FloatMath.sqrt(x * x + y * y);}/** 实现处理拖动 **/private void setPosition(int left, int top, int right, int bottom) {this.layout(left, top, right, bottom);}/** 处理缩放 **/void setScale(float scale) {int disX = (int) (this.getWidth() * Math.abs(1 - scale)) / 4;// 获取缩放水平距离int disY = (int) (this.getHeight() * Math.abs(1 - scale)) / 4;// 获取缩放垂直距离// 放大if (scale > 1 && this.getWidth() <= MAX_W) {current_Left = this.getLeft() - disX;current_Top = this.getTop() - disY;current_Right = this.getRight() + disX;current_Bottom = this.getBottom() + disY;this.setFrame(current_Left, current_Top, current_Right,current_Bottom);/*** * 此时因为考虑到对称，所以只做一遍判断就可以了。 */if (current_Top <= 0 && current_Bottom >= screen_H) {//Log.e("jj", "屏幕高度=" + this.getHeight());isControl_V = true;// 开启垂直监控} else {isControl_V = false;}if (current_Left <= 0 && current_Right >= screen_W) {isControl_H = true;// 开启水平监控} else {isControl_H = false;}}// 缩小else if (scale < 1 && this.getWidth() >= MIN_W) {current_Left = this.getLeft() + disX;current_Top = this.getTop() + disY;current_Right = this.getRight() - disX;current_Bottom = this.getBottom() - disY;/*** * 在这里要进行缩放处理 */// 上边越界if (isControl_V && current_Top > 0) {current_Top = 0;current_Bottom = this.getBottom() - 2 * disY;if (current_Bottom < screen_H) {current_Bottom = screen_H;isControl_V = false;// 关闭垂直监听}}// 下边越界if (isControl_V && current_Bottom < screen_H) {current_Bottom = screen_H;current_Top = this.getTop() + 2 * disY;if (current_Top > 0) {current_Top = 0;isControl_V = false;// 关闭垂直监听}}// 左边越界if (isControl_H && current_Left >= 0) {current_Left = 0;current_Right = this.getRight() - 2 * disX;if (current_Right <= screen_W) {current_Right = screen_W;isControl_H = false;// 关闭}}// 右边越界if (isControl_H && current_Right <= screen_W) {current_Right = screen_W;current_Left = this.getLeft() + 2 * disX;if (current_Left >= 0) {current_Left = 0;isControl_H = false;// 关闭}}if (isControl_H || isControl_V) {this.setFrame(current_Left, current_Top, current_Right,current_Bottom);} else {this.setFrame(current_Left, current_Top, current_Right,current_Bottom);isScaleAnim = true;// 开启缩放动画}}}/*** * 缩放动画处理 */public void doScaleAnim() {myAsyncTask = new MyAsyncTask(screen_W, this.getWidth(),this.getHeight());myAsyncTask.setLTRB(this.getLeft(), this.getTop(), this.getRight(),this.getBottom());myAsyncTask.execute();isScaleAnim = false;// 关闭动画}/*** * 回缩动画執行 */class MyAsyncTask extends AsyncTask<Void, Integer, Void> {private int screen_W, current_Width, current_Height;private int left, top, right, bottom;private float scale_WH;// 宽高的比例/** 当前的位置属性 **/public void setLTRB(int left, int top, int right, int bottom) {this.left = left;this.top = top;this.right = right;this.bottom = bottom;}private float STEP = 8f;// 步伐private float step_H, step_V;// 水平步伐，垂直步伐public MyAsyncTask(int screen_W, int current_Width, int current_Height) {super();this.screen_W = screen_W;this.current_Width = current_Width;this.current_Height = current_Height;scale_WH = (float) current_Height / current_Width;step_H = STEP;step_V = scale_WH * STEP;}@Overrideprotected Void doInBackground(Void... params) {while (current_Width <= screen_W) {left -= step_H;top -= step_V;right += step_H;bottom += step_V;current_Width += 2 * step_H;left = Math.max(left, start_Left);top = Math.max(top, start_Top);right = Math.min(right, start_Right);bottom = Math.min(bottom, start_Bottom);                Log.e("jj", "top="+top+",bottom="+bottom+",left="+left+",right="+right);onProgressUpdate(new Integer[] { left, top, right, bottom });try {Thread.sleep(10);} catch (InterruptedException e) {e.printStackTrace();}}return null;}@Overrideprotected void onProgressUpdate(final Integer... values) {super.onProgressUpdate(values);mActivity.runOnUiThread(new Runnable() {@Overridepublic void run() {setFrame(values[0], values[1], values[2], values[3]);}});}}}

具体使用方式如下:

public class MainActivity extends Activity {private int window_width, window_height;private DragImageView dragImageView;private int state_height;private ViewTreeObserver viewTreeObserver;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE);setContentView(R.layout.main);WindowManager manager = getWindowManager();window_width = manager.getDefaultDisplay().getWidth();window_height = manager.getDefaultDisplay().getHeight();dragImageView = (DragImageView) findViewById(R.id.div_main);Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.huoying);dragImageView.setImageBitmap(bmp);dragImageView.setmActivity(this);/**控制不会无限变小**/viewTreeObserver = dragImageView.getViewTreeObserver();viewTreeObserver.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {@Overridepublic void onGlobalLayout() {if (state_height == 0) {Rect frame = new Rect();getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);state_height = frame.top;dragImageView.setScreen_H(window_height-state_height);dragImageView.setScreen_W(window_width);}}});}}