/**
*在网上找了一个图片裁剪算法，当执行最后一个方法getCroppedBitmap（）时报出异常信息：java.lang.IllegalArgumentException:y must be >=0，经调试发现y的确小于0，但我不知道代*码里面到底是哪里出错了。请指导问题的大侠可以指出问题，最好把完整的代码页贴出来，先感谢了！
**/

package com.jean.imagecroptool;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Point;
import android.graphics.PointF;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.ImageView;

public class CropView extends ImageView {

 Paint paint = new Paint();
 private int initial_size = 300;
 private static Point leftTop, rightBottom, center, previous;// yellow
                // rectangle

 private static final int DRAG = 0;
 private static final int LEFT = 1;
 private static final int TOP = 2;
 private static final int RIGHT = 3;
 private static final int BOTTOM = 4;

 private int imageScaledWidth, imageScaledHeight;

 // Adding parent class constructors
 public CropView(Context context) {
  super(context);
  initCropView();
 }

 public CropView(Context context, AttributeSet attrs) {
  super(context, attrs, 0);
  initCropView();
 }

 public CropView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
  initCropView();
 }

 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  if (leftTop.equals(0, 0))
   resetPoints();
  canvas.drawRect(leftTop.x, leftTop.y, rightBottom.x, rightBottom.y,
    paint);
 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  int eventaction = event.getAction();
  switch (eventaction) {
  case MotionEvent.ACTION_DOWN:
   previous.set((int) event.getX(), (int) event.getY());
   break;
  case MotionEvent.ACTION_MOVE:
   if (isActionInsideRectangle(event.getX(), event.getY())) {
    adjustRectangle((int) event.getX(), (int) event.getY());
    invalidate(); // redraw rectangle
    previous.set((int) event.getX(), (int) event.getY());
   }
   break;
  case MotionEvent.ACTION_UP:
   previous = new Point();
   break;
  }
  return true;
 }

 private void initCropView() {
  paint.setColor(Color.YELLOW);
  paint.setStyle(Style.STROKE);
  paint.setStrokeWidth(5);
  leftTop = new Point();
  rightBottom = new Point();
  center = new Point();
  previous = new Point();
 }

 public void resetPoints() {
  center.set(getWidth() / 2, getHeight() / 2);
  leftTop.set((getWidth() - initial_size) / 2,
    (getHeight() - initial_size) / 2);
  rightBottom.set(leftTop.x + initial_size, leftTop.y + initial_size);
 }

 private static boolean isActionInsideRectangle(float x, float y) {
  int buffer = 10;
  return (x >= (leftTop.x - buffer) && x <= (rightBottom.x + buffer)
    && y >= (leftTop.y - buffer) && y <= (rightBottom.y + buffer)) ? true
    : false;
 }

 private boolean isInImageRange(PointF point) {
  // Get image matrix values and place them in an array
  float[] f = new float[9];
  getImageMatrix().getValues(f);

  // Calculate the scaled dimensions
  imageScaledWidth = Math.round(getDrawable().getIntrinsicWidth()
    * f[Matrix.MSCALE_X]);
  imageScaledHeight = Math.round(getDrawable().getIntrinsicHeight()
    * f[Matrix.MSCALE_Y]);

  return (point.x >= (center.x - (imageScaledWidth / 2))
    && point.x <= (center.x + (imageScaledWidth / 2))
    && point.y >= (center.y - (imageScaledHeight / 2)) && point.y <= (center.y + (imageScaledHeight / 2))) ? true
    : false;
 }

 private void adjustRectangle(int x, int y) {
  int movement;
  switch (getAffectedSide(x, y)) {
  case LEFT:
   movement = x - leftTop.x;
   if (isInImageRange(new PointF(leftTop.x + movement, leftTop.y
     + movement)))
    leftTop.set(leftTop.x + movement, leftTop.y + movement);
   break;
  case TOP:
   movement = y - leftTop.y;
   if (isInImageRange(new PointF(leftTop.x + movement, leftTop.y
     + movement)))
    leftTop.set(leftTop.x + movement, leftTop.y + movement);
   break;
  case RIGHT:
   movement = x - rightBottom.x;
   if (isInImageRange(new PointF(rightBottom.x + movement,
     rightBottom.y + movement)))
    rightBottom.set(rightBottom.x + movement, rightBottom.y
      + movement);
   break;
  case BOTTOM:
   movement = y - rightBottom.y;
   if (isInImageRange(new PointF(rightBottom.x + movement,
     rightBottom.y + movement)))
    rightBottom.set(rightBottom.x + movement, rightBottom.y
      + movement);
   break;
  case DRAG:
   movement = x - previous.x;
   int movementY = y - previous.y;
   if (isInImageRange(new PointF(leftTop.x + movement, leftTop.y
     + movementY))
     && isInImageRange(new PointF(rightBottom.x + movement,
       rightBottom.y + movementY))) {
    leftTop.set(leftTop.x + movement, leftTop.y + movementY);
    rightBottom.set(rightBottom.x + movement, rightBottom.y
      + movementY);
   }
   break;
  }
 }

 private static int getAffectedSide(float x, float y) {
  int buffer = 10;
  if (x >= (leftTop.x - buffer) && x <= (leftTop.x + buffer))
   return LEFT;
  else if (y >= (leftTop.y - buffer) && y <= (leftTop.y + buffer))
   return TOP;
  else if (x >= (rightBottom.x - buffer) && x <= (rightBottom.x + buffer))
   return RIGHT;
  else if (y >= (rightBottom.y - buffer) && y <= (rightBottom.y + buffer))
   return BOTTOM;
  else
   return DRAG;
 }

 public Bitmap getCroppedBitmap() {
  BitmapDrawable drawable = (BitmapDrawable) getDrawable();
//这里的x和y也不知道为什么是这样写的
  float x = leftTop.x - center.x + (drawable.getBitmap().getWidth() / 2);
  float y = leftTop.y - center.y + (drawable.getBitmap().getHeight() / 2);
  Bitmap cropped = Bitmap.createBitmap(drawable.getBitmap(), (int) x,
    (int) y, (int) rightBottom.x - (int) leftTop.x,
    (int) rightBottom.y - (int) leftTop.y);
  ByteArrayOutputStream stream = new ByteArrayOutputStream();
  cropped.compress(Bitmap.CompressFormat.PNG, 100, stream);

  return cropped;

 }

}