Android实现图片的裁剪(不调用系统功能)

接上一篇文章：Android实现图片区域裁剪功能

上一篇文章提及了通过调用系统相册或拍照来实现图片的缩放\裁剪。不过这对于笔者项目的要求同样不适合,笔者需要的是通过对手机屏幕整个进行一个截图,并对这个截图进行裁剪操作。

依靠系统功能确实可以实现图片的裁剪，但是不够灵活。这里笔者提供一种较为灵活的做法。

但是这种做法的用户体验没有上篇文章的好，至于使用何种方法，读者应该自己衡量。

同样，我们先看实际效果图。

这里展示的是笔者项目的一小部分(阅读器):

我们点击左下角的剪切按钮

我们通过红色边框的四个角来控制裁剪的大小,移动红色框体来控制裁剪的位置区域。

接下来我们看看源码的实现：

首先点击剪切按钮的时候，我们应该生成一个Bitmap对象，传递给另一个Activty处理

具体做法如下：

cutP.setOnClickListener(new View.OnClickListener() { 

   public void onClick(View v) {
    //将一些按钮隐藏
    cutP.setVisibility(View.INVISIBLE);
    mTopBarSwitcher.setVisibility(View.INVISIBLE);
    mPageSlider.setVisibility(View.INVISIBLE);
    back.setVisibility(View.INVISIBLE);
    mPageNumberView.setVisibility(View.INVISIBLE);
    View view = MuPDFActivity.this.getWindow().getDecorView();
    if (false == view.isDrawingCacheEnabled()) {
     view.setDrawingCacheEnabled(true);
    }
    Bitmap bitmap = view.getDrawingCache();
    ImageView imgv = new ImageView(MuPDFActivity.this);
    imgv.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,
      LayoutParams.FILL_PARENT-200));
    imgv.setImageBitmap(bitmap);
    backBitmap = bitmap;
    //传递给另一个Activity进行裁剪
    Intent intent = new Intent();
    intent.setClass(MuPDFActivity.this, CutActivity.class);
    startActivity(intent); 

   } 

  });

Tips：这里笔者是将这个截取的Bitmap对象传递给另一个Actvity做相关处理，这里如何在Activity之间进行Bitmap传递呢？这里我们简单的运用java语法特性来完成具体做法如下：

我们在ActvityA中有一个public static Bitmap bitmap对象，当ActivityA跳转到B时，我们直接通过ActivityA.bitmap来获取这个对象。

之后就是如何进行裁剪的操作了。操作在另一个Activity中进行。XML配置文件信息如下：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 >
 <com.artifex.mupdf.Crop_Canvas
  android:id="@+id/myCanvas"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:background="#313131"
  />
 <Button
  android:id="@+id/cutCancel"
  android:layout_height="wrap_content"
  android:layout_width="wrap_content"
  android:text="取消"
  android:layout_alignParentBottom="true"
  android:layout_alignParentLeft="true"/>
 <Button
  android:id="@+id/cutEnsure"
  android:layout_height="wrap_content"
  android:layout_width="wrap_content"
  android:text="确定"
  android:layout_alignParentBottom="true"
  android:layout_centerInParent="true"/>
 <Button
  android:id="@+id/toPDF"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:text="ToPDF"
  android:layout_alignParentBottom="true"
  android:layout_alignParentRight="true"/>
</RelativeLayout>

通过配置文件可以看到我们自定义了一个View(ImageView)其实现如下：

package com.artifex.mupdf; 

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Bitmap.Config;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ImageView; 

public class Crop_Canvas extends ImageView { 

 private final static int PRESS_LB = 0;//表示左下角矩形框
 private final static int PRESS_LT = 1;//表示左上角矩形框
 private final static int PRESS_RB = 2;//表示右下角矩形框
 private final static int PRESS_RT = 3;//表示右上角矩形框 

 private Bitmap bitMap = null;    //原始图片
 private RectF src = null;     //经过比例转换后的裁剪区域
 private RectF dst = null;     //图片显示区域，也就是drawBitmap函数中的目标dst
 private RectF ChooseArea = null;    //选择区域
 private Paint mPaint = null;    //画笔
 private Matrix matrix = null;    //矩阵 

 private int mx = 0;       //存储触笔移动时，之前�?��的触笔的x坐标
 private int my = 0;       //存储触笔移动时，之前�?��的触笔的y坐标
 private boolean touchFlag = false;   //触笔是否在屏幕之�?
 private boolean cutFlag = false;   //是否点击了menu上的裁剪按钮
 private int recFlag = -1;     //用来存储触笔点击了哪个小矩形框（改变选择区域大小的小矩形框）
 private boolean firstFlag = false; 

 private RectF recLT = null;     //左上角的小矩形框
 private RectF recRT = null;     //右上角的小矩形框
 private RectF recLB = null;     //左下角的小矩形框
 private RectF recRB = null;     //右下角的小矩形框
 private static final int LEFT_AREA_ALPHA = 50 * 255 / 100;
 private RectF leftRectL = null;
 private RectF leftRectR = null;
 private RectF leftRectT = null;
 private RectF leftRectB = null;
 private Paint leftAreaPaint = null; 

 public Crop_Canvas(Context context, AttributeSet attrs) {
  super(context, attrs);
  this.init();
 } 

 public Crop_Canvas(Context context) {
  super(context);
  this.init();
 } 

 public void init(){
  cutFlag = true;
  recLT = new RectF();
  recLB = new RectF();
  recRT = new RectF();
  recRB = new RectF();
  dst = new RectF();
  mPaint = new Paint();
  mPaint.setColor(Color.RED);
  mPaint.setStyle(Paint.Style.STROKE);  //将画笔的风格改为空心
  ChooseArea = new RectF();
  this.setPressRecLoc();
  src = null;
  firstFlag = true; 

  //选择框之外的灰色区域，分成四个矩形框 

  leftAreaPaint = new Paint();
  leftAreaPaint.setStyle(Paint.Style.FILL);
  leftAreaPaint.setAlpha(Crop_Canvas.LEFT_AREA_ALPHA);
 } 

 public void setBitmap(Bitmap bitmap){
  BitmapDrawable bd = new BitmapDrawable(bitmap);
  src = new RectF(0,0,bd.getIntrinsicWidth(),bd.getIntrinsicHeight());
  this.bitMap = bitmap.copy(Config.ARGB_8888, true); 

  this.setImageBitmap(bitMap);
  leftRectB = new RectF();
  leftRectL = new RectF();
  leftRectR = new RectF();
  leftRectT = new RectF();
 } 

 public void imageScale(){
  matrix = this.getImageMatrix();
  matrix.mapRect(dst, src);
  int padding = this.getPaddingBottom();
  int width = bitMap.getWidth();
  int height = bitMap.getHeight();
  //dst.set(dst.left+padding,dst.top+padding,dst.right+padding,dst.bottom+padding);
  dst.set(dst.left+20,dst.top+20,width-20,height - 40);
  ChooseArea = new RectF(dst);
  this.setPressRecLoc();
 } 

 public Bitmap getSubsetBitmap(){
  float ratioWidth = bitMap.getWidth()/(float)(dst.right-dst.left);
  float ratioHeight = bitMap.getHeight()/(float)(dst.bottom - dst.top);
  int left = (int)((ChooseArea.left - dst.left) * ratioWidth);
  int right = (int)(left + (ChooseArea.right - ChooseArea.left) * ratioWidth);
  int top = (int)((ChooseArea.top - dst.top) * ratioHeight);
  int bottom = (int)(top + (ChooseArea.bottom - ChooseArea.top) * ratioHeight);
  src = new RectF(left,top,right,bottom);
  firstFlag = true;
  set_LeftArea_Alpha();
  return Bitmap.createBitmap(bitMap, left, top, right-left, bottom-top);
 } 

 //获得ChooseArea对象
 public RectF getChooseArea(){
  return ChooseArea;
 } 

 public void moveChooseArea(int move_x,int move_y){
  if(ChooseArea.left + move_x >= dst.left && ChooseArea.right + move_x <= dst.right
  && ChooseArea.top + move_y >= dst.top && ChooseArea.bottom + move_y <= dst.bottom){
   ChooseArea.set(ChooseArea.left + move_x,ChooseArea.top+move_y
     ,ChooseArea.right + move_x,ChooseArea.bottom+move_y);
  }else{
   if(ChooseArea.left + move_x < dst.left){
    ChooseArea.set(dst.left,ChooseArea.top
      ,ChooseArea.right+dst.left-ChooseArea.left,ChooseArea.bottom);
   }
   if(ChooseArea.right + move_x > dst.right){
    ChooseArea.set(ChooseArea.left+dst.right-ChooseArea.right,ChooseArea.top
      ,dst.right,ChooseArea.bottom);
   } 

   if(ChooseArea.top + move_y < dst.top){
    ChooseArea.set(ChooseArea.left,dst.top
      ,ChooseArea.right,ChooseArea.bottom+dst.top-ChooseArea.top);
   } 

   if(ChooseArea.bottom + move_y > dst.bottom){
    ChooseArea.set(ChooseArea.left,ChooseArea.top+dst.bottom-ChooseArea.bottom
      ,ChooseArea.right,dst.bottom);
   }
  }
  this.setPressRecLoc();
  mPaint.setColor(Color.GREEN);
  this.invalidate();
 } 

 public boolean onTouchEvent(MotionEvent event){
  mPaint.setColor(Color.RED); 

  if(event.getAction() == MotionEvent.ACTION_DOWN && cutFlag){
   //System.out.println(event.getX() + "," + event.getY()); 

   mx = (int)event.getX();
   my = (int)event.getY();
   if(this.judgeLocation(mx,my)){
    touchFlag = true;
    mPaint.setColor(Color.GREEN);
    this.invalidate();
    return true;
   }else{ 

    if(this.findPresseddst((int)event.getX(), (int)event.getY())){
     touchFlag = true;
     mPaint.setColor(Color.RED);
     return true;
    }
   }
  } 

  if(event.getAction() == MotionEvent.ACTION_MOVE && touchFlag){
   //判断是否点击了哪个个小矩形框
   if(this.isOutOfArea((int)event.getX(), (int)event.getY())){
    return true;
   } 

   //如果选择区域大小跟图像大小一样时，就不能移动
   if(ChooseArea.left == dst.left && ChooseArea.top == dst.top &&
    ChooseArea.right == dst.right && ChooseArea.bottom == dst.bottom){
   }else{
    this.moveChooseArea((int)event.getX() - mx, (int)event.getY() - my);
    mx = (int)event.getX();
    my = (int)event.getY();
   }
  } 

  if(event.getAction() == MotionEvent.ACTION_UP){
   recFlag = -1;
   this.invalidate();
   touchFlag = false;
  } 

  return super.onTouchEvent(event);
 } 

 private boolean isOutOfArea(int x,int y){
  switch(recFlag){
  case Crop_Canvas.PRESS_LB:
   this.pressLB(x - mx, y - my);
   break;
  case Crop_Canvas.PRESS_LT:
   this.pressLT(x - mx, y - my);
   break;
  case Crop_Canvas.PRESS_RB:
   this.pressRB(x - mx, y - my);
   break;
  case Crop_Canvas.PRESS_RT:
   this.pressRT(x - mx, y - my);
   break;
  default:return false;
  }
  mx = x;
  my = y;
  this.invalidate();
  return true;
 } 

 public boolean findPresseddst(int x,int y){
  boolean returnFlag = false;
  if(this.isInRect(x, y, recLB)){
   recFlag = Crop_Canvas.PRESS_LB;
   returnFlag = true;
  }else if(this.isInRect(x, y, recLT)){
   recFlag = Crop_Canvas.PRESS_LT;
   returnFlag = true;
  }else if(this.isInRect(x, y, recRB)){
   recFlag = Crop_Canvas.PRESS_RB;
   returnFlag = true;
  }else if(this.isInRect(x, y, recRT)){
   recFlag = Crop_Canvas.PRESS_RT;
   returnFlag = true;
  } 

  return returnFlag;
 } 

 public boolean isInRect(int x,int y,RectF rect){
  if(x >= rect.left -20 && x <= rect.right + 20 && y > rect.top - 20 && y < rect.bottom + 20){
   return true;
  }
  return false;
 } 

 private void pressLB(int x,int y){
  float left = ChooseArea.left + x;
  float right = ChooseArea.right;
  float top = ChooseArea.top;
  float bottom = ChooseArea.bottom + y;
  if(left <= right - 30 && left >= dst.left && bottom <= dst.bottom && bottom >= top + 30){
    ChooseArea.set(left,top,right,bottom);
  }else{
   if(left + x < dst.left){
    left = dst.left;
   } 

   if(bottom + y > dst.bottom){
    bottom = dst.bottom;
   } 

   if(ChooseArea.left + x > ChooseArea.right - 30){
    left = ChooseArea.right - 30;
   } 

   if(ChooseArea.bottom + y < ChooseArea.top + 30){
    bottom = ChooseArea.top + 30;
   }
   ChooseArea.set(left,top,right,bottom);
  }
  this.setPressRecLoc();
 } 

 private void pressLT(int x,int y){
  float left = ChooseArea.left + x;
  float right = ChooseArea.right;
  float top = ChooseArea.top + y;
  float bottom = ChooseArea.bottom;
  if(left <= right - 30 && left >= dst.left && top <= bottom - 30 && top >= dst.top){
   ChooseArea.set(left,top,right,bottom);
  }else{
   if(left < dst.left){
    left = dst.left;
   } 

   if(top < dst.top){
    top = dst.top;
   } 

   if(left > right - 30){
    left = right - 30;
   } 

   if(top > bottom - 30){
    top = bottom - 30;
   }
   ChooseArea.set(left,top,right,bottom);
  }
  this.setPressRecLoc();
 } 

 private void pressRT(int x,int y){
  float left = ChooseArea.left;
  float right = ChooseArea.right + x;
  float top = ChooseArea.top + y;
  float bottom = ChooseArea.bottom; 

  if(right <= dst.right && right >= left + 30 && top <= bottom - 30 && top >= dst.top){
   ChooseArea.set(left,top,right,bottom);
  }else{
   if(right > dst.right){
    right = dst.right;
   } 

   if(top < dst.top){
    top = dst.top;
   } 

   if(right < left + 30){
    right = left + 30;
   } 

   if(top > bottom - 30){
    top = bottom - 30;
   }
   ChooseArea.set(left,top,right,bottom);
  }
  this.setPressRecLoc();
 } 

 private void pressRB(int x,int y){
  float left = ChooseArea.left;
  float right = ChooseArea.right + x;
  float top = ChooseArea.top;
  float bottom = ChooseArea.bottom + y; 

  if(right<= dst.right && right >= left + 30 && bottom <= dst.bottom && bottom >= top + 30){
   ChooseArea.set(left,top,right,bottom);
  }else{
   if(right > dst.right){
    right = dst.right;
   } 

   if(bottom > dst.bottom){
    bottom = dst.bottom;
   } 

   if(right < left + 30){
    right = left + 30;
   } 

   if(bottom < top + 30){
    bottom = top + 30;
   }
   ChooseArea.set(left,top,right,bottom);
  }
  this.setPressRecLoc();
 } 

 //每次改变选择区域矩形的大小或者移动，各角落上的小矩形也要改变它的Location
 private void setPressRecLoc(){
  recLT.set(ChooseArea.left-5,ChooseArea.top-5 , ChooseArea.left+5, ChooseArea.top+5);
  recLB.set(ChooseArea.left-5,ChooseArea.bottom-5 , ChooseArea.left+5, ChooseArea.bottom+5);
  recRT.set(ChooseArea.right-5,ChooseArea.top-5 , ChooseArea.right+5, ChooseArea.top+5);
  recRB.set(ChooseArea.right-5,ChooseArea.bottom-5 , ChooseArea.right+5, ChooseArea.bottom+5);
 } 

 public boolean judgeLocation(float x,float y){
  float start_x = this.getChooseArea().left;
  float start_y = this.getChooseArea().top;
  float last_x = this.getChooseArea().right;
  float last_y = this.getChooseArea().bottom;
  //System.out.println("chubi:" + x + "," + y);
  //System.out.println(start_y + "," + last_y);
  if(x > start_x+10 && x < last_x-10 && y > start_y+10 && y < last_y-10){
   return true;
  }
  return false;
 } 

 public void onDraw(Canvas canvas){
  super.onDraw(canvas);
  if(firstFlag){
   this.imageScale();
   firstFlag = false;
   mPaint.setColor(Color.RED);
   System.out.println("Width: " + (dst.right - dst.left));
   System.out.println("Height: " + (dst.bottom - dst.top));
   System.out.println("Width: " + this.getDrawable().getIntrinsicWidth());
   System.out.println("Height: " + this.getDrawable().getIntrinsicHeight());
  }else{
   set_LeftArea_Alpha();
  }
  canvas.drawRect(ChooseArea, mPaint);
  mPaint.setColor(Color.BLUE);
  canvas.drawRect(recLT, mPaint);
  canvas.drawRect(recLB, mPaint);
  canvas.drawRect(recRT, mPaint);
  canvas.drawRect(recRB, mPaint); 

  canvas.drawRect(leftRectL, leftAreaPaint);
  canvas.drawRect(leftRectR, leftAreaPaint);
  canvas.drawRect(leftRectT, leftAreaPaint);
  canvas.drawRect(leftRectB, leftAreaPaint); 

 } 

 public void set_LeftArea_Alpha(){
  leftRectL.set(dst.left, dst.top, ChooseArea.left, dst.bottom);
  leftRectR.set(ChooseArea.right,dst.top,dst.right,dst.bottom);
  leftRectT.set(ChooseArea.left, dst.top, ChooseArea.right, ChooseArea.top);
  leftRectB.set(ChooseArea.left,ChooseArea.bottom,ChooseArea.right,dst.bottom);
 }
}

接下来直接看看Activity源码：

package com.artifex.mupdf.cut; 

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList; 

import android.app.Activity;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.widget.Button; 

import com.andorid.shu.love.R;
import com.artifex.mupdf.Crop_Canvas;
import com.artifex.mupdf.MuPDFActivity; 

public class CutActivity extends Activity {
 private Crop_Canvas canvas = null;
 private Bitmap backBitmap;
 private Button cancel;
 private Button ensure;
 private Button toPDF; 

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  requestWindowFeature(Window.FEATURE_NO_TITLE);
  setContentView(R.layout.cut_image);
  backBitmap = MuPDFActivity.backBitmap;
  init();
  cancel = (Button) findViewById(R.id.cutCancel);
  cancel.setOnClickListener(new OnClickListener() { 

   @Override
   public void onClick(View v) {
    CutActivity.this.finish();
   }
  });
  ensure = (Button) findViewById(R.id.cutEnsure);
  ensure.setOnClickListener(new OnClickListener() {
   @Override
   public void onClick(View v) {
    //图片保存的路径，之后将之转换为PDF，并以附件的形似发送邮件
    File tmp = new File("/sdcard/lovereader/pic");
    tmp.mkdirs();
    File f = new File("/sdcard/lovereader/pic/" + "testpic" + ".png");
    try {
     f.createNewFile();
    } catch (IOException e1) {
     // TODO Auto-generated catch block
     e1.printStackTrace();
    }
    FileOutputStream fOut = null;
    try {
      fOut = new FileOutputStream(f);
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    }
    canvas.getSubsetBitmap().compress(Bitmap.CompressFormat.PNG, 100, fOut);
    try {
      fOut.flush();
    } catch (IOException e) {
      e.printStackTrace();
    }
    try {
      fOut.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
   }
  }); 

  toPDF = (Button)findViewById(R.id.toPDF);
  toPDF.setOnClickListener(new OnClickListener() { 

   @Override
   public void onClick(View v) {
    // TODO Auto-generated method stub
    ArrayList<String> imageUrllist = new ArrayList<String>();
    imageUrllist.add("/sdcard/lovereader/pic/" + "testpic" + ".png");
    String pdfUrl = "/sdcard/lovereader/tmp/Foreverlove.pdf";
    File tmp = new File("/sdcard/lovereader/tmp");
    tmp.mkdirs();
    File file = PdfManager.Pdf(imageUrllist, pdfUrl);
    try {
     file.createNewFile();
    } catch (IOException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    } 

   }
  });
 } 

 private void init() {
  canvas = (Crop_Canvas) findViewById(R.id.myCanvas);
  Bitmap bitmap = backBitmap;
  canvas.setBitmap(bitmap);
 } 

}

ok，不依靠系统的简单裁剪功能就实现了，这里笔者就不给出源代码下载了，上述代码读者只要自己改改就可以用了。

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