首先声明，我是一个菜鸟。一下文章中出现技术误导情况盖不负责
接上一篇文章:
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
要求一样不适合,笔者需要的是通过对手机屏幕整个停止一个截图,并对这个截图停止裁剪操作。
依托系统功能确实可以实现图片的裁剪，但是不够灵巧。这里笔者供给一种较为灵巧的做法。
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，读者应该自己权衡。
一样，我们先看现实效果图。
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停止裁剪 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做相干处理，这里如何
在Activity之间停止Bitmap传递呢？这里我们简略的应用java语法特性来实现具体做法如下：
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来获得这个对象。
之后就是如何停止裁剪的操作了。操作在另一个Activity中停止。XML配置文件信息如下：
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：
每日一道理 “多难兴才”曾一度被人定为规律。请看：屈原被放逐而作《离骚》；司马迁受宫刑而作《史记》；欧阳修两岁丧父笃学而成才；曹雪芹举家食粥而写出了不朽的《红楼梦》；越王勾践卧薪尝胆而雪洗国耻；韩信遭胯下辱而统率百万雄兵……他们都是在与逆境搏斗中成为伟人的！
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;//表现左下角矩形框 private final static int PRESS_LT = 1;//表现左上角矩形框 private final static int PRESS_RB = 2;//表现右下角矩形框 private final static int PRESS_RT = 3;//表现右上角矩形框 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（转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); //将画笔的风格改成空心 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); } //取得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(); } //每次转变选择区域矩形的大小或者移动，各角落上的小矩形也要转变它的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 imageUrllist = new ArrayList (); 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，不依托系统的简略裁剪功能就实现了，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能够用了。
文章结束给大家分享下程序员的一些笑话语录： 一个合格的程序员是不会写出 诸如 “摧毁地球” 这样的程序的，他们会写一个函数叫 “摧毁行星”而把地球当一个参数传进去。