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。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。

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