android 画板（选择图片作为背景并保存）

我看了一下网上画板的写法有很多种，这篇文章的写法就是简单便捷，个人觉得不错，大家可以参考一下，

http://blog.csdn.net/qq_31530015/article/details/51115680  

当然这篇文章只是描述了以白色背景作为画板底色，如果是要选择图片作为背景并且保存呢，下面是我自己在这个基础上修改的，代码有点粗糙，但是能实现我们所需要的功能，废话不多说了，直接上代码吧

1、利用drawable（mimap）中的图片资源作为背景

package com.example.viewtest;import android.app.Activity;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.PixelFormat;import android.graphics.drawable.Drawable;import android.os.Bundle;import android.os.Environment;import android.view.MotionEvent;import android.view.View;import android.view.View.OnTouchListener;import android.widget.Button;import android.widget.ImageView;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;public class SecondActivity extends Activity {private ImageView img,imageTwo;private Bitmap mBitmap;private Canvas canvas;private Paint paint;// 重置按钮private Button reset_btn,save_btn;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_second);img = (ImageView) findViewById(R.id.img);imageTwo = (ImageView) findViewById(R.id.img_two);reset_btn = (Button) findViewById(R.id.reset_btn);save_btn = (Button) findViewById(R.id.save_btn);reset_btn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {img.setImageBitmap(null);showImage();}});save_btn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {setmBitmap();}});// 绘图showImage();}private void showImage() {int height = getWindow().getWindowManager().getDefaultDisplay().getHeight();int wehit = getWindow().getWindowManager().getDefaultDisplay().getWidth();// 创建一张图片mBitmap = drawableToBitamp(getResources().getDrawable(R.drawable.siji));   //drawable中的图片// 创建一张画布canvas = new Canvas(mBitmap);// 创建画笔paint = new Paint();// 画笔颜色为蓝色paint.setColor(Color.BLUE);// 宽度5个像素paint.setStrokeWidth(5);// 先将背景画上canvas.drawBitmap(mBitmap, new Matrix(), paint);img.setImageBitmap(mBitmap);img.setOnTouchListener(new OnTouchListener() {int startX;int startY;@Overridepublic boolean onTouch(View v, MotionEvent event) {switch (event.getAction()) {case MotionEvent.ACTION_DOWN:// 获取手按下时的坐标startX = (int) event.getX();startY = (int) event.getY();break;case MotionEvent.ACTION_MOVE:// 获取手移动后的坐标int endX = (int) event.getX();int endY = (int) event.getY();// 在开始和结束坐标间画一条线canvas.drawLine(startX, startY, endX, endY, paint);// 刷新开始坐标startX = (int) event.getX();startY = (int) event.getY();img.setImageBitmap(mBitmap);break;}return true;}});}

<span style="white-space:pre"></span>//保存到内存卡中 public void setmBitmap(){ File file = new File(Environment.getExternalStorageDirectory(), "/test" + ".png"); if(!file.exists()){ OutputStream stream; try { file.createNewFile() ; stream = new FileOutputStream(file); mBitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); stream.close(); } catch (IOException e) { e.printStackTrace(); } }else { OutputStream stream; try { stream = new FileOutputStream(file); mBitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); stream.close(); } catch (IOException e) { e.printStackTrace(); } } readSdPic(); }<span style="white-space:pre"></span>//读取出图片并显示public void readSdPic(){File file = new File(Environment.getExternalStorageDirectory(),"/test" + ".png");Bitmap bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());imageTwo.setImageBitmap(bitmap);   //显示图片}<span style="white-space:pre"></span>//<span style="font-family: Arial, Helvetica, sans-serif;">drawable转换为bitmap</span>private Bitmap bitmap;private Bitmap drawableToBitamp(Drawable drawable){int w = drawable.getMinimumWidth();int h = drawable.getMinimumHeight();//int height = getWindow().getWindowManager().getDefaultDisplay().getHeight();int wehit = getWindow().getWindowManager().getDefaultDisplay().getWidth();System.out.println("Drawable转Bitmap");Bitmap.Config config =drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888: Bitmap.Config.RGB_565;bitmap = Bitmap.createBitmap(wehit,500,config);//注意，下面三行代码要用到，否在在View或者surfaceview里的canvas.drawBitmap会看不到图Canvas canvas = new Canvas(bitmap);drawable.setBounds(0, 0, w, h);drawable.draw(canvas);return bitmap;}}

这样就可以实现图片的保存了，这种方式相对来说要简单一些，下面第二种通过读取手机图片或者拍照就要麻烦一点了

2、我们获取到的图片大小不一，有的能显示全屏，有的则不能显示。上面的代码如果试过就知道，只有当你点击到图片原来尺寸上的时候才能够绘画，如果强行让imageview全屏显示，那么就会出现错位的情况，因为画笔只监听了bitmap（获取图片）原来的尺寸，超出的部分则不会画到图片上，相当于无效的绘图，这样就出现了错位的感觉

package com.house.checkhouse.activity;import android.app.Activity;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.os.Bundle;import android.os.Environment;import android.view.KeyEvent;import android.view.MotionEvent;import android.view.View;import android.view.View.OnTouchListener;import android.widget.Button;import android.widget.ImageView;import com.house.checkhouse.R;import com.house.checkhouse.model.message.ImageInfo;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import java.text.SimpleDateFormat;import java.util.Calendar;public class SecondActivity extends Activity {public static final String IMAGE = "images";private ImageView img;private Bitmap mBitmap,nowBitmap;private Canvas canvas;private Paint paint;private ImageInfo imageInfo;private String fileUri;// 重置按钮private Button reset_btn,save_btn;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_second);imageInfo = getIntent().getParcelableExtra("image");   //通过打开相册或者照相传递过来的bitmap图片fileUri = getNowFileName();mBitmap = imageInfo.getBitmap();nowBitmap = mBitmap;img = (ImageView) findViewById(R.id.img);reset_btn = (Button) findViewById(R.id.reset_btn);save_btn = (Button) findViewById(R.id.save_btn);reset_btn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {img.setImageBitmap(null);showImage();}});save_btn.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View view) {//setmBitmap();}});// 绘图showImage();}@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {System.gc();setmBitmap();Intent intent = new Intent();intent.putExtra(IMAGE,fileUri);setResult(RESULT_OK, intent);return super.onKeyDown(keyCode, event);}private void showImage() {// 创建一张图片nowBitmap = mBitmap.copy(Bitmap.Config.ARGB_8888,true);nowBitmap = big(nowBitmap);   //放大bitmap// 创建一张画布canvas = new Canvas(nowBitmap);// 创建画笔paint = new Paint();// 画笔颜色为蓝色paint.setColor(Color.BLUE);// 宽度1个像素paint.setStrokeWidth(3);// 先将背景画上canvas.drawBitmap(nowBitmap, new Matrix(), paint);img.setImageBitmap(nowBitmap);img.setOnTouchListener(new OnTouchListener() {int startX;int startY;@Overridepublic boolean onTouch(View v, MotionEvent event) {switch (event.getAction()) {case MotionEvent.ACTION_DOWN:// 获取手按下时的坐标startX = (int) event.getX();startY = (int) event.getY();break;case MotionEvent.ACTION_MOVE:// 获取手移动后的坐标int endX = (int) event.getX();int endY = (int) event.getY();// 在开始和结束坐标间画一条线canvas.drawLine(startX, startY, endX, endY, paint);// 刷新开始坐标startX = (int) event.getX();startY = (int) event.getY();img.setImageBitmap(nowBitmap);break;}return true;}});}/** * 获取文件路径和名字（保存路径） * @return     */public String getNowFileName(){SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd");//格式大小写有区别String sysDatetime = fmt.format(Calendar.getInstance().getTime());//2016年02月25日  13:23:40String fileName = Environment.getExternalStorageDirectory()+File.separator+"com.house"+File.separator+sysDatetime+".png";return fileName;} public void setmBitmap(){ File file = new File(fileUri); if(!file.exists()){ OutputStream stream; try { file.createNewFile() ; stream = new FileOutputStream(file); nowBitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); stream.close(); } catch (IOException e) { e.printStackTrace(); } }else { OutputStream stream; try { stream = new FileOutputStream(file); nowBitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); stream.close(); } catch (IOException e) { e.printStackTrace(); } } }/** * 放大bitmap（放大到全屏显示，这样才不会出现错位情况，完全可以指哪儿画哪儿） * @param bitmap * @return     */private Bitmap big(Bitmap bitmap) {int height = bitmap.getHeight();int width = bitmap.getWidth();int heightWon = getWindow().getWindowManager().getDefaultDisplay().getHeight();int widthWon = getWindow().getWindowManager().getDefaultDisplay().getWidth();float sizeW = (float) widthWon/width;float sizeH = (float) heightWon/height;Matrix matrix = new Matrix();float size = sizeH<sizeW?sizeH:sizeW;  //(按照一长或宽的比例来缩放)matrix.postScale(size,size); //长和宽放大缩小的比例Bitmap resizeBmp = Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);return resizeBmp;}}

好了，这样就大功告成了，写起来感觉很简单，但是花费了我一天的时间才搞出来，如果大家有什么更好的方法，希望能分享一下