Android编程实现的手写板和涂鸦功能

本文实例讲述了Android编程实现的手写板和涂鸦功能。分享给大家供大家参考，具体如下：

下面仿一个Android手写板和涂鸦的功能，直接上代码：

write_pad.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:greendroid="http://schemas.android.com/apk/res/com.cyrilmottier.android.gdcatalog"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:orientation="vertical" >
 <FrameLayout
   android:id="@+id/tablet_view"
   android:layout_width="fill_parent"
   android:layout_height="300dp" >
 </FrameLayout>
 <LinearLayout
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:background="@android:drawable/bottom_bar"
   android:paddingTop="4dp" >
   <Button
     android:id="@+id/write_pad_ok"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_weight="1"
     android:text="确定" />
   <Button
     android:id="@+id/write_pad_clear"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_weight="1"
     android:text="清除" />
   <Button
     android:id="@+id/write_pad_cancel"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_weight="1"
     android:text="取消" />
 </LinearLayout>
</LinearLayout>

这个是手写板的主要布局文件，能够手写的部分是一个FrameLayout。下面有确定、清除和取消按钮，用来保存和擦除签名。

主要代码逻辑如下：

MainActivity.java

package com.jackie.handwriting;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import android.widget.TextView;
public class MainActivity extends Activity {
 private ImageView mIVSign;
 private TextView mTVSign;
 private Bitmap mSignBitmap;
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   setContentView(R.layout.activity_main);
   mIVSign = (ImageView) findViewById(R.id.iv_sign);
   mTVSign = (TextView) findViewById(R.id.tv_sign);
   mTVSign.setOnClickListener(new OnClickListener() {
     @Override
     public void onClick(View view) {
       WritePadDialog mWritePadDialog = new WritePadDialog(
           MainActivity.this, new WriteDialogListener() {
             @Override
             public void onPaintDone(Object object) {
               mSignBitmap = (Bitmap) object;
               createSignFile();
               mIVSign.setImageBitmap(mSignBitmap);
               mTVSign.setVisibility(View.GONE);
             }
           });
       mWritePadDialog.show();
     }
   });
 }
 //创建签名文件
 private void createSignFile() {
   ByteArrayOutputStream baos = null;
   FileOutputStream fos = null;
   String path = null;
   File file = null;
   try {
     path = Environment.getExternalStorageDirectory() + File.separator + System.currentTimeMillis() + ".jpg";
     file = new File(path);
     fos = new FileOutputStream(file);
     baos = new ByteArrayOutputStream();
     //如果设置成Bitmap.compress(CompressFormat.JPEG, 100, fos) 图片的背景都是黑色的
     mSignBitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
     byte[] b = baos.toByteArray();
     if (b != null) {
       fos.write(b);
     }
   } catch (IOException e) {
     e.printStackTrace();
   } finally {
     try {
       if (fos != null) {
         fos.close();
       }
       if (baos != null) {
         baos.close();
       }
     } catch (IOException e) {
       e.printStackTrace();
     }
   }
 }
}

PaintView.java

package com.jackie.handwriting;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.view.MotionEvent;
import android.view.View;
public class PaintView extends View {
 private Paint mPaint;
 private Path mPath;
 private Bitmap mBitmap;
 private Canvas mCanvas;
 private int screenWidth, screenHeight;
 private float currentX, currentY;
 public PaintView(Context context, int screenWidth, int screenHeight) {
   super(context);
   this.screenWidth = screenWidth;
   this.screenHeight = screenHeight;
   init();
 }
 private void init() {
   mPaint = new Paint();
   mPaint.setAntiAlias(true); // 去除锯齿
   mPaint.setStrokeWidth(5);
   mPaint.setStyle(Paint.Style.STROKE);
   mPaint.setColor(Color.BLACK);
   mPath = new Path();
   mBitmap = Bitmap.createBitmap(screenWidth, screenHeight, Config.ARGB_8888);
   mCanvas = new Canvas(mBitmap);
//   mCanvas.drawColor(Color.WHITE);
 }
 @Override
 protected void onDraw(Canvas canvas) {
   canvas.drawBitmap(mBitmap, 0, 0, null);
   canvas.drawPath(mPath, mPaint);
 }
 @Override
 public boolean onTouchEvent(MotionEvent event) {
   float x = event.getX();
   float y = event.getY();
   switch (event.getAction()) {
   case MotionEvent.ACTION_DOWN:
     currentX = x;
     currentY = y;
     mPath.moveTo(currentX, currentY);
     break;
   case MotionEvent.ACTION_MOVE:
     currentX = x;
     currentY = y;
     mPath.quadTo(currentX, currentY, x, y); // 画线
     break;
   case MotionEvent.ACTION_UP:
     mCanvas.drawPath(mPath, mPaint);
     break;
   }
   invalidate();
   return true;
 }
 public Bitmap getPaintBitmap() {
   return resizeImage(mBitmap, 320, 480);
 }
 public Path getPath() {
   return mPath;
 }
 // 缩放
 public static Bitmap resizeImage(Bitmap bitmap, int width, int height) {
   int originWidth = bitmap.getWidth();
   int originHeight = bitmap.getHeight();
   float scaleWidth = ((float) width) / originWidth;
   float scaleHeight = ((float) height) / originHeight;
   Matrix matrix = new Matrix();
   matrix.postScale(scaleWidth, scaleHeight);
   Bitmap resizedBitmap = Bitmap.createBitmap(bitmap, 0, 0, originWidth,
       originHeight, matrix, true);
   return resizedBitmap;
 }
 //清除画板
 public void clear() {
   if (mCanvas != null) {
     mPath.reset();
     mCanvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
     invalidate();
   }
 }
}

WritePadDialog.java

package com.jackie.handwriting;
import android.app.Dialog;
import android.content.Context;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.Toast;
public class WritePadDialog extends Dialog {
 private Context mContext;
 private WriteDialogListener mWriteDialogListener;
 private PaintView mPaintView;
 private FrameLayout mFrameLayout;
 private Button mBtnOK, mBtnClear, mBtnCancel;
 public WritePadDialog(Context context,
     WriteDialogListener writeDialogListener) {
   super(context);
   this.mContext = context;
   this.mWriteDialogListener = writeDialogListener;
 }
 @Override
 protected void onCreate(Bundle savedInstanceState) {
   super.onCreate(savedInstanceState);
   requestWindowFeature(Window.FEATURE_NO_TITLE); //无标题
   setContentView(R.layout.write_pad);
   mFrameLayout = (FrameLayout) findViewById(R.id.tablet_view);
   // 获取屏幕尺寸
   DisplayMetrics mDisplayMetrics = new DisplayMetrics();
   getWindow().getWindowManager().getDefaultDisplay().getMetrics(mDisplayMetrics);
   int screenWidth = mDisplayMetrics.widthPixels;
   int screenHeight = mDisplayMetrics.heightPixels;
   mPaintView = new PaintView(mContext, screenWidth, screenHeight);
   mFrameLayout.addView(mPaintView);
   mPaintView.requestFocus();
   mBtnOK = (Button) findViewById(R.id.write_pad_ok);
   mBtnOK.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {
       if (mPaintView.getPath().isEmpty()) {
         Toast.makeText(mContext, "请写下你的大名", Toast.LENGTH_SHORT).show();
         return;
       }
       mWriteDialogListener.onPaintDone(mPaintView.getPaintBitmap());
       dismiss();
     }
   });
   mBtnClear = (Button) findViewById(R.id.write_pad_clear);
   mBtnClear.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {
       mPaintView.clear();
     }
   });
   mBtnCancel = (Button) findViewById(R.id.write_pad_cancel);
   mBtnCancel.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View v) {
       cancel();
     }
   });
 }
}

WriteDilogListener.java

package com.jackie.handwriting;
/**
* 监听手写板对话框
* @author chengcj1
*
*/
public interface WriteDialogListener {
 public void onPaintDone(Object object);
}

效果如下：

希望本文所述对大家Android程序设计有所帮助。

来源：http://blog.csdn.net/shineflowers/article/details/45952441