Android 手写签名实例

  这篇文章本来想在一个月前就发布的，最近一直忙于国家电网手持终端的应用开发，所以没抽出时间来写。周末到了，终于可以闲下来整理整理。话不多说，直奔主题。

 

Android 提供了很多丰富、实用而且很有特色的功能。比如，语音识别、手写签名等等。本篇就为你介绍如何在android上进行个性化的手写签名。

 

首先大致说说需求：这是一个追求时尚、张扬个性的时代，我们希望在签名的地方，签名的是自己手写出来的很有个性的艺术字，而非根据手势识别出来的标准字体。

 

设计思路如下，在画板上进行签名（其实就是绘制图片），完成后保存为图片。然后将图片按照一定的比率进行缩放并显示在指定的位置。

 

这里给出一个实例，实例只是一个简单的例子，如有需要可以进行必要的扩展。这里我们需要一个Listener、一个Dialog、一个Activity这个三个java类。两个layout XML文件。

 

Listener很简单，主要是对手写板对话框的一个监听。

public interface DialogListener {
	
	public void refreshActivity(Object object);

}

 

 

接着是画板的Dialog

package cn.handwriting;

import android.app.Dialog;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;
import android.view.WindowManager.LayoutParams;
import android.widget.Button;
import android.widget.FrameLayout;


public class WritePadDialog extends Dialog {

	Context context;
	LayoutParams p ;
	DialogListener dialogListener;

	public WritePadDialog(Context context,DialogListener dialogListener) {
		super(context);
		this.context = context;
		this.dialogListener = dialogListener;
	}

	static final int BACKGROUND_COLOR = Color.WHITE;

	static final int BRUSH_COLOR = Color.BLACK;

	PaintView mView;

	/** The index of the current color to use. */
	int mColorIndex;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		requestWindowFeature(Window.FEATURE_PROGRESS);
		setContentView(R.layout.write_pad);
		
		p = getWindow().getAttributes();  //获取对话框当前的参数值   
		p.height = 320;//(int) (d.getHeight() * 0.4);   //高度设置为屏幕的0.4 
		p.width = 480;//(int) (d.getWidth() * 0.6);    //宽度设置为屏幕的0.6		   
		getWindow().setAttributes(p);     //设置生效
		
		
		mView = new PaintView(context);
		FrameLayout frameLayout = (FrameLayout) findViewById(R.id.tablet_view);
		frameLayout.addView(mView);
		mView.requestFocus();
		Button btnClear = (Button) findViewById(R.id.tablet_clear);
		btnClear.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View v) {
				 mView.clear();
			}
		});

		Button btnOk = (Button) findViewById(R.id.tablet_ok);
		btnOk.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View v) {
				try {
					dialogListener.refreshActivity(mView.getCachebBitmap());
					WritePadDialog.this.dismiss();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		});
		
		Button btnCancel = (Button)findViewById(R.id.tablet_cancel);
		btnCancel.setOnClickListener(new View.OnClickListener() {
			
			@Override
			public void onClick(View v) {
				cancel();
			}
		});
	}
	

	/**
	 * This view implements the drawing canvas.
	 * 
	 * It handles all of the input events and drawing functions.
	 */
	class PaintView extends View {
		private Paint paint;
		private Canvas cacheCanvas;
		private Bitmap cachebBitmap;
		private Path path;

		public Bitmap getCachebBitmap() {
			return cachebBitmap;
		}

		public PaintView(Context context) {
			super(context);					
			init();			
		}

		private void init(){
			paint = new Paint();
			paint.setAntiAlias(true);
			paint.setStrokeWidth(3);
			paint.setStyle(Paint.Style.STROKE);
			paint.setColor(Color.BLACK);					
			path = new Path();
			cachebBitmap = Bitmap.createBitmap(p.width, (int)(p.height*0.8), Config.ARGB_8888);			
			cacheCanvas = new Canvas(cachebBitmap);
			cacheCanvas.drawColor(Color.WHITE);
		}
		public void clear() {
			if (cacheCanvas != null) {
				
				paint.setColor(BACKGROUND_COLOR);
				cacheCanvas.drawPaint(paint);
				paint.setColor(Color.BLACK);
				cacheCanvas.drawColor(Color.WHITE);
				invalidate();			
			}
		}

		
		
		@Override
		protected void onDraw(Canvas canvas) {
			// canvas.drawColor(BRUSH_COLOR);
			canvas.drawBitmap(cachebBitmap, 0, 0, null);
			canvas.drawPath(path, paint);
		}

		@Override
		protected void onSizeChanged(int w, int h, int oldw, int oldh) {
			
			int curW = cachebBitmap != null ? cachebBitmap.getWidth() : 0;
			int curH = cachebBitmap != null ? cachebBitmap.getHeight() : 0;
			if (curW >= w && curH >= h) {
				return;
			}

			if (curW < w)
				curW = w;
			if (curH < h)
				curH = h;

			Bitmap newBitmap = Bitmap.createBitmap(curW, curH, Bitmap.Config.ARGB_8888);
			Canvas newCanvas = new Canvas();
			newCanvas.setBitmap(newBitmap);
			if (cachebBitmap != null) {
				newCanvas.drawBitmap(cachebBitmap, 0, 0, null);
			}
			cachebBitmap = newBitmap;
			cacheCanvas = newCanvas;
		}

		private float cur_x, cur_y;

		@Override
		public boolean onTouchEvent(MotionEvent event) {
			
			float x = event.getX();
			float y = event.getY();

			switch (event.getAction()) {
			case MotionEvent.ACTION_DOWN: {
				cur_x = x;
				cur_y = y;
				path.moveTo(cur_x, cur_y);
				break;
			}

			case MotionEvent.ACTION_MOVE: {
				path.quadTo(cur_x, cur_y, x, y);
				cur_x = x;
				cur_y = y;
				break;
			}

			case MotionEvent.ACTION_UP: {
				cacheCanvas.drawPath(path, paint);
				path.reset();
				break;
			}
			}

			invalidate();

			return true;
		}
	}

}

 

 

Activity是程序的入口，这个必不可少。

package cn.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 HandwritingActivity extends Activity {
    /** Called when the activity is first created. */
	
	private Bitmap mSignBitmap;
	private String signPath;
	private ImageView ivSign;
	private TextView tvSign;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        setTitle("欢迎使用手写签名");
        ivSign =(ImageView)findViewById(R.id.iv_sign);
        tvSign = (TextView)findViewById(R.id.tv_sign);      
        
        ivSign.setOnClickListener(signListener);
        tvSign.setOnClickListener(signListener);
    }
    
	
	private OnClickListener signListener = new View.OnClickListener() {
		
		@Override
		public void onClick(View v) {
			WritePadDialog writeTabletDialog = new WritePadDialog(
					HandwritingActivity.this, new DialogListener() {
						@Override
						public void refreshActivity(Object object) {							
							
							mSignBitmap = (Bitmap) object;
							signPath = createFile();
							/*BitmapFactory.Options options = new BitmapFactory.Options();
							options.inSampleSize = 15;
							options.inTempStorage = new byte[5 * 1024];
							Bitmap zoombm = BitmapFactory.decodeFile(signPath, options);*/														
							ivSign.setImageBitmap(mSignBitmap);
							tvSign.setVisibility(View.GONE);
						}
					});
			writeTabletDialog.show();
		}
	};
	
	/**
	 * 创建手写签名文件
	 * 
	 * @return
	 */
	private String createFile() {
		ByteArrayOutputStream baos = null;
		String _path = null;
		try {
			String sign_dir = Environment.getExternalStorageDirectory() + File.separator;			
			_path = sign_dir + System.currentTimeMillis() + ".jpg";
			baos = new ByteArrayOutputStream();
			mSignBitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
			byte[] photoBytes = baos.toByteArray();
			if (photoBytes != null) {
				new FileOutputStream(new File(_path)).write(photoBytes);
			}

		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			try {
				if (baos != null)
					baos.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return _path;
	}
}

 

 

对应的两个layout文件

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

 	<ImageView 
         android:id="@+id/iv_sign"
         android:layout_marginTop="50dp"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content" 
         android:layout_gravity="center"
         />
 	
     <TextView
        android:id="@+id/tv_sign"
        android:layout_marginTop="50dp"
        android:layout_below="@id/iv_sign"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:text="点此签名"
        />	   
</LinearLayout>

 

 

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="0dp"
        android:layout_weight="1" 
        android:background="@color/white">
    </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/tablet_ok"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="确定" />
        
        <Button
            android:id="@+id/tablet_clear"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="清除" />

        <Button
            android:id="@+id/tablet_cancel"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="取消" />
    </LinearLayout>

</LinearLayout>

这里还有个样式的设置，所以在values下添加了一个colors.xml文件。具体参见样例。