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;@Overrideprotected 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() {@Overridepublic void onClick(View v) { mView.clear();}});Button btnOk = (Button) findViewById(R.id.tablet_ok);btnOk.setOnClickListener(new View.OnClickListener() {@Overridepublic 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() {@Overridepublic 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();}}@Overrideprotected void onDraw(Canvas canvas) {// canvas.drawColor(BRUSH_COLOR);canvas.drawBitmap(cachebBitmap, 0, 0, null);canvas.drawPath(path, paint);}@Overrideprotected 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;@Overridepublic 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() {@Overridepublic void onClick(View v) {WritePadDialog writeTabletDialog = new WritePadDialog(HandwritingActivity.this, new DialogListener() {@Overridepublic 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。

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