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。
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public interface DialogListener {
public void refreshActivity(Object object);
}
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接着是画板的Dialog
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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
;
}
}
}
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Activity是程序的入口，这个必不可少。
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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;
}
}
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对应的两个layout文件
main.xml
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<?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>
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write_pad.xml
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<LinearLayout xmlns:android=
"http://schemas.android.com/apk/res/android"
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>
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这里还有个样式的设置，所以在values下添加了一个colors.xml文件。
