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：
更多关于Android相关内容感兴趣的读者可查看本站专题：《Android图形与图像处理技巧总结》、《Android开发入门与进阶教程》、《Android调试技巧与常见问题解决方法汇总》、《Android基本组件用法总结》、《Android视图View技巧总结》、《Android布局layout技巧总结》及《Android控件用法总结》
希望本文所述对大家Android程序设计有所帮助。
