android 自定义 画板

View

package com.restore;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;

public class myview extends View {

	Path mPath;
	Bitmap mBitmap;
	Canvas mCanvas;
	Paint mPaint;
	int width;
	int height;
	int color;

	float mX = 0.0f;
	float mY = 0.0f;
	private Bitmap cachebBitmap;

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		int act = event.getAction();
		float x = event.getX();
		float y = event.getY();
		switch (act) {
		case MotionEvent.ACTION_DOWN:
			mPath.moveTo(x, y);
			break;
		case MotionEvent.ACTION_MOVE:
			mPath.quadTo(mX, mY, x, y);
			break;
		case MotionEvent.ACTION_UP:
			mCanvas.drawPath(mPath, mPaint);
			mPath.reset();
			break;

		}
		invalidate();
		mX = x;
		mY = y;
		return true;
	}

	@Override
	protected void onDraw(Canvas canvas) {
		// TODO Auto-generated method stub
		super.onDraw(canvas);

		// mcanvas = new Canvas(mBitmap);
		canvas.drawColor(Color.WHITE);
		canvas.drawBitmap(cachebBitmap, 0, 0, null);
		canvas.drawPath(mPath, mPaint);
	}

	public void clear()
	{
		mCanvas.drawColor(Color.WHITE);
		mCanvas.drawBitmap(cachebBitmap, 0, 0, null);
		invalidate();
	}
	public void setColor(int c){
		mPaint.setColor(c);
	}
	public void setBlock(float size)
	{
		mPaint.setStrokeWidth(size);
	}
	public myview(Context context) {
		super(context);

		init();


	}

	public myview(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		init();
	}

	public myview(Context context, AttributeSet attrs) {
		super(context, attrs);
		
init();
	}

	public void init(){
		DisplayMetrics metrics = new DisplayMetrics();
		WindowManager wm = (WindowManager) this.getContext().getSystemService("window");
		wm.getDefaultDisplay().getMetrics(metrics);
		width = metrics.widthPixels;
		height = metrics.heightPixels;

		mPaint = new Paint();
		mPaint.setAntiAlias(true);
		mPaint.setColor(Color.BLUE);
		mPaint.setStyle(Paint.Style.STROKE);
		mPaint.setStrokeWidth(12);
		cachebBitmap = Bitmap.createBitmap(width, height,
				Bitmap.Config.ARGB_8888);

		mCanvas = new Canvas(cachebBitmap);
		mPath = new Path();
	}
}

ACTIVITY

package com.restore;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;

public class TestRestoreActivity extends Activity implements OnClickListener {
	Path mPath;
	Bitmap mBitmap;
	Canvas mCanvas;
	Paint mPaint;
	int width;
	int height;
	myview m;
	Button l1, l2, l3,cred,cbule,cblack;
	Button colorBtn = null;
	Button clearBtn = null;
	Button lineBtn = null;
	LinearLayout linelayout, colorlayout = null;

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);

		 setContentView(R.layout.main);
		height = getWindowManager().getDefaultDisplay().getHeight();
		width =  getWindowManager().getDefaultDisplay().getWidth();
		 m = (myview) findViewById(R.id.myview);
		 linelayout = (LinearLayout) findViewById(R.id.lineBar);
		 colorlayout = (LinearLayout) findViewById(R.id.colorBar);
		 colorBtn = (Button) findViewById(R.id.color);
		 lineBtn = (Button) findViewById(R.id.line);
		 clearBtn = (Button) findViewById(R.id.clear);
		 cred = (Button) findViewById(R.id.colorred);
		 cbule = (Button) findViewById(R.id.colorblue);
		 cblack = (Button) findViewById(R.id.colorblack);
		 l1 = (Button) findViewById(R.id.l1);
		 l3 = (Button) findViewById(R.id.l3);
		 l2 = (Button) findViewById(R.id.l2);
		
		 colorBtn.setOnClickListener(this);
		 lineBtn.setOnClickListener(this);
		 clearBtn.setOnClickListener(this);
		 l1.setOnClickListener(this);
		 l2.setOnClickListener(this);
		 l3.setOnClickListener(this);
		 cred.setOnClickListener(this);
		 cbule.setOnClickListener(this);
		 cblack.setOnClickListener(this);


	}

	@Override
	public void onClick(View v) {

		if (v == colorBtn) {
			if (!colorlayout.isShown()) {
				if (linelayout.isShown()) {
					linelayout.setVisibility(View.INVISIBLE);
				}
				colorlayout.setVisibility(View.VISIBLE);
			} else {
				colorlayout.setVisibility(View.INVISIBLE);
			}
		} else if (v == lineBtn) {
			if (!linelayout.isShown()) {
				if (colorlayout.isShown()) {
					colorlayout.setVisibility(View.INVISIBLE);
				}
				linelayout.setVisibility(View.VISIBLE);
			} else {
				linelayout.setVisibility(View.INVISIBLE);
			}
		} else if (v == clearBtn) {

			m.clear();
		} else if (v == cbule) {
			m.setColor(Color.BLUE);
			colorlayout.setVisibility(View.INVISIBLE);
		} else if (v == cred) {
			m.setColor(Color.RED);
			colorlayout.setVisibility(View.INVISIBLE);
		} else if (v == cblack) {
			m.setColor(Color.BLACK);
			colorlayout.setVisibility(View.INVISIBLE);
		}
		else if(v == l1)
		{
			m.setBlock(12.0f);
			linelayout.setVisibility(View.INVISIBLE);
		}
		else if(v == l2)
		{
			m.setBlock(24.0f);
			linelayout.setVisibility(View.INVISIBLE);
		}
		else if(v == l3)
		{
			m.setBlock(36.0f);
			linelayout.setVisibility(View.INVISIBLE);
		}

	}

}

mainfest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.restore"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="8" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".TestRestoreActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>