在嵌套布局中画图

1.类

public class MyLayout extends RelativeLayout{
    
    private Path mPath;
    private Paint mPaint;
    private int color;
    private int size;
    
    private Canvas mCanvas;
    private Bitmap  mBitmap;
    private Paint   mBitmapPaint;


    public MyLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPath = new Path(); 
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(Color.RED);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(3);
        
        mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        setWillNotDraw(false);


    }
    public void setPaintColor(int color){
        this.color = color;
        mPaint.setColor(color);
        invalidate();
    }
    public void setPaintSize(int size){
        this.size = size;
        mPaint.setStrokeWidth(size) ;
        invalidate();
    }
    
    public Paint getPaint() {
        return mPaint;
    }


    public void setPaint(Paint mPaint) {
        this.mPaint = mPaint;
    }


    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        mCanvas = new Canvas(mBitmap); 
    }
    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);
        // canvas.drawColor(0xFFAAAAAA);
         canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
        canvas.drawPath(mPath, mPaint);
    }
    private float mX ,mY;
    
    private static final float TOUCH_TOLERANCE = 4;
    private void touchStart(float x,float y){
        mPath.reset();
        mPath.moveTo(x, y);
        mX = x;
        mY = y;
    }
    private void touchMove(float x, float y){
        float dx = Math.abs(x-mX);
        float dy = Math.abs(y-mY);
        if(dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE){
            mPath.quadTo(mX, mY, (x+mX)/2,(y+mY)/2);
            mX = x;
            mY = y;
        }
    }
    private void touchUp(){
        mPath.lineTo(mX, mY);
        mCanvas.drawPath(mPath, mPaint);
        mPath.reset();
    }
    
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            touchStart(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_MOVE:
            touchMove(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_UP:
            touchUp();
            break; 
        default:
            break;
        }
                
        return true;
    }
}

2. xml 文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/background"
    android:gravity="center"
    android:orientation="vertical" >

    <com.cvte.remotecontrol.MyLayout
        android:id="@+id/third_relativeLayout"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:background="@color/third_background"
        android:layout_margin="100dp" >

        <TextView
            android:id="@+id/third_guide_textview"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_centerHorizontal="true"
            android:layout_marginBottom="50dp"
            android:textSize="30dp"
            android:text="请打开飞鼠，按住CLICK按钮，在方框中移动一个直线轨迹" />

        <Button
            android:id="@+id/third_next_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentBottom="true"
            android:layout_centerHorizontal="true"
            android:gravity="center_vertical|center_horizontal"
            android:text="下一步" />

        <TextView
            android:id="@+id/third_result"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_above="@+id/third_guide_textview"
            android:layout_centerHorizontal="true"
            android:textAppearance="?android:attr/textAppearanceLarge" />

</com.cvte.remotecontrol.MyLayout>
</LinearLayout>

3. 在activity类中

package com.cvte.remotecontrol;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class RCThirdLayout extends Activity implements OnClickListener {
    private Button mButtonNextStep;
    private View view;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.rcthird_layout);
        init();
    }

    private void init() {

        view = new MyLayout(this,null);
        view.setBackgroundColor(R.color.third_background);
        mButtonNextStep = (Button) this.findViewById(R.id.third_next_button);
        mButtonNextStep.setOnClickListener(this);
                

    }


    @Override
    public void onClick(View v) {
        Intent mIntent = new Intent(RCThirdLayout.this, RCSecondLayout.class);
        finish();
        startActivity(mIntent);
    }


    
}