在屏幕 preview 畫圖 Canvas 的用法

 

package com.example.mycamera1;

 

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.view.Menu;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.ImageView.ScaleType;

public class MyCamera1 extends Activity
{
 FrameLayout frameLayout;
 MyView1 myView;
 @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.my_camera1);
         myView=new MyView1(MyCamera1.this);
         frameLayout=(FrameLayout)findViewById(R.id.relativeLayout);
         frameLayout.addView(myView);

    }

 

 @Override
 public boolean onCreateOptionsMenu(Menu menu)
 {
  getMenuInflater().inflate(R.menu.my_camera1, menu);
  return true;
 }
}

 

 

//用於畫線的類

package com.example.mycamera1;

 import java.util.Arrays;

import android.annotation.SuppressLint;
import android.content.Context; 
 import android.graphics.Canvas; 
 import android.graphics.Paint; 
import android.graphics.Rect;
import android.graphics.Paint.Style;
import android.graphics.RectF;
import android.util.Log;
import android.view.View;
import android.widget.TextView; 
 public class MyView1 extends View  { 
  public MyView1(Context context) { 
         super(context);
     } 
     @SuppressLint("DrawAllocation")
 public void update(){postInvalidate();}
 
    protected void onDraw(Canvas canvas) 
    { 
        super.onDraw(canvas); 
        Paint paint = new Paint(); 
        paint.setColor(android.graphics.Color.RED);
        paint.setStrokeWidth(5.0f);
        paint.setStyle(Style.STROKE);
        canvas.drawLine(100, 0, 100, 600, paint);
        paint.setColor(android.graphics.Color.GREEN);
        canvas.drawRect(200, 100, 600, 500, paint);
    } 
 }  

 

 

 

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
      android:orientation="vertical"
      android:id="@+id/relativeLayout">

</FrameLayout>