多媒體--圖畫板

package com.example.drawing;

import java.io.File;
import java.io.FileOutputStream;
import java.util.Random;

import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Bitmap.CompressFormat;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.Toast;
import android.view.View.OnTouchListener;

public class MainActivity extends Activity
{

	private ImageView iv;
	private Bitmap basebitmap;
	private Canvas canvas;
	private Paint paint;

	@Override
	protected void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		/**
		 * 初始化
		 */
		iv = (ImageView) findViewById(R.id.iv);

		// 畫筆
		paint = new Paint();
		paint.setStrokeWidth(5);
		final int R=0;
		final int G=0;
		final int B=0;
		int color=Color.rgb(R, G,B);
		paint.setColor(color);

		// 畫布
		canvas = new Canvas();
		
		canvas.drawColor(Color.WHITE);

		// 得知手指移動軌跡
		iv.setOnTouchListener(new OnTouchListener()
		{
			// 手指開始的座標
			float startX =0;
			float startY=0;

			@Override
			public boolean onTouch(View v, MotionEvent event)
			{
				
				switch (event.getAction())
				{
				// 首次接觸屏幕
				case MotionEvent.ACTION_DOWN:
					System.out.println("手指按下……");

					if (basebitmap != null)
					{
						basebitmap = Bitmap.createBitmap(basebitmap);
					} else
					{
						basebitmap = Bitmap.createBitmap(iv.getWidth(), iv.getHeight(), Bitmap.Config.ARGB_8888);
					}
					
					canvas.setBitmap(basebitmap);
					startX = (float) event.getX();
					startY = (float) event.getY();

					canvas.drawPoint(startX, startY, paint);
					break;
				// 手指移動
				case MotionEvent.ACTION_MOVE:
					System.out.println("手指移動……");
					//動態更改顏色
					Random random=new Random();
					int color=Color.rgb(R+random.nextInt(256), G+random.nextInt(256), B+random.nextInt(256));
					paint.setColor(color);
					
					
					float newX = (float) event.getX();
					float newY = (float) event.getY();
					canvas.drawLine(startX, startY, newX, newY, paint);
					
					// 更新畫筆開始位置
					startX = (float) event.getX();
					startY = (float) event.getY();
					break;
				// 手指擡起
				case MotionEvent.ACTION_UP:
					System.out.println("手指擡起……");
					break;
				default:
					break;
				}
				iv.setImageBitmap(basebitmap);
				// 使得事件不停被執行 須要返回true
				return true;
			}

		});
	}

	public void save(View v)
	{
		try
		{
			File file=new File(Environment.getExternalStorageDirectory()+"/DCIM/",System.currentTimeMillis()+".jpg");
			FileOutputStream fos=new FileOutputStream(file);
			basebitmap.compress(CompressFormat.JPEG, 100, fos);
			fos.close();
			Toast.makeText(this, "保存成功", Toast.LENGTH_SHORT).show();
			//通知系統SD卡從新掛載
			Intent intent=new Intent();
			intent.setAction(Intent.ACTION_MEDIA_MOUNTED);
			intent.setData(Uri.fromFile(Environment.getExternalStorageDirectory()));
			sendBroadcast(intent);
			
		} catch (Exception e)
		{
			Toast.makeText(this, "失敗", Toast.LENGTH_SHORT).show();
		}
		
	}
	
	public void clear(View v)
	{
		basebitmap = Bitmap.createBitmap(iv.getWidth(), iv.getHeight(), Bitmap.Config.ARGB_8888);
		iv.setImageBitmap(basebitmap);
	}
}