package graphics;

import java.util.Random;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.View;
import android.view.Window;

public class BitmapActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		this.requestWindowFeature(Window.FEATURE_NO_TITLE);
		this.setContentView(new DrawView(this));
	}

	public class DrawView extends View {
		Bitmap bufferBitmap;
		Canvas bufferCanvas;
		Point screenSize;
		Random rand = new Random();

		public DrawView(Context context) {
			super(context);
			DisplayMetrics metrics = new DisplayMetrics();
			getWindowManager().getDefaultDisplay().getMetrics(metrics);
			screenSize = new Point(metrics.widthPixels - 20,
					metrics.heightPixels - 20);

			bufferBitmap = Bitmap.createBitmap(this.screenSize.x,this.screenSize.y, Bitmap.Config.ARGB_8888);//建立記憶體點陣圖
			bufferCanvas = new Canvas(bufferBitmap);//建立繪圖畫布
		}

		@Override
		protected void onDraw(Canvas canvas) {
			super.onDraw(canvas);
			drawOnBuffer();
			canvas.drawBitmap(bufferBitmap, 0, 0,new Paint());//在雙緩衝中繪圖，將自定義緩衝繪製到螢幕上
		}

		private void drawOnBuffer() {
			Paint paint=new Paint();
			paint.setAntiAlias(true);
			bufferCanvas.drawColor(Color.WHITE);
			for(int n=0;n<500;n++){                     //隨機在繪圖畫布上繪製500個圓
				int r=rand.nextInt(256);
				int g=rand.nextInt(256);
				int b=rand.nextInt(256);
				paint.setColor(Color.rgb(r, g, b));
				int x=rand.nextInt(bufferCanvas.getWidth());
				int y=rand.nextInt(bufferCanvas.getHeight());
				int radius=rand.nextInt(100)+20;
				bufferCanvas.drawCircle(x, y, radius, paint);
				Log.d("Circle", "第n個"+n);
			}
		}
	}
}