Android: 繪圖

## 簡單圖形繪製

protected void onDraw(Canvas canvas) {//重寫的繪製方法

super.onDraw(canvas);

canvas.drawColor(Color.BLACK);//繪製黑色背景

Paint paint = new Paint();//建立畫筆

paint.setColor(Color.WHITE);//設置畫筆顏色為紅色

canvas.drawRect(10, 10, 110, 110, paint);//繪製矩形

canvas.drawText("這是字符串", 10, 130, paint);//字符串，以字符串下面為基準

RectF rf1 = new RectF(10, 130, 110, 230);//定義一個矩形

canvas.drawArc(rf1, 0, 45, true, paint);//畫弧，順時針

canvas.drawLine(150, 10, 250, 110, paint);//畫線

RectF rf2 = new RectF(150, 130, 250, 230);//定義一個矩形

canvas.drawOval(rf2, paint);//畫圓 

}

## 貼圖功能

public void initBitmap(){ 

paint = new Paint();//建立一個畫筆

myBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.img);//獲得圖片資源

}

@Override

protected void onDraw(Canvas canvas) {//重寫的繪製方法

// TODO Auto-generated method stub

super.onDraw(canvas);

paint.setAntiAlias(true);//打開抗鋸齒

paint.setColor(Color.WHITE);//設置畫筆的顏色

paint.setTextSize(15);

canvas.drawBitmap(myBitmap, 10, 10, paint);//繪製圖片

canvas.save();  //儲存畫布

Matrix m1=new Matrix();

m1.setTranslate(500, 10);  // 平移

Matrix m2=new Matrix();

m2.setRotate(15);  // 旋轉

Matrix m3=new Matrix();

m3.setConcat(m1, m2);  

m1.setScale(0.8f, 0.8f);

m2.setConcat(m3, m1);

canvas.drawBitmap(myBitmap, m2, paint);

canvas.restore();

canvas.save();

paint.setAlpha(180);

m1.setTranslate(200,100);

m2.setScale(1.3f, 1.3f);

m3.setConcat(m1, m2);

canvas.drawBitmap(myBitmap, m3,  paint);

paint.reset();

canvas.restore();

paint.setTextSize(40);

paint.setColor(0xffFFFFFF);

canvas.drawText("圖片的寬度: "+myBitmap.getWidth(), 20, 380, paint);//繪製字符串，圖片的寬度

canvas.drawText("圖片的高度: "+myBitmap.getHeight(), 20, 430, paint);//繪製字符串，圖片的高度

paint.reset();

}