得到canvas画布对象
[java] 
Canvas canvas = getHolder().lockCanvas(); 

画布的一些属性和方法以及一些应用
[java] 
if (canvas != null) { 
    //----设置画布绘图无锯齿 
    canvas.setDrawFilter(pfd); 
    //----利用填充画布，刷屏 
    canvas.drawColor(Color.BLACK); 
    //----绘制文本 
    canvas.drawText("drawText", 10, 10, paint); 
    //----绘制像素点 
    canvas.drawPoint(10, 20, paint); 
    //----绘制多个像素点 
    canvas.drawPoints(new float[] { 10, 30, 30, 30 }, paint); 
    //----绘制直线 
    canvas.drawLine(10, 40, 50, 40, paint); 
    //----绘制多条直线 
    canvas.drawLines(new float[] { 10, 50, 50, 50, 70, 50, 110, 50 }, paint); 
    //----绘制矩形 
    canvas.drawRect(10, 60, 40, 100, paint); 
    //----绘制矩形2 
    Rect rect = new Rect(10, 110, 60, 130); 
    canvas.drawRect(rect, paint); 
    canvas.drawRect(rect, paint); 
    //----绘制圆角矩形 
    RectF rectF = new RectF(10, 140, 60, 170); 
    canvas.drawRoundRect(rectF, 20, 20, paint); 
    //----绘制圆形 
    canvas.drawCircle(20, 200, 20, paint); 
    //----绘制弧形 
    canvas.drawArc(new RectF(150, 20, 200, 70), 0, 230, true, paint); 
    //----绘制椭圆 
    canvas.drawOval(new RectF(150, 80, 180, 100), paint); 
    //----绘制指定路径图形 
    Path path = new Path(); 
    //设置路径起点 
    path.moveTo(160, 150); 
    //路线1 
    path.lineTo(200, 150); 
    //路线2 
    path.lineTo(180, 200); 
    //路径结束 
    path.close(); 
    canvas.drawPath(path, paint); 
    //----绘制指定路径图形 
    Path pathCircle = new Path(); 
    //添加一个圆形的路径 
    pathCircle.addCircle(130, 260, 20, Path.Direction.CCW); 
    //----绘制带圆形的路径文本 
    canvas.drawTextOnPath("PathText", pathCircle, 10, 20, paint); 
} 
 
注：以上代码参考自《Android游戏编程之从零开始》

得到自定义图片宽高的bitmap（参数一：上下文对象，参数二：资源ID，参数三：自定义宽度，参数四：自定义高度）
[java] 
public static Bitmap loadBallView(Context context,int resId,int width,int height) { 
         
    Resources resources = context.getResources(); 
         
    Drawable image = resources.getDrawable(resId); 
         
    Bitmap bitmap = Bitmap.createBitmap(width,height, Bitmap.Config.ARGB_8888); 
         
         Canvas canvas = new Canvas(bitmap); 
         image.setBounds(0, 0, width,height); 
         image.draw(canvas); 
         
         return bitmap; 
    } 
 
利用canvas绘制bitmap
[java] 
Bitmap bitmap = loadBallView(context,R.drawable.image,100,100); 
 
Paint paint = new Paint(); 
 
canvas.drawBitmap(bitmap, startX, startY, paint); //参数一：bitmap资源,参数二：起始X坐标，参数三：起始Y坐标，参数四：画笔paint对象