想要学习SurfaceView，必须了解SurfaceView、Surface、SurfaceHolder。

一、Surface

下面是Google提供的关于Surface的API的概述：

Handle onto a raw buffer that is being managed by the screen compositor.

直接从raw缓冲区中读取数据到屏幕。

surface的意思就是界面，可以理解为我们要显示的画面，不过知识先将它存储到内存中，完成后，才显示到屏幕中，也就是SurfaceView中。

几个重要的方法

二、SurfaceHolder

下面是Google提供的关于SurfaceHolder的API的概述：

Abstract interface to someone holding a display surface. Allows you to control the surface size and format, edit the pixels in the surface, and monitor changes to the surface. This interface is typically available through theSurfaceView
class.

When using this interface from a thread other than the one running its SurfaceView, you will want to carefully read the methodslockCanvas() andCallback.surfaceCreated().

SurfaceHolder是一个抽象的接口，用来支持显示一个surface。它允许你控制这个surface的大小和格式，允许你编辑这个surface，并且监测这个surface的变化。这个接口

的典型应用是通过SurfaceView类来实现的。

当你在一个线程中使用这个接口，而不是通过运行一个SurfaceView得到，那么，你就要自己掌握lockCanvas()和Callback.surfaceCreated().

也就是说SurfaceHolder是操作Surface的接口。

SurfaceHolder的方法

关于SurfaceHolder的setType()方法的参数：

SURFACE_TYPE_NORMAL：用RAM缓存原生数据的普通Surface
SURFACE_TYPE_HARDWARE：适用于DMA(Direct memory access )引擎和硬件加速的Surface
SURFACE_TYPE_GPU：适用于GPU加速的Surface
SURFACE_TYPE_PUSH_BUFFERS：表明该Surface不包含原生数据，Surface用到的数据由其他对象提供，在Camera图像预览中就使用该类型的Surface，有Camera 负责提供给预览Surface数据，这样图像预览会比较流畅。如果设置这种类型则就不能调用lockCanvas来获取Canvas对象了。

虽然setType()方法已经被声明deprecated，但是必要的时候还是设置下比较好。

几个需要注意的方法：
(1)、abstract void addCallback(SurfaceHolder.Callback callback);
// 给SurfaceView当前的持有者一个回调对象。
(2)、abstract Canvas lockCanvas();
// 锁定画布，一般在锁定后就可以通过其返回的画布对象Canvas，在其上面画图等操作了。
(3)、abstract Canvas lockCanvas(Rect dirty);
// 锁定画布的某个区域进行画图等..因为画完图后，会调用下面的unlockCanvasAndPost来改变显示内容。
// 相对部分内存要求比较高的游戏来说，可以不用重画dirty外的其它区域的像素，可以提高速度。
(4)、abstract void unlockCanvasAndPost(Canvas canvas);
// 结束锁定画图，并提交改变。

三、SurfaceView

下面是Google提供的关于SurfaceView的API的概述：

Provides a dedicated drawing surface embedded inside of a view hierarchy. You can control the format of this surface and, if you like, its size; the SurfaceView takes care of placing the surface at the correct location on the screen

The surface is Z ordered so that it is behind the window holding its SurfaceView; the SurfaceView punches a hole in its window to allow its surface to be displayed. The view hierarchy will take care of correctly compositing with the Surface any siblings
of the SurfaceView that would normally appear on top of it. This can be used to place overlays such as buttons on top of the Surface, though note however that it can have an impact on performance since a full alpha-blended composite will be performed each
time the Surface changes.

Access to the underlying surface is provided via the SurfaceHolder interface, which can be retrieved by callinggetHolder().

The Surface will be created for you while the SurfaceView's window is visible; you should implementsurfaceCreated(SurfaceHolder) andsurfaceDestroyed(SurfaceHolder) to discover when the Surface is created and destroyed
as the window is shown and hidden.

One of the purposes of this class is to provide a surface in which a secondary thread can render into the screen. If you are going to use it this way, you need to be aware of some threading semantics:

翻译(Copy别人的，唉，英语太差了，伤不起啊！，努力学习英文！)

SurfaceView是视图(View)的继承类，这个视图里内嵌了一个专门用于绘制的Surface。你可以控制这个Surface的格式和尺寸。Surfaceview控制这个Surface的绘制位置。

surface是纵深排序(Z-ordered)的，这表明它总在自己所在窗口的后面。surfaceview提供了一个可见区域，只有在这个可见区域内 的surface部分内容才可见，可见区域外的部分不可见。surface的排版显示受到视图层级关系的影响，它的兄弟视图结点会在顶端显示。这意味者 surface的内容会被它的兄弟视图遮挡，这一特性可以用来放置遮盖物(overlays)(例如，文本和按钮等控件)。注意，如果surface上面 有透明控件，那么它的每次变化都会引起框架重新计算它和顶层控件的透明效果，这会影响性能。

你可以通过SurfaceHolder接口访问这个surface，getHolder()方法可以得到这个接口。