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Android系统的智能指针（轻量级指针、强指针和弱指针）的实现原理分析（3）

提供引用计数器的类RefBase我们就暂时介绍到这里，后面我们再结合智能指针类一起分析，现在先来看看强指针类和弱指针类的定义。强指针类的定义我们在前面介绍轻量级指针的时候已经见到了，就是sp类了，这里就不再把它的代码列出来了。我们来看看它的构造函数的实现： template<typ...

Android帧缓冲区（Frame Buffer）硬件抽象层（HAL）模块Gralloc的实现原理分析（4）

成员变量fd指向一个文件描述符，这个文件描述符要么指向帧缓冲区设备，要么指向一块匿名共享内存，取决于它的宿主结构体private_handle_t描述的一个图形缓冲区是在帧缓冲区分配的，还是在内存中分配的。 ...

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Android帧缓冲区（Frame Buffer）硬件抽象层（HAL）模块Gralloc的实现原理分析（6）

函数fb_device_open在打开fb设备的过程中，会调用另外一个函数mapFrameBuffer来获得系统帧缓冲区的信息，并且将这些信息保存在参数module所描述的一个private_module_t结构体的各个成员变量中。有了系统帧缓冲区的...

Android帧缓冲区（Frame Buffer）硬件抽象层（HAL）模块Gralloc的实现原理分析（9）

5. 图形缓冲区的释放过程前面提到，用户空间的应用程序用到的图形缓冲区是由Gralloc模块中的函数gralloc_free来释放的，这个函数实现在文件hardware/libha...

Android系统的智能指针（轻量级指针、强指针和弱指针）的实现原理分析（2）

3. 强指针强指针所使用的引用计数类为RefBase，它LightRefBase类要复杂多了，所以才称后者为轻量级的引用计数基类吧。我们先来看看RefBase类的实现，它定义在frameworks/base/includ...

Android系统的智能指针（轻量级指针、强指针和弱指针）的实现原理分析（5）

即如果目标对象的生命周期只受到强引用计数控制或者在目标对象的具体实现中总是允许这种情况发生。怎么理解呢？如果目标对象的生命周期只受强引用计数控制（它的标志位mFlags为0），而这时目标对象又还未被强指针引用过，它自然就不会被delete掉，因此，这时候可以判断出...

Android系统的智能指针（轻量级指针、强指针和弱指针）的实现原理分析（1）

Android系统的运行时库层代码是用C++来编写的，用C++来写代码最容易出错的地方就是指针了，一旦使用不当，轻则造成内存泄漏，重则造成系统崩溃。不过系统为我们提供了智能指针，避免出现上述问题，本文将系统地分析Android系统智能指针（轻量级指针、强指针和弱指针）的实现原...

Android帧缓冲区（Frame Buffer）硬件抽象层（HAL）模块Gralloc的实现原理分析（1）

前面在介绍Android系统的开机画面时提到，Android设备的显示屏被抽象为一个帧缓冲区，而Android系统中的SurfaceFlinger服务就是通过向这个帧缓冲区写入内容来绘制应用程序的用户界面的。Android系统在硬件抽象层中提供了一个Gralloc模块，封装了对帧缓冲区的...

Android帧缓冲区（Frame Buffer）硬件抽象层（HAL）模块Gralloc的实现原理分析（5）

3. fb设备的打开过程在Gralloc模块中，fb设备的ID值定义为GRALLOC_HARDWARE_FB0。GRALLOC_HARDWARE_FB0是一个宏，定义在文件hardware/libhardwa...

Android帧缓冲区（Frame Buffer）硬件抽象层（HAL）模块Gralloc的实现原理分析（7）

显示屏的刷新频率与显示屏的扫描时序相关。显示屏的扫描时序可以参考Linux内核源代码目录下的Documentation/fb/framebuffer.txt文件。我们结合图2来简单说明上述代码是如何计算显示屏的刷新频率的。图 2 显示屏扫描时序示意图 &nbs...

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