The graphical user interface for an Android app is built using a hierarchy of View and ViewGroup objects.

hierarchy
英['haɪərɑːkɪ]美['haɪərɑrki]





n. 层级；等级制度

Hierarchy Viewer allows you to debug and optimize your user interface. It provides a visual representation of the layout’s View hierarchy (the Layout View) and a magnified inspector of the display (the Pixel Perfect View).
To start Hierarchy Viewer, enter the following command from the SDK tools/ directory:
hierarchyviewer
For more information on how to use Hierarchy Viewer, see Debugging and Profiling UIs

Hierarchy窗口



 

父子化

Hierarchy窗口中的列表是项目中的 “对象”。这些对象一一对应着Scene窗口中的对象。

但是在Hierarchy窗口中有一个显著的特征：父子化的列表形式。

父子化的主要表现的形式是：子对象的Transform或者RectTransform组件属性会根据父对象的Transform或者RectTransformation组件属性变化而变化。

比如：

父对象的Transform的Position的X属性为3时，子对象的Transform的Position的X属性会自动加3。

父对象的Transform的Rotation的X属性为30时，子对象的Transform的Rotation的X属性会自动加30。

父对象的Transform的Scale的X属性为3时，子对象的Transform的Scele的X属性会自动乘以3。

 

设置位置

我们可以在Hierarchy窗口中拖动以改变Hierarchy窗口对象的顺序或者父子关系。



在此图中，Object 4（选定对象）被拖到目标父对象 Object 1（以蓝色胶囊形状突出显示）上。

 

字母数字排序

Hierarchy 窗口中对象的顺序可以更改为字母数字顺序。在菜单栏中，选择 Edit > Preferences（在 Windows 中）或者选择 Unity > Preferences（在 OS X 中），启动 Preferences 窗口。选中 Enable Alpha Numeric Sorting。

选中此复选框时，Hierarchy 窗口的右上角会出现一个图标，允许在 Transform 排序（默认值）或 Alphabetic 排序之间切换。



Tips：Hierarcyh窗口中的对象和Scene窗口中的显示的先后顺序没有关系，对象间的互相遮挡是因为对象离摄像机的远近关系形成。

 

 

 

 

文章目录
Different Kinds of Memory
SRAM (made with logic gates)
DRAM (transistor and capacitor)
Flash (floating gate transistors)
Disks (Mechanical, Giant Magnetoresistance GMR)
Memory Hierarchy Goals
Hierarchical Memory

Different Kinds of Memory
SRAM (made with logic gates)

Fast: ~2ns access time
Expensive, high area requirement

~$5.0 per megabyte
$0.13 for LC2
$20000 for MIPS



DRAM (transistor and capacitor)

Slower: ~60ns access time

Must stall for dozens of cycles on each memory load


Less expensive than SRAM

~$0.004 per megabyte
$0.00 for LC2
$16 for MIPS/Pentium-IV/Athlon-XP



Flash (floating gate transistors)

Slower still: ~250ns access time

Must stall for dozens of cycles on each memory load


Less expensive than SRAM

~$0.0012 per megabyte
$0.00 for LC2
$4.9 for MIPS/Pentium-IV/Athlon-XP


Non-volatile

Disks (Mechanical, Giant Magnetoresistance GMR)

Obnoxiously slow: 3,000,000ns (3 ms) access time
Cheap

~$0.000043 per megabyte
$0.00 LC2
$0.18 for MIPS


Non-volatile

Memory Hierarchy Goals

Hierarchical Memory

A small array of SRAM

Small so fast and cheap
Cache (hopefully covers most loads and stores)


A larger amount of DRAM

Cheaper than SRAM, faster than flash/disk
Main Memory


A lot of flash and/or disk

Non-volatile. Cheap. Big

flash and/or disk
Non-volatile. Cheap. Big
Virtual Memory