July 2014
Intermediate to advanced
248 pages
5h 19m
Chinese
Content preview from Android Developer Tools深入精要
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202
|
第十三章：最佳化使用者介面
[Page-206]
圖
13-4
層級檢視：
Tree View
量測數值的資訊
中間的區塊（圖
13-5
）裡有兩個重要的項目：
此排版佈局裡的
Views
個數；在這例子裡是
24
個，這是很大的數目，因為這發
生在樹狀結構中的主要節點上。
該節點（與它的所有子元件）的測量（
Measure
）、佈局（
Layout
）與描繪（
Draw
）
次數；要注意的是次數高並不一定表示有問題，特別是在畫面上有許多物件時這
自然需要較長的時間來繪製。
識別資訊與效能指標
在節點資訊下方處（圖
13-6
）有一些其他有用的資訊，你可以利用這資訊快速地在階
層架構中識別出物件；這也包含效能指標，你可以掃描過而很快地了解
View
的執行（與
相同版面中的其他
Views
相比）。你可以在這找到的資訊有：
層級檢視器（
Hierarchy Viewer
）
|
203
[Page-207]
圖
13-5
層級檢視：節點的數值資訊
這個
View
的類別型態（在此例此元件為
FrameLayout
）
這個
View
的內部
ID
（即此
View
在
R
類別中是如何被參考的）
此元件在
XML
內被建立時所使用的
android:id
三個彩球說明此
View
相對於樹狀結構裡其他物件的描繪效率；左邊的彩球表示 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.