Android Custom View Basics: Introduction ViewRoot, DecorView & Window is

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Foreword

• Custom View is the principle of Android developers need to know basis, before Understanding Custom View, you need to have some knowledge reserves.
• Today, it will be fully resolved on the basis of Custom View: ViewRoot, DecorView & Window , hope you like it.

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table of Contents

schematic diagram

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1. ViewRoot

1.1 Introduction

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1.2 Special attention

// 在主线程中，Activity对象被创建后：
// 1. 自动将DecorView添加到Window中 & 创建ViewRootImpll对象
root = new ViewRootImpl(view.getContent(),display);

// 3. 将ViewRootImpll对象与DecorView建立关联
root.setView(view,wparams,panelParentView)

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2. DecorView

2.1 Definitions

Top View, i.e. the root node of the tree view Android; subclass also FrameLayout

2.2 Role

Load & display layout. Event View layers have to go through DecorView, and then passed to View

2.3 Special Note

Containing a vertical direction LinearLayout, divided into two parts:

1. = On the title bar (titlebar)
2. Under Column = content (content)

schematic diagram

In Activitythrough setContentView（）into the layout file set is actually being added to the contents of the column, becoming the only son View = id for the content of FrameLayoutthe

// 在代码中可通过content得到对应加载的布局

// 1. 得到content
ViewGroup content = (ViewGroup)findViewById(android.R.id.content);
// 2. 得到设置的View
ViewGroup rootView = (ViewGroup) content.getChildAt(0);

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3. Window

Brief introduction

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4. Activity

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5. The relationship between

Relations ViewRoot, DecorView, Window and Activity is very important.

5.1 summary

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The relationship between 5.2

schematic diagram

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6. Summary

• In this paper a comprehensive analysis on the basis of Custom View: ViewRoot, DecorView & Window ,
• About Custom Viewother articles of:
  (1) Custom View basis - most understandable Custom View principles Series
  (2) Customize View Measure process - most understandable Custom View principles Series
  (3) Custom View Layout Process - the most straightforward principle series custom View
  (4) customize View Draw process - the most straightforward principle series custom View
• Next, I will continue to View from the application of the definition to explain, are interested can continue to focus on Android development Carson_Ho notes

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Welcome concern Carson_Ho Jane book!

From time to time to share about Android development dry goods, the pursuit of short, flat, fast , but does not lack depth .

Reproduced in: https: //www.jianshu.com/p/28d396a0f05f