Talking about Layout_weight in Android

Introduction

During the development of Android, we often need to lay out the interface proportionally, and we will generally use the Layout_ property to set it. Today's article we will briefly introduce the use and layout of the layout_weight principle. As the project experience accumulates, the blog post may be updated at all times.

use layout_weight under LinearLayout

Today, let's introduce the problem of using layout_weight under LinearLayout. Let's say we need to implement something like this:

Let's look at the layout style settings at this time:

1 <!--layout When adjusting a horizontal screen -2     <LinearLayout3         android:orientation= "Horizontal"4 Android:layout_width= "Match_parent"5 Android:layout_height= "Wrap_content"6 Android:layout_marginleft= "16DP"7 Android:layout_marginright= "16DP">8 9         <ButtonTen             Android:layout_width= "Wrap_content" One Android:layout_height= "Wrap_content" A Android:id= "@+id/crime_date" - Android:layout_weight= "1"/> -  the         <CheckBox -             Android:layout_width= "Wrap_content" - Android:layout_height= "Wrap_content" - Android:text= "@string/crime_solved_label" + Android:id= "@+id/crime_solved" - Android:layout_weight= "1"/> +     </LinearLayout>

We see in the layout style file that we see the button layout_weight is the layout_weight of 1,checkbox is 1. What does that mean? Let's take a detailed introduction below.

The Layout_weight property tells LinearLayout how to arrange the sub-component layout. We see that the Layout_weight value of the button is the same as the layout_weight value of the checkbox, but it does not mean that they occupy the same width on the screen. In fact, when calculating the width of a subassembly, LinearLayout uses a mixed value of Layout_width layout_weight. let's look at the detailed steps:

　　First step : LinearLayout View the value of the Layout_width property (the vertical orientation is the value of the Layout_height property). The Layout_width property values for the button and checkbox components are set to wrap_content, so they get only enough space to draw themselves.

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　　Step two : LinearLayout the allocation of additional space based on the value of the Layout_weight attribute. ：

　　

In a layout, the button and checkbox components have the same Layout_weight property values, so they share the same size of extra space. If you set the weight value of the button component to 2, it will get 2/3 extra space and the checkbox component gets the remaining 1/3. Let's take a look at the effect:

　　

　　What do you do if you want LinearLayout to assign exactly the same width to the respective view? It is simple to set the Layout_width property value of each component to 0DP to avoid the space allocation of the first step, so that LinearLayout will only consider using the Layout_weight property value to complete the required space allocation.

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Talking about Layout_weight in Android