Personal Technology Blog-android Layout tips

(1) Rational Application of weight attribute

When using Match_parent (fill_parent), it needs to be calculated, otherwise the following conditions will occur
Code:

  <linearlayout xmlns:android= "http://schemas.android.com/apk/res/android" xmlns:tools= "http/ Schemas.android.com/tools "android:id=" @+id/linearlayout1 "android:layout_width=" Match_parent "Android:layout_hei        ght= "Match_parent" > <textview android:layout_weight= "1" android:layout_width= "Fill_parent" android:layout_height= "Fill_parent" android:text= "one" android:background= "#98FB98"/> <text         View android:layout_weight= "2" android:layout_width= "Fill_parent" android:layout_height= "Fill_parent" android:text= "android:background=" #FFFF00 "/> <textview android:layout_weight="        3 "android:layout_width=" Fill_parent "android:layout_height=" Fill_parent "android:text=" three " Android:background= "#FF00FF"/></linearlayout>  

The effect is as follows

This time found a problem, three disappeared? There is three in the code, but also set 3, and 1 and 2 of the proportion is not right, 1:2:3 into 2:1:0, why so? After consulting the data I found that it is not so simple, this is needed to calculate, the online algorithm has several step 1: all are fill_parent, But the screen is only one, then 1-3 = 2 fill_parent Step 2: The ratio is 1/6,2/6,3/6 Step 3: First come first served first, calculate: 1-2 * (1/6) = 2/3 fill_parent then to the second, count Count: 1-2 * (2/6) = 1/3 Fill_parent Last to three, calculation 1-2 * (3/6) = 0 fill_parent Step 4: So the final result: one accounted for two, two accounted for, and three had nothing. That's why three didn't show up.

If the ratio is 1:1:1, the effect is as follows

Calculated as above, the result is: 1/3 1/3 1/3, yes.

If the ratio is 2:3:4, the effect is as follows

Calculation results: 5/9 3/9 1/9, contrast, 5:3:1, that's right.

(2) The difference between margin and padding

For these two properties may be a bit confusing, first margin represents an offset, such as MarginLeft = "5DP" means that the component is offset from the left edge of the container 5DP; While padding represents the fill, and the filled object is for elements in the component, such as TextView in the text such as TextView set paddingleft = "5DP", then the element in the component of the left padding 5DP space. Margin is for the components in the container, and padding is for the elements in the component. Here's a simple code to demonstrate the difference:

<relativelayout xmlns:android= "http://schemas.android.com/apk/res/android" xmlns:tools= "http// Schemas.android.com/tools "android:layout_width=" match_parent "android:layout_height=" Match_parent "a        ndroid:paddingbottom= "@dimen/activity_vertical_margin" android:paddingleft= "@dimen/activity_horizontal_margin"        android:paddingright= "@dimen/activity_horizontal_margin" android:paddingtop= "@dimen/activity_vertical_margin" Tools:context= ". Mainactivity "> <button android:id=" @+id/btn1 "android:layout_height=" wrap_content "Android:layout_width=" wrap_content "android:text=" button "/> <button androi            d:paddingleft= "100DP" android:layout_height= "wrap_content" android:layout_width= "Wrap_content" android:text= "button" android:layout_torightof= "@id/btn1"/> <button Android  Oid:id= "@+id/btn2"           android:layout_height= "Wrap_content" android:layout_width= "wrap_content" android:text= "Bu Tton "android:layout_alignparentbottom=" true "/> <button android:layout_marginleft=" 100d P "android:layout_height=" Wrap_content "android:layout_width=" Wrap_content "Android:text            = "button" android:layout_torightof= "@id/btn2" android:layout_alignparentbottom= "true"/>  </RelativeLayout>

The effect is as follows

In addition, margin can be set to negative, such as after entering the software, pop-up ads page, the top right corner of the cancle button margin is used negative, the code is as follows

    <ImageView          android:id="@+id/imgBack"          android:layout_width="200dp"          android:layout_height="200dp"          android:layout_centerInParent="true"          android:background="@drawable/myicon" />        <ImageView          android:id="@+id/imgCancle"          android:layout_width="28dp"          android:layout_height="28dp"          android:layout_alignRight="@id/imgBack"          android:layout_alignTop="@id/imgBack"          android:background="@drawable/cancel"          android:layout_marginTop="-15dp"  //cancle按钮的margin使用负数        android:layout_marginRight="-10dp" />  

This is my Android layout summed up in some of the tips, relatively low, only for reference ha ha ~

Personal Technology Blog-android Layout tips