Android-约束布局
约束布局(ConstraintLayout)
是Android开发中最常用的,最灵活,编程效率最高的布局方式,
重要的属性:
constraintTop:表示当前控件的方向
toTopOf:表示所要对齐的控件的方向
其中top是可变的,可以是left ,right, boottom等
比如:
app:layout_constraintEnd_toStartOf="@+id/guideline"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="parent"
这个属性就是把一个View的尺寸设为特定的宽高比,比如设置一张图片的宽高比为 1:1,4:3, 16:9 等。
通过使用ConstraintLayout,只需使用layout_constraintDimensionRatio属性即可。
如果在布局文件中没有明确的写出偏移比例,那么系统默认偏移比例值为:0.5 。
基线约束控件
app:layout_constraintGuide_percent="0.5" 表示基线的百分比例
android:orientation="vertical" 方向,水平和垂直
主要用于将基线两边的控件以基线为标准对齐,如果把手机屏幕看成一张纸,就是将纸以基线对折
效果展示
<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <android.support.constraint.Guideline android:id="@+id/guideline" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.33" /> <android.support.constraint.Guideline android:id="@+id/guideline2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" app:layout_constraintGuide_percent="0.66" /> <android.support.constraint.Guideline android:id="@+id/guideline3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" app:layout_constraintGuide_percent="0.25" /> <android.support.constraint.Guideline android:id="@+id/guideline4" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" app:layout_constraintGuide_percent="0.75" /> <android.support.constraint.Guideline android:id="@+id/guideline5" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" app:layout_constraintGuide_percent="0.4189189" /> <android.support.constraint.Guideline android:id="@+id/guideline6" android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="vertical" app:layout_constraintGuide_percent="0.5912162" /> <ImageView android:id="@+id/imageView2" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="8dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toStartOf="@+id/guideline3" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="@+id/guideline2" app:srcCompat="@android:color/holo_red_light" /> <ImageView android:id="@+id/imageView5" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="16dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" android:layout_marginTop="8dp" app:layout_constraintBottom_toTopOf="@+id/guideline2" app:layout_constraintEnd_toStartOf="@+id/guideline4" app:layout_constraintStart_toStartOf="@+id/guideline3" app:layout_constraintTop_toTopOf="parent" app:srcCompat="#ff3344" /> <ImageView android:id="@+id/imageView9" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="8dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" android:layout_marginTop="8dp" app:layout_constraintBottom_toTopOf="@+id/guideline" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="@+id/guideline4" app:layout_constraintTop_toTopOf="parent" app:srcCompat="@android:color/holo_red_light" /> <ImageView android:id="@+id/imageView7" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="8dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toStartOf="@+id/guideline5" app:layout_constraintStart_toStartOf="@+id/guideline3" app:layout_constraintTop_toTopOf="@+id/guideline2" app:srcCompat="@android:color/holo_red_light" /> <ImageView android:id="@+id/imageView11" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="8dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toStartOf="@+id/guideline6" app:layout_constraintStart_toStartOf="@+id/guideline5" app:layout_constraintTop_toTopOf="@+id/guideline2" app:srcCompat="@android:color/holo_red_light" /> <ImageView android:id="@+id/imageView10" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="8dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toStartOf="@+id/guideline4" app:layout_constraintStart_toStartOf="@+id/guideline6" app:layout_constraintTop_toTopOf="@+id/guideline2" app:srcCompat="@android:color/holo_red_light" /> <ImageView android:id="@+id/imageView6" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="16dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" android:layout_marginTop="8dp" app:layout_constraintBottom_toTopOf="@+id/imageView12" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="@+id/guideline4" app:layout_constraintTop_toTopOf="@+id/guideline" app:srcCompat="@android:color/holo_red_light" /> <ImageView android:id="@+id/imageView12" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="8dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="@+id/guideline4" app:layout_constraintTop_toTopOf="@+id/guideline2" app:srcCompat="@android:color/holo_red_light" /> <ImageView android:id="@+id/imageView4" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="16dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" android:layout_marginTop="8dp" app:layout_constraintBottom_toTopOf="@+id/guideline2" app:layout_constraintEnd_toStartOf="@+id/guideline3" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="@+id/guideline" app:srcCompat="@android:color/holo_red_light" /> <ImageView android:id="@+id/imageView3" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginBottom="8dp" android:layout_marginEnd="8dp" android:layout_marginLeft="8dp" android:layout_marginRight="8dp" android:layout_marginStart="8dp" android:layout_marginTop="8dp" app:layout_constraintBottom_toTopOf="@+id/guideline" app:layout_constraintEnd_toStartOf="@+id/guideline3" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" app:srcCompat="@android:color/holo_red_light" /> </android.support.constraint.ConstraintLayout>