Android-约束布局-如何对齐以其他视图的边缘为中心的视图? [英] Android - Constraint layout - How to align a view centered over edge of other view?

问题描述

我要构建这样的布局:

在约束布局内，有一个像横幅广告一样的图像视图，然后有一个与横幅广告的底部边缘居中对齐的卡片，然后还有另一个与横幅广告的顶部边缘居中对齐的图像视图.卡.

Inside the constraint layout there is an Image View which acts like a banner, then there is a Card that is center aligned with the bottom edge of the banner and then there is another Image View that is center aligned with the top edge of the card.

我面临的问题是，与卡对齐时，第二个图像视图(绿色的一个)在背景中而不是在前景中.

The problem I am facing is that the second Image View (GREEN one) when aligned with the card goes in the background instead of staying in the foreground.

这是xml

<android.support.constraint.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:fitsSystemWindows="true"
            app:layout_collapseMode="parallax"
            android:paddingBottom="@dimen/padding_10">

            <ImageView
                android:id="@+id/imageView_jobBackdrop_jobDetails"
                android:layout_width="match_parent"
                android:layout_height="175dp"
                android:fitsSystemWindows="true"
                android:scaleType="centerCrop"
                android:src="@drawable/backdrop_job_details"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent"
                app:layout_collapseMode="parallax"/>

            <ImageView
                android:id="@+id/imageView_companyLogo_jobDetails"
                android:layout_width="75dp"
                android:layout_height="75dp"
                android:fitsSystemWindows="true"
                app:layout_collapseMode="parallax"
                app:layout_constraintBottom_toTopOf="@+id/cardView_jobHeader_jobDetails"
                app:layout_constraintEnd_toEndOf="@id/cardView_jobHeader_jobDetails"
                app:layout_constraintStart_toStartOf="@id/cardView_jobHeader_jobDetails"
                app:layout_constraintTop_toTopOf="@+id/cardView_jobHeader_jobDetails" />

            <android.support.v7.widget.CardView
                android:id="@+id/cardView_jobHeader_jobDetails"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginBottom="24dp"
                android:layout_marginEnd="16dp"
                android:layout_marginStart="16dp"
                app:layout_constraintBottom_toBottomOf="@+id/imageView_jobBackdrop_jobDetails"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/imageView_jobBackdrop_jobDetails"
                app:layout_constraintVertical_bias="0.5">

                <android.support.constraint.ConstraintLayout
                    android:id="@+id/parent"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:id="@+id/textView_jobTitle_jobDetails"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_marginEnd="16dp"
                        android:layout_marginStart="16dp"
                        android:layout_marginTop="32dp"
                        android:gravity="center"
                        android:text="Fresher Software Developer Job. Urgent Openning. Angular Js, HTML, JavaScript, CSS"
                        app:layout_constraintEnd_toEndOf="parent"
                        app:layout_constraintStart_toStartOf="parent"
                        app:layout_constraintTop_toTopOf="parent" />

                </android.support.constraint.ConstraintLayout>
            </android.support.v7.widget.CardView>
        </android.support.constraint.ConstraintLayout>

推荐答案

尝试一下:

<?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"
    android:orientation="vertical"
    android:padding="20dp">

    <android.support.v7.widget.CardView
        android:id="@+id/card_1"
        android:layout_width="0dp"
        android:layout_height="200dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginTop="8dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <android.support.v7.widget.CardView
        android:id="@+id/card_2"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_marginBottom="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginTop="0dp"
        app:cardBackgroundColor="#69F"
        app:layout_constraintBottom_toBottomOf="@+id/card_1"
        app:layout_constraintLeft_toLeftOf="@+id/card_1"
        app:layout_constraintRight_toRightOf="@+id/card_1"
        app:layout_constraintTop_toBottomOf="@+id/card_1" />

</android.support.constraint.ConstraintLayout>

说明:-之所以有效，是因为这四行

Explanation :- This works because of these four lines

以下几行将蓝色CardView设置为在White CardView的底部边缘居中.

Following lines sets the blue CardView centered on the bottom edge of White CardView.

<!-- top constraint is set to bottom of White CardView -->
app:layout_constraintTop_toBottomOf="@+id/card_1"

<!-- bottom constraint is set to bottom of White CardView -->
app:layout_constraintBottom_toBottomOf="@+id/card_1"

以下几行将蓝色CardView设置为水平居中

Following lines set the blue CardView centered horizontally

<!-- left constraint is set to left of White CardView -->
app:layout_constraintLeft_toLeftOf="@+id/card_1"

<!-- right constraint is set to right of White CardView -->
app:layout_constraintRight_toRightOf="@+id/card_1"

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