按钮不显示（左）图像

Question

我正在开发 Android 应用程序。在片段中，我需要放置一些带有文本和图像的按钮。我使用 drawableStart 属性来放置一个可绘制对象。关于它不显示图像的任何想法？

另外一个信息：我的项目正在使用 JetPack 库（最新版本）。

布局代码：

<?xml version="1.0" encoding="utf-8"?>

<androidx.constraintlayout.widget.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:clipChildren="false"
    android:fillViewport="true"
    app:behavior_overlapTop="128dp"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".ui.activities.DocumentoDetailActivity"
    tools:showIn="@layout/activity_documento_detail">

    <androidx.cardview.widget.CardView
        android:id="@+id/documento_card"
        style="@style/Widget.MaterialComponents.Button.OutlinedButton"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginLeft="@dimen/text_margin"
        android:layout_marginTop="32dp"
        android:layout_marginRight="@dimen/text_margin"
        android:layout_marginBottom="@dimen/text_margin"
        android:transitionName="@{@string/event_card_transition + eventDetailViewModel.event.id}"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/documento_image_thumbnail"
        android:layout_width="58dp"
        android:layout_height="0dp"
        android:background="@android:color/darker_gray"
        android:contentDescription="@string/app_img_content_description"
        android:cropToPadding="true"
        android:elevation="@dimen/app_cardview_default_elevation"

        android:scaleType="centerCrop"
        app:layout_constraintDimensionRatio="W,4:3"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:src="@drawable/ic_thumbnail_laboratorio_analisi" />
    <!--app:loadUrl="@{eventDetailViewModel.event.thumbnail}"-->
    <!--android:transitionName="@{@string/event_image_transition + eventDetailViewModel.event.id}"-->


    <!--<androidx.cardview.widget.CardView-->
    <!--android:id="@+id/documento_preferred"-->
    <!--android:layout_width="wrap_content"-->
    <!--android:layout_height="wrap_content"-->
    <!--android:layout_marginTop="8dp"-->
    <!--android:layout_marginEnd="8dp"-->
    <!--android:transitionGroup="true"-->
    <!--android:visibility="visible"-->
    <!--app:cardBackgroundColor="#FFFFFF"-->
    <!--app:cardElevation="@dimen/app_design_appbar_elevation"-->
    <!--app:layout_constraintEnd_toEndOf="@+id/documento_card"-->
    <!--app:layout_constraintRight_toRightOf="@id/documento_card"-->
    <!--app:layout_constraintTop_toTopOf="@+id/documento_card">-->


    <!--<ImageView-->
    <!--android:id="@+id/documento_star"-->
    <!--android:layout_width="wrap_content"-->
    <!--android:layout_height="wrap_content"-->


    <!--android:layout_marginStart="8dp"-->
    <!--android:layout_marginTop="8dp"-->
    <!--android:layout_marginEnd="8dp"-->
    <!--android:layout_marginBottom="8dp"-->
    <!--app:srcCompat="@drawable/ic_item_unstarred" />-->
    <!--android:text="@{eventDetailViewModel.event.price}"-->

    <!--</androidx.cardview.widget.CardView>-->

    <TextView
        android:id="@+id/documento_titolo"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:layout_marginStart="8dp"

        android:layout_marginTop="8dp"
        android:layout_marginEnd="8dp"
        android:elevation="@dimen/app_cardview_default_elevation"
        android:ellipsize="end"
        android:maxLines="3"
        android:textAppearance="@style/TextAppearance.AppCompat.Title"
        android:transitionName="@{@string/event_name_transition + eventDetailViewModel.event.id}"
        app:layout_constraintLeft_toRightOf="@id/documento_image_thumbnail"
        app:layout_constraintStart_toEndOf="@+id/documento_image_thumbnail"
        app:layout_constraintTop_toTopOf="@+id/documento_card"
        tools:text="@sample/documenti.json/data/titolo" />
    <!--android:text="@{eventDetailViewModel.event.name}"-->

    <TextView
        android:id="@+id/documento_info1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"

        android:layout_margin="@dimen/text_margin"
        android:layout_marginEnd="8dp"
        android:elevation="@dimen/app_cardview_default_elevation"
        android:maxLines="1"
        android:textAppearance="@style/TextAppearance.AppCompat.Body2"
        android:textColor="@color/primary_dark"
        app:layout_constraintEnd_toEndOf="@+id/documento_card"
        app:layout_constraintStart_toEndOf="@+id/documento_info1_label"
        app:layout_constraintTop_toBottomOf="@+id/documento_titolo"
        tools:text="@sample/documenti.json/data/info" />
    <!--android:text="@{eventDetailViewModel.venue.name}"-->

    <TextView
        android:id="@+id/documento_info1_label"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:elevation="@dimen/app_cardview_default_elevation"
        android:text="Data:"
        app:layout_constraintStart_toEndOf="@+id/documento_image_thumbnail"
        app:layout_constraintTop_toBottomOf="@+id/documento_titolo" />


    <Button
        android:id="@+id/documento_btn_cancella"
        style="@style/Widget.MaterialComponents.Button.OutlinedButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:elevation="@dimen/app_cardview_default_elevation"
        android:text="@string/documento_cancella"
        android:drawableStart="@drawable/ic_action_delete_24dp"
        app:layout_constraintStart_toStartOf="@+id/documento_card"
        app:layout_constraintTop_toBottomOf="@+id/documento_info1" />

    <Button
        android:id="@+id/documento_btn_modifica"
        style="@style/Widget.MaterialComponents.Button.OutlinedButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:layout_marginStart="8dp"
        android:layout_marginEnd="8dp"
        android:elevation="@dimen/app_cardview_default_elevation"
        android:text="@string/documento_modifica"
        android:drawableStart="@drawable/ic_action_delete_24dp"
        app:layout_constraintEnd_toStartOf="@+id/documento_btn_vedi"
        app:layout_constraintStart_toEndOf="@+id/documento_btn_cancella"
        app:layout_constraintTop_toBottomOf="@+id/documento_info1" />

    <Button
        android:id="@+id/documento_btn_vedi"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="@dimen/text_margin"
        android:layout_marginEnd="8dp"
        android:elevation="@dimen/app_cardview_default_elevation"
        android:text="@string/documento_vedi"
        android:drawableStart="@drawable/ic_action_search__white_24dp"
        app:layout_constraintEnd_toEndOf="@+id/documento_card"
        app:layout_constraintTop_toBottomOf="@+id/documento_info1" />

    <!--android:rating="@{eventRatingViewModel.result.rating}"-->

    <androidx.viewpager.widget.ViewPager
        android:id="@+id/documento_view_pager"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginLeft="@dimen/text_margin"
        android:layout_marginTop="8dp"
        android:layout_marginRight="@dimen/text_margin"
        android:layout_marginBottom="@dimen/text_margin"
        android:elevation="4dp"
        android:transitionGroup="true"
        app:layout_constraintBottom_toBottomOf="@id/documento_card"
        app:layout_constraintLeft_toLeftOf="@id/documento_card"
        app:layout_constraintRight_toRightOf="@id/documento_card"
        app:layout_constraintTop_toBottomOf="@+id/documento_btn_vedi">
        <!--app:pageMargin="@{@dimen/activity_horizontal_margin}}"-->
        <!--app:sectionAdapter="@{eventDetailViewModel.event.id}"-->
        <!--app:pageMargin="@dimen/activity_horizontal_margin"-->

        <com.google.android.material.tabs.TabLayout
            android:id="@+id/documento_tab_layout"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            app:tabTextAppearance="@style/AppTabLayoutStyle"

            />
        <!--app:setupWithViewPager="@{viewPager}"-->

    </androidx.viewpager.widget.ViewPager>

</androidx.constraintlayout.widget.ConstraintLayout>

    <!--</layout>-->

提前致谢！

Answer 1

因为您将 layout_width 设置为 wrap_content，可绘制对象缺少要绘制的宽度。

试试把它改成这样：

<android.support.v7.widget.AppCompatButton
    android:id="@+id/documento_btn_modifica"
    android:layout_width="0dp"
    android:layout_height="56dp"
    android:drawableStart="@drawable/ic_action_delete_24dp"
    app:layout_constraintDimensionRatio="1:1"
    />

这样 app:layout_constraintDimensionRatio="1:1" 和 android:layout_width="0dp" 将确保宽度与高度匹配。

Answer 2

终于找到了。我在这里写信来分享我的解决方案。我解决了使用 app:icon 属性而不是 android:drawableStart.

按钮不显示（左）图像

Button does not display (left) image

android

button

android-drawable

material-design