Why is the look of the activity different in the Android Studio preview than on the device?

Question

I created an navigation drawer activity and found that its content page looks different in the preview.

This is the preview.

And this is the AVD appearance (it looks like a real device too).

XML code is:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    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"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.xy.xy.HomePage">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="160sp"
        android:layout_marginLeft="5sp"
        android:layout_marginRight="5sp"
        android:layout_marginTop="5sp">

    <ImageView
        android:id="@+id/TestMenuImage"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:contentDescription="@string/app_name"
        app:srcCompat="@drawable/bg1"
        tools:scaleType="centerCrop" />

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        tools:background="@color/hbm_text_background">

    <TextView
        android:id="@+id/TestMenuName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5sp"
        android:contentDescription="@string/app_name"
        android:text="@string/test"
        android:textColor="@color/white" />

    </RelativeLayout>

    <Button
        android:id="@+id/TestMenuButton"
        style="?android:attr/buttonBarButtonStyle"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    </RelativeLayout>

</LinearLayout>

What do you think where the problem is?

Answer 1

EDIT: I see you've included the style file and it does appear that your app is running the same style (AppTheme) as your preview so I think we can possibly rule out that as a culprit.

I doubt this makes a difference but I noticed your preview is running api 27 and your device is running api 27.

Try removing the tools:context="com.xy.xy.HomePage" and see if it makes a difference.

---

The preview can only show you the current view. It doesn't know the parent view. The child view may have a parent view that constricts the size of the child view . Let's say that your image is set to width="match_parent". In this case, the preview may expand the image to fill the full width but at runtime your image my be placed inside a parent with a width="100dp" which would cause the image to have a width of only 100dp. Padding and margin of the parent view can also cause an issue.

If this isn't the problem then it may be a styling issue. I'd have to see more of your Theme and Style setup in order to know for sure. Your preview might be showing you a different style/theme than what you are actually using at runtime.

Answer 2

Try adding android:scaleType="fitXY" in ImageView like this:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    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"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.xy.xy.HomePage">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="160sp"
        android:layout_marginLeft="5sp"
        android:layout_marginRight="5sp"
        android:layout_marginTop="5sp">

    <ImageView
        android:id="@+id/TestMenuImage"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:contentDescription="@string/app_name"
        app:srcCompat="@drawable/bg1"
        android:scaleType="fitXY"/>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        tools:background="@color/hbm_text_background">

    <TextView
        android:id="@+id/TestMenuName"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5sp"
        android:contentDescription="@string/app_name"
        android:text="@string/test"
        android:textColor="@color/white" />

    </RelativeLayout>

    <Button
        android:id="@+id/TestMenuButton"
        style="?android:attr/buttonBarButtonStyle"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    </RelativeLayout>

</LinearLayout>

That's probably a little bug with ImageViews´ previews in Android Studio,

Hope it helps

Answer 3

"styles.xml" file:

<resources>

<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
    <item name="android:textColorPrimary">@android:color/background_light</item>
</style>

<style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />

<style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />

</resources>

"AndroidManifest.xml" file :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.xy.xy">

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity
        android:name=".HomePage"
        android:label="@string/title_activity_home_page"
        android:parentActivityName=".MainActivity"
        android:theme="@style/AppTheme">
        <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.wordwave.wordwave.MainActivity" />
    </activity>
</application>

</manifest>

"MainActivity.kt" file:

package com.xy.xy

import android.content.Intent
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.content_home_page)

}