How to force Android XML vector graphics to scale to fill an image button?-CodePudding

I've made my own version of an action bar across the bottom of the screen for my app, and have encountered a puzzling issue with icons placed in the buttons of that action bar. The layout is really simple.

    <LinearLayout
        android:id="@ id/navbar"
        android:layout_width="match_parent"
        android:layout_height="64dp"
        android:layout_alignParentBottom="true"
        android:elevation="1dp"
        android:gravity="center"
        android:background="@color/black_overlay" >

        <ImageButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center|center"
            android:layout_marginStart="8dp"
            android:layout_marginEnd="8dp"
            android:backgroundTintMode="multiply"
            android:backgroundTint="@android:color/transparent"
            android:foregroundTint="@color/white"
            android:src="@drawable/ic_list_48"
            android:contentDescription="Map Button" />

        <ImageButton
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center|center"
            android:layout_marginStart="8dp"
            android:layout_marginEnd="8dp"
            android:backgroundTintMode="multiply"
            android:backgroundTint="@android:color/transparent"
            android:src="@android:drawable/ic_popup_reminder"
            android:contentDescription="Notifications Button" />

The issue I'm encountering is when using a "system" icon like in the "Notifications Button" above, that icon properly scales to fill the ImageButton. But when using an icon that was created from a system icon like the "Map Button" above, the icon does NOT scale to fill the ImageButton like it should. Is there a way to make it do so?

CodePudding user response：

try

android:scaleType="fitxy"

CodePudding user response：

Your icons are not scaling up to fit the ImageButtons but, rather, the ImageButtons are scaling to fit the icons which each have an intrinsic width because you specify 'wrap_content'. You can see that here:

The left button has the standard vector drawable launch icon (width/height=108dp) and the icon on the right is the system defined PNG with a size that varies by platform.

You don't specify how you want the layout to look, but I suggest the following:

<LinearLayout 
    android:id="@ id/navbar"
    android:layout_width="match_parent"
    android:layout_height="64dp"
    android:layout_alignParentBottom="true"
    android:background="@color/black"
    android:elevation="1dp"
    android:gravity="center"
    tools:context=".MainActivity">

    <ImageButton
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_gravity="center|center"
        android:layout_marginStart="8dp"
        android:layout_marginEnd="8dp"
        android:layout_weight="1"
        android:backgroundTint="@android:color/transparent"
        android:backgroundTintMode="multiply"
        android:contentDescription="Map Button"
        android:foregroundTint="@color/white"
        android:src="@drawable/ic_launcher_foreground" />

    <ImageButton
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:layout_marginStart="8dp"
        android:layout_marginEnd="8dp"
        android:layout_weight="1"
        android:backgroundTint="@android:color/transparent"
        android:backgroundTintMode="multiply"
        android:contentDescription="Notifications Button"
        android:src="@android:drawable/ic_popup_reminder" />
</LinearLayout>

Here weights are used to expand the size of the icons. This results in the following: