How to set Floating Action Button image to fill the button?

The solution is app:maxImageSize = "56dp" property set to your FAB size.

  1. Have an image or vector asset, preferably in perfect circle shape and perfectly fit to canvass (no empty margins).
  2. Know the actual size of Floating Action Bar (FAB) - Default (56 x 56dp) or Mini (40 x 40dp).
  3. XML Code thusly:
<com.google.android.material.floatingactionbutton.FloatingActionButton
   android:src="@drawable/perfect_fit_circle_image"
   app:maxImageSize="56dp"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content" />

Set the following property for the FAB

android:scaleType="center"

if that does not work try using property

app:fabSize="mini"

Use below code

android:scaleType="fitXY"

If you are setting a rounded png image, work around for this is to extend the floatingActionButton class then override the on onMeasure method and set the padding to 0, and scaleType To centerCrop

public class FloatingImageButton extends FloatingActionButton {


public FloatingImageButton(Context context) {
    super(context);
}

public FloatingImageButton(Context context, AttributeSet attrs) {
    super(context, attrs);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    setPadding(0, 0, 0, 0);
    setScaleType(ScaleType.CENTER_CROP);


}
}

xml sample

    <com.tabz.app.FloatingImageButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/camera_circle"
    android:layout_gravity="bottom|end"
    android:layout_margin="16dp"/>

output

enter image description here

Set scale for the float button in xml

android:scaleX="2.0"

Or you can do it programmaticaly:

someButton.setScaleX(2.0f);
someButton.setScaleY(2.0f);

With the Material Components library, according to the doc, you can use the attribute app:maxImageSize.

You can use a custom dimension, but you can also refer to these defined dimensions.

<dimen name="design_fab_size_mini">40dp</dimen>
<dimen name="design_fab_size_normal">56dp</dimen>

Just use:

 <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/fab"
        app:srcCompat="@drawable/ic_add_24px"
        app:maxImageSize="@dimen/design_fab_size_normal"
        ../>

Here the result with the standard dimension (<dimen name="design_fab_image_size">24dp</dimen>) and the design_fab_size_normal.

enter image description hereenter image description here