Android ImageView - 16:9

Question

I need to set the Bitmap into ImageView to keep ratio 16:9. Do you have any advice? The main solution is probably in the override method onMeasure of custom ImageView but how?

Answer 1

Since PercentFrameLayout and PercentRelativeLayout were deprecated in API level 26.0.0, I'd suggest you to consider using of ConstraintLayout to keep ratio 16:9 for your ImageView. ConstraintLayout is really powerful tool to build Responsive UI for Android platform, you can find more details here Build a Responsive UI with ConstraintLayout.

Here is the example how to build your ImageView into ConstraintLayout to keep 16:9 ratio:

<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginEnd="0dp"
        android:layout_marginStart="0dp"
        android:layout_marginTop="0dp"
        app:srcCompat="@mipmap/ic_launcher"
        app:layout_constraintDimensionRatio="H,16:9"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

Don't forget to add constraint-layout dependency to your module's build.gradle file

implementation "com.android.support.constraint:constraint-layout:1.0.2"

---

Or instead of editing your XML file, edit your layout directly in Layout Editor:

Answer 2

EDIT 01/03/2019: After all this time, I strongly recommend using ConstraintLayout that @Eugene Brusov introduced below. I personally would never use my image view that does Math by overriding onMeasure.

EDIT 03/29/2018: My answer below may be simple, but may be too much of raw answer. If you want to utilize what's already given by Google's ConstraintLayout, follow this answer or scroll down and see @Eugene Brusov's answer.

Old answer:

public class CustomImageView extends ImageView {

    // some other necessary things

    @Override 
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        int width = getMeasuredWidth();

        //force a 16:9 aspect ratio             
        int height = Math.round(width * .5625f);
        setMeasuredDimension(width, height);
    }
}

Then in your xml

<path.to.package.CustomImageView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:src="@drawable/img"/>