How to scale an image to the top center?

I have an imageview as background. It is bigger than screen. I want to center it horizontally. It should align to the top. So, top of the original image should seen in the screen. I can resize the original images if necessary.

For example, in the giraffe image, I should be able to see from head to neck, not to the foot. Because the width allows that much.

XML Code

...

<androidx.constraintlayout.widget.ConstraintLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
     >

    <ImageView
        android:id="@ id/imageView5"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="matrix"
        android:src="@drawable/home_screen_wallpaper_image"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

Image to what i want when image is too big to phone size, scale should be like this

CodePudding user response：

The usual scale types will not work for you. You will need to use the MATRIX scale type.

Here is how to apply it:

binding.matrixImage.doOnNextLayout {
    // We will use a Matrix to shift the image left.
    binding.matrixImage.scaleType = ImageView.ScaleType.MATRIX
    
    // Compute how far to shift the image
    val dx = (binding.matrixImage.drawable.intrinsicWidth - binding.matrixImage.width) / 2f
    
    // Create and set the Matrix.
    val matrix = Matrix()
    matrix.postTranslate(-dx, 0f)
    binding.matrixImage.imageMatrix = matrix
}