Fit image into ImageView, keep aspect ratio and th

Question

How to fit an image of random size to an ImageView?
When:

• Initially ImageView dimensions are 250dp * 250dp
• The image's larger dimension should be scaled up/down to 250dp
• The image should keep its aspect ratio
• The ImageView dimensions should match scaled image's dimensions after scaling

E.g. for an image of 100*150, the image and the ImageView should be 166*250.
E.g. for an image of 150*100, the image and the ImageView should be 250*166.

If I set the bounds as

<ImageView
    android:id="@+id/picture"
    android:layout_width="250dp"
    android:layout_height="250dp"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="20dp"
    android:adjustViewBounds="true" />

images fit properly in the ImageView, but the ImageView is always 250dp * 250dp.

Answer 1

I needed to get this done in a constraint layout with Picasso, so I munged together some of the above answers and came up with this solution (I already know the aspect ratio of the image I'm loading, so that helps):

Called in my activity code somewhere after setContentView(...)

protected void setBoxshotBackgroundImage() {
    ImageView backgroundImageView = (ImageView) findViewById(R.id.background_image_view);

    if(backgroundImageView != null) {
        DisplayMetrics displayMetrics = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(displayMetrics);
        int width = displayMetrics.widthPixels;
        int height = (int) Math.round(width * ImageLoader.BOXART_HEIGHT_ASPECT_RATIO);

        // we adjust the height of this element, as the width is already pinned to the parent in xml
        backgroundImageView.getLayoutParams().height = height;

        // implement your Picasso loading code here
    } else {
        // fallback if no element in layout...
    }
}

In my XML

<?xml version="1.0" encoding="utf-8"?>

<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:layout_editor_absoluteY="0dp"
tools:layout_editor_absoluteX="0dp">

    <ImageView
        android:id="@+id/background_image_view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:scaleType="fitStart"
        app:srcCompat="@color/background"
        android:adjustViewBounds="true"
        tools:layout_editor_absoluteY="0dp"
        android:layout_marginTop="0dp"
        android:layout_marginBottom="0dp"
        android:layout_marginRight="0dp"
        android:layout_marginLeft="0dp"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>

    <!-- other elements of this layout here... -->

</android.support.constraint.ConstraintLayout>

Note the lack of a constraintBottom_toBottomOf attribute. ImageLoader is my own static class for image loading util methods and constants.

Answer 2

(The answer was heavily modified after clarifications to the original question)

After clarifications:
This cannot be done in xml only. It is not possible to scale both the image and the ImageView so that image's one dimension would always be 250dp and the ImageView would have the same dimensions as the image.

This code scales Drawable of an ImageView to stay in a square like 250dp x 250dp with one dimension exactly 250dp and keeping the aspect ratio. Then the ImageView is resized to match the dimensions of the scaled image. The code is used in an activity. I tested it via button click handler.

Enjoy. :)

private void scaleImage(ImageView view) throws NoSuchElementException  {
    // Get bitmap from the the ImageView.
    Bitmap bitmap = null;

    try {
        Drawable drawing = view.getDrawable();
        bitmap = ((BitmapDrawable) drawing).getBitmap();
    } catch (NullPointerException e) {
        throw new NoSuchElementException("No drawable on given view");
    } catch (ClassCastException e) {
        // Check bitmap is Ion drawable
        bitmap = Ion.with(view).getBitmap();
    }

    // Get current dimensions AND the desired bounding box
    int width = 0;

    try {
        width = bitmap.getWidth();
    } catch (NullPointerException e) {
        throw new NoSuchElementException("Can't find bitmap on given view/drawable");
    }

    int height = bitmap.getHeight();
    int bounding = dpToPx(250);
    Log.i("Test", "original width = " + Integer.toString(width));
    Log.i("Test", "original height = " + Integer.toString(height));
    Log.i("Test", "bounding = " + Integer.toString(bounding));

    // Determine how much to scale: the dimension requiring less scaling is
    // closer to the its side. This way the image always stays inside your
    // bounding box AND either x/y axis touches it.  
    float xScale = ((float) bounding) / width;
    float yScale = ((float) bounding) / height;
    float scale = (xScale <= yScale) ? xScale : yScale;
    Log.i("Test", "xScale = " + Float.toString(xScale));
    Log.i("Test", "yScale = " + Float.toString(yScale));
    Log.i("Test", "scale = " + Float.toString(scale));

    // Create a matrix for the scaling and add the scaling data
    Matrix matrix = new Matrix();
    matrix.postScale(scale, scale);

    // Create a new bitmap and convert it to a format understood by the ImageView 
    Bitmap scaledBitmap = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);
    width = scaledBitmap.getWidth(); // re-use
    height = scaledBitmap.getHeight(); // re-use
    BitmapDrawable result = new BitmapDrawable(scaledBitmap);
    Log.i("Test", "scaled width = " + Integer.toString(width));
    Log.i("Test", "scaled height = " + Integer.toString(height));

    // Apply the scaled bitmap
    view.setImageDrawable(result);

    // Now change ImageView's dimensions to match the scaled image
    LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) view.getLayoutParams(); 
    params.width = width;
    params.height = height;
    view.setLayoutParams(params);

    Log.i("Test", "done");
}

private int dpToPx(int dp) {
    float density = getApplicationContext().getResources().getDisplayMetrics().density;
    return Math.round((float)dp * density);
}

The xml code for the ImageView:

<ImageView a:id="@+id/image_box"
    a:background="#ff0000"
    a:src="@drawable/star"
    a:layout_width="wrap_content"
    a:layout_height="wrap_content"
    a:layout_marginTop="20dp"
    a:layout_gravity="center_horizontal"/>

Thanks to this discussion for the scaling code:
http://www.anddev.org/resize_and_rotate_image_-_example-t621.html

UPDATE 7th, November 2012:
Added null pointer check as suggested in comments

Answer 3

After searching for a day, I think this is the easiest solution:

imageView.getLayoutParams().width = 250;
imageView.getLayoutParams().height = 250;
imageView.setAdjustViewBounds(true);

Answer 4

The Below code make the bitmap perfectly with same size of the imageview. Get the bitmap image height and width and then calculate the new height and width with the help of imageview's parameters. That give you required image with best aspect ratio.

int currentBitmapWidth = bitMap.getWidth();
int currentBitmapHeight = bitMap.getHeight();

int ivWidth = imageView.getWidth();
int ivHeight = imageView.getHeight();
int newWidth = ivWidth;

newHeight = (int) Math.floor((double) currentBitmapHeight *( (double) new_width / (double) currentBitmapWidth));

Bitmap newbitMap = Bitmap.createScaledBitmap(bitMap, newWidth, newHeight, true);

imageView.setImageBitmap(newbitMap)

enjoy.

Answer 5

The Best solution that works in most cases is

Here is an example:

<ImageView android:id="@+id/avatar"
           android:layout_width="match_parent"
           android:layout_height="match_parent"
           android:scaleType="fitXY"/>

Answer 6

this can all be done using XML... the other methods seem pretty complicated. Anyway, you just set the height to what ever you want in dp, then set the width to wrap content or visa versa. Use scaleType fitCenter to adjust the size of the image.

<ImageView
    android:layout_height="200dp"
    android:layout_width="wrap_content"
    android:scaleType="fitCenter"
    android:adjustViewBounds="true"
    android:src="@mipmap/ic_launcher"
    android:layout_below="@+id/title"
    android:layout_margin="5dip"
    android:id="@+id/imageView1">