When designing Android layouts using ImageView, the adjustViewBounds="true" attribute is essential for maintaining the aspect ratio of images. However, many developers face an issue where this attribute doesn’t work properly in the layout preview, even though it behaves correctly on a physical device or emulator. If you’re dealing with this, here’s a practical guide to resolve the issue and ensure consistent results across your design and runtime environments.
What Does adjustViewBounds="true" Do?
Setting android:adjustViewBounds="true" tells the ImageView to scale the image uniformly (maintaining the image’s aspect ratio) so that both dimensions (width and height) fit within the bounds of the view, depending on the scale type.
<ImageView
android:id="@+id/sampleImage"
android:layout_width="wrap_content"
android:layout_height="200dp"
android:src="@drawable/sample"
android:adjustViewBounds="true"
android:scaleType="fitCenter" />
In theory, this should resize the image to fit the view’s height while keeping the width proportional. But sometimes the preview doesn’t reflect that.
Common Reason: Missing Width Constraints
If your layout uses wrap_content for width but doesn’t provide any constraints or parent limits, the preview might not interpret the bounds properly.
✅ Fix: Set an Explicit Max Width or Width Constraint
You can add android:maxWidth or set a defined width via constraints to help the preview engine calculate layout bounds correctly.
<ImageView
android:layout_width="0dp"
android:layout_height="200dp"
android:layout_constraintStart_toStartOf="parent"
android:layout_constraintEnd_toEndOf="parent"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="@drawable/sample" />
In ConstraintLayout, this ensures the ImageView knows its horizontal limits. The 0dp width works as “match constraints”, and combined with adjustViewBounds, it respects the image’s aspect ratio.
Pro Tip: Use Tools Namespace for Preview Fine-Tuning
Sometimes the issue lies in the layout editor, not the actual layout logic. To improve preview accuracy, use the tools: namespace to guide Android Studio’s rendering engine.
xmlns:tools="http://schemas.android.com/tools"
<ImageView
android:layout_width="wrap_content"
android:layout_height="200dp"
android:adjustViewBounds="true"
android:scaleType="fitCenter"
android:src="@drawable/sample"
tools:ignore="MissingConstraints"
tools:layout_editor_absoluteX="0dp"
tools:layout_editor_absoluteY="0dp" />
Note: These
tools:attributes don’t affect runtime behavior—they’re only for design-time layout rendering.
Test on a Real Device or Emulator
Android Studio’s layout preview doesn’t always reflect what you’ll see on a physical device. If your image is correctly scaled at runtime but distorted in the preview, trust the device behavior over the editor.
Clean Build Cache
Layout rendering issues may sometimes be caused by outdated or cached resources.
Steps:
- Click Build > Clean Project
- Then Build > Rebuild Project
This forces Android Studio to recompile resources, which may fix incorrect previews.
Final Thoughts
While adjustViewBounds="true" is a powerful attribute, it needs proper layout constraints to work correctly—especially in Android Studio’s layout preview. Combine it with scaleType="fitCenter" or fitStart, use explicit layout constraints, and always verify on actual devices.
For more detail on ImageView and layout behavior, visit the official Android Developers Guide on ImageView.
By following these tips, you’ll avoid misleading previews and ensure your UI behaves consistently across all screens.