How to round the edges of a button in Android Studio

Developing a user interface in an environment Android Studio requires attention to the smallest details, and the shape of the controls plays an important role here. The square corners of the buttons look outdated and do not correspond to modern Material Design standards, which dictate smooth and soft lines. Rounding the edges not only improves the visual experience of the application, but also improves the tapping experience for the user, especially on large smartphone screens. In this article we will analyze in detail all the current methods of giving buttons a rounded shape.

There are several approaches to solving this problem, starting from creating custom XML drawable files and ending with using ready-made components from the library Material Components for Android. The specific method you choose depends on the version of the API you support and your design flexibility requirements. We will consider both classic methods that work on any device, and modern solutions that offer maximum ease of integration.

It is important to understand that simply changing a property cornerRadius is not directly available for all standard widgets. Often you need to create a special background resource or use wrapper containers. Proper implementation of rounding will ensure that your interface will look professional and consistent on any version of the Android operating system.

Using XML Shape to create a background

The most versatile and common way to round the corners of any element is to create your own XML resource type shape. This method works regardless of the Android version and gives full control over the corner radius of each individual corner. You create a file in the folder drawable, where you describe the geometry of the future background.

Inside the file you need to use a tag <corners>, which allows you to set the rounding radius. You can specify a single value for all corners or set individual parameters for top left, top right, and so on. This is especially useful if you want to create a button with a fillet on only one side.

After creating the resource file, you need to apply it to your widget Button or TextView via the android:backgroundattribute. It is important to consider that a standard button has its own internal padding and click effects, which may conflict with a custom background. Therefore, it is often necessary to additionally customize colors and states (pressed, focused).

⚠️ Attention: When using custom background you lose the standard click animation (ripple effect), which is found in standard Android themes. To return it, you will have to create a separate file selector or use the attribute android:foreground to overlay the effect on top of your color.

To implement complex geometry, for example, when you need to round only the top corners for a tab, the following code structure is used. Note the use of the topLeftRadius and topRightRadiusattributes, while the lower ones remain null.

<shape xmlns:android="http://schemas.android.com/apk/res/android">
<solid android:color="#FF6200EE" />
<corners
android:topLeftRadius="16dp"
android:topRightRadius="16dp"
android:bottomLeftRadius="0dp"
android:bottomRightRadius="0dp" />
</shape>

Using the component CardView

Library AndroidX CardView provides a convenient way to create containers with rounded corners and shadows. Although this component was originally intended for content cards, it is often used as a wrapper for buttons to quickly achieve the desired visual style without writing unnecessary code.

The main advantage CardView is the attribute app:cardCornerRadiusthat allows you to change the rounding radius directly in the layout. You place a regular button inside a card, set the background of the card to the desired color, and make the button itself transparent or match the background color. This creates the illusion of a single rounded button with a shadow.

However, this method has its own nuances. Nesting views may have a minor performance impact if there are a large number of views in the list. In addition, click handling must be configured correctly so that the touch is registered on the button and not on the container, although in most cases this works transparently to the user.

When using this approach, make sure that you include the dependency cardview in your project's build file. Without this library, the tag androidx.cardview.widget.CardView will not be recognized by the compiler, and the project will not be built.

• 🔹 Easy to set the radius through one attribute in XML.
• 🔹 Automatically adding a shadow (elevation) without additional code.
• 🔹 Possibility dynamically changing the shape during app execution.
• 🔹 Support for different rounding shapes for different versions of Android through styles.

Working with MaterialButton

Component MaterialButton from the library Material Components is a modern standard for creating buttons in Android applications. It inherits from the standard button, but provides advanced styling capabilities, including built-in support for rounded corners through the Usage attribute, eliminating the need for the developer to create separate XML files for the background. All settings are made directly in the button tag. This makes the code easier to maintain and the markup more readable. You can set the radius to app:cornerRadius.

Usage MaterialButton eliminates the need for the developer to create separate XML files for the background. All settings are made directly in the button tag. This makes the code easier to maintain and the markup more readable. You can set the radius to dp or set the value 0dp for a rectangular shape.

If you want to create a pill shape button, where the height of the button automatically determines the radius of the rounding, just set the attribute value app:cornerRadius equal to half the height of the button. However, there is a more elegant solution - using a value @dimen/design_default_shape_corner_radius or simply specifying a very large radius value, which the component itself will limit to the maximum possible.

It is important to note that MaterialButton also supports various styles through the styleattribute. You can choose an outlined style, a filled style, or a text button, and in each of them the fillet will be applied correctly while maintaining compliance with Material Design guidelines.

⚠️ Attention: Do not set the android:background attribute if you want to preserve the built-in effects and styles. This will override the component's internal rendering logic. To change the color, use the attribute MaterialButton, if you want to save built-in effects and styles. This will override the component's internal rendering logic. To change the color use the attribute app:backgroundTint.

Dynamically changing the shape of the button in the code is also possible. You can access the button object in Java or Kotlin and call the setCornerRadius()method. This allows you to respond to user actions by changing the shape of an interface element in real time.

Comparison of implementation methods

The choice between different approaches depends on the specific tasks of your project. If you want maximum compatibility with older devices and complete control over every pixel, Classic shape remains the best choice. For modern projects focused on Material Design, the use of MaterialButton is preferable.

Below is a table comparing the main characteristics of the considered methods. It will help you quickly decide on a tool for your current task.

Method	Complexity of implementation	Flexibility	Ripple support	Requires libraries
XML Shape	Medium	High	Manual setting	No
CardView	Low	Medium	Automatic	Yes (AndroidX)
MaterialButton	Low	High	Automatic	Yes (Material)
Vector Drawable	High	Maximum	Implementation dependent	No

Fillet via Vector Drawable

For complex cases when standard tools are not enough, you can use VectorDrawable. This approach allows you to draw a button of any shape, including complex Bezier curves that cannot be obtained through standard attributes corners. These are vector graphics that scale without losing quality.

Creating a vector manually in XML can be a labor-intensive process, requiring knowledge of coordinates and paths. However, you can draw the desired shape in a graphics editor (for example, Figma or Adobe Illustrator) and export it to SVG format, and then import it into Android Studio. The studio automatically converts SVG to VectorDrawable.

Using a vector as a button background provides unique opportunities. You can animate the button's shape by transforming the vector path. This opens up space for creating micro-interactions that make the application feel alive and responsive.

However, it is worth keeping performance in mind. Drawing complex vectors every frame of animation can be CPU intensive. For static buttons this is not a problem, but for dynamic interfaces it is better to limit yourself to easier methods.

How to import SVG into Android Studio?

Right-click on the drawable -> New -> Vector Asset folder. In the window that opens, select Local file (SVG) and specify the path to your file. The import wizard will automatically create the required XML code.

Common errors and their solutions

When working with fillets, developers often encounter a number of typical problems. One of the most common is cutting off the button content. If you use CardView with the app:cardPreventCornerOverlap="true"option, the text or icon inside the button may move as the system tries to prevent them from overlapping with rounded corners.

Another problem arises when mixing different methods. For example, an attempt to apply android:background to MaterialButton at the same time as using app:cornerRadius leads to unpredictable results. The system cannot decide what priority this or that attribute has, and the rendering breaks down.

It is also worth paying attention to the units of measurement. Always use dp (density-independent pixels) for the fillet radius rather than px. Using pixels will make the button look too sharp on High DPI screens, and too round on older screens.

If you notice artifacts on the edges of the button, try turning on hardware acceleration for this view or check if a too complex gradient is used in combination with rounding. Sometimes simply changing the stacking order of layers in the layout hierarchy solves the problem.

Adaptation for different Android versions

Although modern methods work reliably, supporting older versions of Android (below API 21) may require additional effort. Some attributes available in new versions of libraries may be ignored on older devices. To ensure compatibility, it is recommended to use libraries that provide backward compatibility for many interface functions. In particular, Android Studio and libraries may be ignored on older devices.

To ensure compatibility, it is recommended to use libraries AndroidX, which provide backwards compatibility for many interface features. In particular, AppCompatButton and its descendants handle styling correctly even on older systems.

You can create alternative resources for different versions of the API. Place the file button_background.xml in the folder drawable-v21 using the new functions, and in the regular folder drawable the simplified version for older devices. The system will automatically select the appropriate resource depending on the OS version of the user's smartphone.

⚠️ Attention: Interfaces and attribute names in support libraries may change with the release of new versions of Android Studio. Always check Google's official documentation when updating file dependencies to avoid compilation errors. build.gradleto avoid compilation errors.

Testing on real devices or emulators running different Android versions is a must. What looks perfect on Android 14 may have visual glitches on Android 6.0. Take the time to check edge cases.

FAQ: Frequently Asked Questions

How to make a button completely round?

To make a button round (in a circle shape), set the attribute app:cornerRadius equal to half the height of the button. If the height of the button is fixed, for example 48dp, then the radius should be 24dp. For MaterialButton you can also use a style that assumes a round shape, if the content allows it.

Why is the round not applied to the button?

The most common reason is that you have set an attribute android:backgroundthat overwrites the internal styles of the component. Try removing this attribute and using app:backgroundTint to change the color, or make sure that your custom one is set as the background shape with the correct parameters corners.

Is it possible to round only one corner of a button?

Yes, this is possible when using XML shape. In the tag <corners> you can set parameters individually: android:topLeftRadius, android:topRightRadius and so on. Set the desired angles to the radius value, and the rest to 0dp. Standard components like MaterialButton do not support individual rounding of corners through simple attributes.

How to add a shadow to a rounded button?

If you use CardView, the shadow is added automatically through the attribute app:cardElevation. For a regular button with shape background, a shadow is not added automatically. You will have to either wrap the button in CardView, or use an attribute android:elevation (works on API 21+), or draw a shadow as part of the vector background.

Does rounding affect application performance?

The impact is minimal and invisible to the user. Drawing rounded rectangles is a standard operation in the Android graphics engine. Problems can only arise when using very complex vector paths with many real-time animation points on very weak devices.