Many UI platforms use multiple languages; front-end development requires HTML, CSS, and JavaScript knowledge, while Kotlin/Java and XML must be learned for Android development.
Flutter simplifies things because only one programming language is needed: Dart. Plus, everything in Flutter is defined as a Business Logic widget--AnimatedWidgets, BottomNavigationBars, Containers Drawers ElevatedButtons FormFields, Images Opacity Padding are some examples! Flutter uses plain English terms, which makes Flutter user-friendly as it uses plain English names that describe each widget type quickly!
What are Custom Widgets?
Custom widgets, or user-defined components, allow for user-defined functionality or visual representations within a Flutter app.
As custom widgets form its core building block structure, Flutter developers can build reusable UI elements which will be reused throughout an application.
Custom widgets could even be seen as React components if switching from React Native; props refer to Stateful Widget parameters.
Flutter Custom Widgets
Widgets can be created when we require a tailored look in our application and anticipate repeated instances of certain widgets.
Custom widgets can be built using dart files with all their needed codes; then, in their constructor, we define parameters that make up its structure; you can learn more about dividing widgets in our Flutter article.
Here we present an example of building a basic application by assigning custom properties to widgets, which are kept separate from their native properties.
In our BMI Calculator app, we used height and weight information as data points to calculate your BMI calculation; to demonstrate custom widgets at work on the Lib Folder screen, we also defined several additional items.
Now that Home Screen has been defined to display all components, once we've cleaned up our main file, we will create a widgets directory and add three files containing custom_button.
Dart, custom_column. Dart, and custom_container.dart to it contain our widget code.
GestureDetectorwidget has been used to implement an onTapproperty for widgets; properties for them include onTap, which takes an event handler function as its first parameter; child properties which accept Widgets' height and width data as parameters; as well as color, which will be utilized later when setting up our Home Widget.
This Stateless widget is designed to act like a button and uses gestureDetector for function detection. This round button features fixed width and height dimensions with translucent white color; we may Email Newsletter change that as needed.
Widgets for Flutter
Widgets extend StatefulWidget or StatelessWidget, and your local installation of Flutter will include various widgets; to access them open your package folder in any text editor of choice and search "extends StatefulWidget," "extends StatelessWidget," etc...
then count how many results appear when searching the terms.
Flutter version 2.10 offers 408 States Widgets and 272 StatelessWidgets, totaling 680. These will typically provide all of what is necessary; if not, Pub.
dev has many additional widgets that may come in handy. Pub. dev hosts many widgets; searching an empty string with Flutter selected as SDK'll obtain the total package count published to date.
Over 23,000 Flutter packages on the Pub. dev include at least one widget; as such, more than 23,000 Column Widget widgets may be implemented (in addition to 680 already present) using Flutter to implement any desired user experience UI or application development project.
Custom widget creation also can increase Flutter usage exponentially and bring its application closer.
Flutter's quick evolution since its launch by Google in 2017 has had a huge impact on the mobile app development business.
Flutter is a UI software development toolkit that allows you to create natively built mobile, web, and desktop applications from a single codebase. Its distinguishing benefit lies in its rapid development process, excellent performance, and expressive UI, making it a developer's preferred choice.
Flutter is gaining popularity among developers. According to a 2025 study, 46% of developers chose Flutter as their preferred cross-platform mobile framework.
The increasing number of developers who use Flutter reflects this growth. As we approach 2024, various trends are shaping Flutter app development, reflecting not only the toolkit's growing maturity but also the changing demands of any software development firm and end customers.
As organizations strive to provide more engaging user experiences in less time and with fewer resources, Flutter's role becomes increasingly important.
Why Use Custom Widgets?
Custom widgets encase complex UI elements more effectively while increasing code reuse and maintainability in Flutter apps.
Custom widgets serve multiple purposes - let's explore some here!
Code Reusability
Developers can utilize custom widgets to break complex functionality into easily reusable components that reduce code duplication while encouraging modular development.
Reusability makes these Listview Widget components highly cost-effective as developers don't need to rewrite entire applications to incorporate multiple times within one app.
Maintenance
Custom widgets make codebase maintenance more manageable by providing visual or functional Listview Widget representations for different aspects.
Furthermore, using them makes it simpler to identify, modify and debug individual UI components within code.
Consistent UI
Developers can utilize them to achieve a uniform interface across their applications.
Absorption
Custom widgets also add another level of abstraction that hides implementation details and complexity of certain UI elements, offering greater modularity by hiding implementation details while simplifying implementation logic for other developers who use your widget without worrying about its internal Child Widget workings.
Furthermore, this abstraction increases comprehension when testing or maintaining code; it makes understanding modular code much more straightforward.
The Widget Tree
Once you create and remove comments from a new Flutter project, this code becomes part of its placeholder code: It takes three parameters, appBar, body, and floating action button: appear takes an "AppBar Title Text Value," body takes "Center Value with Column and its Two Text Children; while "FloatingActionButton takes OnPressed Callback, an Increment Tooltip as its child and an Icon for its callback child;" etc.
This widget tree is straightforward. It consists of parents and descendants. Most Flutter widgets provide their parents and descendants as child properties; as more widgets become parented by one or more, your app gradually transforms into an enormous widget tree.
As you implement Flutter UIs, keep this fact in mind as your code indents inward from its left margin; your code appears to develop some virtual Code Snippet greater-than sign (of space at its left edge).
Why Build a Custom Widget?
Although you might not see immediate benefits from using custom widgets in an app for a client, they could ultimately experience them down the line.
Here's an example to demonstrate this point. Let's assume you created this complex app with 20 instances of custom widget usage throughout it before finally releasing it and seeing its user success.
About six months later, your client returns with another set of changes. One item on their long list was: Flutter Code "We want a slight shift in theme: change all social media referral buttons so they have an outline shape instead of solid shapes; change their color from red to green."
Imagine making this configuration change without creating the custom widget and copying/pasting its code to 20 different instances.
Each instance would require you to carefully inspect each location where this code landed and replace each instance without disrupting other parts of the code!
But with refactoring, this change would be implemented 20 times throughout your code base. We have shared both changes on GitHub - please see master for non-refactored code and refactor for refactoring.
Also Read: Creating Interactive UIs with Gestures and Animations in Flutter
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How to Implement Any UI in Flutter
Write Your Code Starting At The Top Left And Moving Down To The Bottom Right
Implement design for flutter widget after widget according to their elements' positions within the interface, writing code accordingly for items appearing at the top, then proceeding down until reaching its conclusion at its base.
It is intuitive that on the horizontal axis, you implement from left to right; otherwise, if necessary, revert it.
Choose a Widget
Next, you must logically determine which widget best serves a given UI element. At a minimum, use widgets you are already familiar with that serve their function based on their names or what the component looks like (we recommend Flutter's online community for assistance if that proves difficult!).
If necessary, an online search may also give helpful leads.
Use Widget Groups
When organizing items vertically or horizontally in succession, use columns. When they need to be stacked on top of one another, use rows with floating widgets enclosed within Positioned widgets - otherwise called stacking them up!
Column/Row
Within each Column and Row, you can modify how widgets align themselves along either main or cross axes using their CrossAxisAlignment and MainAxisAlignment properties for such adjustments.
Cross axes allow for alignment to center, end, start, and stretch actions; main axes enable alignments to center, end, space around/between/evenly spaced evenly across, as well as aligns that span multiple columns or rows (in columns/rows the vertical axis is paramount and the horizontal one cross axis); expanded widgets in columns and rows allow widgets to take advantage of available space by taking full advantage of available vertical space as opposed to taking up all available horizontal space (columns are like display/flex/flex/flex in CSS;).
Columns/Rows provide flexibility that would not exist otherwise; these elements likely fall somewhere along these axis/cross combinations when dealing with a web front-end, similar techniques used when working on web front-end environments flex display: flex; in CSS!
Stack Widget
With Stack, each child list's last widget(s) appear at the top. To accurately represent relative positions between widgets such as top-center, center, and bottom, editing of its alignment might also be required to indicate this change to use this strategy effectively.
A stack's size is calculated based on non-positioned widgets (those not wrapped by an explicitly set parent widget) in its children's list.
When writing code for it, remember that at least one non-positioned widget or an explicit setter widget must exist within your Stack to calculate its size correctly.
Positioned comprises bottom, top, left, and proper parameters that determine a child's placement relative to its Stack parent.
Add More Customization
Custom widgets should not simply be customized due to refactoring and repetitions (DRY code) but due to your particular UI implementation needs.
In other words, custom widgets won't just appear out of nowhere: instead, they must meet specific user interface needs that don't fall within any existing widget's footprint; you might require customizing existing ones further or even combine multiple ones in some unique way for best performance in implementing that particular UI.
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About CustomPaint
Flutter offers unmatched flexibility to the UI world. CustomPaint provides maximum freedom when designing or drawing in Flutter, similar to HTML's Canvas API or SVG images' SVG capabilities.
CustomPaint gives designers and artists freedom of design; it acts like a canvas from which one may draw with a paintbrush.
CustomPaint may only come into play occasionally, but be mindful that it exists as there may be complex UIs where widget combinations alone won't provide adequate solutions.
You will have no other recourse but to draw with CustomPaint instead. However, drawing will be accessible when this time arrives because you know other widgets well.
Flutter has quickly gained popularity recently. You can use it to quickly build complex apps for MacOS, Windows, and Linux without encountering performance issues, but building these applications may take more work - sometimes, having to refactor code for maximum app efficiency may require further modifications to ensure its optimal functioning.
Refactoring techniques involve extracting duplicate code and components and reusing them elsewhere, like extracting code duplication to replace one with something that fits better; here, you will learn to build custom widgets using Flutter instead.
How to Build a Custom Widget in Flutter
Let's start building our custom widget.
Clone The Repo
Instead of starting from scratch, we created a Flutter app in GitHub and added duplicate code/components. Let's use that as our base: run this command from within GitHub to fetch code into our current main branch; later on, we switched over to switching it into its final form by switching branches (no need for you all to follow suit!) Let's look at initial and final versions - first from the main branch, then into the final.
Run The App
Launch an emulator once Visual Studio Code has loaded the repo (you may also connect your mobile device). When your emulator is up and running, press F5 to run your app in it - here is its first run view: Congratulations if this far.
Analyze The Code
Look at the code: open lib/main-dart file. Our MyApp class calls MyHomePage class which calls our code for our entire UI defined within _MyHomePageState class; so here is a visually depicting line number: If you prefer writing clean code, this would likely rank among your least desirable work.
Here's the reason: carefully analyze this code - lines 44 to 56 and lines 58 to 70 are almost entirely duplicates with some minor word swaps (for instance, "Twitter" being replaced by "Instagram").
A skilled developer would undoubtedly refactor such code before adding new features/functionalities - let us follow these best practices now as well!
Refactor The Code And Build A Custom Widget
Assign text and button elements into separate components; each should accept platform and compressed parameters as input parameters and template out any familiar texts.
As discussed previously, template text files accept platform and onPressed parameters that we replace where needed, calling its onPressed method as part of showing snack bars.
Add this code at the very end of your principal-dart file.
Integrate The Custom Widget
Let's integrate our custom widget into our code. Identify a block of code between 44 to 56, as shown here, and replace it with this line: [Using custom widget for Twitter button].
Refactor another block from lines 58 to 70 as below (Refrigerate the second block of code as before); here is our final code after we finished refactoring: Here is also an image showing line numbers:
Run your app now; unfortunately, no noticeable UI change should have occurred, yet your underlying code has undergone changes - this is what refactoring means! However, upon closer examination, you might wonder why we didn't include all three pieces into one component.
Line 43 contains a similar code (const SizedBox(height:16), for instance). Why didn't they include that in our component instead?
No need for this question to arise in terms of custom widget components; instead, the SizedBox component should only ever appear on your Home page and give space between each element; when adding widgets, it doesn't always create spaces at either top/bottom; it should such cases occur however you could always include one into your custom widget as an added measure.
Use Cases for Custom Widgets
Always utilize custom widgets for their intended uses - in our case, social media redirects. Unexpected bugs could result when this widget is used outside its intended use case.
Consider our client's requirement of changing just social media referral buttons design only...but our change was applied elsewhere, too, resulting in unexpected bugs being introduced into their project.
As with all Custom Widgets, unit tests should always be written for custom widgets to reduce bugs sooner and make your code readable for other developers - in our case, we named component CustomButton which makes no sense; some good alternatives would include SocialMediaButton or SocialButton that more closely fit our use case.
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10 Best Practises for Flutter User Interface Design
Flutter is Google's Mobile SDK to quickly develop native iOS and Android, Desktop (Windows, Linux, and macOS), and Web apps from one codebase.
flutter design templates focus on widgets; building applications with them requires all focus to be directed toward Widgets as they form structural building blocks equipped with material design-specific functionalities; new widgets may even be composed of existing ones!
Flutter is an excellent cross-platform application development framework with numerous tools for generating stunning user interfaces (UIs).
In this section, we will go over the recommended practices for developing user interfaces in Flutter.
Use Material Design Guidelines
Flutter allows designers to follow Material Design principles more easily when crafting user interfaces for Android apps, making using Material Design guidelines seamless for end-users and consistent with other Android apps.
By adhering to Material Design principles and using Flutter's widgets which implement them, creating interfaces that follow this philosophy will ensure users can navigate and understand it seamlessly.
Keep the UI Simple and Clean
Designing an app's user interface (UI) requires keeping things straightforward and uncluttered rather than overloading screens with too much information or elements.
Instead, prioritize critical features of your app by presenting them clearly and easily understandably.
Use Consistent Colors and Typography
Consistency is vital when it comes to user interface design. Implement a consistent color palette and typography throughout your app to give users a cohesive, polished feeling and simplify navigation.
Doing this will allow users to remember who your brand is more efficiently while also helping them recognize it quickly and navigate freely within it.
Make Sure Your UI is Responsive
Flutter's biggest strength lies in its capability to create responsive UIs. Your app should adapt seamlessly across screen sizes and resolutions - make sure that it looks good on both small phones and large tablets!
Pay Attention to Layout and Spacing
The position and spacing of user interface elements are critical in crafting an excellent user experience. Use space on screen wisely and ensure no two elements overlap too closely on screen; use alignment/padding combinations to establish a visual hierarchy that guides their gaze through your interface.
Use Widgets to Create Custom UI Elements
Flutter comes equipped with an extensive list of widgets out-of-the-box, but sometimes custom user interface elements must be created from scratch.
Use Flutter's widget-building system to craft unique UI elements explicitly tailored to your app's design and functionality requirements.
Use Animations and Transitions
Animations and transitions add character and life to an app, giving it more of a human feel. Use animation widgets and APIs Flutter offers for easy animation creation in your application.
Use Images and Icons Wisely
Images and icons can add visual interest to an app, yet at times can appear overwhelming and unruly. Use images sparingly; ensure their relevance with content displayed on a screen; optimize high-resolution images tailored explicitly for screen resolution to ensure crisp, clear images that look professional and polished.
Consider Accessibility
Accessibility should always be top of mind when designing the interface of any app or website. Make sure it's user-friendly for people of different abilities by choosing colors with high contrast ratio and ensuring text fits on smaller screens comfortably; additionally, consider providing alternative text for images and support for screen readers.
Test Your UI With Real Users
Test your UI with real users to obtain feedback about its usability and effectiveness. Testing with real users will enable you to identify areas where users may be struggling and make any necessary modifications that enhance user experiences tools such as UserTesting or TestFlight can provide valuable feedback from real people.
Conclusion
Flutter app designer provides an effective tool for designing an intuitive user interface by following best practices in user experience design, which require attention to detail, consistency, and focusing on key features of an app's UI design.
By adhering to them, you can craft user-friendly user experiences while remaining visually attractive across screen sizes and resolutions.
Building custom widgets in Flutter promotes code reusability, maintainability, consistency, abstraction flexibility, and community collaboration they're an indispensable asset in the Flutter developer toolset, allowing us to design beautiful user experiences while optimizing efficiency and maintainability.
Flutter makes creating great user interfaces easy! Select a widget, write its code, assemble the piece with other widgets, and observe what fabulous result arises using Flutter for that piece.
Implementation is at the heart of mobile, web, and desktop app development - Flutter offers cross-platform UI toolkit support across these platforms with its declarative nature and widget abundance, making implementation quick and painless - implement as often as you're comfortable until using Flutter becomes second nature; soon it will allow you to build anything imaginable using Flutter as it becomes second nature allowing you to implement any design possible using Flutter with no limitations.
Paul is a highly skilled Full Stack Developer with a solid educational background that includes a Bachelor's degree in Computer Science and a Master's degree in Software Engineering, as well as a decade of hands-on experience. Certifications such as AWS Certified Solutions Architect, and Agile Scrum Master bolster his knowledge. Paul's excellent contributions to the software development industry have garnered him a slew of prizes and accolades, cementing his status as a top-tier professional. Aside from coding, he finds relief in her interests, which include hiking through beautiful landscapes, finding creative outlets through painting, and giving back to the community by participating in local tech education programmer.
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