In Flutter, the size of elements can be controlled through various factors such as absolute pixel values or relative values such as percentages. When it comes to resizing elements, percentage values offer a lot of flexibility and adaptability to different screen sizes and resolutions. The process of converting percentage values to a 0-1 range is simple, as percentages are just a representation of a fraction of 100. For example, 25% can be represented as 0.25 in the 0-1 range, 50% as 0.5, and so on.
By using the fractional values in widgets like the FractionallySizedBox or the Flexible widget, developers can ensure that the elements they create will be proportional to the screen size and will automatically adapt to different screen sizes and resolutions.
Here is an example of how to use percentage values in Flutter:
Container(
height: MediaQuery.of(context).size.height * 0.25,
width: MediaQuery.of(context).size.width * 0.5,
color: Colors.red,
child: Text("I am 25% of the screen height and 50% of the screen width"),
),In this example, the Container’s height is set to 25% of the total screen height and its width is set to 50% of the total screen width, ensuring that the element remains proportional and adaptable to different screen sizes.
Why Use Percentage Values to Scale Screen Elements in Flutter
In Flutter, using percentage values to scale screen elements offers a number of benefits compared to fixed pixel values. By utilizing percentages, the dimensions of elements become relative to the size of the screen, resulting in a more dynamic and flexible user interface.
One of the key advantages of using percentage-based scaling is that it enables the same layout to be adapted to various screen sizes with ease. This is because the proportions of the elements remain consistent, regardless of the physical size of the device’s display. This ensures that the layout looks good and functions optimally on different screens, ranging from small smartphones to large tablets.
Additionally, percentage scaling allows for greater design consistency across platforms. Since the layout adjusts to the screen size, designers and developers do not need to worry about the specifics of each platform’s screen dimensions, making it easier to create a consistent and cohesive experience for the user.
Furthermore, percentage scaling can also help to improve accessibility. For instance, by using percentages to size elements, developers can ensure that the text remains legible on small screens, even if the device is used in bright sunlight or other challenging conditions.
In conclusion, using percentage values to scale elements in Flutter is a smart and efficient approach that offers a number of benefits over fixed pixel values. It enables the creation of dynamic and flexible user interfaces that adapt to various screen sizes, promotes design consistency, and can improve accessibility.
How to convert percentages to values between 0 and 1
When it comes to scaling elements in flutter, it’s common to use values between 0 and 1. The values between 0 and 1 are used as a proportion of the available space. In other words, the value 0.5 represents half of the available space, 0.25 represents a quarter of the available space, and so on. To convert percentages to 0 to 1 values, simply divide the percentage by 100. For example, if you have a percentage value of 50%, you would divide 50 by 100 to get 0.5. Here are a few examples to demonstrate this process:
- 75% is equal to 0.75 (75 divided by 100)
- 33% is equal to 0.33 (33 divided by 100)
- 100% is equal to 1.0 (100 divided by 100)
By using these 0 to 1 values, you can easily scale your elements proportionally based on the available space.
Size screen elements with FractionallySizedBox in Flutter
In Flutter, sizing screen elements can be achieved effectively using the FractionallySizedBox widget. This widget allows developers to size elements in a fraction of the total available space, rather than using fixed pixel values or percentages.
One of the key benefits of using FractionallySizedBox is that it provides greater control over the size and position of elements. For instance, a FractionallySizedBox can be set to occupy a specific fraction of the width or height of its parent container, or to be sized based on the dimensions of another FractionallySizedBox within the same parent.
To illustrate, consider the following code snippet, which creates a FractionallySizedBox that takes up half of the available width:
FractionallySizedBox(
widthFactor: 0.5,
child: Container(
color: Colors.blue,
),
)In this example, the FractionallySizedBox widget is given a widthFactor of 0.5, meaning that it will occupy half of the available width. The child of the FractionallySizedBox is a simple Container with a blue background color.
Another advantage of using FractionallySizedBox is that it can be used in combination with other widgets to create complex and dynamic layouts. For instance, FractionallySizedBox can be stacked on top of each other, or nested within other FractionallySizedBox widgets to create intricate and adaptive layouts that respond to changes in screen size and orientation.
Flutter FractionallySizedBox example
Here’s a simple example of how you can use FractionallySizedBox in Flutter:
return Scaffold(
appBar: AppBar(
title: Text('flutterassets.com'),
),
body: Center(
child: FractionallySizedBox(
widthFactor: 0.5,
heightFactor: 0.5,
child: Container(
decoration: BoxDecoration(
shape: BoxShape.circle,
image: DecorationImage(
image: NetworkImage('https://picsum.photos/200'),
fit: BoxFit.cover,
),
),
),
),
),
);
In this example, we have a Scaffold widget with an AppBar and a body which contains a Center widget. Inside the Center widget, we have a FractionallySizedBox widget with widthFactor and heightFactor set to 0.5, which means the size of the widget will be half the size of its parent. The FractionallySizedBox widget has a Container widget as its child, which is decorated with a BoxDecoration that makes the widget look like a circular image. The image is loaded from a URL using NetworkImage.
Size screen elements with Expanded in Flutter
Sizing screen elements in Flutter can be accomplished using the Expanded widget. The Expanded widget allows you to divide the available space into portions and allocate a specific portion of the space to a child widget. This makes it ideal for creating complex, responsive layouts that adjust to different screen sizes and orientation.
Here is an example of how you can divide the screen into two portions, with one portion taking up 75% of the screen and the other taking up 25%:
Row(
children: [
Expanded(
flex: 3,
child: Container(
color: Colors.red,
),
),
Expanded(
flex: 1,
child: Container(
color: Colors.blue,
),
),
],
)
In this example, the Row widget is used as the parent container to hold the two Expanded widgets. The first Expanded widget has its flex property set to 3, which means it will take up 3 parts of the available space, while the second Expanded widget has its flex property set to 1, which means it will take up 1 part of the available space. The sum of these two values is 4, so each part represents 25% of the available space. This means that the first Expanded widget will take up 75% of the screen and the second one will take up 25%.
You can use any widget as a child of Expanded, including Container, Text, Image, etc. This allows you to create complex and flexible layouts that adapt to different screen sizes and orientations.
Flutter Expanded Flex property
In Flutter, the Expanded widget is used to control the size of a child element within a Row or Column. The Expanded widget is flexible and can adjust its size according to the available space in its parent widget. This is achieved through the use of the flex property, which determines the relative weight of the Expanded widget in comparison to its sibling widgets.
When using the Expanded widget, it’s important to understand the concept of flex. The flex property assigns a weight to the Expanded widget, determining how much of the available space it should occupy. For example, if an Expanded widget has a flex value of 2 and another Expanded widget has a flex value of 1, the first widget will occupy twice as much space as the second widget. This allows for a proportional distribution of the available space between multiple Expanded widgets.
In a Row or Column layout, the Expanded widget can be used to divide the screen into two or more sections, with each section taking up a proportional amount of space. By using the flex property, the Expanded widgets can be adjusted to occupy the desired proportions of the screen.
In conclusion, the Expanded widget with its flex property is a powerful tool in Flutter for controlling the size of child elements within a Row or Column layout. By assigning weights to the Expanded widgets, a proportional distribution of available space can be achieved, allowing for a flexible and responsive screen layout.
Size screen elements with Flexible in Flutter
Sizing screen elements in Flutter can also be achieved using the Flexible widget. The Flexible widget is similar to the Expanded widget, as it allows you to divide the available space into portions and allocate a specific portion of the space to a child widget. The difference is that Flexible provides more control over the layout and can adjust the size of the child widget based on the constraints provided by the parent.
Here is an example of how you can divide the screen into two portions, with one portion taking up 75% of the screen and the other taking up 25%:
Row(
children: [
Flexible(
fit: FlexFit.tight,
flex: 3,
child: Container(
color: Colors.red,
),
),
Flexible(
fit: FlexFit.tight,
flex: 1,
child: Container(
color: Colors.blue,
),
),
],
)In this example, the Row widget is used as the parent container to hold the two Flexible widgets. The fit property of both Flexible widgets is set to FlexFit.tight, which means the widgets will take up all the available space, but no more. The first Flexible widget has its flex property set to 3, while the second Flexible widget has its flex property set to 1. This means that the first Flexible widget will take up 3 parts of the available space and the second one will take up 1 part. The sum of these two values is 4, so each part represents 25% of the available space. This means that the first Flexible widget will take up 75% of the screen and the second one will take up 25%.
Like Expanded, you can use any widget as a child of Flexible, allowing you to create complex and flexible layouts that adapt to different screen sizes and orientations.
Flutter Flexible Flex and Fit property
In Flutter, the Flexible widget is used to control the size of a child element within a Row or Column layout. The Flexible widget is similar to the Expanded widget, but with some added functionality. The two main properties used to control the size of a Flexible widget are flex and fit.
The flex property works in a similar manner to the flex property of the Expanded widget. It determines the relative weight of the Flexible widget in comparison to its sibling widgets, and assigns a proportional amount of available space to the widget. The flex property of a Flexible widget can be any positive integer value, with higher values indicating a greater portion of available space.
The fit property is unique to the Flexible widget and determines how the widget should shrink or grow to fit within the available space. The fit property can be set to FlexFit.tight, FlexFit.loose, or FlexFit.passthrough. When set to FlexFit.tight, the widget will shrink or grow to fill the available space, without leaving any unused space. When set to FlexFit.loose, the widget will shrink or grow to occupy its flex value, regardless of the available space. And when set to FlexFit.passthrough, the widget will occupy the same amount of space as its child widget, without being affected by the flex value.
In conclusion, the Flexible widget is a powerful tool in Flutter for controlling the size of child elements within a Row or Column layout. By combining the flex and fit properties, the Flexible widget provides a flexible and customizable way to adjust the size of child widgets, allowing for a responsive and dynamic screen layout.
Flutter Flexible FlexFit examples
Here are a few code snippets to demonstrate the use of the fit property in the Flexible widget in Flutter:
Example 1:
Flexible(
fit: FlexFit.tight,
child: Container(
color: Colors.red,
child: Text("Tight fit"),
),
)In this example, the fit property is set to FlexFit.tight, which means that the child widget will be as small as possible while still being fully visible.
Example 2:
Flexible(
fit: FlexFit.loose,
child: Container(
color: Colors.blue,
child: Text("Loose fit"),
),
)In this example, the fit property is set to FlexFit.loose, which means that the child widget can be larger than the maximum size.
Example 2:
Flexible(
fit: FlexFit.passthrough,
child: Container(
color: Colors.green,
child: Text("Passthrough fit"),
),
)In this example, the fit property is set to FlexFit.passthrough, which means that the size of the child widget will be passed through to the parent, and the Flexible widget will have no impact on the size of the child.
Size screen elements with AspectRatio in Flutter
The AspectRatio widget in Flutter is used to size a child widget based on a specified aspect ratio. This can be particularly useful for ensuring that an image or other rectangular widget maintains its aspect ratio as it is resized. In other words, it is used to ensure that the width and height of a widget are proportional to each other.
Here’s a simple example of how to use AspectRatio in a Row widget:
Column(
children: [
AspectRatio(
aspectRatio: 3 / 2,
child: Container(
color: Colors.red,
),
),
AspectRatio(
aspectRatio: 5 / 2,
child: Container(
color: Colors.blue,
),
),
AspectRatio(
aspectRatio: 6 / 2,
child: Container(
color: Colors.green,
),
),
],
),
In this example, each AspectRatio widget has a different aspect ratio, and as a result, each child container will have a different width and height. The aspectRatio property takes a double value that represents the width-to-height ratio of the widget.
By using AspectRatio, we can ensure that each child widget maintains its aspect ratio as the Column is resized. This can be particularly useful when working with images or other rectangular widgets that should maintain their shape as they are resized.
Where Flutter AspectRatio can be used
the AspectRatio widget can be useful in a variety of situations where you need to maintain a specific aspect ratio for a widget. Here are a few examples:
- Displaying images: If you want to display an image with a specific aspect ratio, you can wrap it in an
AspectRatiowidget and set the desired aspect ratio. - Video playback: When playing a video, you may want to maintain the aspect ratio of the video, even if the size of the video player changes. In this case, you can wrap the video player in an
AspectRatiowidget and set the aspect ratio of the video. - Graphs and charts: If you want to display a graph or chart with a specific aspect ratio, you can wrap the graph or chart in an
AspectRatiowidget and set the desired aspect ratio.
Here’s a code example that demonstrates the use of AspectRatio to display an image with a 4:3 aspect ratio:
Container(
child: AspectRatio(
aspectRatio: 4 / 3,
child: Image.network(
'https://picsum.photos/500',
fit: BoxFit.cover,
),
),
)
In this example, the AspectRatio widget is used to maintain a 4:3 aspect ratio for the image. The image is displayed inside the AspectRatio widget and the fit property is set to BoxFit.cover to ensure that the entire image is visible and centred within the widget.
Size screen elements with MediaQuery in Flutter
The MediaQuery widget in Flutter can be used to size screen elements based on the screen dimensions of the device that your app is running on. This is useful when you want to create a responsive design that adapts to different screen sizes and aspect ratios. The following code snippet demonstrates how to divide the screen into two elements, one taking up 75% of the screen width and the other taking up 25%.
@override
Widget build(BuildContext context) {
// Get the screen dimensions using MediaQuery
final screenWidth = MediaQuery.of(context).size.width;
final screenHeight = MediaQuery.of(context).size.height;
return Scaffold(
appBar: AppBar(
title: Text('flutterassets.com'),
),
body: Row(
children: [
// First child takes up 75% of the screen width
Container(
width: screenWidth * 0.75,
color: Colors.red,
),
// Second child takes up 25% of the screen width
Container(
width: screenWidth * 0.25,
color: Colors.blue,
),
],
),
);
}In this code, the MediaQuery widget is used to get the screen dimensions of the device. The dimensions are then used to set the width of the two Container widgets that make up the screen. The first Container takes up 75% of the screen width, while the second Container takes up 25%. You can see the resulting screen split into two elements with different widths.
With this code, you can easily create responsive designs that adapt to different screen sizes and aspect ratios, using the `MediaQuery.of(context).size` property. You can then use these dimensions to size and position your screen elements as needed. In this case, we are using the screen width to determine the width of the two Container widgets.
It’s important to note that the MediaQuery widget must be used within a build method of a widget, as shown in the example code. This is because the screen dimensions may change at any time, such as when the device is rotated, so it’s important to re-query the dimensions whenever the build method is called.
In summary, the MediaQuery widget in Flutter provides a convenient way to size and position your screen elements based on the dimensions of the device. With this, you can create responsive designs that adapt to different screen sizes and aspect ratios, without having to manually calculate and adjust the dimensions of your elements.
Size screen elements with LayoutBuilder in Flutter
LayoutBuilder is a widget in Flutter that allows you to dynamically size screen elements based on the dimensions of the parent widget. Unlike MediaQuery, which is based on the screen dimensions of the device, LayoutBuilder is based on the dimensions of its parent widget. This makes it ideal for creating responsive designs that adapt to different screen sizes and aspect ratios.
Here’s a code snippet that demonstrates how to use LayoutBuilder to divide the screen into two elements, one taking up 75% of the screen width and the other taking up 25%:
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('flutterassets.com'),
),
body: LayoutBuilder(
builder: (BuildContext context, BoxConstraints constraints) {
final width = constraints.maxWidth;
return Row(
children: [
Container(
width: width * 0.75,
color: Colors.red,
),
Container(
width: width * 0.25,
color: Colors.blue,
),
],
);
},
),
);
}In this code, we first pass a BuildContext to the LayoutBuilder widget. Inside the builder argument, we use the constraints argument to get the maximum width of the screen. Then, we use that width to calculate the widths of the two containers, with the first container having a width of 75% of the screen and the second container having a width of 25% of the screen.
With this code, you can create responsive designs that adapt to different screen sizes and aspect ratios. The LayoutBuilder widget is a powerful tool that allows you to dynamically size screen elements based on the dimensions of the screen, making it easy to create dynamic, responsive designs in Flutter.
Size screen elements with GridView in Flutter
The GridView widget in Flutter is an excellent way to divide the screen into elements of different sizes and aspect ratios. In this case, we will be dividing the screen into two elements, one taking up 75% of the screen width and the other taking up 25%. Here’s a code snippet to demonstrate this concept:
GridView.count(
crossAxisCount: 2,
childAspectRatio: 3 / 2,
children: [
Container(
color: Colors.red,
),
Container(
color: Colors.blue,
),
],
),In this code, the GridView is set to have 2 columns using crossAxisCount. The childAspectRatio property is set to 3/2, which means that the height of each element will be 50% of its width. This allows us to control the size of each element, in this case making the first element 75% of the screen width and the second element 25% of the screen width.
With this code, you can easily create responsive designs that adapt to different screen sizes and aspect ratios, using the GridView widget in Flutter. You can also modify the childAspectRatio property to change the size and aspect ratio of each element as desired.
Flutter GridView with photos pseudo code
Imagine you want to create a photo gallery app where you can display your photos in a grid-based layout. You can use the GridView widget to achieve this. The code snippet below demonstrates how you can display photos in a grid-based layout, with each photo taking up an equal amount of screen space:
final List<String> photos = [
'photo1.jpeg', 'photo2.jpeg', 'photo3.jpeg', 'photo4.jpeg',
'photo5.jpeg', 'photo6.jpeg', 'photo7.jpeg', 'photo8.jpeg',
];
@override
Widget build(BuildContext context) {
return Scaffold(
body: GridView.count(
crossAxisCount: 2,
children: photos.map((photo) {
return Image.asset(photo);
}).toList(),
),
);
}In this code, we define a list of photos and pass it to the GridView.count widget. The crossAxisCount property is set to 2, which means that the grid will have two columns. The children property is set to a list of Image widgets, which are created using the map method and the Image.asset constructor. The Image.asset constructor is used to display an image from the asset bundle.
With this code, you can easily create a photo gallery app that displays photos in a grid-based layout. The GridView widget automatically adjusts the size of the photos based on the screen dimensions of the device, ensuring that your app looks great on any device.
Flutter GridView with photos example
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final List<String> photos = [
'https://picsum.photos/200/100',
'https://picsum.photos/200/101',
'https://picsum.photos/200/102',
'https://picsum.photos/200/103',
'https://picsum.photos/200/104',
'https://picsum.photos/200/105',
'https://picsum.photos/200/106',
'https://picsum.photos/200/107',
'https://picsum.photos/200/108',
'https://picsum.photos/200/109',
'https://picsum.photos/200/110',
'https://picsum.photos/200/111',
'https://picsum.photos/200/112',
'https://picsum.photos/200/113',
'https://picsum.photos/200/114',
'https://picsum.photos/200/115'
];
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('flutterassets.com'),
),
body: GridView.count(
// crossAxisCount: 2,
crossAxisCount: MediaQuery.of(context).size.width <= 400.0
? 3
: MediaQuery.of(context).size.width >= 600.0
? 5
: 2,
childAspectRatio: 3 / 2,
children: photos.map((photo) {
return Image.network(photo, fit: BoxFit.cover,);
}).toList(),
),
);
}
}
The body of the Scaffold widget is where the magic happens, it contains a GridView widget that displays the images from the photos list. The GridView.count constructor is used to specify the number of columns to display in the grid. The number of columns is based on the width of the device, for a device with a width of 400.0 or less, three columns are displayed. For devices with a width of 600.0 or more, five columns are displayed, otherwise, two columns are displayed.
crossAxisCount: MediaQuery.of(context).size.width <= 400.0
? 3
: MediaQuery.of(context).size.width >= 600.0
? 5
: 2,The childAspectRatio property is used to specify the aspect ratio of each child widget. It is set to 3/2, meaning the height of the widget should be 50% of the width. The children property of the GridView is a list of widgets obtained from the map method of the photos list. The map method is used to convert the elements of the photos list into Image widgets. The Image widgets are displayed in the grid with each one having a fit property set to BoxFit.cover, which means the image is scaled to fit within the bounds of the container while maintaining its aspect ratio.
Size screen elements with Align widget in Flutter
The Align widget in Flutter allows you to specify the alignment of its child widget in the available space. The widthFactor and heightFactor properties of the Align widget can be used to specify the width and height scaling factors for the child widget. These factors are multipliers applied to the width and height of the child widget, effectively scaling it up or down.
Container(
color: Colors.red,
child: Align(
alignment: Alignment.center,
widthFactor: 2,
heightFactor: 2,
child: Container(
color: Colors.blue,
width: 100,
height: 100,
),
),
)
In the code snippet, the Align widget has its widthFactor and heightFactor properties set to 2. This means that the width and height of the child Container widget, which has a width of 100 and a height of 100, will be scaled up by a factor of 2. Therefore, the child container will have a width of 200 and a height of 200.
Here is a more in-depth explanation of how it works:
The code defines a Container widget with a red background color. The child property of the Container widget is set to an Align widget. The Align widget’s alignment property is set to Alignment.center, which means that the child widget will be centered in the available space. The widthFactor property is set to 2, which means that the width of the child widget will be scaled up by a factor of 2.
Similarly, the heightFactor property is set to 2, which means that the height of the child widget will be scaled up by a factor of 2. The child property of the Align widget is set to a Container widget with a blue background color and a width of 100 and a height of 100. As a result, the blue container will have a width of 200 and a height of 200.
