text
stringlengths 1
372
|
|---|
),
|
);
|
}
|
}
|
<code_end>
|
info note
|
the cupertino library implements widgets that follow
|
apple’s human interface guidelines for iOS.
|
when designing your UI, you can use
|
widgets from the standard widgets library, or the cupertino library.
|
you can mix widgets from both libraries, you can customize existing widgets,
|
or you can build your own set of custom widgets.
|
<topic_end>
|
<topic_start>
|
Non-Material apps
|
for a non-Material app, you can add the center widget to the app’s
|
build() method:
|
<code_start>
|
class MyApp extends StatelessWidget {
|
const MyApp({super.key});
|
@override
|
widget build(BuildContext context) {
|
return container(
|
decoration: const BoxDecoration(color: colors.white),
|
child: const center(
|
child: text(
|
'hello world',
|
textDirection: TextDirection.ltr,
|
style: TextStyle(
|
fontSize: 32,
|
color: colors.black87,
|
),
|
),
|
),
|
);
|
}
|
}
|
<code_end>
|
by default, a non-Material app doesn’t include an AppBar, title,
|
or background color. if you want these features in a non-Material app,
|
you have to build them yourself. this app changes the background
|
color to white and the text to dark grey to mimic a material app.
|
that’s it! when you run the app, you should see hello world.
|
app source code:
|
<topic_end>
|
<topic_start>
|
lay out multiple widgets vertically and horizontally
|
one of the most common layout patterns is to arrange
|
widgets vertically or horizontally. you can use a
|
row widget to arrange widgets horizontally,
|
and a column widget to arrange widgets vertically.
|
<topic_end>
|
<topic_start>
|
what's the point?
|
to create a row or column in flutter, you add a list of children
|
widgets to a row or column widget. in turn,
|
each child can itself be a row or column, and so on.
|
the following example shows how it is possible to nest rows or
|
columns inside of rows or columns.
|
this layout is organized as a row. the row contains two children:
|
a column on the left, and an image on the right:
|
the left column’s widget tree nests rows and columns.
|
you’ll implement some of pavlova’s layout code in
|
nesting rows and columns.
|
info note
|
row and column are basic primitive widgets for horizontal
|
and vertical layouts—these low-level widgets allow for maximum
|
customization. flutter also offers specialized, higher level widgets
|
that might be sufficient for your needs. for example,
|
instead of row you might prefer ListTile,
|
an easy-to-use widget with properties for leading and trailing icons,
|
and up to 3 lines of text. instead of column, you might prefer
|
ListView, a column-like layout that automatically scrolls
|
if its content is too long to fit the available space.
|
for more information, see common layout widgets.
|
<topic_end>
|
<topic_start>
|
aligning widgets
|
you control how a row or column aligns its children using the
|
mainAxisAlignment and crossAxisAlignment properties.
|
for a row, the main axis runs horizontally and the cross axis runs
|
vertically. for a column, the main axis runs vertically and the cross
|
axis runs horizontally.
|
the MainAxisAlignment and CrossAxisAlignment
|
enums offer a variety of constants for controlling alignment.
|
info note
|
when you add images to your project,
|
you need to update the pubspec.yaml file to access
|
them—this example uses image.asset to display
|
the images. for more information, see this example’s
|
pubspec.yaml file or adding assets and images.
|
you don’t need to do this if you’re referencing online
|
images using image.network.
|
in the following example, each of the 3 images is 100 pixels wide.
|
the render box (in this case, the entire screen)
|
is more than 300 pixels wide, so setting the main axis
|
alignment to spaceEvenly divides the free horizontal
|
space evenly between, before, and after each image.
|
app source: row_column
|
columns work the same way as rows. the following example shows a column
|
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