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|
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void initState() { |
super.initState(); |
loadData(); |
} |
widget getBody() { |
bool showLoadingDialog = widgets.isEmpty; |
if (showloadingdialog) { |
return getProgressDialog(); |
} else { |
return getListView(); |
} |
} |
widget getProgressDialog() { |
return const center(child: CircularProgressIndicator()); |
} |
@override |
widget build(BuildContext context) { |
return scaffold( |
appBar: AppBar( |
title: const Text('Sample app'), |
), |
body: getBody(), |
); |
} |
ListView getListView() { |
return ListView.builder( |
itemCount: widgets.length, |
itemBuilder: (context, position) { |
return getRow(position); |
}, |
); |
} |
widget getRow(int i) { |
return padding( |
padding: const EdgeInsets.all(10), |
child: Text("Row ${widgets[i]["title"]}"), |
); |
} |
future<void> loadData() async { |
var dataURL = uri.parse('https://jsonplaceholder.typicode.com/posts'); |
http.Response response = await http.get(dataURL); |
setState(() { |
widgets = jsonDecode(response.body); |
}); |
} |
} |
<code_end> |
<topic_end> |
<topic_start> |
project structure & resources |
<topic_end> |
<topic_start> |
where do i store my resolution-dependent image files? |
while android treats resources and assets as distinct items, |
flutter apps have only assets. all resources that would live |
in the res/drawable-* folders on android, |
are placed in an assets folder for flutter. |
flutter follows a simple density-based format like iOS. |
assets might be 1.0x, 2.0x, 3.0x, or any other multiplier. |
flutter doesn’t have dps but there are logical pixels, |
which are basically the same as device-independent pixels. |
flutter’s devicePixelRatio expresses the ratio |
of physical pixels in a single logical pixel. |
the equivalent to android’s density buckets are: |
assets are located in any arbitrary folder—Flutter |
has no predefined folder structure. |
you declare the assets (with location) in |
the pubspec.yaml file, and flutter picks them up. |
assets stored in the native asset folder are |
accessed on the native side using android’s AssetManager: |
flutter can’t access native resources or assets. |
to add a new image asset called my_icon.png to our flutter project, |
for example, and deciding that it should live in a folder we |
arbitrarily called images, you would put the base image (1.0x) |
in the images folder, and all the other variants in sub-folders |
called with the appropriate ratio multiplier: |
next, you’ll need to declare these images in your pubspec.yaml file: |
you can then access your images using AssetImage: |
<code_start> |
AssetImage('images/my_icon.jpeg') |
<code_end> |
or directly in an image widget: |
<code_start> |
@override |
widget build(BuildContext context) { |
return image.asset('images/my_image.png'); |
} |
<code_end> |
<topic_end> |
<topic_start> |
where do i store strings? how do i handle localization? |
flutter currently doesn’t have a dedicated resources-like system for strings. |
the best and recommended practice is to hold your strings in a .arb file as key-value pairs for example: |
<code_start> |
{ |
"@@locale": "en", |
"hello":"hello {username}", |
"@hello":{ |
"description":"a message with a single parameter", |
"placeholders":{ |
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