How can I get the screen size in Flutter without BuildContext?

Question

Firstly, this, though similiar in Question, is not what I need as the Answer does not help me in my case.

I have my AppConfig decide the fontsize, based on device, so that very big devices, such as Tablets, get bigger Texts (by a bit). My config gets called before any Views, so I have no BuildContext while this is running. So how can I do this?

class AppConfig {
  static AppConfig _instance;

  static AppConfig instance() {
    if (_instance == null) {
      _instance = AppConfig();
    }
    return _instance;
  }

// config stuff for colours and themes

double width = MediaQuery.of(context).size.width;

if (width > 500) { //arbitrary number I haven't decided yet
    initWithBigFonts();
} else {
    initWithSmallFonts();
}

@pskink that looks like what i'd need but - how would i use it here? — Maritn Ge, Feb 19 '21 at 12:12
check [Window](https://api.flutter.dev/flutter/dart-ui/Window-class.html) class properties — pskink, Feb 19 '21 at 12:34

score 11 · Accepted Answer · answered Feb 19 '21 at 12:50

For future reference the full solution to this:

By adding

Size size = WidgetsBinding.instance.window.physicalSize;
double width = size.width;
double height = size.height;

You can, from anywhere and without BuildContext, get the Size from the device screen.

score 5 · Answer 2 · answered Jul 28 '22 at 14:45

5

in this case, you should think about the devicePixelRatio;

Size size = WidgetsBinding.instance.window.physicalSize;
double ratio = WidgetsBinding.instance.window.devicePixelRatio;
double width = size.width / ratio;

answered Jul 28 '22 at 14:45

Arthur Mao

51
1
1

score 2 · Answer 3 · answered May 25 '23 at 13:08

the "window" singleton has been deprecated as of v3.7.0-32.0.pre because "window" assumed that the app consists of a single view which is not the case anymore. You can use one of the following two options.

PlatformDispatcher.instance.views.first.physicalSize. or,
PlatformDispatcher.instance.implicitView?.physicalSize (nullable)

divide the physicalSize by the devicePixelRatio (PlatformDispatcher.instance.views.first.devicePixelRatio) to get the view size.

For more info, https://docs.flutter.dev/release/breaking-changes/window-singleton

score 1 · Answer 4 · answered Dec 25 '22 at 19:27

1

Size size = MediaQueryData.fromWindow(WidgetsBinding.instance.window).size;

answered Dec 25 '22 at 19:27

Nishal Sehan

11
1

How can I get the screen size in Flutter without BuildContext?

4 Answers4