Flutter – How to Determine Screen Height and Width

dartflutterscreen-size

I've created a new application on flutter, and I've had problems with the screen sizes when switching between different devices.

I created the application using the Pixel 2XL screen size, and because I've had containers with a child of ListView it's asked me to include a height and width for the container.

So when I switch the device to a new device the container is too long and throws an error.

How can I go about making it so the application is optimized for all screens?

Best Answer

You can use:

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

To get height just of SafeArea (for iOS 11 and above):

var padding = MediaQuery.of(context).padding;
double newheight = height - padding.top - padding.bottom;

Related Solutions

Android – Smallest Width for Galaxy S and Galaxy S2

Screen density, as defined by the reference material is:

The quantity of pixels within a physical area of the screen; usually referred to as dpi (dots per inch). For example, a "low" density screen has fewer pixels within a given physical area, compared to a "normal" or "high" density screen. For simplicity, Android groups all actual screen densities into four generalized densities: low, medium, high, and extra high.

low = 120dpi med = 160dpi high = 240dpi xhi = 320dpi

So the Galaxy SII, with a real density of 218, gets assigned a "high" density of 240 in dp calculations. Thus the width of the screen in dp is 480/240*160 = 320.

This sucks, I agree. But it's how it works.

http://developer.android.com/guide/practices/screens_support.html

Flutter – Why Flutter Container does not respects its width and height constraints when it is inside other Container

Constraints in Flutter works a bit different than usual. Widgets themselves do not have constraints.

When you specify a width/height on a Container, you're not constraining Container. You're constraining the child of Container.

Container will then size itself based on the size of its child.

As such, parent widgets always have the last word on how their descendants should be sized.

If you want to go around this, you have to use Align widget:

Container(
  width: 200.0,
  height: 200.0,
  child: Align(
    alignment: Alignment.topLeft,
    child: Container(
      width: 50.0,
      height: 50.0,
      decoration:
          BoxDecoration(shape: BoxShape.circle, color: Colors.red),
    ),
  ),
);

This may seem weird and limiting. But this single weirdness is the reason why Flutter's layout is so powerful and composable.

Best Answer

Related Solutions

Android – Smallest Width for Galaxy S and Galaxy S2

Flutter – Why Flutter Container does not respects its width and height constraints when it is inside other Container

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