使视图适合Xamarin形式的屏幕

Question

In my cross platform mobile app, I've been sizing all of my views using constant pixel values based on my devices screen size. The app is meant to be ran on a number of different sizes of screen, though, and I can't find anything on fitting views to the screen size.

So far my best attempt at this was to store the values of the height and width of the StackLayout on the login page and size the views relative to those values, but I was getting incorrect values of -1 for both. Here is the code I used:

var Test = new StackLayout
          {
                HorizontalOptions = LayoutOptions.CenterAndExpand,
                VerticalOptions = LayoutOptions.CenterAndExpand,
          }
double ScreenHeight = Test.Height;
double ScreenWidth = Test.Width;

Answer 1

You will get -1 because the Width and Height of a view will be set only after the screen is appeared, otherwise Xamarin.Forms wouldn't know these values beforehand.

The solution can be implementing the OnAppearing event of any given view (in this case Test) and in that method you can get Width and Height.