Get grid row absolute width - user-interface

Question

I'm trying to mimic an iOS UICollectionView for hard-coded data. Really I just need to display 5 squares in a grid made of 2 columns and 3 rows (last one being half emp... full)
The width of each column should be half the screen, which is done using the Star (*). And I need the height to always be a little bit smaller than the width. The idea is to have thick rectangles.
Right now the Grid is inside a scrollview, I'm not sure that's relevant but we never know. I'm doing this so smaller phones will always be able to scroll through the grid, while others might just have blank space.
I've been fiddling aroudn trying to get the screen size or the column width. I can neither get the absolute value of my column width or my screenwidth at all (always -1 !?). I can easily get the Star value of my grid items, which is 1, but I would really need just the frame size, the double value, so I can just resize my grid in the constructor of my view and give it an absolute value.
Questions :
How do I get my column absolute width? Or how do I set my row height to a column-width-related value ?
If no possible, how do I get the screen width, so I can do the horrible rowheight = screenWdith/2 - padding ?
Maybe there is a very simple other way that makes this process trivial?
Or is this at all possible?

Answer 1

I will go with answers #2, get the screen width and height, you'll need a dependency service to do that you will need something like this:
interface IScreen
{
double Width { get; }
double Height { get; }
double convertPx(int px);
string locationName(double latitude, double longitude);
Task<string> locationNameAsync(double latitude, double longitude);
string Version { get; }
void ShowAlertMessage(string aTitle, string aMessage);
}
Android:
class Screen_Android : Java.Lang.Object, IScreen
{
public Screen_Android() { }
public double Width
{
get
{
var ctx = Forms.Context;
var metrics = ctx.Resources.DisplayMetrics;
return (ConvertPixelsToDp(metrics.WidthPixels));
}
}
public double Height
{
get
{
var ctx = Forms.Context;
var metrics = ctx.Resources.DisplayMetrics;
return (ConvertPixelsToDp(metrics.HeightPixels));
}
}
private static int ConvertPixelsToDp(float pixelValue)
{
var ctx = Forms.Context;
var dp = (int)((pixelValue) / ctx.Resources.DisplayMetrics.Density);
return dp;
}
public double convertPx(int px)
{
var ctx = Forms.Context;
//var dp = (int)((px) / ctx.Resources.DisplayMetrics.Density);
//return (int)((dp * ctx.Resources.DisplayMetrics.Density) + 0.5);
double density = ctx.Resources.DisplayMetrics.Density;
if (density >= 4.0)
{
//"xxxhdpi";
return px * 4;
}
if (density >= 3.0 && density < 4.0)
{
//"xxhdpi";
return px * 3;
}
if(density >= 2.0)
{
//xhdpi
return px * 2;
}
if(density >= 1.5 && density < 2.0)
{
//hdpi
return px * 1.5;
}
if(density >= 1.0 && density < 1.5)
{
//mdpi
return px * 1;
}
return px;
//return (int)TypedValue.ApplyDimension(ComplexUnitType.Dip, px, ctx.Resources.DisplayMetrics);
//var resources = ctx.Resources;
//var metrics = resources.DisplayMetrics;
//int dp = px * ((int)metrics.DensityDpi / 160);
//return dp;
}
public string locationName(double latitude, double longitude)
{
//List<Address> addresses;
Geocoder geocoder = new Geocoder(Forms.Context, Locale.Default);
try
{
var addresses = geocoder.GetFromLocation(latitude, longitude, 10);
if (addresses.All(item => item == null)) return "";
string address = addresses[0].GetAddressLine(0);
string city = addresses[0].GetAddressLine(1);
string country = addresses[0].GetAddressLine(2);
return address + " " + city + " " + country;
}
catch
{
return "";
}
}
public string Version
{
get { throw new NotImplementedException(); }
}
public void ShowAlertMessage(string aTitle, string aMessage)
{
Toast.MakeText(Forms.Context, aMessage, ToastLength.Short).Show();
}
public System.Threading.Tasks.Task<string> locationNameAsync(double latitude, double longitude)
{
throw new NotImplementedException();
}
iOS:
public class Screen_iOS : IScreen
{
public double Width
{
get
{
return UIScreen.MainScreen.Bounds.Width;
}
}
public double Height
{
get
{
return UIScreen.MainScreen.Bounds.Height;
}
}
public double convertPx(int px)
{
throw new NotImplementedException();
}
public string locationName(double latitude, double longitude)
{
string locationName = "";
CLLocation c = new CLLocation(Math.Round(latitude, 2), Math.Round(longitude, 2));
CLGeocoder geocoder = new CLGeocoder();
geocoder.ReverseGeocodeLocation(c, (placemarks, error) =>
{
if ((placemarks != null) && (placemarks.Length > 0))
locationName = placemarks[0].Name + placemarks[0].PostalCode + placemarks[0].AdministrativeArea + placemarks[0].Country;
});
return locationName;
}
public string Version
{
get
{
NSObject ver = NSBundle.MainBundle.InfoDictionary["CFBundleShortVersionString"];
return ver.ToString();
}
//get { throw new NotImplementedException(); }
}
public void ShowAlertMessage(String aTitle, string aMessage)
{
UIAlertView error = new UIAlertView(aTitle, aMessage, null, "OK" , null);
error.Show();
}
public async Task<string> locationNameAsync(double latitude, double longitude)
{
string locationName = "";
CLLocation loc = new CLLocation(latitude, longitude);
CLGeocoder geocoder = new CLGeocoder();
CLPlacemark[] r = null;
var task = Task.Factory.StartNew(() =>
{
r = geocoder.ReverseGeocodeLocationAsync(loc).Result;
Console.WriteLine("it ran! {0}", r.Length);
});
task.Wait(TimeSpan.FromSeconds(10));
if ((r != null) && (r.Length > 0))
locationName = r[0].Name + r[0].PostalCode + r[0].AdministrativeArea + r[0].Country;
return locationName;
}
}