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using System;
using Xamarin.Forms.CustomAttributes;
using System.Text;
#if UITEST
using Xamarin.UITest;
using NUnit.Framework;
#endif
namespace Xamarin.Forms.Controls
{
[Preserve (AllMembers = true)]
[Issue (IssueTracker.Bugzilla, 27642, "[Windows Phone] Adding a ScrollView control to a ContentView, remove it and re-add it will cause an exception on Windows Phone")]
public class Bugzilla27642 : TestContentPage // or TestMasterDetailPage, etc ...
{
ContentView _mainContent;
protected override void Init ()
{
var rootGrid = new Grid {
RowDefinitions = new RowDefinitionCollection
{
new RowDefinition { Height = new GridLength(1, GridUnitType.Star) },
new RowDefinition { Height = new GridLength(1, GridUnitType.Auto) },
},
};
_mainContent = new ContentView { Content = new ScrollView { Content = new Label { Text = Description } } };
rootGrid.AddChild (_mainContent, 0, 0);
var buttons = new StackLayout { Orientation = StackOrientation.Horizontal };
var button1A = new Button { Text = "View 1A" };
button1A.Clicked += (sender, args) => ShowView (_view1A);
buttons.Children.Add (button1A);
var button1B = new Button { Text = "View 1B" };
button1B.Clicked += (sender, args) => ShowView (_view1B);
buttons.Children.Add (button1B);
var button2 = new Button { Text = "View 2" };
button2.Clicked += (sender, args) => ShowView (_view2);
buttons.Children.Add (button2);
rootGrid.AddChild (buttons, 0, 1);
Content = rootGrid;
}
const string Description = "A view containing a ScrollView cannot be re-used (same instance, Singleton) \n\n\n"
+ "Steps to reproduce: \n\n" + "View1a contains a ScrollView \n"
+ "Click: View1A -> View2 -> View1A => Exception\n\n"
+ "View1b also contains a ScrollView, but its Content (including ScrollView!) will be re-generated during activation.\n"
+ "Click: View1B -> View2 -> View1B => Exception\n\n"
+ "View2 doesn't contain a ScrollView and therefore can be called again without problems.\n\n"
+ "The Error-Message-View contains a ScrollView, too but will be re-created every time.";
readonly View1A _view1A = new View1A (); // always same instance, simulates Singleton from IoC
readonly View1B _view1B = new View1B (); // -"-
readonly View2 _view2 = new View2 (); // -"-
void ShowView (ExtendedContentView view)
{
try {
view.Activating (); // implemented only for View1B
_mainContent.Content = view;
}
catch (Exception ex) {
_mainContent.Content = new ErrorView (ex);
}
}
[Preserve (AllMembers = true)]
public class ExtendedContentView : ContentView
{
public virtual void Activating ()
{
}
}
[Preserve (AllMembers = true)]
public class View1A : ExtendedContentView
{
public View1A ()
{
BackgroundColor = Color.Olive;
var scrollView = new ScrollView ();
var sb = new StringBuilder ();
for (var i = 0; i < 100; i++)
sb.Append ("View 1a with ScrollView +++ ");
#pragma warning disable 618
var label = new Label { Text = sb.ToString (), HorizontalOptions = LayoutOptions.Center, VerticalOptions = LayoutOptions.Center, XAlign = TextAlignment.Center, };
#pragma warning restore 618
scrollView.Content = label;
Content = scrollView;
}
}
[Preserve (AllMembers = true)]
public class View1B : ExtendedContentView
{
public View1B ()
{
BackgroundColor = Color.Navy;
}
public override void Activating ()
{
var scrollView = new ScrollView ();
var sb = new StringBuilder ();
for (var i = 0; i < 50; i++)
sb.Append ("View 1b with ScrollView and recreation of content +++++ ");
#pragma warning disable 618
var label = new Label { Text = sb.ToString (), HorizontalOptions = LayoutOptions.Center, VerticalOptions = LayoutOptions.Center, XAlign = TextAlignment.Center, };
#pragma warning restore 618
scrollView.Content = label;
Content = scrollView;
}
}
public class View2 : ExtendedContentView
{
public View2 ()
{
BackgroundColor = Color.Teal;
#pragma warning disable 618
Content = new Label { Text = "View 2", HorizontalOptions = LayoutOptions.Center, VerticalOptions = LayoutOptions.Center, XAlign = TextAlignment.Center, };
#pragma warning restore 618
}
}
[Preserve (AllMembers = true)]
public class ErrorView : ExtendedContentView
{
public ErrorView (Exception ex)
{
BackgroundColor = Color.Maroon;
Content = new ScrollView { Content = new Label { Text = ex.ToString () } };
}
}
}
public static class GridExtension
{
public static void AddChild (this Grid grid, View view, int column, int row, int columnspan = 1, int rowspan = 1)
{
if (row < 0) {
throw new ArgumentOutOfRangeException ("row");
}
if (column < 0) {
throw new ArgumentOutOfRangeException ("column");
}
if (rowspan <= 0) {
throw new ArgumentOutOfRangeException ("rowspan");
}
if (columnspan <= 0) {
throw new ArgumentOutOfRangeException ("columnspan");
}
if (view == null) {
throw new ArgumentNullException ("view");
}
Grid.SetRow (view, row);
Grid.SetRowSpan (view, rowspan);
Grid.SetColumn (view, column);
Grid.SetColumnSpan (view, columnspan);
grid.Children.Add (view);
}
}
}
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