C# ListView Bug - c#

When I keep clicking any ListViews rapidly, the app will eventually freeze and become inaccessible. Any Idea how to prevent this from happening?
to generate the bug:
1. run the app
2. keep clicking the listview randomly as fast as possible
3. the app will then freeze
this is my code:
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
namespace DragDropCF
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
SetupListView(lv1, new ObservableCollection<String> { "VarOne", "VarTwo", "VarThree" });
SetupListView(lv2, new ObservableCollection<String> { "VarFour", "VarFive", "VarSix", "VarSeven" });
SetupListView(lv3, new ObservableCollection<String> { "VarEight", "VarNine", "VarTen", "VarEleven", "VarTwelve" });
}
private void SetupListView(ListView listView, ObservableCollection<String> itemsSource)
{
listView.ItemsSource = itemsSource;
listView.AllowDrop = true;
listView.CanDrag = true;
listView.CanDragItems = true;
listView.CanReorderItems = true;
listView.DragItemsStarting += ListView_DragItemsStarting;
lv1.DragEnter += Lv1_DragEnter;
lv1.Drop += Lv1_Drop;
}
private void Lv1_Drop(object sender, DragEventArgs e)
{
}
private void Lv1_DragEnter(object sender, DragEventArgs e)
{
}
private void ListView_DragItemsStarting(object sender, DragItemsStartingEventArgs e)
{
}
}
}

Related

Select printer name without showing PrintDialog

I have this code. When I need to print my report, it shows me a Print Dialog. I want to select my print name by code, and print my report without showing PrintDialog.
This is my code.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Drawing.Printing;
namespace POS.Reports
{
public partial class ProductsReceiptPreview : Form
{
BindingSource _data;
string _total, _cashr, _cashc;
public ProductsReceiptPreview(BindingSource data, string total,
string cashr, string cashc)
{
InitializeComponent();
_total = total; _cashr = cashr; _cashc = cashc;
_data = data;
}
private void ProductsReceipt_Load(object sender, EventArgs e)
{
DataReceiptBindingSource.DataSource = _data;
Microsoft.Reporting.WinForms.ReportParameter[] param = new
Microsoft.Reporting.WinForms.ReportParameter[]
{
new Microsoft.Reporting.WinForms.ReportParameter("ptotal",
_total),
new Microsoft.Reporting.WinForms.ReportParameter("pcashr",
_cashr),
new Microsoft.Reporting.WinForms.ReportParameter("pcashc",
_cashc),
new Microsoft.Reporting.WinForms.ReportParameter
("pdate",DateTime.Now.ToString())
};
this.rptProductsReceipt.LocalReport.SetParameters(param);
this.rptProductsReceipt.RefreshReport();
this.rptProductsReceipt.ZoomMode =
Microsoft.Reporting.WinForms.ZoomMode.PageWidth;
}
private void btnReports_Click(object sender, EventArgs e)
{
rptProductsReceipt.PrintDialog();
}
}
}
i never use your method but i use this
rptProductsReceipt.PrintToPrinter(1, false, 0, 0);
after using adapter and data table

System.UnauthorizedAccessException: 'Access is denied location UWP

I try to make a simple weather aplication but i get an exception.
I have location activated. I try to run in emulator for phone, not working
the exception
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
namespace TryToMakeWeatherApp
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
}
private async void Button_Click(object sender, RoutedEventArgs e)
{
var pos = await LocationManage.GetLocation(); //Here i'm geting the error
var lat = pos.Coordinate.Latitude;
var lon = pos.Coordinate.Longitude;
var weather = WeatherMap.GetWeather(lat, lon).ToString();
WeatherTxt.Text = weather;
}
}
}
This is code from MainPage.
And this is the LocationManage class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.Devices.Geolocation;
namespace TryToMakeWeatherApp
{
class LocationManage
{
public async static Task<Geoposition> GetLocation()
{
var accessStatus = await Geolocator.RequestAccessAsync();
var geolocator = new Geolocator { DesiredAccuracyInMeters = 0 };
var position = await geolocator.GetGeopositionAsync();
return position;
}
}
}
in your package.manifest file have to turn on this capability too

Error: SQLite Wrapper assembly for the current platform was not found

The structure of my application
Content mainpage
using MyBD;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.ApplicationModel.Background;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
namespace MyApp
{
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
this.NavigationCacheMode = NavigationCacheMode.Required;
}
protected override void OnNavigatedTo(NavigationEventArgs e)
{
}
private void button_Click(object sender, RoutedEventArgs e)
{
historyBD HBD = new historyBD("history");
}
}
}
Content MyBD
using SQLitePCL;
namespace MyBD
{
public class historyBD
{
public SQLiteConnection con;
private string mynull = "0";
public historyBD(string dbname)
{
con = new SQLiteConnection(dbname);
}
}
}
when you press the button , the line "con = new SQLiteConnection(dbname);"
gives an error message : "A SQLite Wrapper assembly for the current platform was not found. Ensure that the current project references both SQLitePCL and the following platform-specific assembly: SQLitePCL.Ext."
What am I doing wrong?

C# - Tier Separation - How to use these delegates?

Here's the relevant code:
ClickMeGame.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ClassLibrary
{
public class ClickMeGame
{
public OnClickMe onClickMeCallback;
public int score;
public ClickMeGame()
{
score = 0;
}
private void IncrementScore()
{
score++;
}
}
}
ClickMeCallBackDefinitions.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ClassLibrary
{
public delegate void OnClickMe();
}
MainWindow.cs (Windows Form)
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using ClassLibrary;
namespace ClickMe
{
public partial class mainWindow : Form
{
private ClickMeGame game;
public mainWindow()
{
InitializeComponent();
game = new ClickMeGame();
game.onClickMeCallback = clickMeButton_Click();
}
private void clickMeButton_Click(object sender, EventArgs e)
{
UpdateUI();
}
private void UpdateUI()
{
scoreLabel.Text = string.Format("The score is: {0}", game.score);
}
}
}
So what I'm trying to do is, when the user clicks a button present on the form, I want a label on the form to update with the game score which increments with every click.
I'm learning about/want to be able to do this with delegates in that I want to separate the project into 2 tiers; Presenation and Logic. I know it's unnecessary to do so, but I'd like to make it such that when you click the button, the Windows Form receives information about the game score via delegates/callback methods. I'm unsure how to do this, but I tried making the callback definition and referencing it, but I'm lost from there.
Assuming that the UI button uses the click event clickMeButton_Click then here you go.
public partial class mainWindow : Form
{
private ClickMeGame game;
public mainWindow()
{
InitializeComponent();
game = new ClickMeGame();
game.onClickMeCallback = param => UpdateUI();
}
private void clickMeButton_Click(object sender, EventArgs e)
{
game.onClickMeCallback.Invoke();
}
private void UpdateUI()
{
scoreLabel.Text = string.Format("The score is: {0}", game.score);
}
}

Change button text from another class in another namespace

I have a problem changing text from another class in another namespace. I have the first Form1 class :
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
static Form1 mainForm;
[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool AllocConsole();
public static String LinkToApi = "http://google.com/api/";
public static Comunicator comunicator;
public static int debug = 5;
public Form1()
{
InitializeComponent();
AllocConsole(); // allow console
if(Form1.debug >= 3) Console.WriteLine("Application started");
comunicator = new Comunicator();
mainForm = this;
}
private void TestButton_Click(object sender, EventArgs e)
{
TestButton.Text = "Loading";
comunicator.TestConnection();
}
}
}
and this Comunicator class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Collections.Specialized;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.IO;
using System.Threading;
namespace WindowsFormsApplication1
{
public class Comunicator
{
private String action = "idle";
public static Thread Start(Action action)
{
Thread thread = new Thread(() => { action(); });
thread.Start();
return thread;
}
public Comunicator()
{
}
public void TestConnection()
{
if (Form1.debug >= 3) Console.WriteLine("Testing connection");
// thread test
Start(new Action(ApiTest));
}
public void ApiTest()
{
if (Form1.debug >= 3) Console.WriteLine("API test begin");
// Create a request for the URL.
WebRequest request = WebRequest.Create("http://www.bogotobogo.com/index.php");
// If required by the server, set the credentials.
request.Credentials = CredentialCache.DefaultCredentials;
// Get the response.
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
// Display the status.
Console.WriteLine(response.StatusDescription);
// Get the stream containing content returned by the server.
Stream dataStream = response.GetResponseStream();
// Open the stream using a StreamReader for easy access.
StreamReader reader = new StreamReader(dataStream);
// Read the content.
string responseFromServer = reader.ReadToEnd();
// Display the content.
Console.WriteLine(responseFromServer);
// Cleanup the streams and the response.
reader.Close();
dataStream.Close();
response.Close();
// Console.Read();
if (Form1.debug >= 3) Console.WriteLine("API test end");
// Form1.StaticTestButton.Text = "Loaded"; <---- CHANGE HERE
}
}
}
which is not even a form class (I want to keep everything nice and clean). I want to change the TestButton text into "LOADED" but i get an error when I try to do that as if Form1.TestButton does not exist in Comunicator class.
I have tried to instantiate the class, I made a couple of variables static ... nothing, still getting error.
What is the problem? How may I solve this?
The request must be asynchronous, that's why I am using threads.
You should separate concerns, and you shouldn't communicate with UI in class which is not related to UI.
You should rewrite your code.
But as quick fix you should do the following.
In class Comunicator, you can do such field.
private readonly Action<string> _notifySimpleMessageAction;
Then add to Communicator constructor parameter notifyFunction. Code in constructor:
_notifySimpleMessageAction = notifyFunction
After that you should create Communicator in following manner:
communicator = new Communicator((notification)=>
{
StaticTestButton.BeginInvoke((MethodInvoker)(() => StaticTestButton.AppendText(notification)));
});
Then at the end of your method you should do
_notifySimpleMessageAction("Loaded")
Controller class:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace ControllerDemonstrator
{
public class Controller
{
public event EventHandler CommunicatorDataLoaded;
public event EventHandler FormTestConnection;
private Form1 _form;
private Communicator _communicator;
public Form1 MainForm
{
get { return _form; }
}
public Controller()
{
_form = new Form1(this);
_form.TestConnection += _form_TestConnection;
_form.FormClosed += _form_FormClosed;
_communicator = new Communicator(this);
_communicator.DataLoaded += _communicator_DataLoaded;
}
public void Start()
{
_form.Show();
}
void _form_FormClosed(object sender, System.Windows.Forms.FormClosedEventArgs e)
{
// put any code to clean up the communicator resources (if needed) here
// --------------------------------------------------------------------
_communicator = null;
// Then exit
// ---------
Application.Exit();
}
private void _communicator_DataLoaded(object sender, EventArgs e)
{
if (null != CommunicatorDataLoaded)
{
CommunicatorDataLoaded(sender, e);
}
}
private void _form_TestConnection(object sender, EventArgs e)
{
if (null != FormTestConnection)
{
FormTestConnection(sender, e);
}
}
}
}
Basic form with one button (_testButton):
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace ControllerDemonstrator
{
public partial class Form1 : Form
{
public event EventHandler TestConnection;
public Form1(Controller controller)
{
InitializeComponent();
controller.CommunicatorDataLoaded += controller_CommunicatorDataLoaded;
}
void controller_CommunicatorDataLoaded(object sender, EventArgs e)
{
_testButton.Text = "Loaded";
}
private void _testButton_Click(object sender, EventArgs e)
{
if (null != TestConnection)
{
TestConnection(this, new EventArgs());
}
}
}
}
Communicator class (everything has been stripped out, you will need to add in your logic):
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace ControllerDemonstrator
{
public class Communicator
{
public event EventHandler DataLoaded;
public Communicator(Controller controller)
{
controller.FormTestConnection += controller_FormTestConnection;
}
private void controller_FormTestConnection(object sender, EventArgs e)
{
// put your code that does the connection here
// -------------------------------------------
if (null != DataLoaded)
{
DataLoaded(this, new EventArgs());
}
}
}
}
And in your Program.cs (assuming that is how you are starting your application):
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace ControllerDemonstrator
{
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Controller c = new Controller();
Application.Run(c.MainForm);
}
}
}
With this kind of design, the communicator doesn't know about the form and vice verse. You can expand it out to have different kind's of communicators/forms/etc and have the controller keep track of everything. It is also much easier to test code like this as you can test each separate piece on it's own since they don't depend on each other. This is a quick and dirty implementation. Do some research on the Model View Controller design pattern (not Microsoft MVC for asp.Net, but the actual design pattern). It is more code up-front to code an application with the MVC design pattern but it makes it easier to test and more maintainable.

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