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Message Closed
modified 27-Oct-17 11:10am.
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Peter Vegter wrote: Is there a reason you don't just subscribe to the 'original' event (MouseDown)? Hi Peter, a very good question to ask.
I can't speak for OG's intent, but, note that in my code example the only thing that the sub-classed PictureBox exposes to the "outside" is a property of Type 'Action. In OG's code the MouseDown event handler is public, and the 'event delegate is public. Is that a significant difference: I'm not sure.
My code injects a reference to executable code (a "callback," if you will) into the sub-classed PictureBox: imho, that achieves minimal dependency. I believe "injection," and use of 'Action, and 'Func, are useful in educating C# students in a way that moves them toward the kind of thinking that, hopefully, will help them get to SOLID; my experience teaching this usage has reinforced that conviction.
Some students have a very difficult time grokking C#/,NET's Delegate/EventHandler syntax where you first have to create a Type declaration, the Delegate, then create an instance of that Type, then create an On-EventHandler/Event with its required null-check.
I welcome your feedback.
cheers, Bill
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it. A few hundred years later another traveler despairing as myself, may mourn the disappearance of what I may have seen, but failed to see.» Claude Levi-Strauss (Tristes Tropiques, 1955)
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Message Closed
modified 27-Oct-17 11:08am.
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Bill Woodruff has given you you excellent suggestions. I would change one detail. Instead of using MouseDown for your event, use MouseUp. A lot of events can happen in between and MouseUp is the last event in the chain. It can make debugging easier.
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I started to use .NET Standard in earnest recently. And also updated them to lastest .csproj format (the one with almost nothing inside! ) and quite often what happens is, when I "try to compile" the compilation of my .NET Standard project (new .csproj style) just hang there and does nothing...
I only waited half an hour for my longuest test (playing game at home while waiting on a project with only 3 files in it) and.. nothing ever happens...
Any idea?
[EDIT]
It just happened to me right now and I had to delete BOTH the .vs and package folder to make it work.
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I have been using VS2017 for over a year and never seen this. I suspect something is wrong with your installation.
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yes but.. are you using the new .csproj format? looks like that:
(the whole .csproj file!)
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<TargetFramework>netstandard1.4</TargetFramework>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="System.Collections.Immutable" Version="1.4.0" />
<PackageReference Include="System.Net.Sockets" Version="4.3.0" />
<PackageReference Include="System.ValueTuple" Version="4.4.0" />
<PackageReference Include="System.Interactive.Async" Version="3.1.1" />
<PackageReference Include="System.Reactive.Core" Version="3.1.1" />
</ItemGroup>
<ItemGroup>
<ProjectReference Include="..\..\Galador.Reflection\Galador.Reflection.PCL\Galador.Reflection.PCL.csproj" />
</ItemGroup>
</Project>
Also.. I have to admit to edit the .csproj (to convert from old to new format), but it was already 3 days ago...
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Ah, I see. No, mine are still old format.
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Super Lloyd wrote: And also updated them to lastest .csproj format
Updated what exactly?
I just you start with a brand new project. Don't update anything. Do a hello world program. If that doesn't work then something is wrong with your platform (hardware, OS, other apps and/or install.)
If it works, then presuming that you have some existing code, add that in to the new project above. If this fails then I would expect same problem as above.
If that works then I would suppose the problem is with how you "updated" the project file.
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Hi. I want the MainForm to start minimized and inactive - no focus on it and its taskbar button. I tried many solutions (including the one below) but nothing worked: the form still gets focus when it's started. I'm using Windows 10. Also the TopMost property is off.
Any ideas how to make it work?
protected override bool ShowWithoutActivation
{
get
{
return true;
}
}
const int WS_EX_NOACTIVATE = 0x08000000;
protected override CreateParams CreateParams
{
get
{
CreateParams createParams = base.CreateParams;
createParams.ExStyle |= WS_EX_NOACTIVATE;
return createParams;
}
}
modified 22-Oct-17 10:21am.
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Keep in mind that the TaskBar Button "belongs to" Windows, not your WinForms App: it triggers standard window size/activation functions that your WF App has no way to cancel.
While you can do "weird stuff," like setting the Main Form Location property so it's off-screen, imho, you should have a compelling reason for changing such standard behavior ... behavior Users learn to expect. Of course, your WinForms App can infer the effects of those Win behaviors by handling the Form's events like 'Activated and 'SizeChanged.
There is a technique, for taking full control of showing a series of Forms, without direct Win API invocations, which I'll be happy to show you an example of ... but, first ... you ...
1. confirm this is Windows Forms
2. describe what you want to do here in more detail: more than one Form ? What id each Form's purpose ?
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it. A few hundred years later another traveler despairing as myself, may mourn the disappearance of what I may have seen, but failed to see.» Claude Levi-Strauss (Tristes Tropiques, 1955)
modified 21-Oct-17 6:56am.
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Simplest solution? For winForms, just set the main Form.WindowState to FormWindowState.Minimized
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
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Hi, OG, I think, but am not sure, the OP is looking to show another Form before the Main Form ... perhaps a log-in Form, or a splash-screen ... without activating the Main Form. That can be done using a custom ApplicationContext.
Hopefully, the OP will clarify what he's doing
cheers, Bill
«While I complain of being able to see only a shadow of the past, I may be insensitive to reality as it is now, since I'm not at a stage of development where I'm capable of seeing it. A few hundred years later another traveler despairing as myself, may mourn the disappearance of what I may have seen, but failed to see.» Claude Levi-Strauss (Tristes Tropiques, 1955)
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Could be - difficult to tell with some of these.
How are you doing? Had your eyes fixed yet?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
AntiTwitter: @DalekDave is now a follower!
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What I'm trying to do: I start my app from another app (XnView). My app gets a list of files from XnView. I want my app to start minimized and to not steal the focus from XnView.
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I did that too. The form starts minimized but it still steals the focus from the current app.
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I've seen that. Actually the code that I posted is from that site. Anyone could make a working test solution with just an empty form that is not activated when it's launched and send it to me?
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The "override ShowWithoutActivation"-method works for me - on Windows 7.
For testing I made two projects, one Forms-Project, one Console-Project. The Console-Project is basically mimicking XnView starting your app.
Essentials of the Forms-Project:
static class Program
{
[STAThread]
static void Main(string[] args)
{
bool withoutActivation = false;
if (args.Length > 0 && !String.IsNullOrWhiteSpace(args[0]))
withoutActivation = args[0] == "1";
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1(withoutActivation));
}
}
public partial class Form1 : Form
{
private bool WithoutActivation;
public Form1(bool withoutActivation)
{
WithoutActivation = withoutActivation;
InitializeComponent();
label1.Text = WithoutActivation ? "without activation" : "with activation";
}
protected override bool ShowWithoutActivation
{
get
{
return WithoutActivation;
}
}
}
Essentials of the Console-Project:
class Program
{
static void Main(string[] args)
{
bool withoutActivation = false;
while (!Console.KeyAvailable)
{
Thread.Sleep(3000);
Process.Start("[path to forms-app.exe goes here]", withoutActivation ? "1" : "0");
withoutActivation = !withoutActivation;
}
}
}
Every second "invocation" of the forms-app steals the focus from the currently active app, every other one does not.
Edit: Just realized that I didn't do the "start minimized" part (it's late here..). When I do show it minimized (by inserting WindowState = FormWindowState.Minimized; after InitializeComponent(); ) then neither "invocation" steals the focus, regardless whether WithoutActivation is true or false. So either Windows 10 behaves differently there or you're doing something not quite right.
If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson
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Thanks for help. The test is working. But I'm a beginner and I have troubles implementing this on my actual project. I'm using SingleInstanceController at Program.cs in order to prevent opening the same app twice (forced single instance). Because of that, the simple ShowWithoutActivation doesn't work.
This app works in 2 main stages:
1. The app starts minimized, then it reads the arguments (file paths), then it displays those arguments in a listbox, then it waits.
2. If it's started again, it gets other arguments (actually just one), rename the files from stage 1, then it quits.
Basically it's a file (picture) arranger: the user selects the files to be renamed (stage 1) and the target file after those files will be placed through auto-renaming (stage 2). Like this: FileArranger - Streamable[^] Each stage means a launch of this app.
I want this app to stay minimized and without focus during its whole "lifetime". Of course, except when the user activates it by clicking its taskbar button. I uploaded the whole project here: MEGA[^] This app has around 300 LOC (MainForm.cs + Program.cs). Please, could you modify it in order to start without focus? That would be very helpful.
modified 21-Oct-17 21:37pm.
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You using WindowsFormsApplicationBase and its event StartupNextInstance to implement a "SingleInstanceController" is the important piece of information here.
The code in WindowsFormsApplicationBase that is calling your event handler ThisStartupNextInstance (which I would suggest renaming to something like "StartedAgain") is bringing your MainForm to the foreground. Unless you explicitly tell it not to by inserting this line into the event handler method:
e.BringToForeground = false; (Take a look at the tooltip of BringToForeground .)
I assume the line form.Hide(); there was an attempt to solve your problem; you probably want to remove it.
If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson
modified 22-Oct-17 3:11am.
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I tried that but the form still steals the focus. This is how Program.cs looks like now:
using System;
using System.Windows.Forms;
using System.Linq;
using Microsoft.VisualBasic.ApplicationServices;
namespace FileArranger
{
internal sealed class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
string[] args = Environment.GetCommandLineArgs();
var controller = new SingleInstanceController();
controller.Run(args);
}
}
public class SingleInstanceController : WindowsFormsApplicationBase
{
public SingleInstanceController()
{
IsSingleInstance = true;
StartupNextInstance += StartedAgainInstance;
}
void StartedAgainInstance(object sender, StartupNextInstanceEventArgs e)
{
var form = MainForm as MainForm;
e.BringToForeground = false;
form.ReadArguments(e.CommandLine.ToArray());
}
protected override void OnCreateMainForm()
{
MainForm = new MainForm();
}
}
}
What should I modify next?
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You also still have this bit in your Form, right?
protected override bool ShowWithoutActivation
{
get { return true; }
}
Please test the following: Start your app directly, without doing anything with XnView. For me, it's showing minimized in the taskbar and doesn't take focus. Start it again. For me, it remains minimized in the taskbar without focus. Does it behave the same for you this far?
If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson
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"You also still have this bit in your Form, right?"
Yes.
"Please test the following: Start your app directly, without doing anything with XnView. For me, it's showing minimized in the taskbar and doesn't take focus. Start it again. For me, it remains minimized in the taskbar without focus. Does it behave the same for you this far?"
I did that. The app still gets the focus. If I press Enter after the app is launched it restores the form, hence it still has focus. This is by far the most stubborn app I did. Please, could you send me the project modified by you?
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Well, this is awkward. For testing, I commented the ShowWithoutActivation -override. As expected, it did activate then. Then I removed the comments and it still activates. I don't know what's happening there.
However, I have another solution for you:
1) Go to this article and download the code: All Three Features of Single-Instance Applications at One Shot, .NET[^]
2) Copy the files IRemoteFileLoader.cs , Server.cs and SingleInstanceManager.cs to your project folder.
3) Include them into your project (Project > Add existing item)
4) Add a reference to the System.Runtime.Remoting -assembly to your project (Project > Add reference).
5) Replace the code of your Program.cs by this:
using System;
using System.Windows.Forms;
using SA.Universal.SingleInstance;
namespace FileArranger
{
internal sealed class Program
{
[STAThread]
static void Main(string[] commandLine)
{
if (SingleInstanceManager.IsSecondInstance)
{
SingleInstanceManager.HandleRemoteCommandLine(commandLine);
SingleInstanceManager.ActivateFirstInstance();
return;
}
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new MainForm());
}
}
} 6) Add a using-Directive to your MainForm.cs :
using SA.Universal.SingleInstance; 7) Add this to the constructor of MainForm :
SingleInstanceManager.FilesLoading += (sender, eventArgs) => {
Invoke(new System.Action(() => ReadArguments(eventArgs.CommandLine)));
};
That should do it.
If the brain were so simple we could understand it, we would be so simple we couldn't. — Lyall Watson
modified 22-Oct-17 9:04am.
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