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Kevin Marois wrote: TimeSpan is starting from 10 and counting forward
Yes. But wouldn't you do the same when computing a time interval? For the first day, you'd count the hours left (not elapsed) and for all successive days you'd count the hours elapsed, right? Hence, Mon 10pm to Tue 1am would be a time interval of 3 hours, right? 
/ravi
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The TimeSpan isn't counting forward or backward from any specific time.
It is representing (in this case) the elapsed time from one DateTime to another.
It has no concept of forward from "10 am".
If you used an hourglass to count time from 10 am Aug 11 until 8pm Aug 14, you would just be turning the glass over for the 82nd time at the 8pm Aug 14. The TimeSpan is just representing the amount of sand that flowed through neck of the hourglass (with much more precision than counting each grain of sand!!)
It is a signed difference.
If you did the subtraction in the other order it would return -82 hours.
It is just a counter.
[Edit]
var TimelineStart = new DateTime(2015, 08, 11, 10, 00, 00);
var TimelineEnd = new DateTime(2015, 08, 14, 20, 00, 00);
TimeSpan delta = TimelineEnd - TimelineStart;
Debug.WriteLine(TimelineEnd.Ticks);
Debug.WriteLine(TimelineStart.Ticks);
Debug.WriteLine(delta.Ticks);
gives the output:
635751792000000000
635748840000000000
2952000000000
The DateTime items are counters forward from a reference date and time.
The TimeSpan is just representing the difference.
"Fairy tales do not tell children the dragons exist. Children already know that dragons exist. Fairy tales tell children the dragons can be killed."
- G.K. Chesterton
modified 17-Aug-15 13:20pm.
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Consider a simpler example:
TimelineStart = new DateTime(2015, 08, 11, 10, 00, 00);
TimelineEnd = new DateTime(2015, 08, 11, 11, 00, 00);
TotalHours = (TimelineEnd - TimelineStart).TotalHours;
Subtracting two DateTime instances gives you a TimeSpan representing the difference between the two points on the timeline - ie: how many hours are there between 10:00 and 11:00 on 11th August 2015.
With your approach to the problem, TotalHours would contain 21. Unless you live next to a black hole, there aren't 21 hours between 10:00 and 11:00 on the same day. 
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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I'm using VS Community 2013 and I'd like to start a VSTO (Excel) project. However, I don't find any templates listed, local or online.
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I have a form and want to display formatted text. I use a RichTextBox control. But I want windows message such as mouse clicks on the text to be handled by the parent form. So I disable the control. But that changes the background colour to grey, which is unacceptable as I want to set the background colour. Okay, so I override the WndProc method of the RichTextBox and use SendMessage to send messages such as mouse double click to the parent. That works, the form WndProc DOES receive the double click. But, the form's handler for a mouse double click is not invoked. Why is this? Does the system invoke Form event handlers instead of WndProc?
Note that the mouse bouble click message includs the client position in the lParam arg. I changed that from the location in the RichTextBox to the location in the parent form.
SOLVED
The problem is how to make a RichTextBox transparent to mouse events, so that it does no more than draw text on screen. Disabling the richtextbox sets a fixed background colour, which is not what I want.
The solution is to handle mouse events from the richeditbox in the form. Then in each event handler call Form.OnXXXXXX method e.g. Form.OnDoubleClick().
So in the end this is actually quite simple!
Thanks all for comments.
modified 14-Aug-15 11:03am.
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You actually don't need to override WndProc callback in your RichEdit control class. Really, You have to declare and send a notify message as follows:
#define EN_MYMSG1 (WM_USER + 200)
NMHDR nmhdr;
::ZeroMemory((LPVOID)&nmhdr, sizeof(NMHDR));
nmhdr.hwndFrom = hRichEditWnd;
nmhdr.idFrom = IDC_MYRICHEDIT;
nmhdr.code = EN_MYMSG;
::SendMessage(hWndView, WM_NOTIFY, (WPARAM)nmhdr.idFrom, (LPARAM)&nmhdr);
And then, process this message by handling WM_NOTIFY in your parent window class using whatever predefined MFC message map macros or overriding WndProc callback method:
ON_NOTIFY(EN_MYMSG, IDC_MYRICHEDIT, OnMyMessage) or
ON_NOTIFY_REFLECT(EN_MYMSG, OnMyMessage)
afx_msg void OnMyMessage(NMHDR* pnmhdr , LRESULT* pResult);
void CMyWnd::OnMyMessage(NMHDR* pnmhdr, LRESULT* pResult)
{
if (pnmhdr->code == EN_MYMSG)
{
}
*pResult = 0;
}
LRESULT CALLBACK CMyWnd::WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch(message)
{
case WM_NOTIFY:
NMHDR* pnmhdr = &(NMHDR)message.GetLParam(typeof(NMHDR));
if (pnmhdr->code == EN_MYMSG)
{
}
break;
default: break;
}
return WndProcDefault(hWnd, uMsg, wParam, lParam);
}
That's all
modified 14-Aug-15 8:19am.
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That doesn't look like C# to me! 
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Maybe it is .Net 5. 
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Besides, this code has been written using C++ MFC, but you can easily convert it into C#.NET
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This code is just a prototype and describes the basic concept of notify message handling, it's no matter you implement it in C++ or C#. The notify message handling works similar in either C#.NET or C++ MFC. The main post of this post is the concept.
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Sadly I don't think it does do what I need. Basically I want the RichTextBox to display text, with the correct font, bold, background colour, etc, but to be transparent to mouse events such as double click.
I am able to intercept mouse double clicks in a class derived from RichTextBox, and SendMessage them to the parent form. They are passed in to the parent form WndProc. But for some reason they do not invoke the MouseDoubleClick event handler. I tried overriding the Form.WndProc, but could not invoke MouseDoubleClick, for reasons I understand.
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Surely, because in Win32API, to be able to handle control's messages in parent window you have to send and process notification messages. For example, if you need to process MouseDblClick message outside the RichEditCtrl, first you have to handle this message in RichEditCtrl window class by posting WM_NOTIFY message and then process the WM_NOTIFY in the parent window as just I have shown in my reply.
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Baby, help me solve my problem: FormDesigner Runtime
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I made a function of having a Form Designer software.
In this software, I use this namespace:System.Drawing.Design.
I use the following code in my program is designed .to Program run A pop-up It is designed to form.
Now I have a problem: How can The program Run time Right click It is designed to form A pop-up with a menu.
DesignSurface surface = new DesignSurface();
surface.BeginLoad(typeof(Form));
Control view = (Control)surface.View;
view.Dock = DockStyle.Fill;
this.Controls.Add(view);
toolBoxService = new DemoToolboxService();
toolBoxService.ToolBox = new ListBox();
toolBoxService.ToolBox.Items.Add(new ToolboxItem(typeof(Button)));
toolBoxService.ToolBox.Items.Add(new ToolboxItem(typeof(TextBox)));
toolBoxService.ToolBox.Items.Add(new ToolboxItem(typeof(Label)));
toolBoxService.ToolBox.Items.Add(new ToolboxItem(typeof(TabControl)));
toolBoxService.ToolBox.Items.Add(new ToolboxItem(typeof(StatusBar)));
toolBoxService.ToolBox.Dock = DockStyle.Fill;
this.panel1.Controls.Add(toolBoxService.ToolBox);
IServiceContainer container = surface.GetService(typeof(IServiceContainer)) as IServiceContainer;
if (container != null)
{
container.AddService(typeof(IToolboxService), toolBoxService);
}
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How to do Automatically select the Next items of list box using Timer?
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It depends on the UI technology you use, but for example if you use forms, you can create the timer and wire Tick[^] event. In the event, you set the SelectedItem[^] property.
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Keep a class level index to the currently selected item, and either use it to set the ListBox.SelectedIndex property, or to pick the appropriate entry from the ListBox.Items collection.
In your timer Tick handler, you use the index and increment it.
What part of this is giving you difficulties?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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if i click the button,list box items automatically go to next and display the image.Each image displayed at 10 second.
Timer t= new timer();
private void button_click(object ,Event )
{
for(int i=0;i<listbox1.items.count;i++)
{
if(i<=listbox1.items.count)
{
listbox1.SelectedIndex =i;
t.Tick += new System.EventHandler(showcurrentimage);
t.interval=10*1000;
t.start();
}
}
}
private void showcurrentimage (object , event)
{
picture.Load(listbox1.Selecteditems.Tostring());
t.sop();
}
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Why are you adding a new tick event for each iteration round the loop?
You do realize that you will get a Tick event handler call for each time you add it?
Seriously, start by moving the timer setup code to your form load, and start it only once.
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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ok,how to use the Tick event with out loop? please show any example code
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The whole idea of a tick event is that you don't need a loop!
Try an experiment: set up and start your timer in the load event, and make the tick event write to the console:
Console.WriteLine(DateTime.Now); Comment everything else out of the handler.
Run your app in the debugger, and look at the output pane. See what I mean?
Bad command or file name. Bad, bad command! Sit! Stay! Staaaay...
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Baby, help me solve my problem: FormDesigner Runtime
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Increase the SelectedIndex of the ListBox in the Timer_Tick event handler. Build in safeguard to reset index after last item in the list.
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