Managed C++ And C++/CLI :: Message Loop In Windows Forms
May 13, 2014
I'm trying to port a Win32 application over to Windows Forms so that I can have better graphical control over the interface. The program itself is pretty simple; in the main message loop it listens for a WM_CopyData containing a certain char array, and occasionally sends WM_CopyData itself after the user clicks a certain sequence of buttons.
I found a couple of pages discussing how to completely override the Windows Forms WndProc, but I rather like having the framework do all of the control and would prefer to only latch onto it, rather than replace it. So, what would be the best way to have a Win Forms application listen for Windows Messages continuously and execute a function upon receiving them?
If I do need to override WndProc, what is the syntax? I found the following code:
Code:
protected override void WndProc(ref Message m) {
base.WndProc (ref m);
if (m.Msg==0x4a) // WM_COPYDATA {
// do your stuff here...
}
}
But when I stick that into my main.cpp file right after int main function, "protected" gets highlighted as a syntax error with the message "IntelliSense: expected a declaration".
I'm pretty much newbie in creating a successful GUI in C++. Although, i managed to create 4 buttons that should show a certain form. Lets say, Form1 is my main form, therefore - Button 1 will open Form2, and Button 2 will open Form3..... But the conditions is - If there is a form that is already open, clicking again on the Button that should open it, will Close it, but all the forms (form1,2,3,4,5) can be enabled together.
Also, a very important note is that whenever i close a form, in any way of closing it (Not the main form) It will "save" the changes i made (Such as ticking checkboxes and so..) and won't reopen it, it will just use "Visible" i guess ?
Notes :
If i use Form2 ^form2show = gcnew Form2;
and then Form2->Show();
I will be able to simply ATTACK the button and open Billions of form2 ^_^
Although, when i use Form2->ShowDialog();
It won't let me open the form3,4,5.
Which isn't so bad, but when i exit from the form2, it won't save my changes (Such as checkboxes..)
I have tried to submit this topic before but i didn't submit my whole code and it was removed. So here it is. All I am trying to do is load form2 from form1 then back to form1 from form2 for a certain number of times the get out of the loop. I am new to C-Sharp and it seems as though I cant seem to figure out a way to do this.
Here is form1 and form2 code. I have commented out a few things I have tried.
using System; using System.Collections.Generic; using System.ComponentModel; using System.Data;
I tried to get the Urdu Fonts from MySql Database using C# in Visual Studio 2010 in Windows Forms Application. When I get the value from table into my variable it shows the characters in ???? symbols. But in PHP i have used the following code:
<?php class CRUD { var $con; //function to make connection to database
I'm trying to write a program that passes Windows messages back and forth from another program that controls a laboratory instrument. I was able to write a program that successfully passes instructions, as evidenced by the instrument doing what I tell it. However, I am having trouble getting a return status from the instrument. The manual instructs the following:
// demo code, etc. // send message to the instrument operating software here... SendMessage(hwnd, WM_COPYDATA, tag, (LPARAM) &cd)
Either a completion message or return data is returned. Remote commands ReturnStatus, ReturnTiming, and ReturnData return data. In either case, data is received through an asynchronous windows message inside Win32 COPYDATASTRUCT type data packet.For example, a typical OnCopyData window callback is shown below, where the string data retrieved is finally stored into a Microsoft CString object. Note the use of variable replyTag, discussed above, which is used to isolate the correct windows message returned.
BOOL CUserDlg::OnCopyData(CWnd* pWnd, COPYDATASTRUCT* cd) { …. if (cd->dwData == replyTag) { /* String pointing to status */ CString retStatus = (char*) cd->lpData; } …. }
I can't tell if my problem is in generating the replyTag, getting the HWND to my own console window, or the actual receiving part of the code.
When setting the replyTag, the manual instructs: UINT replyTag = RegisterWindowMessage(“SOFTMaxProReplyMsg”);. However, I have to put an "L" in front of the string or I get a data type error (can't convert const char* to LPCWSTR).
When setting a HWND for myself, the manual instructs: HWND MyWnd = GetSafeHwnd().
That produces an error because GetSafeHwnd is a function of the Cwnd class, and I don't have a Cwnd. I have replaced it with HWND MyWnd = GetConsoleWindow();
When listening for the reply message, the manual instructs what I quoted above. However, I again don't have a Cwnd. I therefore simply used
The above if statement always evaluates false, and the cd.lpdata contains the message that I had sent out instead of a reply message. How to get a reply using my console application. Here is the full code of my function:
Code: #include "stdafx.h" #include<iostream> #include<vector> #include<string> #include<afxwin.h> using namespace std; void SendCommand(string command) { // Get tags to identify the receiving and sending messages
You place a breakpoint at one of locations within the message loop. But I want the breakpoint to trigger when I click on the application window, for example. But I can't, it went so fast so long as I switch from VS to the application program, the breakpoint is hitted again, then the application is frozen again. I don't know how to setup a conditional breakpoint.
I am trying to get this simple validation loop to work so that it only displays the error message when the input is outside the range 1-3. yet it always seems to display the message.
I am writing a program to auto login in a web site. Before making next attempt I have to wait for some time like some 10 seconds(it is configurable). But during waiting UI should not freeze. I wrote code something like this. Here event m_hEvent[1]) will be set by another thread after 10 seconds.The problem is UI still freezes some times!
while(1) { //m_hEvent[1] will be set by another thread after 10 seconds dwRet = MsgWaitForMultipleObjects(1, &m_hEvent[1], FALSE, dwMilliseconds, QS_ALLINPUT); ResetEvent(m_hEvent[1]);
I have created a MFC application on Visual c++ 2012. My computer work in Win 7 - 64bits. When I see many tutorial about making the executable file which is independent on .dll library (by changing Configuration Properties ->C/C++->Code Generation->Runtime Library ->Multi Threaded Deburg (MT/d)) the compiler becomes error then I can not get the result as tutorial on internet.
Is there any other way to make the .exe file for this?
I am working on my project of gesture recognition using c++ and open cv and i am also designing GUI simultaneously. I am using system namespace for GUI part and cv namespace for gestures.
After compiling i am getting error as Ambiguous symbol String is used.
This the link for msdn error support : [URL] .....
Right now, I have and application that opens a multi file dialog box. I want to take all of the files I highlight when the dialog box shows up and display a messsage box with the path and file names. This is what I have right now:
Currently, it only shows the first file that I choose. I want to make it so that the message box shows all of the files that I select when the open file dialog shows up.
I'm trying to make sure my code is written in smaller modules, so my first step is to create my initialization process in and external file to load the necessary data from external sources and set up things like the content of drop down list boxes.
My first attempt failed to give me access to the combobox items add function so I moved that code back into the form1.h file:
Code: public: Form1(void) { InitializeComponent(); // //TODO: Add the constructor code here // } void AddDate(char *date, int ID) { this->comboBox1->Items->Add("line 1"); }
It compiles fine, but the call to it in my Initialize.cpp file
Code: MarketView::Form1::AddDate("abs",1); Gives error C2352: 'MarketView::Form1::AddDate' : illegal call of non-static member function
OK, so I change "void AddDate" to "static void AddDate" and now get the error that "static member functions do not have 'this' pointers" so I go back to the "MarketView::Form1::comboBox1" situation where there is no legal syntax after "Box1 to get me to Items->Add
I've been an old fashion programmer for over 47 years. It seems as is the concept of programming computers has changed from the concepts of logic to memorization of complex syntax.
There has to be a simple answer to do this other than to write thousands of lines of code in one Form1.h file. I refuse to believe that the new programming concepts will not allow you to write code in smaller more manageable modules.
What is the proper syntax for breaking up the larger file into more manageable chucks?
I am developing an app that shows a pixelated picture in a window. I am trying to capture the image, which is composed of a number of tiles processed from a mother image, but I am having difficulty since I can't reference the image on the screen. I have placed a rectangle around the image and my understanding is that I have get the window handle for the rectangle in order to save the Image as a jpg file. In the literature there is something about a Device Context and a window handle but my compiler throws out HWND and I don't really understand the device context. I am using Windows Forms, not native code.
I've been attempting to design a multiform WFA in Visual Studio 2010, but I'm so rusty with the language it's hard to remember how to do a lot of things, especially when it comes to visual programming, which my class only partially covered. I've never made a multiform application before, and my problem essentially boils down to how to pass data between forms.
My application is a simple item list and order form, sort of mimicking what you might see on a site like Amazon or eBay. My first form contains a drop down list and 'checkout' button. The dropdown list has been populated with an object collection, each object holding the product's name and price.
public partial class Form1 : Form { //Item class for dropdown menu public class Item { public string Name; public decimal Price; public string itemName
[Code] ....
When the 'checkout' button on form 1 is clicked, I want the Price and Name properties of the selected droplist item to appear in a pair of text boxes on form 2 for the purpose of lowering the user's cognitive load (if they can see what they've selected, it's one less thing to remember).
I've seen plenty of tutorials on how to send a textbox Text property between forms, but none for how to do this. As I said, I'm rusty with the language, and I'm pretty sure there's a better way to set up my combobox items, but I can't remember how to set it up.
So form two needs to pass information that was typed in its text box to form 3. So then form 3 can use this information. I think I am creating a new instance of form 2 because I get the exception can not divide by 0 so it is empty even if I typed in a integer in the text boxes. How to pass information from the textbox to a var that can be used in another form.
public partial class MapProperties : Form { private int _numRows; public int NumRows { get { return _numRows; }
I am writing a program in Visual C++ 10 with 2 forms.
In the first form I have a textbox and a button. The button opens the second form.
In the second form, I have a button that changes the text in the textbox in form1 to an item from a listbox in form2.
Here is my problem. When I do the code for the button in form2 to change the textbox in form1 I get the errors:
error C2065: 'textBox1' : undeclared identifier error C2227: left of '->Text' must point to class/struct/union/generic type
I thought maybe I should just include the "Form1.h" file but I can't do that because I already included "Form2.h" in form1 in order to be able to open the second form. If I try to include form1 in form2, it says that the code to open form2 is an error now.
My question is, how can I access identifiers such as "textbox1" from other forms and other files when I already used the first form to open the second form? I also want to know how to do this for all identifiers between all files.
how to print the selecteditem from a listbox into a textbox because that doesn't work by just setting them equal either.
Here is my code:
#pragma once #include "Form2.h" namespace Test1 { using namespace System;
Well I know how to pass values between forms using get and set properties. But the problem with it is everytime I want to pass values from form2 to form1 it doesn't appear. To make it appear I have to type form1.Show(); which open form1 a second time and then show the value. Is there any way I could make it appear without using form1.Show();?
I am currently writing a program which needs an edit form. This form is to edit a country in the datagridview which I have. I am however confused about how to pass the data from the data gridview in the main form to the relative places on the edit form. I have done most of the coding as shown below. I know I need a method in my AVL class to return all the information of the selected country back to the main form method which then passes it back to the edit form and displays it. I am unsure what to pass and what to write in this method.
Main form method
public void button2_Click(object sender, EventArgs e) { // creates new form referencing data grid view and AVL Tree EditCountryForm editform = new EditCountryForm(ref this.countryTree, dataGridView1); string CountryName = ""; //set name of country selected to string
What I'm doing is giving the user the choice to show 2 different dates. 1 in yyyy-mm-dd notation and the other in dd-mm-yyyy notation.
I'm using a second form to do this.
So from Form1 I have my data in the datagrid and in Form2 I have 2 radio buttons giving the user the choice between Date1 and Date2. So how would I be able to interact with the first form with the radio buttons?
I've changed up my code to the retail checkout WFA I am trying to make. I have an item list filled with objects of the now globally accessible 'Item' class, but I'm having trouble.
Essentially, I want to send an object of the item class chosen from a dropdown menu to form2, where I will fill in certain blank attributes with data entered in form2's text boxes and comboboxes. The problem, it seems, is I need another itemlist in form2 that will hold the object being passed to form 2, so I can then pass all the information to textboxes on form3 (the receipt/review page). It's been more than a year since I coded with C#, and I've forgotten quite a bit. I was also not able to find any tutorials on building an item list without an associated combobox or droplist, which is what I need.
This is my item class (minus most of its properties so the page doesn't stretch).
class Item { public string prodName; public string fName; public string lName; public string ccNum; public string ccProv; public string shipAddr;
[code] ....
For anyone who didn't see my last question, I'm in a User Interface Design class, not a C# class. I know this probably isn't the best code out there, but for my purposes the program just needs to compile beginning to end and pass the data like it should.
So the thing is I have 2 forms, form 1 is displayed first, and form2 would be open when click the next button on form1.
So i was success in moving to the next form, and even getting back to the previous, and then next again, but on the second time I try to go back from form2 to form 1, this error show up.
The error:
Form that is already displayed modally cannot be displayed as a modal dialog box. Close the form before calling showDialog.
I made 2 forms and Form2 has buttons with images like planets and game wallpapers etc. When I write the code for button:
this.BackgroundImage = new Bitmap(Properties.Resources._8_8008_by_amplifier404); this.BackgroundImageLayout = ImageLayout.Stretch;
// where _8_8008_by_amplifier404 is name of the image located in resources
It only changes background in form which has those buttons as long the form is used. Once I go back to form1 it's changed to null. How to set background in all forms with a button click which will be there until another button with an image is clicked.
