In C++, type conversion can access member variable. However, in C#, type conversion can not. Every time we cast a type A object to Type B, a new object of Type B will be created.
The following is how type conversion operator is implemented in c++.
I have worked with the issue for several days. Basically as long as I set the state image list for a list view, I will end up with a big GDI Object leakage and eventually the listview will not be able to work properly.
Following article describes the issue more clearly.
Make sure the web browser control is visible and in a windows form.
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You can use COM object Microsoft Web Browser (customize your toolbox) After that put the web browser control to form.
In your code it looks like: private AxSHDocVw.AxWebBrowser axWebBrowser1;
You can get HTML content and show it so: object flags=null; object postData=null; object header=null; object targetFrame=null; axWebBrowser1.Navigate("www.namip.ru", ref flags, ref targetFrame, ref postData, ref header);
When the fetching will be finished you can do so: object pv = null; object pva = null; axWebBrowser1.ExecWB(SHDocVw.OLECMDID.OLECMDID_PRINTPREVIEW,SHDocVw.OLECMDEXECOPT.OLECMDEXECOPT_DODEFAULT,ref pv, ref pva);
===========================
We can also use the IE browser to directly perform the task.
================================
SHDocVw.InternetExplorer browser = new SHDocVw.InternetExplorerClass();
{214115} normal block at 0x06C6B208, 20 bytes long.
Data: < > B0 AA C6 06 00 AD C6 06 B0 A9 C6 06 00 AE C6 06
You can put following code at the start of the application. Make sure it is called before the allocation happened.
int allocateNo = 214137;
_CrtSetBreakAlloc(allocateNo);
_crtBreakAlloc = allocateNo;
allocateNo = 214136;
_CrtSetBreakAlloc(allocateNo);
_crtBreakAlloc = allocateNo;
allocateNo = 214116;
_CrtSetBreakAlloc(allocateNo);
_crtBreakAlloc = allocateNo;
allocateNo = 214115;
_CrtSetBreakAlloc(allocateNo);
_crtBreakAlloc = allocateNo;
Now when you start application in debug mode, VS will break when the memory that is not properly freed is allocated and you will be able to trace down the object that need to be properly handled.
Some people suggest to use a indes in the control navigating event because everytime a new document downloading will trigger the navigating event. However,
The indicator never reaches 0 if you add one to the index in navigating event and minus 1 in the document completed event.
I have also tried the browser ready state and check whether the browser has a ready state equal to Complete.
I am working on a problem that UI response is very slow because the application has to initialize a collection of very complex grid view and the process will take as long as 8 seconds. I am trying to create another thread to initialize the grid views in a parallel thread. Then I came across the problem of cross thread operation not valid error because .Net does not allow the form controls to be updated in a thread other than the thread to create it.
The following is a solution that I can found from web.
However, I noticed that even I can remove the exception, I can not solve the problem of performance because the time consuming operation is still executed in the main thread with invoke.
The following is the code.
using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Timers;
namespace UIThread {
class SampleThread { public delegate void TestEventHandler(string sParameter); public event TestEventHandler TestEvent;
protected System.Timers.Timer TestTimer = new System.Timers.Timer(); protected ISynchronizeInvoke SyncObject;
public SampleThread(ISynchronizeInvoke SyncObject) { this.SyncObject = SyncObject; TestTimer.Elapsed += new ElapsedEventHandler(Tick); TestTimer.Interval = 300; }
protected delegate void TickDelegate(object source, ElapsedEventArgs e); private void Tick(object source, ElapsedEventArgs e) { if (SyncObject.InvokeRequired) { SyncObject.BeginInvoke(new TickDelegate(Tick), new object[] { source, e });
//the following funciton are executed in the parellel thread string sParameter = ""; for (int i = 0; i < 2000000; i++) { sParameter = sParameter + (i * i * i).ToString(); } } else { TestEvent(DateTime.Now.ToString()); } }
public void Go() { TestTimer.Enabled = true; } }
public partial class Form1 : Form { SampleThread sampleThread;
public Form1() { InitializeComponent(); sampleThread = new SampleThread(this); sampleThread.TestEvent += new SampleThread.TestEventHandler(FunctionInMainThread); }
void FunctionInMainThread(string sParameter) { //basically this funciton is called from other thread by executed in main thread. this.Text = sParameter;
//If following lines are turned on, the UI will become very slow in response. //for (int i = 0; i < 2000000; i++) //{ // sParameter = sParameter + (i * i * i).ToString(); //} }
Create a new C++ dynamic library project by default and name it as MCDLL. The default class will be as following.
First file:
// MCDll.h
#pragmaonce
usingnamespace System;
namespace MCDll {
publicrefclass Class1
{
// TODO: Add your methods for this class here.
};
}
Second file:
// This is the main DLL file.
#include"stdafx.h"
#include"MCDll.h"
Step 2:
Now we can add a class in the empty dll as following
// MCDll.h
#pragmaonce
usingnamespace System;
namespace MCDll {
publicrefclass Class1
{
// TODO: Add your methods for this class here.
public:
array<double>^ m_adTestArray;// array that can be passed to C#
//function to return double array
array<double>^ GetTestArray(int iLength);
};
}
Second file:
// This is the main DLL file.
#include"stdafx.h"
#include"MCDll.h"
array<double>^
MCDll::
Class1::
GetTestArray(int iLength)
{
m_adTestArray = gcnewarray<double>(iLength);
for(int i=0;i<iLength;i++)
{
m_adTestArray[i] = i*i*i;
}
return m_adTestArray;
}
Compile the MCDLL project and you will see how it works.
Step 3:
Now we can create a simple window Form application with C#, and the project MCDll as a project reference to our C# form application in order to access the function defined in C++.
The following is a simple code to demo the use of the c++ class.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace CSApp
{
publicpartialclassForm1 : Form
{
public Form1()
{
InitializeComponent();
}
privatevoid button1_Click( object sender, EventArgs e )
{
MCDll.Class1 class1 = new MCDll.Class1();
double[] adFromC = null;
adFromC = class1.GetTestArray( 5 );
for ( int i = 0; i < adFromC.Length; i++ )
{
Console.WriteLine( adFromC[ i ].ToString() );
}
}
}
}
Compile above application and execute it, we will see that the double array is initialized in C++ dll but is accessible from C# application.
A few more cases are demoed here to show how to pass parameters by reference, how to return a dimensional array back and how to return a string array. Full code can be found at following
// MCDll.h
#pragmaonce
usingnamespace System;
namespace MCDll {
publicrefclass Class1
{
// TODO: Add your methods for this class here.
private:
array<double>^ m_adTestArray;// array that can be passed to C#
array<double,3>^ m_adDimensionalArray;
public:
//function to return double array
array<double>^ GetTestArray(int iLength);
//funciton to return a string array
array<System::String^>^ GetTestStringArray( int iLength );
The following sample provides a class to extract geo information from any IP address using a completely free web service provided by www.IPInfoDB.com.
This is the code for a simple windows form application in C#. The class IPInfor will construct itself from an IP address and return available attributes as properties.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Net;
using System.Xml;
namespace test
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
/// <summary>
/// A class respresent the data structure from IPInfoDB REST web service
/// </summary>
public class IPInfor
{
private string m_sIP;
private string m_sCountryCode;
private string m_sCountryName;
private string m_sRegionCode;
private string m_sRegionName;
private string m_sCityName;
private string m_sZipPostCode;
private double m_dLatitude;
private double m_dLongigitude;
private double m_dGmtoffset;
private double m_dDstoffset;
public string IP
{
get
{
return m_sIP;
}
}
public string CountryCode
{
get
{
return m_sCountryCode;
}
}
public string CountryName
{
get
{
return m_sCountryName;
}
}
public string RegionCode
{
get
{
return m_sRegionCode;
}
}
public string RegionName
{
get
{
return m_sRegionName;
}
}
public string CityName
{
get
{
return m_sCityName;
}
}
public string ZipPostCode
{
get
{
return m_sZipPostCode;
}
}
public double Latitude
{
get
{
return m_dLatitude;
}
}
public double Longigitude
{
get
{
return m_dLongigitude;
}
}
public double Gmtoffset
{
get
{
return m_dGmtoffset;
}
}
public double Dstoffset
{
get
{
return m_dDstoffset;
}
}
///
/// return the orignal REST response returned by "http://ipinfodb.com/ip_query.php?ip=" + sIP;
///
///
/// the original response string from web service based on the
