Managed C++/CLI Discussion Boards

Re: Saving Bitmap image data to HGLOBAL

Mark Salsbery21-Jan-10 6:19

Mark Salsbery

21-Jan-10 6:19

alleyes wrote:
Didn't make sense to call another GlobalLock on it again.

There's nothing wrong with locking again as long as you have
an equal number of unlock calls.

GlobalRealloc on a locked handle can only reallocate
memory in the same place so has more chance of failing,
since there may not be enough room in that place.

For best results the handle should be unlocked before
reallocating then locked again when you need the pointer.

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Saving Bitmap image data to HGLOBAL

alleyes21-Jan-10 9:20

alleyes

21-Jan-10 9:20

Sincere thanks Mark Big Grin | :-D

When I have the time, I think I'll do all this in managed code by Marshalling the native HGLOBAL. But for now it works well.

Re: Saving Bitmap image data to HGLOBAL

alleyes20-Jan-10 7:34

alleyes

20-Jan-10 7:34

I know that I can create from scratch the BITMAPINFOHEADER. Is it a matter of copying the information to the top of the Bitmap array?

Re: Saving Bitmap image data to HGLOBAL

Mark Salsbery20-Jan-10 7:40

Mark Salsbery

20-Jan-10 7:40

alleyes wrote:
Is it a matter of copying the information to the top of the Bitmap array?

If that's where you want it, yes.

You could also start with a pointer to where you want it
so you don't have to copy afterwards...

BITMAPINFOHEADER *pbmiHeader = (BITMAPINFOHEADER *)GlobalLock(myhglobal);
pbmiHeader->biSize = sizeof(BITMAPINFOHEADER);
etc...

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Saving Bitmap image data to HGLOBAL

alleyes20-Jan-10 7:51

alleyes

20-Jan-10 7:51

Mark Salsbery wrote:
If that's where you want it, yes.

Well actually the file header will be at top but I get it.

Mark Salsbery wrote:
BITMAPINFOHEADER *pbmiHeader = (BITMAPINFOHEADER *)GlobalLock(myhglobal);
pbmiHeader->biSize = sizeof(BITMAPINFOHEADER);

That's helpful...

Fade TabPage between TabControl's tab selection

roshihans15-Jan-10 19:02

roshihans

15-Jan-10 19:02

After searching on the internet, the possible solution that come out is by using TabPage.DrawToBitmap, put the bitmap in a PictureBox, set the position of PictureBox to the same location of TabPage, and fade it. The code is below :

System::Void tabControl1_SelectedIndexChanged(System::Object^  sender, System::EventArgs^  e)
{
	alphaBlend = 250;
	repaint = true;
	
	// set TabPicture visibility, location, and size
	TabPictureBox->Visible = true;
	int posX = tabControl1->Location.X + tabControl1->TabPages[tabControl1->SelectedIndex]->Margin.Left + 1;
	int posY = tabControl1->Location.Y + tabControl1->ItemSize.Height + 1 + 
		tabControl1->TabPages[tabControl1->SelectedIndex]->Margin.Top;
	TabPictureBox->Location = System::Drawing::Point(posX, posY);
	TabPictureBox->Size = tabControl1->TabPages[tabControl1->SelectedIndex]->Size;
	
	// set Bitmap
	TabBitmap = gcnew Bitmap(tabControl1->TabPages[tabControl1->SelectedIndex]->Width, 
		tabControl1->TabPages[tabControl1->SelectedIndex]->Height);			
	tabControl1->TabPages[tabControl1->SelectedIndex]->DrawToBitmap(TabBitmap,
			Rectangle(0, 0, tabControl1->TabPages[tabControl1->SelectedIndex]->Width, 
				tabControl1->TabPages[tabControl1->SelectedIndex]->Height));
	
	while (alphaBlend > 0)
	{				
		alphaBlend = alphaBlend - 25;
		TabPictureBox->Refresh();
	}

	TabPictureBox->Visible = false;
	repaint = false;
}

System::Void TabPictureBox_Paint(System::Object^  sender, System::Windows::Forms::PaintEventArgs^  e)
{
	if (repaint)
	{
		if (TabBitmap != nullptr)
		{
			Bitmap^ temp = gcnew Bitmap(TabBitmap);
			Graphics^ bitmapGraphics = Graphics::FromImage(temp);
			if (alphaBlend < 0) alphaBlend = 0;
			SolidBrush^ greyBrush = gcnew SolidBrush(Color::FromArgb(alphaBlend, Color::White));
			bitmapGraphics->CompositingMode = CompositingMode::SourceOver;
			bitmapGraphics->FillRectangle(greyBrush, Rectangle(0, 0, TabBitmap->Width, TabBitmap->Height));
			e->Graphics->CompositingQuality = CompositingQuality::GammaCorrected;
			e->Graphics->DrawImage(temp, 0, 0);
		}
	}
}

The problem is that each time I select the tabPage, my CPU usage spike to 70 - 80% and the fading effect is kind of slow. Is there any solution to fix it so that I can draw the bitmap faster and with minimum CPU usage (less than 50%)?

Thanks.

I need an ebay program

totolcm13-Jan-10 2:22

totolcm

13-Jan-10 2:22

I need a program in PHP which can extract the hidden biders from ebay.I will have to insert the item number and the program must show me all bidders of the auction and their emails.
Also the same program must extract the registered contact information for any specified bidder specially the email address

I will pay for this
If someone can help please contact me at totos_back@yahoo.com

Thanks

Creating image file from pointer to HGLOBAL

alleyes10-Jan-10 12:28

alleyes

10-Jan-10 12:28

In an app that is used to capture images, the information used to store the image data is referenced by a pointer to HGLOBAL. That is then used to re-create the image so it can be written to disk with a call to GlobalFree.

I have two problems:

I need to attach a file header so I can write the image to a file.
The image data is of native type DWORD so I cant use the .NET classes without massaging the image data.

What I have done thus far:

BITMAPINFOHEADER* imgHeader = (BITMAPINFOHEADER*)GlobalLock(gPtrImage);

array<BYTE>^ imgArray = gcnew array<BYTE>(imgHeader->biSizeImage);

if (!imgHeader)
{
GlobalFree(gPtrImage);
return;
}

BITMAPFILEHEADER* bfh = new BITMAPFILEHEADER();
bfh->bfType = 0x4d42; //BM
bfh->bfSize = (DWORD) (sizeof(BITMAPFILEHEADER) + imgHeader->biSize + imgHeader->biSizeImage);
bfh->bfReserved1 = 0;
bfh->bfReserved2 = 0;
bfh->bfOffBits = (DWORD) (bfh->bfSize - imgHeader->biSizeImage);

LPDWORD Pixels = (LPDWORD)((LPBYTE)imgHeader + sizeof(BITMAPINFOHEADER));

Marshal::Copy(static_cast<IntPtr>(bfh), imgArray, 0, sizeof(BITMAPFILEHEADER));
Marshal::Copy(static_cast<IntPtr>(Pixels), imgArray, (sizeof(BITMAPFILEHEADER) + 1), imgHeader->biSizeImage);

GlobalUnlock(gPtrImage);

System::Environment::SpecialFolder saveFolder = System::Environment::SpecialFolder::MyDocuments;
SaveFileDialog^ sfd = gcnew SaveFileDialog();
sfd->InitialDirectory = System::Environment::GetFolderPath(saveFolder);
sfd->Filter = "Device Independent Bitmaps |*.bmp|All files|*.*";

if (sfd->ShowDialog() == System::Windows::Forms::DialogResult::OK)
{
System::IO::Stream^ imgFileStream = sfd->OpenFile();

if (imgFileStream != nullptr)
{
imgFileStream->Write(imgArray, 0, imgArray->Length);
imgFileStream->Close();
}
}

GlobalFree(gPtrImage);
gPtrImage = NULL;

The file size is a lot larger than I would expect for a 640*480 32 bit BMP and it can't be displayed.

The image is fine when written to a picturebox, the data is then unlocked but NOT freed. As a test, I save the image of the picturebox i.e PictureBox->Image and that is fine. The data needs to to be handed off to another application that requires native code so I need to re-create the image from the pointer to HGLOBAL and that's where it falls down

What might be wrong with this?

Thanks for any help

Re: Creating image file from pointer to HGLOBAL

Mark Salsbery12-Jan-10 9:59

Mark Salsbery

12-Jan-10 9:59

BITMAPINFOHEADER.biSizeImage is allowed to be 0...
I would personally feel better about checking for that unless
you know for sure it's never going to be 0...maybe something like

if (imgHeader->biSizeImage == 0)
    imgHeader->biSizeImage = (((imgHeader->biWidth * (long)imgHeader->biBitCount + 31L) & (~31L)) / 8L) * abs(imgHeader->biHeight);

Al_S wrote:
array<BYTE>^ imgArray = gcnew array<BYTE>(imgHeader->biSizeImage);

Your array isn't big enough. What about the size of the
BITMAPFILEHEADER and the BITMAPINFOHEADER?

Al_S wrote:
Marshal::Copy(static_cast<intptr>(Pixels), imgArray, (sizeof(BITMAPFILEHEADER) + 1), imgHeader->biSizeImage);

Array indexes are 0-based... That should be

Marshal::Copy(static_cast<intptr>(Pixels), imgArray, sizeof(BITMAPFILEHEADER), imgHeader->biSizeImage);

Also I'm not sure about those static_casts... why not just use IntPtr(bfh)/IntPtr(Pixels)

Al_S wrote:
The file size is a lot larger than I would expect for a 640*480 32 bit BMP

Should be a little over 1MB - just how big is it? You're the one
calculating the size - what do you see in the debugger?

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: Creating image file from pointer to HGLOBAL

alleyes12-Jan-10 10:25

alleyes

12-Jan-10 10:25

Hi Mark.

Since the original image is from a global pointer to HGLOBAL, which was previously created and displayed, I am aware of all the fields of the BITMAPINFOHEADER. They are all set from grabbing an image in other code. I am trying to re-create the image after handing off the pointer to HGLOBAL elsewhere

With that:

biSizeImage = 0x12c000 (about 1.2M)
biBitCount = 0x20
...
...

I saw that the array size was goofy so I fixed that - I think.

array<byte>^ imgArray = gcnew array<byte>(imgHeader->biSizeImage + sizeof(BITMAPFILEHEADER));

I also fixed copying to the array:

Marshal::Copy(static_cast<IntPtr>(bfh), imgArray, 0, sizeof(BITMAPFILEHEADER));
Marshal::Copy(static_cast<IntPtr>(Pixels), imgArray, sizeof(BITMAPFILEHEADER), imgHeader->biSizeImage);

All this washes out to a correct file size.

When viewed in a hex editor, the BITMAPFILEHEADER appears where it belongs correctly. The rest of the data is different though. The resultant image can not be viewed Dead | X|

As far as the use of the static_cast, I don't have any problems with that and I think I've used it properly.

Thanks for responding.

Re: Creating image file from pointer to HGLOBAL [modified]

Mark Salsbery12-Jan-10 10:34

Mark Salsbery

12-Jan-10 10:34

alleyes wrote:
I saw that the array size was goofy so I fixed that - I think.

array^ imgArray = gcnew array<BYTE>(imgHeader->biSizeImage + sizeof(BITMAPFILEHEADER));

Still not big enough Smile | :)

array<BYTE>^ imgArray = gcnew array<BYTE>(imgHeader->biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER));

alleyes wrote:
Marshal::Copy(static_cast<IntPtr>(Pixels), imgArray, sizeof(BITMAPFILEHEADER), imgHeader->biSizeImage);

You're not writing the BITMAPINFOHEADER to the output array...
I missed that one the first time, sorry Smile | :)

Marshal::Copy(static_cast<IntPtr>(imgHeader), imgArray, sizeof(BITMAPFILEHEADER), sizeof(BITMAPINFOHEADER) + imgHeader->biSizeImage);

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

modified on Tuesday, January 12, 2010 4:47 PM

Re: Creating image file from pointer to HGLOBAL

alleyes12-Jan-10 10:52

alleyes

12-Jan-10 10:52

array size change plus the proper copy nails it.

Thanks very much! Big Grin | :-D

Re: Creating image file from pointer to HGLOBAL

alleyes20-Jan-10 3:02

alleyes

20-Jan-10 3:02

Hi Mark,

Is there a way to do the reverse of this?

That is, one HGLOBAL to store different images, where it normally is one HGLOBAL relating to one image.

Thanks for the valuable help!

Re: Creating image file from pointer to HGLOBAL

Mouzam Basheer23-May-16 20:40

Mouzam Basheer

23-May-16 20:40

Hi Developers.

i am going to wrap lib(static library ) file in c++. one function return HGLOBAL DIB. how can i access Byte Array or Bitmap Image from this and pass this Byte Array or bitmap to My C# Project.
please help me.
thanks in advance.

Here is function that return HGLOBAL DIB Type.

<pre lang="c++">  HGLOBAL m_hDib;
	 	int retval = XRaySensorIsImageAvailable();

        if ( 0 < retval )
        {
            if (m_hDib ) ::GlobalFree(m_hDib);
            m_hDib = XRaySensorGetDIB();

		}

Getting screen width and height

m_mun7-Jan-10 4:12

m_mun

7-Jan-10 4:12

Hi How can i get the screen width and height in Managed C++/CLI? I have used

Screen^ screen = gcnew Screen::PrimaryScreen;

But its not working.

Thanks

Re: Getting screen width and height

Luc Pattyn7-Jan-10 4:19

Luc Pattyn

7-Jan-10 4:19

Within the Screen class, PrimaryScreen is a property, not a constructor. So you don't need gcnew

FYI1: "its not working" is not informative; if there is an error or exception, best is to show us the message.

FYI2: all this is explained in the documentation. Maybe it would be wise to study an introductory book when getting acquainted to a new technology or language.

Smile | :)

Luc Pattyn [Forum Guidelines] [Why QA sucks] [My Articles]

Happy New Year to all.
We hope 2010 soon brings us automatic PRE tags!
Until then, please insert them manually.

Re: Getting screen width and height

Andreoli Carlo17-Jan-10 22:41

Andreoli Carlo

17-Jan-10 22:41

Easy at it's:

int monitor_height=Screen::PrimaryScreen->Bounds.Height;
int monitor_width=Screen::PrimaryScreen->Bounds.Width;

System::String ^ to LPCWSTR conversion?

Mattzimmerer6-Jan-10 22:27

Mattzimmerer

6-Jan-10 22:27

I just recently posted a question very similar to this(System::String ^ to LPCVOID conversion?), it was answered but I still must be missing something.

In this case I need a LPCWSTR. What I've tried should be evident in the following:

......
char* pProcName = (char*)(void*)Marshal::StringToHGlobalAnsi(this->ProcName->Text);//WORKS GREAT
LPCWSTR pProcName2 = (LPCWSTR)(void*)Marshal::StringToHGlobalAnsi(this->ProcName->Text);//THIS LINE FILLS pProcName2 WITH GARBAGE....

LPCWSTR test2 = (LPCWSTR) pProcName;//test2 is now GARBAGE ARRG

HWND windowHandle = FindWindowW(NULL, (LPCWSTR) pProcName);//lets see  if it will find GARBAGE...
if (windowHandle)
	MessageBox::Show("SUCCESS");//Wishfull thinking.... BLAAH
........

I guess one option is to convert a char* to wchar_t*?
If somehow I could make the conversion correctly, uhg. I really just need someone who knows whats up to point it out to me lol...

Re: System::String ^ to LPCWSTR conversion?

Richard MacCutchan7-Jan-10 0:25

Richard MacCutchan

7-Jan-10 0:25

According to the MSDN Documentation[^] StringToHGlobalAnsi() returns a char*, i.e. a pointer to ASCII characters. In order to use this as wide characters you will need to do a string conversion, you cannot just cast it and expect it to work. Use mbtowc() or similar to convert from ASCII to wide characters.

Re: System::String ^ to LPCWSTR conversion?

Mattzimmerer7-Jan-10 9:14

Mattzimmerer

7-Jan-10 9:14

Yea, I didnt expect it to work. But when you have no other ideas... lol thanks man! Ill give it a go!

Re: System::String ^ to LPCWSTR conversion?

Richard MacCutchan7-Jan-10 9:54

Richard MacCutchan

7-Jan-10 9:54

Mattzimmerer wrote:
Yea, I didnt expect it to work.

That suggests you would be well advised to spend some time learning what casts are all about. Remember that all the answers are somewhere in MSDN. I know it's not the easiest site to navigate, but the new Bing search is pretty good; it's where I found your answer!

Re: System::String ^ to LPCWSTR conversion? [modified]

Mark Salsbery7-Jan-10 9:35

Mark Salsbery

7-Jan-10 9:35

Mattzimmerer wrote:
I guess one option is to convert a char* to wchar_t*?

Why use StringToHGlobalAnsi if you don't want an ANSI string?

Maybe try StringToHGlobalUni.

And don't forget to free the allocated memory when you're done with it!

Since you're wanting wide chars, you also can use PtrToStringChars
(from vcclr.h).

Mattzimmerer wrote:
need someone who knows whats up to point it out to me

The documentation knows what's up!

A bunch of interop examples[^] including How to: Access Characters in a System::String[^]
Calling Native Functions from Managed Code[^]

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

modified on Thursday, January 7, 2010 3:42 PM

Re: System::String ^ to LPCWSTR conversion?

Mattzimmerer7-Jan-10 9:59

Mattzimmerer

7-Jan-10 9:59

Okay, you guys were a ton of help, but there is still something I am missing. Why dont I just show you what I am trying to do:
I am trying to get a name from a windows forms textbox converted so that I can use it in FindWindowW() so that I can send a PID out to a driver

this code is pretty messy atm, I usually clean it up after I get the proper way to do something. (imo lol)

char* pProcName = (char*)(void*)Marshal::StringToHGlobalUni(this->ProcName->Text);

wchar_t ProcNameWSTR, *pProcNameWSTR = &ProcNameWSTR;

const wchar_t tester[11] = L"Calculator";

int lengthmbc = mbtowc(pProcNameWSTR,pProcName,sizeof pProcName);

unsigned long Returned;
input bInput; //pre defined struct showing the members
bInput.bytestoread;
bInput.processid;
bInput.startaddress;

HWND windowHandle = FindWindowW(NULL, pProcNameWSTR);
HWND windowHandle2 = FindWindowW(NULL, (LPCWSTR) &tester);
if (windowHandle)
      MessageBox::Show("pProcNameWSTR success");//FAIL
if (windowHandle2)
      MessageBox::Show("tester wchar_t success");//SUCCESS

DWORD* processID = new DWORD;
GetWindowThreadProcessId(windowHandle, processID);

DeviceIoControl(
      hFile,						// Device handle
      IOCTL_MZ_READMEMORY,       // Code
      (LPVOID) &bInput,			// Buffer TO driver
      sizeof bInput,				// Size of InBuffer
      NULL,						// Buffer FROM driver
      0,							// Size of OutBuffer
      &Returned,					// Bytes output
      (LPOVERLAPPED) NULL);		// Overlapped struc

the problem is that I cannot get the contents of ProcNameWSTR to match my tester[11] (the first if check fails and the second succeeds) any insight?

Re: System::String ^ to LPCWSTR conversion?

Mark Salsbery7-Jan-10 12:56

Mark Salsbery

7-Jan-10 12:56

Mattzimmerer wrote:
I cannot get the contents of ProcNameWSTR to match my tester[11]

ProcNameWSTR is a single wchar_t, so isn't very useful here.
Plus you don't even use it anywhere.

Marshal::StringToHGlobalUni returns a const pointer to a wchar_t
string, so casting it to a char* then converting it to a wchar_t
string isnt' going to work.

Try:

const wchar_t *pProcNameWSTR = (const wchar_t *)(void *)Marshal::StringToHGlobalUni(this->ProcName->Text);

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Re: System::String ^ to LPCWSTR conversion?

Mattzimmerer7-Jan-10 22:01

Mattzimmerer

7-Jan-10 22:01

worked great thank you. You know, I tried something like this, I just didnt make it a const, perhaps thats the reason it didnt work... Either that or I threw in some ANSII.. o well thanks man!

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