LoadImage failure?

Llasus

Hello and good day. I currently have a problem with LoadImage (i think) in my application. The application reads a file, changes it into bitmap format, uses LoadImage to display a file, then uses StretchBlt to resize/rotate it. The user selects the file to load and display. Now the problem is, I tried to do a stress test for it and the LoadImage fails after around 100 tries of loading a 2000x2000 bmp file. I checked the HBITMAP handler which receives the data from the LoadImage and it contains NULL at that time. I still am not sure if the LoadImage is really the problem, I think it may be all the memory allocations I made but I checked them again and again and they were certainly released when a new image is loaded. Can somebody please advise me and help me about this problem? Thank you!

Hamid Taebi

Can you show your code?

Llasus

The code is actually too large to paste in here. I can only paste the function which displays has the LoadImage part. void CDlg::DisplayImage() { //then use LoadImage and attach it to a BITMAP handle gOtherClass.gDisplayPanelHandle = (HBITMAP)::LoadImage ( 0, gMapPath, IMAGE_BITMAP, gSourceSize.cx, gSourceSize.cy, LR_DEFAULTCOLOR | LR_LOADFROMFILE ); //check if GlobalMap.bmp was loaded if(gOtherClass.gDisplayPanelHandle == NULL) { AfxMessageBox("Error!\nUnable to load Map File"); return; } //Attach the bitmap handle to the CDC for display gCDC.SelectObject(gOtherClass.gDisplayPanelHandle); //reverse image and stretch it to display correctly gCDC.StretchBlt ( 0, 0, gSourceSize.cx, gSourceSize.cy, &gCDC, 0, gSourceSize.cy - 1, //added - 1 to display image properly gSourceSize.cx, -gSourceSize.cy, SRCCOPY ); Invalidate(FALSE); }

Hamid Taebi

What is gOtherClass.gDisplayPanelHandle?

Llasus

its a class which contains all the shared variables between other characters. I have noticed also that after around 100 times of loading a bitmap, the application's performance is starting to decline.

Naveen

Llasus wrote:

gOtherClass.gDisplayPanelHandle

Do you destroy the handle after every display?

nave [OpenedFileFinder]

jhwurmbach

When calling SelectObject, you need to store the Pointer to the old GdiObject you get from the call and re-SelectObject it after finishing work. You are producing a so called GDI-Resource-Leak. In the ProcessExplorer, you cann swith on display of used GDI-Objects.

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Llasus

yes. I made sure that it destroys the object before loading the next image.

Llasus

Thank you for the help. I will try this tomorrow. I have not encountered this GDI-Resource-Leak though. Sorry but could you please explain further what you mean by re-SelectObject after finishing the work and why I need it? Usually when loading the next image I just use the DeleteObject() to somehow release the object for next use.

jhwurmbach

Llasus wrote:

could you please explain further what you mean by re-SelectObject after finishing the work and why I need it?

What I mean is this:

CBitmap m_bmpSnapshot = ...
CBitmap* pOldBmp = dcSnapshot.SelectObject(&m_bmpSnapshot);
dcSnapshot.BitBlt(0, 0, width, height, &dc, 0, 0, SRCCOPY);
dcSnapshot.SelectObject(pOldBmp);

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Llasus

I see. thank you very much for the help! I will try to test this tomorrow. Again, thank you very much for the time and help!

Llasus

It worked! Thank you so much for your help. I was never aware of the possibility that GDI may leak if you don't save and re-select the pointer that SelectObject returned. I did past applications though without doing that. Though not as much on loading in images like this one. Again, thank you to all that helped specially jhwurmbach. :)