WM_DEVICECHANGE sets wParam to DBT_DEVNODES_CHANGED to update list (tree?) nodes.
No other info is available then. I have not retrieved any device list, so it is useless for me.
To receive DBT_DEVICEARRIVAL it is necessary to first use RegisterDeviceNotification.
At this point no other help is required.
I need some help / hints with implementing WM_DEVICECHANGE in MFC Document /View setup.
I have managed to intercept the WM_DEVICECHANGE in CmainFrame message map and process it .
The problem m is that the wParam is nowhere near the 0x8xxx, but it is plain “7” and the lParam is 0.
I went thru the Dbt.h and cannot figure out what is the wParam = 7 telling me.
Here is the code snippet and if it is not formatted to you liking – I am sorry , but I write my stuff in OpenOffice and than copy it to CodeProject so it cannot be formatted properly.
<b>I just need some troubleshooting pointer / suggestion how to analyze these mysterious parameters. </b>
Maybe CmainFRame is not the place to start, but I got same parameters values when I used Cdialog message map directly.
JUst found this info, so the additional question is - is CMainFrame "top window" and if not will RegisterDeviceNotification solve this ? I shall try it next.
The DBT_DEVICEARRIVAL and DBT_DEVICEREMOVECOMPLETE events are automatically broadcast to all top-level windows for port devices. Therefore, it is not necessary to call RegisterDeviceNotification for ports, and the function fails if the dbch_devicetype member is DBT_DEVTYP_PORT.
Your code and text can be formatted properly. It must be done manually after pasting (it does not care if pasting from OpenOffice or a plain text editor but you should remove HTML tags when pasting from Ooo). Select text with mouse and use the buttons above the edit window to apply specific formatting. If you know HTML, you may also type the HTML tags. Check the preview to see how it looks.
Thank you, obviously I have not look all the way to the end of the page!
However, what the dickens is " ring3 people" note talking about?
So when "new node is detected / chaged" is not same as
DBT_DEVICEARRIVAL A device has been inserted and is now available.
Mr MS - I am not sure this note is in English!
and to get the device more work is necessary???
I am not sure I can figure that out, getting tired of this USB mess.
* Message = WM_DEVICECHANGE
* wParam = DBT_DEVNODES_CHANGED
* lParam = 0
* send when configmg finished a process tree batch. Some devnodes
* may have been added or removed. This is used by ring3 people which
* need to be refreshed whenever any devnode changed occur (like
* device manager). People specific to certain devices should use
* DBT_DEVICE* instead.
#define DBT_DEVNODES_CHANGED 0x0007
i have a appilcation consists of thousands lines of code. when i do some specific operation, i.e. open a very large document, the app almost eats up my memory. but after a while, the memory is given back. i have tested the codes and found no memory leak.
so, my problem is how to find the codes who eat up my memory.
any one can help me?
First, when you do a malloc or new, you extend the heap. For optimization reasons, the memory manager may not return the heap back to the OS immediately. When needing to allocate especially large chunks of memory, you can use a low level API directly or, with some compilers/CRTs, a different heap (for Windows, here's an article discussion various options: http://msdn.microsoft.com/en-us/library/windows/desktop/aa366533%28v=vs.85%29.aspx[^].)
Also note that if you allocate memory and sit around, the OS may page it out. To understand the difference in Windows, look into "private bytes" and "working set".
I want to ask you something: what would you use for image processing and more important, convert images from an format to other ? I am using MFC, and I was thinking of GDI+, but I didn't find so many examples to how to convert images ...
I see here so interesting controls, CBitmapEx, CxImage, CImageStone, but I don't know what is proper to do the job ... I will appreciate any hint.
No, I didn't look over by now ... Thank you for your interest, so you suggest to use GDI+ ... I didn't try to load some not common image file, .raw, .tiff multipage, etc. ... I don't know if does function ...
No, I just asked if you had looked at that function and if it solved your problem. Your question is not particularly clear, i.e. what do you want to convert from, and what do you want to convert to? I am sure that Google could find you lots of information if you were more specific about your requirements.
One of these days I'm going to think of a really clever signature.
The Win32 API offers very limited image conversion. There are many third party libraries, some free, others not. I'm currently looking at CxImage to replace Leadtools, which is now even more expensive than before and isn't royalty free. If you are willing to pay more, one royalty free library I've used is http://www.gdpicture.com/[^]. The ActiveX part always annoyed me, but it had a good PDF viewer component, so I lived with it. I'm also going to evaluate http://www.data-tech.com/products/imaging/imageman-dll.aspx[^]. (I work for none of these companies.)
Last Visit: 31-Dec-99 19:00 Last Update: 28-Feb-24 15:05