LabVIEW
Windows Keyboard Entry
The DLL was created in a C version for which you have not the correct C runtime version installed. That's just one of many problems with providing compiled DLLs for random users to download! In this particular case it has to do with the CVI Runtime needed since the DLL was compiled in LabWindows/CVI. But using Microsoft Visual C is unfortunately no guarantee to avoid this kind of trouble.
@Sable wrote:
It works perfectly - exactly what I was looking for!
If I'd like to add more keystrokes (or) change the keystroke in the future, what should I do?
That's exactly why I hesitate more and more to provide such ready made solutions here in the forum. As Andrey already answered you, you would have to modify the C code accordingly and compile a new DLL from it. Yes it could be made more universal by adding a list of keypress combinations to the register hook function that the hook function then uses to filter key presses. That would likely also require a more complex value return through the user event. And before you have thought twice, you spend many times the initial amount of time to create the quick and dirty proof of concept, want that's basically what you have so far gotten from Andrey.
@Sable wrote:
The solution worked after the CVI-based runtime installation.
I understand that adding more keys to the C code could be challenging and complex, but I don’t see this solution as a simple drop-in fix. It’s more of a guide that allows people like me to reverse-engineer and learn from how you approach these tasks, ultimately enhancing my own skills.
I still recommend to get this compiled. Just obtain CVI from NI, it is relative simple IDE (in comparizon with Visual Studio), but if you will be able to create DLL and call it from LabVIEW (and understand how it works), then it will open much mo possibilities for you and enhance your skills.
Anyway, quick change which I can made for you is the following:
Now array of modifiers and hot keys provided externally.
Technically LabVIEW's array of clusters passed to DLL like this:
#include "cintools/lv_prolog.h"
/* Typedefs */
typedef struct {
uint16_t Modifier;
uint16_t Key;
} TD2;
typedef struct {
int32_t dimSize;
TD2 HotKey[1];
} TD1;
typedef TD1 **HotKeysHdl;
#include "cintools/lv_epilog.h"
Prolog/Epilog guard is needed for proper alignment in case if used in 32-bit environment.
DLL function is modified:
//==============================================================================
// Exported function
//
int RegisterHook(LVUserEventRef *LVevent, HotKeysHdl hot_keys)
{
Keys_Amount = ((*hot_keys)->dimSize > MAX_HOT_KEYS) ? MAX_HOT_KEYS : (*hot_keys)->dimSize;
for (int i = 0; i < Keys_Amount; i++){
Modifiers[i] = (*hot_keys)->HotKey[i].Modifier;
Keys[i] = (*hot_keys)->HotKey[i].Key;
}
lvEvent = LVevent;
return 0;
}
And how Hot key checked in callback:
__declspec(dllexport) LRESULT CALLBACK KeyboardEvent (int nCode, WPARAM wParam, LPARAM lParam)
{
int hotkey = -1;
if ((nCode == HC_ACTION) && ((wParam == WM_SYSKEYDOWN) || (wParam == WM_KEYDOWN))) {
KBDLLHOOKSTRUCT hooked_key = *((KBDLLHOOKSTRUCT*)lParam);
int key = hooked_key.vkCode;
for (int i = 0; i < Keys_Amount; i++){
if (key == Keys[i]){
DWORD Mod_Key = GetAsyncKeyState(Modifiers[i]);
if (Mod_Key){ hotkey = i; break; }
}
}
if (hotkey >= 0 && lvEvent) PostLVUserEvent(*lvEvent, (void *)&hotkey); //Fire LV Event
}
return CallNextHookEx(hKeyboardHook, nCode,wParam,lParam);
}
(also please read suggestion from Rolf above, there is more elegant way to get this).
Please try from attachment.
I successfully opened the CVI project file in CVI 2013 and recompiled the DLL.
The process was straightforward. I simply deleted all the unnecessary files, leaving only the essential ones:
Next, I copied the cintools folder from my LabVIEW installation, opened the CVI project file in CVI 2013, updated the path to the labview.dll file to point to the cintools folder, and compiled the project.
The DLL hook example code continues to function as expected.
Could you please clarify the section highlighted in blue?
For debugging and tracing purposes, I am using OutputDebugStringA(), and the output can be captured using DebugView from Sysinternals.
