Load icon from .DLL in wxWidgets - c++

Question

I am attempting to load a wxIcon in Windows by loading from a system DLL (as the mime system told me that the icon for such a file type was in the DLL), eg.
wxIcon icon;
icon.LoadFile("C:\\WINDOWS\\system32\\zipfldr.dll", wxICON_DEFAULT_TYPE);
This fails but I was wondering if there was any way in the codebase of loading this, other than resorting to native Win32 functions.
Also, if there are native Win32 functions, does anyone know what they are?
EDIT: I have tried the following with no success:
::wxInitAllImageHandlers();
wxMimeTypesManager manager;
wxFileType* type = manager.GetFileTypeFromExtension("sys");
wxIconLocation location;
if (type->GetIcon(&location))
{
// location is something like C:\WINDOWS\system32\imageres.dll
wxIcon icon;
if (!icon.LoadFile(location.GetFileName(), wxBITMAP_TYPE_ICON /*I have tried wxICON_DEFAULT_TYPE too*/))
{
// Failed!
}
}
EDIT 2: In response to VZ, I have tried the following with no success sadly:
::wxInitAllImageHandlers();
wxMimeTypesManager manager;
wxFileType* type = manager.GetFileTypeFromExtension("sys");
wxIconLocation location;
if (type->GetIcon(&location))
{
// location is something like C:\WINDOWS\system32\imageres.dll,
//with an appropriate index as retrieved by location.GetIndex(), which is -67.
wxIcon icon(location);
if (!icon.IsOk())
{
BREAK;
// Failed!
}
}
EDIT 3:
Thanks for everyone's help - works fine if I use wxBITMAP_TYPE_ICO instead of wxBITMAP_TYPE_ICON (notice the N), and also I was putting my test code in my app's constructor instead of in ::OnInit. It worked in OnInit but not in the constructor so that's a lesson learned!
Thanks everyone for the help and speedy responses, much appreciated as always.

Answer 1

It should work if you specify type wxBITMAP_TYPE_ICO.

Answer 2

The first argument to LoadFile() must specify the icon resource ID when using wxBITMAP_TYPE_ICO (which is indeed what you need to use when loading icons from files, and not resources of the current module), i.e. you're also missing the ;N part at the end, where N is the value returned by wxFileTypeInfo::GetIconIndex().
But to avoid dealing with this explicitly, you should just use wxFileType::GetIcon() and construct wxIcon from the wxIconLocation filled in by it.
For example, this:
diff --git a/samples/minimal/minimal.cpp b/samples/minimal/minimal.cpp
index 0d91f7fc75..3623aacc56 100644
--- a/samples/minimal/minimal.cpp
+++ b/samples/minimal/minimal.cpp
## -123,6 +123,12 ## bool MyApp::OnInit()
if ( !wxApp::OnInit() )
return false;
+ wxIcon icon(wxIconLocation(R"(c:\Windows\system32\imageres.dll)", -67));
+ if ( icon.IsOk() )
+ {
+ wxLogMessage("Loaded icon of size %d*%d", icon.GetWidth(), icon.GetHeight());
+ }
+
// create the main application window
MyFrame *frame = new MyFrame("Minimal wxWidgets App");
shows the expected message about loading the icon of size 32 by 32.