Update: I used Richard's suggestion to fix the setting of Tag. But I am having some issues using the getter for Tag and using the .as/try_as operator on it.
class DerivedController : public winrt::implements<DerivedController, Controller> {
public:
DerivedController() {}
virtual ~DerivedController() {}
static winrt::com_ptr<DerivedController> from(const winrt::FrameworkElement& control) {
return control ? control.Tag().try_as<DerivedController>() : nullptr;
}
}
This is the error I get:
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(8013): error C2440: 'static_cast': cannot convert from 'winrt::impl::producer<D,I,void> *' to 'D *'
1> with
1> [
1> D=`anonymous-namespace'::DerivedController,
1> I=winrt::Windows::Foundation::IInspectable
1> ]
1> and
1> [
1> D=`anonymous-namespace'::DerivedController
1> ]
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(8013): note: Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(8012): note: while compiling class template member function 'D &winrt::impl::produce_base<D,I,void>::shim(void) noexcept'
1> with
1> [
1> D=`anonymous-namespace'::DerivedController,
1> I=winrt::Windows::Foundation::IInspectable
1> ]
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(7777): note: see reference to function template instantiation 'D &winrt::impl::produce_base<D,I,void>::shim(void) noexcept' being compiled
1> with
1> [
1> D=`anonymous-namespace'::DerivedController,
1> I=winrt::Windows::Foundation::IInspectable
1> ]
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(7737): note: see reference to class template instantiation 'winrt::impl::produce_base<D,I,void>' being compiled
1> with
1> [
1> D=`anonymous-namespace'::DerivedController,
1> I=winrt::Windows::Foundation::IInspectable
1> ]
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(7777): note: see reference to class template instantiation 'winrt::impl::produce<D,winrt::Windows::Foundation::IInspectable>' being compiled
1> with
1> [
1> D=`anonymous-namespace'::DerivedController
1> ]
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(4088): note: see reference to function template instantiation 'D *winrt::get_self<To,winrt::Windows::Foundation::IInspectable>(const I &) noexcept' being compiled
1> with
1> [
1> D=`anonymous-namespace'::DerivedController,
1> To=`anonymous-namespace'::DerivedController,
1> I=winrt::Windows::Foundation::IInspectable
1> ]
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(2387): note: see reference to function template instantiation 'winrt::com_ptr<D> winrt::impl::as<To,winrt::impl::IUnknown>(From *)' being compiled
1> with
1> [
1> D=`anonymous-namespace'::DerivedController,
1> To=`anonymous-namespace'::DerivedController,
1> From=winrt::impl::IUnknown
1> ]
1>note: see reference to function template instantiation 'winrt::com_ptr<D> winrt::Windows::Foundation::IUnknown::as<`anonymous-namespace'::DerivedController>(void) const' being compiled
1> with
1> [
1> D=`anonymous-namespace'::DerivedController
1> ]
1>note: see reference to class template instantiation 'winrt::com_ptr<D>' being compiled
1> with
1> [
1> D=Controller
1> ]
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(10615): note: see reference to class template instantiation 'winrt::com_ptr<winrt::impl::IContextCallback>' being compiled (compiling source file
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(10349): note: see reference to class template instantiation 'winrt::com_ptr<winrt::impl::IServerSecurity>' being compiled
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(10308): note: see reference to class template instantiation 'std::chrono::time_point<winrt::clock,winrt::Windows::Foundation::TimeSpan>' being compiled
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(6462): note: see reference to class template instantiation 'winrt::com_ptr<winrt::impl::IMarshal>' being compiled
1>C:\Program Files (x86)\Windows Kits\10\Include\10.0.18362.0\cppwinrt\winrt/base.h(210): note: see reference to class template instantiation 'std::array<uint8_t,8>' being compiled
Controller is constructor as:
auto controller = winrt::make<Controller>().as<Controller>();
DerivedController is constructed as:
DerivedController dController{};
DerivedController used to be like this in c++/cx:
ref class DerivedController sealed : public Controller {
internal : explicit DerivedController(Windows::UI::Xaml::FrameworkElement ^ &control)
: Controller(control) {}
static DerivedController ^
from(Windows::UI::Xaml::FrameworkElement ^ control) {
return control ? dynamic_cast<SvgCanvasController ^>(control->Tag) : nullptr;
}
}
Not sure what I am doing wrong, the error seems to be related to how the classes are defined. Would appreciate any thoughts on it!
Original: In C++/CX, I used to be able to do:
ref class Controller {
Controller() {
container = ref new UserControl();
container->Tag = this;
...
...
}
}
When I try to convert this to C++/WinRT, direct conversion would like this:
class Controller : public winrt::implements<Controller, winrt::Windows::Foundation::IInspectable> {
Controller::Controller() {
winrt::UserControl container;
1===> container.Tag(this);
...
...
}
}
Controller is a hand-authored class (no idls) whose definition looks like this:
class Controller : public winrt::implements<Controller, winrt::Windows::Foundation::IInspectable>
{
...
...
...
}
But I get an error at (1):
Error C2664 'void winrt::impl::consume_Windows_UI_Xaml_IFrameworkElement<D>::Tag(const winrt::Windows::Foundation::IInspectable &) const': cannot convert argument 1 from 'Controller *' to 'const winrt::Windows::Foundation::IInspectable &'
- Is it possible to set a Com pointer to Tag using some interop with ABI?
If you want to convert the code container->Tag=this; in C++/CX to the corresponding code in C++/WinRT, you could try to pass *this as the parameter instead of using interop with ABI , like this:
class Controller : public winrt::implements<Controller, winrt::Windows::Foundation::IInspectable>
{
public:
UserControl container;
Controller::Controller()
{
container.Tag(*this);
}
……
};
- Is there anything else I am missing?
You did a good job, but maybe we can pay attention to the defference of this between C++/CX and C++/WinRT. Here we use *this instead this.
- Is this the right approach? Or is there a way around it?
If you want to get the object added into Tag property, then the approach is right. You can try this code:
Controller cc{};
UserControl uc = cc.container;
auto item1 = uc.Tag();
auto item2= item1.try_as<Controller>();
auto item3 = item2.get();
UserControl uc2 = item3->container;
if (uc = uc2)
{
int t = 1;
}
Update:
You can use static_cast to implement the conversion from Controller pointer to DerivedController pointer and change the return type of from method as DerivedController* like this:
static DerivedController* from(winrt::Windows::UI::Xaml::FrameworkElement const& control)
{
auto con = static_cast<winrt::Windows::UI::Xaml::FrameworkElement>(control);
if (con != nullptr)
{
auto it1=con.Tag();
auto it2 = it1.try_as<Controller>();
Controller* cc = it2.get();
DerivedController* der = static_cast< DerivedController* >(cc);
return der;
}
return nullptr;
}
Then call the from method:
Controller cc{};
DerivedController dController{};
DerivedController* aa = dController.from(cc.container);