C++Builder TMouseWheelEvent 编译错误
C++Builder TMouseWheelEvent compiler error
无论我如何尝试使用它,我都无法动态创建 TScrollBox
并为其分配 OnMouseWheelEvent
处理程序。我收到以下编译器错误:
E2034 Cannot convert 'void (_fastcall * (_closure )(TObject *,TShiftState,int,TPoint &,bool &))(TObject *,TShiftState,int,TPoint &,bool &)' to 'TMouseWheelEvent'
我对 OnMouseWheelEvent
处理程序的声明是正确的(据我所知):
....
TScrollBox *sb = new TScrollBox(funnelCharts);
sb->Top = 5000;
sb->Parent = funnelCharts;
sb->Align = alClient;
sb->Height = funnelCharts->ClientHeight;
sb->OnMouseWheel = scrollEvent;
....
// --------------------------------------------------------------
void __fastcall TForm1::scrollEvent(TObject *Sender, TShiftState Shift, int WheelDelta, TPoint &MousePos, bool &Handled)
{
TScrollBox *scrollbox = dynamic_cast<TScrollBox*>(Sender);
if (scrollbox)
{
for (int i = 1; i < Mouse->WheelScrollLines; i++)
{
if (WheelDelta > 0)
{
scrollbox->Perform(WM_VSCROLL, SB_LINEUP, 0);
}
else
{
scrollbox->Perform(WM_VSCROLL, SB_LINEDOWN, 0);
}
}
scrollbox->Perform(WM_VSCROLL, SB_ENDSCROLL, 0);
Handled = true;
}
}
这是一个编译器错误,而不是链接器错误。
查看Controls.hpp
中TMouseWheelEvent
的实际声明。您的 scrollEvent()
方法与实际声明的不匹配,否则您不会收到错误。
根据您是为 32 位还是 64 位编译,TMouseWheelEvent
(具体来说,其 MousePos
参数)的声明方式不同:
32 位:
typedef void __fastcall (__closure *TMouseWheelEvent)(System::TObject* Sender, System::Classes::TShiftState Shift, int WheelDelta, const System::Types::TPoint &MousePos, bool &Handled);
64 位:
typedef void __fastcall (__closure *TMouseWheelEvent)(System::TObject* Sender, System::Classes::TShiftState Shift, int WheelDelta, System::Types::TPoint MousePos, bool &Handled);
原因是 BCC32 和 BCC64 在传递 8 字节结构类型(如 TPoint
)方面有所不同。这种差异记录在 Embarcadero 的 DocWiki 上:
Events with Structures or Sets of 5-8 Bytes Are Not Valid for BCC64
受此差异影响的其他事件类型包括 TGetSiteInfoEvent
、TMouseWheelUpDownEvent
和 TContextPopupEvent
。
要解决此问题,您必须 #ifdef
您的代码如文档所述:
class TForm1 : public TForm
{
...
#ifndef _WIN64
void __fastcall scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, const TPoint &MousePos, bool &Handled);
#else
void __fastcall scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, TPoint MousePos, bool &Handled);
#endif
...
};
...
#ifndef _WIN64
void __fastcall TForm1::scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, const TPoint &MousePos, bool &Handled)
#else
void __fastcall TForm1::scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, TPoint MousePos, bool &Handled)
#endif
{
...
}
或者,更简洁的方法:
class TForm1 : public TForm
{
...
void __fastcall scrollEvent(
TObject* Sender, TShiftState Shift, int WheelDelta,
#ifndef _WIN64
const TPoint &MousePos,
#else
TPoint MousePos,
#endif
bool &Handled);
...
};
...
void __fastcall TForm1::scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta,
#ifndef _WIN64
const TPoint &MousePos,
#else
TPoint MousePos,
#endif
bool &Handled)
{
...
}
或者,更干净:
#ifndef _WIN64
#define SAFE_5TO8_PARAM(type, name) const type &name
#else
#define SAFE_5TO8_PARAM(type, name) type name
#endif
class TForm1 : public TForm
{
...
void __fastcall scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, SAFE_5TO8_PARAM(TPoint, MousePos), bool &Handled);
...
};
...
void __fastcall TForm1::scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, SAFE_5TO8_PARAM(TPoint, MousePos), bool &Handled)
{
...
}
无论我如何尝试使用它,我都无法动态创建 TScrollBox
并为其分配 OnMouseWheelEvent
处理程序。我收到以下编译器错误:
E2034 Cannot convert 'void (_fastcall * (_closure )(TObject *,TShiftState,int,TPoint &,bool &))(TObject *,TShiftState,int,TPoint &,bool &)' to 'TMouseWheelEvent'
我对 OnMouseWheelEvent
处理程序的声明是正确的(据我所知):
....
TScrollBox *sb = new TScrollBox(funnelCharts);
sb->Top = 5000;
sb->Parent = funnelCharts;
sb->Align = alClient;
sb->Height = funnelCharts->ClientHeight;
sb->OnMouseWheel = scrollEvent;
....
// --------------------------------------------------------------
void __fastcall TForm1::scrollEvent(TObject *Sender, TShiftState Shift, int WheelDelta, TPoint &MousePos, bool &Handled)
{
TScrollBox *scrollbox = dynamic_cast<TScrollBox*>(Sender);
if (scrollbox)
{
for (int i = 1; i < Mouse->WheelScrollLines; i++)
{
if (WheelDelta > 0)
{
scrollbox->Perform(WM_VSCROLL, SB_LINEUP, 0);
}
else
{
scrollbox->Perform(WM_VSCROLL, SB_LINEDOWN, 0);
}
}
scrollbox->Perform(WM_VSCROLL, SB_ENDSCROLL, 0);
Handled = true;
}
}
这是一个编译器错误,而不是链接器错误。
查看Controls.hpp
中TMouseWheelEvent
的实际声明。您的 scrollEvent()
方法与实际声明的不匹配,否则您不会收到错误。
根据您是为 32 位还是 64 位编译,TMouseWheelEvent
(具体来说,其 MousePos
参数)的声明方式不同:
32 位:
typedef void __fastcall (__closure *TMouseWheelEvent)(System::TObject* Sender, System::Classes::TShiftState Shift, int WheelDelta, const System::Types::TPoint &MousePos, bool &Handled);
64 位:
typedef void __fastcall (__closure *TMouseWheelEvent)(System::TObject* Sender, System::Classes::TShiftState Shift, int WheelDelta, System::Types::TPoint MousePos, bool &Handled);
原因是 BCC32 和 BCC64 在传递 8 字节结构类型(如 TPoint
)方面有所不同。这种差异记录在 Embarcadero 的 DocWiki 上:
Events with Structures or Sets of 5-8 Bytes Are Not Valid for BCC64
受此差异影响的其他事件类型包括 TGetSiteInfoEvent
、TMouseWheelUpDownEvent
和 TContextPopupEvent
。
要解决此问题,您必须 #ifdef
您的代码如文档所述:
class TForm1 : public TForm
{
...
#ifndef _WIN64
void __fastcall scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, const TPoint &MousePos, bool &Handled);
#else
void __fastcall scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, TPoint MousePos, bool &Handled);
#endif
...
};
...
#ifndef _WIN64
void __fastcall TForm1::scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, const TPoint &MousePos, bool &Handled)
#else
void __fastcall TForm1::scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, TPoint MousePos, bool &Handled)
#endif
{
...
}
或者,更简洁的方法:
class TForm1 : public TForm
{
...
void __fastcall scrollEvent(
TObject* Sender, TShiftState Shift, int WheelDelta,
#ifndef _WIN64
const TPoint &MousePos,
#else
TPoint MousePos,
#endif
bool &Handled);
...
};
...
void __fastcall TForm1::scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta,
#ifndef _WIN64
const TPoint &MousePos,
#else
TPoint MousePos,
#endif
bool &Handled)
{
...
}
或者,更干净:
#ifndef _WIN64
#define SAFE_5TO8_PARAM(type, name) const type &name
#else
#define SAFE_5TO8_PARAM(type, name) type name
#endif
class TForm1 : public TForm
{
...
void __fastcall scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, SAFE_5TO8_PARAM(TPoint, MousePos), bool &Handled);
...
};
...
void __fastcall TForm1::scrollEvent(TObject* Sender, TShiftState Shift, int WheelDelta, SAFE_5TO8_PARAM(TPoint, MousePos), bool &Handled)
{
...
}