c++ Builder事件处理程序错误

Question

我是c++ Builder的新手，语法对专家来说是显而易见的。

在我的代码中，我创建了一个TImage，并希望为其OnClick事件分配一个ListBox OnItemClick处理程序。任何帮助将非常感激!

void __fastcall TDetail::Button1Click(TObject *Sender)
{
    Detail->DataSource1->DataSet->Open();
    lynCount = Detail->DataSource1->DataSet->RecordCount;
    for(int lyn = 1; lyn <= lynCount; lyn++)
    {
        try {delete Pic[lyn];} __finally {Pic[lyn] = new TImage(Detail->BordLys);}
        Pic[lyn]->OnClick = TDetail::BordLysItemClick; 
    }
}

I get error:

[bcc32错误]boom.com cpp(262): E2034不能转换'void (_fastcall * (_closure)(const TCustomListBox *，const TListBoxItem *))(const TCustomListBox *，const TListBoxItem *)'到'TNotifyEvent'

也试过了，没有成功:

void __fastcall TDetail::BordLysItemClick(const TCustomListBox *Sender, const TListBoxItem *Item)
{
    Debug->Text =  BordLys->ItemIndex + 1;
}
void __fastcall TDetail::Button1Click(TObject *Sender)
{
    Detail->DataSource1->DataSet->Open();
    lynCount = Detail->DataSource1->DataSet->RecordCount;
    BordItem = new TListBoxItem(Detail->BordLys);
    for(int lyn = 1; lyn <= lynCount; lyn++)
    {
        try {delete Pic[lyn];} __finally {Pic[lyn] = new TImage(Detail->BordLys);}
        BordItem = Detail->BordLys->ItemByIndex(lyn);
        Pic[lyn]->OnClick = TDetail::BordLysItemClick(Detail->BordLys, BordItem);
    }
}

I get error:

[bcc32 Error] Boom.cpp(116): E2283or ->调用'_fastcall TDetail::BordLysItemClick(const TCustomListBox *，const TListBoxItem *)'

Answer 1

BordLysItemClick()的签名与OnClick事件期待的签名不匹配。因此，您必须使用间接解决方案:

void __fastcall TDetail::BordLysItemClick(const TCustomListBox *Sender, const TListBoxItem *Item)
{
    Debug->Text = Item->Index + 1;
}
void __fastcall TDetail::BordLysImgClick(TObject *Sender)
{
    TImage *Img = static_cast<TImage*>(Sender);
    TListBoxItem *Item = reinterpret_cast<TListBoxItem*>(Img->Tag);
    BordLysItemClick(BordLys, Item);
}
void __fastcall TDetail::Button1Click(TObject *Sender)
{
    DataSource1->DataSet->Open();
    lynCount = DataSource1->DataSet->RecordCount;
    for(int lyn = 1; lyn <= lynCount; lyn++)
    {
        try
        {
            delete Pic[lyn];
        }
        __finally
        {
            Pic[lyn] = new TImage(BordLys);
        }
        TListBoxItem *BordItem = BordLys->ItemByIndex(lyn);
        Pic[lyn]->Tag = reinterpret_cast<NativeInt>(BordItem);
        Pic[lyn]->OnClick = &BordLysImgClick;
    }
}