GridHeaderCellElement in C++

[John]

I am using C++/CLI with the Telerik GridView.  I have a checkbox column which I wanted to add the CheckBoxHeaderCell class to.  (Reference: http://www.telerik.com/support/kb/winforms/gridview/add-check-uncheck-all-check-box-in-the-header-cell.aspx).  I wrote the example and compiled it in C++/CLI from the given C# code.  However, I do not know how to tell my grid view to USE this class as a columns header cell.  Any help would be appreciated!

- John

[Stefan]

Hi John,

Thank you for writing.

I can provide you with help in C# and VB, but not in C++. As you can see in the example project attached in the KB article, after the column class is created, you can simply create an instance of the class and add the instantiated column to the Columns collection of RadGridView: 

CustomCheckBoxColumn checkColumn = new CustomCheckBoxColumn();
checkColumn.Name = "Select";
checkColumn.HeaderText = "All";
this.radGridView1.Columns.Insert(0, checkColumn);

I hope that you find this information helpful.

Kind regards,
Stefan
the Telerik team

[John]

For my C++ brethren out there...here is the check box header cell in C++:

public ref class CheckBoxHeaderCell : public GridHeaderCellElement
{
    public: CheckBoxHeaderCell(GridViewColumn^ column, GridRowElement^ row) : GridHeaderCellElement(column, row)
    {
        InitializeComponent();

        this->_suspendProcessingToggleStateChanged = false;

        this->_checkbox = gcnew RadCheckBoxElement();
        this->_checkbox->ToggleStateChanged += gcnew StateChangedEventHandler(this, &CheckBoxHeaderCell::checkbox_ToggleStateChanged);
        this->Children->Add(this->_checkbox);
    }

    protected: ~CheckBoxHeaderCell()
    {
        if (components)
        {
            delete components;
        }
    }

    protected: virtual SizeF ArrangeOverride(SizeF finalSize) override
    {
        SizeF size = this->GridHeaderCellElement::ArrangeOverride(finalSize);

        RectangleF^ rect = GetClientRectangle(finalSize);
        this->_checkbox->Arrange(RectangleF((finalSize.Width - this->_checkbox->DesiredSize.Width) / 2, (rect->Height - 20) / 2, 20, 20));

        return size;
    }

    public: virtual bool IsCompatible(GridViewColumn^ data, System::Object^ context) override
    {
        return data->Name == "Select" && (dynamic_cast<GridTableHeaderRowElement^>(context) != nullptr) && this->GridHeaderCellElement::IsCompatible(data, context);
    }

    protected: void checkbox_ToggleStateChanged(System::Object^ sender, StateChangedEventArgs^ args)
    {
        if(!this->_suspendProcessingToggleStateChanged)
        {
            bool valueState = false;

            if(args->ToggleState == Telerik::WinControls::Enumerations::ToggleState::On)
            {
                valueState = true;
            }

            this->GridViewElement->EditorManager->EndEdit();
            this->TableElement->BeginUpdate();

            for(auto i = 0; i < this->ViewInfo->Rows->Count; i++)
            {
                this->ViewInfo->Rows[i]->Cells[this->ColumnIndex]->Value = valueState;
            }

            this->TableElement->EndUpdate(false);

            this->TableElement->Update(GridUINotifyAction::DataChanged);
        }
    }

    public: void SetCheckBoxState(Telerik::WinControls::Enumerations::ToggleState state)
    {
        this->_suspendProcessingToggleStateChanged = true;
        this->_checkbox->ToggleState = state;
        this->_suspendProcessingToggleStateChanged = false;
    }

    public: virtual void Attach(GridViewColumn^ data, System::Object^ context) override
    {
        this->GridHeaderCellElement::Attach(data, context);
        this->GridControl->ValueChanged += gcnew System::EventHandler(this, &CheckBoxHeaderCell::GridControl_ValueChanged);
    }

    public: virtual void Detach() override
    {
        if(this->GridControl != nullptr)
        {
            this->GridControl->ValueChanged -= gcnew System::EventHandler(this, &CheckBoxHeaderCell::GridControl_ValueChanged);
        }

        this->GridHeaderCellElement::Detach();
    }

    void GridControl_ValueChanged(System::Object^ sender, EventArgs^ e)
    {
        RadCheckBoxEditor^ editor = dynamic_cast<RadCheckBoxEditor^>(sender);

        if(editor != nullptr)
        {
            this->GridViewElement->EditorManager->EndEdit();

            if(static_cast<ToggleState>(editor->Value) == ToggleState::Off)
            {
                SetCheckBoxState(ToggleState::Off);
            }
            else if(static_cast<ToggleState>(editor->Value) == ToggleState::On)
            {
                bool found = false;
                for each(GridViewRowInfo^ row in this->ViewInfo->Rows)
                {
                    if (row != this->RowInfo && row->Cells[this->ColumnIndex]->Value == nullptr || !(bool)row->Cells[this->ColumnIndex]->Value)
                    {
                        found = true;
                        break;
                    }
                }

                if(found == false)
                {
                    SetCheckBoxState(ToggleState::On);
                }
            }
        }
    }

    private: RadCheckBoxElement^ _checkbox;
    private: bool _suspendProcessingToggleStateChanged;
    private: System::ComponentModel::Container ^components;

#pragma region Windows Form Designer generated code
    /// <summary>
    /// Required method for Designer support - do not modify
    /// the contents of this method with the code editor.
    /// </summary>
    void InitializeComponent(void)
    {
    }
#pragma endregion
};

public ref class CustomCheckBoxColumn : public GridViewCheckBoxColumn
{
    public: virtual System::Type^ GetCellType(GridViewRowInfo^ row) override
    {
        if(dynamic_cast<GridViewTableHeaderRowInfo^>(row) != nullptr)
        {
            return CheckBoxHeaderCell::typeid;
        }

        return this->GridViewCheckBoxColumn::GetCellType(row);
    }
};

[Stefan]

Thank you for sharing your code with the community. If you have any other questions, do not hesitate to contact us.

All the best,
Stefan
the Telerik team