Visual c++ WndProc重写MySplitContainerControl::WndProc(m)；

Question

做一些测试..。在ownerdraw自定义控件上。

这段代码会编译，但会崩溃...因为'm‘是<undefined value>

MySplitContainerControl::WndProc(m); /*with brakepoint，我可以看到一条消息....但拆下刹车点会导致撞车！

我正在尝试覆盖Splitcontainer中的窗口外观。

protected: static int WM_PAINT = 0x000F;
protected: virtual void WndProc(Message% m) override 
    {
    MySplitContainerControl::WndProc(m); 
    /*Form::WndProc(m);*/
    if (m.Msg == WM_PAINT)
        {
                Graphics^ graphics = Graphics::FromHwnd(this->Handle);
                PaintEventArgs^ pe = gcnew PaintEventArgs(graphics, Rectangle(0,0, this->Width, this->Height));
                OnPaint(pe);
        }

为了得到一个概念，我在这里做的是完整的代码：

#pragma once

using namespace System;
using namespace System::ComponentModel;
using namespace System::Collections;
using namespace System::Windows::Forms;
using namespace System::Data;
using namespace System::Drawing;


namespace MySplitContainer {

    /// <summary>
    /// Summary for MySplitContainerControl
    /// </summary>
    public ref class MySplitContainerControl : public System::Windows::Forms::SplitContainer
    {
    public:
        MySplitContainerControl(void)
        {
            InitializeComponent();
            //
            //TODO: Add the constructor code here
            //
        }

    protected:
        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        ~MySplitContainerControl()
        {
            if (components)
            {
                delete components;
            }
        }

    private:
        /// <summary>
        /// Required designer variable.
        /// </summary>
        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)
        {
            this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
        }
#pragma endregion

    protected: static int WM_PAINT = 0x000F;
    protected: virtual void WndProc(Message% m) override 
        {
        MySplitContainerControl::WndProc(m);
        /*Form::WndProc(m);*/
        if (m.Msg == WM_PAINT)
            {
                    Graphics^ graphics = Graphics::FromHwnd(this->Handle);
                    PaintEventArgs^ pe = gcnew PaintEventArgs(graphics, Rectangle(0,0, this->Width, this->Height));
                    OnPaint(pe);
            }
        }

    protected: virtual void OnPaint(PaintEventArgs ^e) override
        {

        }

    };
}

Answer 1

您必须：

protected: virtual void WndProc(Message% m) override 
{
    MySplitContainerControl::WndProc(m);
    // ...
}

因此，您调用的是被覆盖的WndProc方法本身。这会导致无限的递归调用，从而导致StackOverflowException。

让它成为Form::WndProc(m) (注释行)。它应该调用基类的WndProc，而不是它本身。

其次，在覆盖WM_PAINT时，您应该调用BeginPaint和EndPaint方法，而不是为窗口创建新的Graphics (和DC)。