Question

我有一个包含多个表单的程序，我需要允许用户在表单之间来回切换。问题是当我在点击“下一步”后隐藏form1并继续执行form2然后按“返回”返回到form1时，我输入的所有数据都消失了。

我曾考虑将所有内容写入文本文件，然后重新读取所有数据。但这是很多额外的代码，我认为这是不必要的。

代码： Form1中：

public: System::Void to_page_2_Click(System::Object^  sender, System::EventArgs^  e) { 
Page2 ^ p2 = gcnew Page2(this);
    p2->Show();
    this->Hide();
}

窗体2：

private: System::Void back_Pg1_Click(System::Object^  sender, System::EventArgs^  e) {
    this->Hide();
PreviousForm->Show();

需要额外的代码才能使代码能够来回运行。但那不是问题。我只想知道刷新Form1而不是加载新Form1的代码。

感谢您的帮助。我希望我很清楚。我正在使用Visual Studio Community 2015.

Answer 1

两种可能的解决方案是：

1）要直接回答这个问题，一种可能的解决方案是使用ShowDialog（）（不在事件处理程序中）而不是Show（）
做类似的事情：

namespace formSwitchTest
{
    ref class tcFormBase : System::Windows::Forms::Form
    {
    public:

        tcFormBase(
            System::String ^ aTitle,
            System::Windows::Threading::Dispatcher ^ aMainDispatcher) :
            mpcForm(nullptr),
            mMainDispatcher(aMainDispatcher)
        {

            this->SuspendLayout();
            this->AutoSize = true;

            mpcSwitchButton = gcnew System::Windows::Forms::Button();
            mpcSwitchButton->AutoSize = true;
            mpcSwitchButton->Click += gcnew System::EventHandler(this, &formSwitchTest::tcFormBase::ButtonClicked);
            mpcSwitchButton->Text = "Click to leave ";
            mpcSwitchButton->Text += aTitle;
            mpcSwitchButton->Dock = System::Windows::Forms::DockStyle::Top;

            mpcExitButton = gcnew System::Windows::Forms::Button();
            mpcExitButton->AutoSize = true;
            mpcExitButton->Click += gcnew System::EventHandler(this, &formSwitchTest::tcFormBase::Exit);
            mpcExitButton->Text = "click to exit";
            mpcExitButton->Dock = System::Windows::Forms::DockStyle::Bottom;

            mpcTextBox = gcnew System::Windows::Forms::TextBox();
            mpcTextBox->Width = 200;
            mpcTextBox->AutoSize = true;
            mpcTextBox->Text = "enter text here";
            mpcTextBox->Dock = System::Windows::Forms::DockStyle::Left;

            this->Controls->Add(mpcTextBox);
            this->Controls->Add(mpcSwitchButton);
            this->Controls->Add(mpcExitButton);
            this->ResumeLayout();
            this->PerformLayout();
        }

        void SetOtherForm(System::Windows::Forms::Form ^ apcForm)
        {
            mpcForm = apcForm;

            // save this action to perform multiple times later
            mShowOtherForm = gcnew System::Action(this, &formSwitchTest::tcFormBase::ShowOtherForm);
        }

        void ShowDialog()
        {
            System::Windows::Forms::Form::ShowDialog();
        }

    private:

        void ShowOtherForm()
        {
            // perform the blocking ShowDialog() because it works better than Show()
            mpcForm->ShowDialog();
        }

        void Exit(System::Object ^ apcSender, System::EventArgs ^ apcArgs)
        {
            // stop the blocking ShowDialog()
            this->Hide();

            // tell the dispatcher to stop, which will stop the Run() call
            mMainDispatcher->BeginInvokeShutdown(System::Windows::Threading::DispatcherPriority::Normal);
        }

        void ButtonClicked(System::Object ^ apcSender, System::EventArgs ^ apcArgs)
        {
            // stop the blocking ShowDialog()
            this->Hide();

            // BeginInvoke() to prevent blocking
            mMainDispatcher->BeginInvoke(mShowOtherForm);
        }

        System::Windows::Forms::Form ^ mpcForm;
        System::Windows::Forms::Button ^ mpcSwitchButton;
        System::Windows::Forms::Button ^ mpcExitButton;
        System::Windows::Forms::TextBox ^ mpcTextBox;
        System::Windows::Threading::Dispatcher ^ mMainDispatcher;
        System::Action ^ mShowOtherForm;
    };
}

int main(void)
{
    System::Windows::Threading::Dispatcher ^ lpcMainDispatcher =
        System::Windows::Threading::Dispatcher::CurrentDispatcher;

    // the only reason for each form being of the same base is for ease of the test
    formSwitchTest::tcFormBase ^ lpcMainForm = gcnew formSwitchTest::tcFormBase(
        "main", lpcMainDispatcher);
    formSwitchTest::tcFormBase ^ lpcSecondForm = gcnew formSwitchTest::tcFormBase(
        "second", lpcMainDispatcher);

    // exchange pointers to each other
    lpcMainForm->SetOtherForm(lpcSecondForm);
    lpcSecondForm->SetOtherForm(lpcMainForm);

    // begin invoke to put the start action in the queue
    lpcMainDispatcher->BeginInvoke(gcnew System::Action(lpcMainForm, &formSwitchTest::tcFormBase::ShowDialog));

    // process the dispatcher queue and wait for it to be shut down
    System::Windows::Threading::Dispatcher::Run();
}

2）它可能更好，更接近你想要使用UserControl类而不是表格

namespace formSwitchTest
{
    ref class tcCtrlBase : System::Windows::Forms::UserControl
    {
    public:
        tcCtrlBase(
            System::String ^ aTitle,
            System::Windows::Forms::Form ^ apcContainerForm) :
            mpcCtrl(nullptr),
            mpcContainerForm(apcContainerForm)
        {

            this->SuspendLayout();
            this->AutoSize = true;

            mpcSwitchButton = gcnew System::Windows::Forms::Button();
            mpcSwitchButton->AutoSize = true;
            mpcSwitchButton->Click += gcnew System::EventHandler(this, &formSwitchTest::tcCtrlBase::ButtonClicked);
            mpcSwitchButton->Text = "Click to leave ";
            mpcSwitchButton->Text += aTitle;
            mpcSwitchButton->Dock = System::Windows::Forms::DockStyle::Top;

            mpcExitButton = gcnew System::Windows::Forms::Button();
            mpcExitButton->AutoSize = true;
            mpcExitButton->Click += gcnew System::EventHandler(this, &formSwitchTest::tcCtrlBase::Exit);
            mpcExitButton->Text = "click to exit";
            mpcExitButton->Dock = System::Windows::Forms::DockStyle::Bottom;

            mpcTextBox = gcnew System::Windows::Forms::TextBox();
            mpcTextBox->Width = 200;
            mpcTextBox->AutoSize = true;
            mpcTextBox->Text = "enter text here";
            mpcTextBox->Dock = System::Windows::Forms::DockStyle::Left;

            this->Controls->Add(mpcTextBox);
            this->Controls->Add(mpcSwitchButton);
            this->Controls->Add(mpcExitButton);
            this->ResumeLayout();
            this->PerformLayout();
        }

        void SetOtherCtrl(System::Windows::Forms::UserControl ^ apcCtrl)
        {
            mpcCtrl = apcCtrl;
        }

    private:

        void ShowOtherForm()
        {
            mpcCtrl->Show();
        }

        void Exit(System::Object ^ apcSender, System::EventArgs ^ apcArgs)
        {
            mpcContainerForm->Hide();
        }

        void ButtonClicked(System::Object ^ apcSender, System::EventArgs ^ apcArgs)
        {
            this->Hide();
            mpcCtrl->Show();
        }

        System::Windows::Forms::UserControl ^ mpcCtrl;
        System::Windows::Forms::Button ^ mpcSwitchButton;
        System::Windows::Forms::Button ^ mpcExitButton;
        System::Windows::Forms::TextBox ^ mpcTextBox;
        System::Windows::Forms::Form ^ mpcContainerForm;
    };
}

int main(void)
{
    System::Windows::Forms::Form ^ lpcContainerForm = gcnew System::Windows::Forms::Form();

    formSwitchTest::tcCtrlBase ^ lpcMainForm = gcnew formSwitchTest::tcCtrlBase(
        "main", lpcContainerForm);
    formSwitchTest::tcCtrlBase ^ lpcSecondForm = gcnew formSwitchTest::tcCtrlBase(
        "second", lpcContainerForm);

    lpcMainForm->SetOtherCtrl(lpcSecondForm);
    lpcSecondForm->SetOtherCtrl(lpcMainForm);

    lpcContainerForm->AutoSize = true;
    lpcContainerForm->Controls->Add(lpcMainForm);
    lpcContainerForm->Controls->Add(lpcSecondForm);
    lpcContainerForm->ShowDialog();
}

Visual C ++重新加载表单以在隐藏隐藏后查看其数据

1 个答案: