Question

I need to create rectangles when the button is clicked.
I have tried the given code but its not working.
i have tried to create a flag “mdraw” that becomes true when a button is clicked. a condition is out in the form_paint where the rectangle will created only when the “mdraw” becomes true. But after clicking the button, nothing comes!

I m using windows forms application (CLR).
Microsoft visual c++ 2008.

    #pragma once


    namespace try1 {

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

/// <summary>
/// Summary for Form1
///
/// WARNING: If you change the name of this class, you will need to change the
///          'Resource File Name' property for the managed resource compiler tool
///          associated with all .resx files this class depends on.  Otherwise,
///          the designers will not be able to interact properly with localized
///          resources associated with this form.
/// </summary>
public ref class Form1 : public System::Windows::Forms::Form
{
public:
    Form1(void)
    {
        InitializeComponent();
        //
        //TODO: Add the constructor code here
        //
    }

protected:
    /// <summary>
    /// Clean up any resources being used.
    /// </summary>
    ~Form1()
    {
        if (components)
        {
            delete components;
        }
    }
private: System::Windows::Forms::Button^  button1;
protected: 

private:
    /// <summary>
    /// Required designer variable.
    /// </summary>
    System::ComponentModel::Container ^components;
private: System::Windows::Forms::Label^  label1;
public:
    bool mdraw;
    #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->button1 = (gcnew System::Windows::Forms::Button());
        this->label1 = (gcnew System::Windows::Forms::Label());
        this->SuspendLayout();
        // 
        // button1
        // 
        this->button1->Location = System::Drawing::Point(98, 35);
        this->button1->Name = L"button1";
        this->button1->Size = System::Drawing::Size(75, 23);
        this->button1->TabIndex = 0;
        this->button1->Text = L"button1";
        this->button1->UseVisualStyleBackColor = true;
        this->button1->Click += gcnew System::EventHandler(this, &Form1::button1_Click);
        // 
        // label1
        // 
        this->label1->AutoSize = true;
        this->label1->Location = System::Drawing::Point(51, 77);
        this->label1->Name = L"label1";
        this->label1->Size = System::Drawing::Size(0, 13);
        this->label1->TabIndex = 1;
        // 
        // Form1
        // 
        this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
        this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
        this->ClientSize = System::Drawing::Size(284, 262);
        this->Controls->Add(this->label1);
        this->Controls->Add(this->button1);
        this->Name = L"Form1";
        this->Text = L"Form1";
        this->Load += gcnew System::EventHandler(this, &Form1::Form1_Load);
        this->Paint += gcnew System::Windows::Forms::PaintEventHandler(this, &Form1::Form1_Paint);
        this->ResumeLayout(false);
        this->PerformLayout();

    }
    #pragma endregion
private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e)               {
             mdraw=true;
             label1->Text=button1->Text;

         }

private: System::Void Form1_Paint(System::Object^  sender, System::Windows::Forms::PaintEventArgs^  e) {
             Pen^ redPen = gcnew Pen(Color::Red);
         int i,n;
         i=20;
         n=0;

         if(mdraw)
         {
                       while(n<=50)
         {
             e->Graphics->DrawRectangle(redPen,i,140,10,60);
             i=i+20;
             n+=1;

         }




         }
     }


    };
    }

Answer 1

Use as below
first initialize mdraw to false

private: System::Void button1_Click(System::Object^  sender, System::EventArgs^  e) 
{ 
    if(!mdraw)
    {
      while(n<=50)
      {
         mdraw=true;
         label1->Text=button1->Text;
         e->Graphics->DrawRectangle(redPen,i,140,10,60);
         i=i+20;
         n+=1;
       }
     }

 }