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C++.NET Windows Forms Course@ZGTRShaker

C++.NET Windows Forms Course

L10-Instantiate Controls At Runtime

Instantiate Controls at Runtime

The Concept of Instantiating Controls at

Runtime

Instantiating at Runtime

• Let’s have the following form

Instantiating at Runtime

• Now, let’s have the following code, what does it mean?It’s just allocating a memory space for a new object (button)

• Does it show a button?!!!

private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

}

Instantiating at Runtime

NO!

Instantiating at Runtime

• What happens?

private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Show();

}

Instantiating at Runtime

Instantiating at Runtime

• Parent! What happens now?

private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Parent = this;

}

Instantiating at Runtime

• Why?

Instantiating at Runtime

• What happens?

private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Parent = this;

MyButton->Location = System::Drawing::Point(10, 20);

MyButton->Name = L"button1";

MyButton->Size = System::Drawing::Size(75, 23);

MyButton->TabIndex = 0;

MyButton->Text = L"MyDynamicButton";

MyButton->UseVisualStyleBackColor = true;

}

Instantiating at Runtime

How can we fire events on the newly created button?

The event wire-up in design time

• Consider that we have the following design …

The event wire-up in design time

• And we add a button_click event to button1

private: System::Void button1_Click(System::Object^ sender,

System::EventArgs^ e)

{

MessageBox::Show("HiiiIiIIiIIIIIiiii");

}

The event wire-up in design time

• Now, we can see the following …

The event wire-up in design time

Instantiating at Runtime

• Now, let’s add sth else!private: System::Void button1_Click(System::Object^ sender,

System::EventArgs^ e)

{

MessageBox::Show("HiiiIiIIiIIIIIiiii");

}

Instantiating at Runtime

• Now, back to our Button:

private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Parent = this;

MyButton->Location = System::Drawing::Point(10, 20);

MyButton->Name = L"button1";

MyButton->Size = System::Drawing::Size(75, 23);

MyButton->TabIndex = 0;

MyButton->Text = L"MyDynamicButton";

MyButton->UseVisualStyleBackColor = true;

}

Instantiating at Runtime

• We can do this:

private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Parent = this;

MyButton->Location = System::Drawing::Point(10, 20);

MyButton->Name = L"button1";

MyButton->Size = System::Drawing::Size(75, 23);

MyButton->TabIndex = 0;

MyButton->Text = L"MyDynamicButton";

MyButton->UseVisualStyleBackColor = true;

MyButton->Click += gcnew System::EventHandler(this,

&Form1::button1_Click_1);

}

Instantiating at Runtime

• What happens when clicking the created Button “MyButton” or Button1?

private: System::Void button1_Click_1(System::Object^

sender, System::EventArgs^ e)

{

MessageBox::Show("Wow!!! ");

}

Instantiating at Runtime

Instantiating at Runtime

• We can do this?

private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Parent = this;

MyButton->Location = System::Drawing::Point(10, 20);

MyButton->Name = L"button1";

MyButton->Size = System::Drawing::Size(75, 23);

MyButton->TabIndex = 0;

MyButton->Text = L"MyDynamicButton";

MyButton->UseVisualStyleBackColor = true;

MyButton->Click += gcnew System::EventHandler(this,

&Form1::Mamy);

}

Instantiating at Runtime

private: System::Void Mamy(System::Object^ sender,

System::EventArgs^ e)

{

MessageBox::Show("Mamy is a great cook! :D");

}

• And change it accordingly like this?

Instantiating at Runtime

Instantiating at Runtime

• Now, Consider we have the following two functions

private: System::Void Mamy(System::Object^ sender,

System::EventArgs^ e)

{

this->Text = "Mamy";

}

private: System::Void Chocolate(System::Object^ sender,

System::EventArgs^ e)

{

MessageBox::Show("There's no chocolate to eat :'( ");

}

Instantiating at Runtime

• We can do this? Try it out!private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Parent = this;

MyButton->Location = System::Drawing::Point(10, 20);

MyButton->Name = L"button1";

MyButton->Size = System::Drawing::Size(75, 23);

MyButton->TabIndex = 0;

MyButton->Text = L"MyDynamicButton";

MyButton->UseVisualStyleBackColor = true;

MyButton->Click += gcnew System::EventHandler(this,

&Form1::Mamy);

MyButton->Click += gcnew System::EventHandler(this,

&Form1::Chocolate);

}

Now, let’s see some more advanced stuff

Event handlingprivate: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Parent = this;

MyButton->Location = System::Drawing::Point(10, 20);

MyButton->Name = L"button1";

MyButton->Size = System::Drawing::Size(75, 23);

MyButton->TabIndex = 0;

MyButton->Text = L"MyDynamicButton";

MyButton->UseVisualStyleBackColor = true;

MyButton->Click += gcnew System::EventHandler(this,

&Form1::button1_Click_1);

MyButton->MouseHover += gcnew System::EventHandler(this,

&Form1::MyProdHover);

}

Event handling

• Compiler error, why?

private: void MyProdHover (System::Object^ sender,

System::EventArgs^ e)

{

while (sender->Width < 200)

{

sender->Width+=3;

sender->Height+=1;

Threading::Thread::Sleep(100);

}

}

dynamic_cast

• We use dynamic_cast

private: void MyProdHover (System::Object^ sender,

System::EventArgs^ e)

{

while ((dynamic_cast<Button^>(sender))->Width < 200)

{

(dynamic_cast<Button^>(sender))->Refresh();

(dynamic_cast<Button^>(sender))->Width+=3;

(dynamic_cast<Button^>(sender))->Height+=1;

Threading::Thread::Sleep(100);

}

}

dynamic_cast

• We can do this for sure

• Now what happens? And what should happen?

private: void MyProdHover (System::Object^ sender,

System::EventArgs^ e)

{

Button ^TempButton = (dynamic_cast<Button^>(sender));

while (TempButton->Width < 200)

{

TempButton->Width+=3;

TempButton->Height+=1;

Threading::Thread::Sleep(100);

}

}

Event handling

• Test it yourself. After seconds “without” motion the button becomes like this:

How can we solve this and see the motion?

Event handling

• Refresh method!

private: void MyProdHover (System::Object^ sender,

System::EventArgs^ e)

{

Button ^TempButton = (dynamic_cast<Button^>(sender));

while (TempButton->Width < 200)

{

TempButton->Refresh();

TempButton->Width+=3;

TempButton->Height+=1;

Threading::Thread::Sleep(100);

}

}

Event handling

Event handling

• Now, let’s add the following …private: System::Void Form1_Load(System::Object^ sender,

System::EventArgs^ e)

{

Button ^MyButton = gcnew Button;

MyButton->Parent = this;

MyButton->Location = System::Drawing::Point(10, 20);

MyButton->Name = L"button1";

MyButton->Size = System::Drawing::Size(75, 23);

MyButton->TabIndex = 0;

MyButton->Text = L"MyDynamicButton";

MyButton->UseVisualStyleBackColor = true;

MyButton->Click += gcnew System::EventHandler(this,

&Form1::button1_Click_1);

MyButton->MouseHover += gcnew System::EventHandler(this,

&Form1::MyProdHover);

MyButton->MouseLeave += gcnew System::EventHandler(this,

&Form1::MyProdLeave);

}

Event handling

• What will happen now? private: void MyProdLeave (System::Object^ sender,

System::EventArgs^ e)

{

while ((dynamic_cast<Button^>(sender))->Width > 50)

{

(dynamic_cast<Button^>(sender))->Refresh();

(dynamic_cast<Button^>(sender))->Width-=3;

(dynamic_cast<Button^>(sender))->Height+=1;

Threading::Thread::Sleep(100);

}

}

Event handling

Mouse still here

Event handling

Now leaving the button area

Event handling

?

What you can do now

• Now, you can create– Any control you want

• textBox, pictureBox, panel, label, …. etc

– How you want it– Controls its behavior– With the number you want (Save references in lists, array, dictionary!!,

…etc)

Test it live!

That’s it for today!