DIALOG BOXES AND CONTROLS

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DIALOG BOXES AND CONTROLS
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Dialog Boxes

• A dialog box is a temporary window that Windows
  creates for special-purpose input and then
  destroys immediately after use. An application
  typically uses a dialog box to prompt the user
  for additional information about a current
  command selection.

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Types of Dialog Boxes

• A modeless dialog box allows the user to supply
  information and return to the previous task
  without canceling or removing the dialog box.
• A modal dialog box requires the user to respond
  to a request or supply information before the
  application can continue. We will create a MODAL
  dialog box.

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What Are They For?

• A Dialog Box is simply a window that holds
  controls provided to allow the user to
  communicate with the program.
• CONTROLS are actually what communicates with the
  program - Not the Dialog Box.

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Controls

• Text Box (where user can type text)
• Drop Down List Box
• Combo Box (both text and drop down list)
• Check Boxes
• Radio Buttons (grouped-only one selected at a
  time)
• Scroll Bars
• Buttons - OK, CANCEL, Buttons on Button Bar
• Menu Items
• Any item intended to receive info from the user
  to be sent back to the program.

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Creating a Dialog Box

• Select the Resource Workshop and/or open the .rc
  file associated with your project.
• Select Resource, New, then select Dialog.
• Select the type of Dialog Box you want to create.
• A Dialog Box will appear. You will use
  drag-n-drop to assign controls to it.

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Adding Controls to a Dialog Box

• Use the Tools bar to select and drop controls
  such as Check Boxes or Buttons onto the Dialog
  Box.
• Double Click each control to make changes to its
  style, name and id.
• Right Click the background of the Dialog Box and
  select Style to change the title that appears on
  the Dialog Box or Test to test the Dialog Box.
• Resource, Edit as text to change the name used
  by the program to access the dialog box.
• Save the Resource Project after making any
  changes or additions to your resources.

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Processing Dialog Box Messages

• Dialog Box controls receive messages from the
  mouse or keyboard and send them to your program.
  You must process these messages in your code.
• The first step is to write a new function to
  process dialog box messages. It will have a
  switch statement that handles the IDs of the
  controls on your dialog box very similar to
  MainWndProc.

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Write a Simple Dialog Procedure

• BOOL CALLBACK Pizza ( HWND hDlg, UINT message,
  WPARAM wParam, LPARAM lParam )
• switch ( message )
• case WM_INITDIALOG / message initialize
  dialog box /
• return ( TRUE )
• case WM_COMMAND / message received
  a command /
• switch (wParam)
• case IDOK
• MessageBox( hWnd, "You clicked OK",
  "Response", MB_OK)
• break
• case IDCANCEL
• EndDialog ( hDlg, TRUE ) /
  Exits the dialog box /
• return ( TRUE )
• return ( FALSE ) / Didn't process a
  message /

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In MainWndProc

• Use MakeProcInstance to get a handle to (or
  memory for) your dialog box procedure.
• Use the DialogBox function to load the dialog box
  resource and show the box on the screen (the
  DialogBox function creates a MODAL dialog box).
• Use FreeProcInstance to clean up after the
  program is finished with the dialog box.

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Add a Call toYour Dialog Procedure

• LRESULT CALLBACK MainWndProc ( HWND hWnd, UINT
  message,WPARAM wParam,
• 
  
  LPARAM
  lParam)
• DLGPROC dlgPizza
• switch ( message )
• case WM_COMMAND
• switch (wParam)
• case CM_EXIT
• DestroyWindow ( hWnd )
• case CM_ORDER
• dlgPizza (DLGPROC)
  MakeProcInstance ( (FARPROC)Pizza, hInst )
• DialogBox ( hInst, "PIZZA_DIALOG",
  hWnd, dlgPizza )
• FreeProcInstance ( (FARPROC)
  dlgPizza )
• default
• return ( DefWindowProc ( hWnd, message,
  wParam, lParam ) )
• default
• return ( DefWindowProc ( hWnd,
  message, wParam, lParam ) )

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Dialog Boxes are Stubborn

• Processing messages received by your Dialog Box
  is your job as the programmer. The Dialog Box
  wont do anything you dont tell it to do.