Visual Programming Horton Chp'1318 MSDN Helptutorials

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Visual ProgrammingHorton (Chp.13-18)MSDN
Help/tutorials
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Horton Chp. 13-18 summary

• Chp. 13 basics of Windows programming
• Chp. 14 adding menu items to the resource editor
  
• Chp. 15 drawing in a window
• Chp. 16 you will need only parts of this chapter
  (to keep your shape objects in a list etc.)
• Chp. 17 adding dialogs to your program
• Chp. 18 serialization how to save a document so
  that you can close and retrieve everything back
  as it was before you closed it.
• The chapters in red are more basic (and important
  for your hw). But you definitely do not need to
  learn everything in a chapter try to use it as a
  reference and quickly find what you need (which
  will become a necessary skill with the quickly
  changing CS material).

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Overview

• Basics of Windows Programming (Chp. 13)
• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

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Windows Programming Overview
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Multi Document Applications
Terminology - Title bar - Tool bar - Parent
window - Child window - (0,0) upper left -
Status bar
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Windows Programming

• Windows programs are event driven
• User clicking the mouse, typing a key,... in your
  application are all events
• External events also recorded and must be taken
  care of
• E.g. other window moved, exposing the undisplayed
  parts of your window
• you need to redraw yours
• Windows records every event in a message and
  places the message in a queue for the program
  for which the message was intended
• you handle messages intended for your application
  in corresponding functions

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Windows Programming

• Windows is in control
• - manages the sharing of machine resources
  (multiple program running at the same time)
• - provides a standard user interface (MFC
  Microsoft Foundations Classes)
• All of the communication between your application
  and Windows are handled through
• the Windows Application Programming Interface
  API
• the Windows API is typically called through MFC
  objects (Microsoft Foundation Classes)
• programmer creates objects from MFC classes and
  call member functions belonging to those objects
  that in turn handles the Windows API.

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simple editor app.
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• In class we created a very simple editor using
  the AppWizard
• just choose the CEditView as your base class
  (near the last choices before making a project)
• and you will have an editor with no added code!
• Where you can type, copy, paste, save...
• This example is shown to demonstrate the powerful
  classes given by MFC.

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Creating a Windows Program

• Using the WinApp Wizard
• also see Lectures/VisualProg-instructions.htm

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Creating a Windows Program

• Two methods
• From scratch (dont do)
• Using New/Project/Win32 application
• You need to write all WinMain, ... functions
• Tell Windows what kind of window you want
• Create it etc.
• Using the New/Project/ MFC AppWizard
• Many functions written for you!
• This is what you should use (much easier)

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Windows Program From Scratch

• include ltafxwin.hgt // For the MFC class
  library
• // Application class definition
• class COurApppublic CWinApp
• public
• virtual BOOL InitInstance()
• // Window class definition
• class COurWndpublic CFrameWnd
• public
• // Class constructor
• COurWnd()
• Create(0, "Our Dumb MFC Application")
• // Function to create an instance of the main
  window
• BOOL COurAppInitInstance(void)

Given only as information - you may skip.
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Application Wizard

• Choices
• MDI (Multiple Document Interface) versus SDI
  (Single Document Interface)
• MFC as shared DLL (makes your code smaller by
  accessing the MFC library at run time, sharing
  with other processes)
• Pick a suitable base class for your view class
• CView
• CEdit
• CScroll (we will see later)
• For other choices you may for now pick default
  option

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• Four basic classes that are going to appear in
  virtually all your Windows applications
• The application class, CMyApp.
• The frame window class, CMyWnd.
• The document class, CmyDoc, defines a document to
  contain the application data.
• The view class, CMyView, which defines how data
  contained in CMyDoc is to be displayed in the
  client area of a window created by a CMyWnd
  object.

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Code Generated

• When your project is created, these files will be
  generated by the Application Wizard (if your
  project name is Draw)
• CDrawApp.cpp stuff related to the whole
  application
• CDrawDoc.cpp
• CDrawView.cpp
• ...
• CDrawDoc.h
• CDrawView.h
• ...
• You will mainly modify the View and Doc files!
  But you will also add your own files
• your classes, include files etc.

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View/Doc

• Document Collection of data in your application,
  with which the user interacts.
• View A view is an object that
• displays some or all of the data stored in a
  document,
• manages user interaction with it, e.g. selection
  and editing.
• Each view is associated by a document
• Each document is associated with one or more
  views
• To retrieve the document associated with a view
• Class CTextEditorView public CeditView
• ...
• CTextEditorDoc GetDocument()
• ...

You should add variables related to a view (not
to the document in general) to the View Class
You should add variables related to the document
(not a particular view), to the Document class.
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Generated Code

• The code is complicated but the parts you need to
  change to embed your code is easy to find and
  modify.
• Change ONLY the parts that say TODO.
• Do not change parts that you do not understand!
  Some parts of the program are Macros to help the
  AppWizard to automatically create necessary code.
  E.g.
• DECLARE_MESSAGE_MAP
• To create mapping between messages and functions
• DECLARE_DYNCREATE
• To recreate objects that were stored
• You cannot easily follow the flow of the program
• event driven program running in many threads
• begins in InitInstance

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Generated Code

• Parts marked as
• //Implementation may change in next VC release
• //Attribute data accessor functions
• //Operations mutator functions
• //Overrides virtual functions

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• winMain()
• theApp.InitInstance()
• initialize the application
• theApp.Run()
• inherited, typically no need to change

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• In Windows programming, you will extensively use
  all of the following
• Class view Members, Private data... displayed
  separately
• File view The usual
• Resource view To add/change menu items
• All on the bottom left tab
• AppWizard (to create the project)
• from New/Project/...
• ClassWizard (to add functions to associated
  messages)
• Ctrl-W or View/Class Wizard
• Resource Editor (to add/change menu items,
  icons...)

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Class Wizard

• Ctrl-W brings the Class Wizard (or choose a menu
  item, right click and choose Class Wizard)
• best way to add buttons and corresponding messages

Windows Messages
Class functions V is for Virtual W is for
Windows Message
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Dialog app. and adding dialog boxes

• Only a short demo is shown in class you can
  learn all about creating fancy dialog boxes from
  Chp. 17 when you need them (you are not
  responsible of knowing more than what is shown to
  you)

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• We made a simple example with just one dialog box
  (choose Dialog app), about which team would be
  champion. In general, you can have a dialog class
  as part of a bigger program.
• There are two main tasks
• change the dialog box by adding buttons, text,...
• connect Ids and functions to each button

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Drawing Application

• Called Sketcher in Horton

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Overview

• We want to develop a simple drawing application
  which shows the various aspects of GUI
  programming. The example program is in
  hw4-sample-draw.exe given under lectures/
• What you need for such a program is given in the
  following slides
• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Pressed, released
• Drawing the shape element
• When the mouse is released
• Keeping a list of the shape elements
• Drawing temporary shape element while the mouse
  is dragged
• When the mouse is released
• Changing the color of the drawing
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

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Working with Menus and Toolbars

• Horton Chp. 14

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How to add a button to the dialog

• Open CDraw.rc or MyEdit.rc (whatever is the
  resource file for your application)
• Add a button to the menu bar
• pop-up will bring a submenu
• ex Pen Tickness or Shape
• it will pop-up to show 2pix, 4pix or to show
  line, circle etc.
• non pop-up no submenu
• For more simpler commands (e.g. increase pen
  thickness)
• Just close the button and an ID will be assigned
  (ID_ONPEN_2PIX etc.)
• You can then add/change the ID
• Finally, you should associate a function
  (typically two) with this menu item (next slide)
• Command (e.g. to save the choice for future use
  in the document when this
  button is pressed)
• Update_Command_UI (to update the associated menu
  when one of the menu items is selected)

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Menu/IDR_DRAWTYPE menu when some document(s) are
open Menu/IDR_MAINFRAME menu when no document is
open
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How to link a function to an ID

• Ctrl-W (brings up the class wizard)
• Pick the ID you want to link a function to
• e.g. ID_THICKNESS_SMALL
• Pick CDrawDoc or CDrawView... (from the Class
  name part)
• You should pick the class which should handle
  messages associated with this ID, by first
  deciding which class you would like to associate
  with the associated data
• Does the data refer to the whole document or just
  one view of the document?
• You can answer this question, by answering if you
  go to another view, would you like the same pen
  thickness to be in effect?
• Probably yes, in that case you should put the
  pen_thickness variable inside the CDrawDoc class,
  as well as the code to handle this associated
  message.
• If you want to draw in thicker pen in a different
  VIEW, you should select the ViewClass

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How to link a function to an ID

• Ctrl-W (brings up the class wizard)
• ...
• Pick UPDATE_COMMAND_UI (called when you click on
  PenThickness, before Menu is displayed)
• - Pick Add Function
• - OnUpdateThicknessSmall() will be added to
  Cdraw.cpp
• - will handle how to update the user interface
  (UI) when this button is pressed
• set checkmark next to 2pix and
• unset checkmark next to 4pix, 6pix etc.pen
  thickness to 2
• Pick COMMAND (called when you click on 2Pix)
• - Pick Add Function
• - OnThicnessSmall() will be added to Cdraw.cpp
• - will handle what this button should do
• set pen thickness to 2

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How to link a function to an ID

• CDrawDoc.h
• protected
• int m_PenWidth
• void CDrawDocOnThicknessSmall()
• m_PenWidth SMALL
• void CDrawDocOnUpdateThicknessSmall(CCmdUI
  pCmdUI)
• pCmdUI-gtSetCheck(m_PenWidth SMALL)

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Sample Data Types

• ourConstants.h
• /element type constants/
• const WORD LINE 101U (WORD is a defined
  type meaning unsigned int)
• const WORD RECTANGLE 102U (U indicates an
  unsigned variable)
• const WORD CIRCLE 103U
• You could simply have something like this as
  well
• const int LINE 1
• const int CIRCLE 2
• const int RECTANGLE 3
• const int CURVE 4
• /pen color constants/
• const COLORREF BLACK RGB(0, 0, 0)
• const COLORREF RED RGB(255, 0, 0)
• const COLORREF GREEN RGB(0, 255, 0)
• const COLORREF BLUE RGB(0, 0, 255)
• /pen width constants/

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Code to Handle Messages

• ourConstants.h
• /pen color constants/
• const COLORREF BLACK RGB(0, 0, 0)
• const COLORREF RED RGB(255, 0, 0)
• const COLORREF GREEN RGB(0, 255, 0)
• const COLORREF BLUE RGB(0, 0, 255)
• ...
• CDrawDoc.h
• protected
• COLORREF m_Color
• int m_PenWidth
• void CDrawDocOnColorBlue()
• m_Color BLUE
• void CDrawDocOnUpdateColorBlue(CCmdUI pCmdUI)

How to state that the default color is BLACK?
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Adding ToolBar Menu Items

• For a more professional look, you should
• 1) Add alternative selection buttons for some of
  the common menu items
• (similar to A, Av etc. that MS Word has)
• 2) Add tooltips (when you linger over some
  button, it will show what that button does) pp.
  589

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Adding Icons

• Adding icons on the toolbar gives quicker access
  compared to a pop-up menu (e.g. Green color icon)
  and it is very similar to adding menu elements.
• Open resource/toolbar
• Add a new icon
• Connect the icon to the already defined
  OnColorGreen() function by sharing the same
  Object ID

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Drawing in a Window

• Horton Chp. 15

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Overview

• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Pressed, released
• Drawing the shape element
• When the mouse is released
• Keeping a list of the shape elements
• Drawing temporary shape element while the mouse
  is dragged
• When the mouse is released
• Changing the color of the drawing
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

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Drawing Basics

• Drawing in a Window
• - Where is the Window?
• - Is it open, resized, covered?
• Update the drawing
• Device Context Data structure defined by Windows
  which
• translates your output (display) requests to
  commands appropriate for the actual physical
  device used
• It has different mapping modes (pp.595-596)
• 0,0 on top left
• x
• MM_TEXT mode
• y

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Drawing Basics

• There is a member function of the View class,
  OnDraw(CDC pDC), which will be automatically
  called by Windows when your application window
  needs to be re-drawn.
• it automatically receives the current device
  context and
• sets a pointer to the Document
• You need to do your (re)drawing calls in this
  function

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Drawing Basics

• void CDrawViewOnDraw(CDC pDC)
• CDrawDoc pDoc GetDocument()
• ASSERT_VALID(pDoc)
• pDC-gtMoveTo(50,70) //move to (x,y) 50, 70
• pDC-gtLineTo(150,170) //draw a line from current
  location to 150, 170
• //changes the current location to 150,170
• Later on, you should use the POINT struct or the
  CPoint class (both already defined in MFC)
  instead of two separate variables x and y.
• Drawing circles etc. is explained in pp. 601-602
• Circle is a special type of Ellipse (gt use the
  Ellipe or Arc functions)

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Drawing in Color

• Create a CPen object with member function
• BOOL CreatePen(int penStyle, int penWidth,
  COLORREF color)
• e.g.
• CPen newPen
• newPen.CreatePen(PS_SOLID, 2, RGB(255,0,0) )
• //or
• newPen.CreatePen(PS_DASH, pDoc-gtm_pen,
  pDoc-gtm_color)
• Pen styles PS_SOLID, PS_DASH, PS_DOT,...
• Select the pen to draw with save the old one
• CPen oldPen pDC-gtSelectObject( newPen )

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Drawing in Color Temporarily

• Sometimes you may want to use a pen only for a
  certain shape, and go back to the old pen
  afterwards
• CPen oldPen pDC-gtSelectObject(newPen)
• ....
• //draw your shape
• ....
• pDC-gtSelectObject(oldPen)
• //notice that rarely it is OK to ignore the
  return value, as in here!
• You can similarly pick a brush to draw/paint with

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Drawing Opaque/Transparent

• Sometimes you need to create/select a brush in
  addition to the pen, so as to be able to draw
  filled or not-filled (opaque, transparent)
  objects
• CBrush temp(m_Color)
• //for filled/opaque objects
• CBrush pOldBrush
• static_castltCBrushgt(pDC-gtSelectObject(temp))
• //for not-filled/transparent objects
• CBrush pOldBrush
• static_castltCBrushgt(pDC-gtSelectStockObject(NULL
  _BRUSH))

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Overview

• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Pressed, released
• Drawing the shape element
• When the mouse is released
• Keeping a list of the shape elements
• Drawing temporary shape element while the mouse
  is dragged
• When the mouse is released
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

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Registering the Mouse Clicks

• Messages associated with the View class for which
  you need to add functions to handle, are as
  follows
• WM_LBUTTONDOWN //when left mouse button is
  clicked
• Will automatically add OnLButtonDown() function
• WM_LBUTTONUP //when left mouse button is
  released
• Will automatically add OnLButtonDown() function
• WM_MOUSEMOVE //when mouse moves

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Drawing the Shapes at Indicated Location

• The mouse handling functions should correspond to
  your drawing
• Left mouse down indicates the beginning of a
  shape
• Left mouse up indicates the end of a shape
• Your shape is now defined and you need to draw it

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Registering the Mouse Clicks

• void CDrawViewOnLButtonDown (UINT nFlags,
  CPoint point)
• // TODO Add your message handler code here
  and/or call default
• CViewOnLButtonDown(nFlags, point) //default
  call
• m_pt1 point //member of CDrawView
• ...
• void CDrawViewOnLButtonUp (UINT nFlags, CPoint
  point)
• // TODO Add your message handler code here
  and/or call default
• CViewOnLButtonUp(nFlags, point) //default
  call
• m_pt2 point //member of CDrawView

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Registering the Mouse Clicks

• You could also check if other mouse buttons are
  pressed
• void CDrawViewOnLButtonDown (UINT nFlags,
  CPoint point)
• // TODO Add your message handler code here
  and/or call default
• CViewOnLButtonDown(nFlags, point) //default
  call
• ...
• if (nFlags MK_MBUTTON) //is the middle button
  pressed?
• if (nFlags MK_SHIFT) //is the SHIFT KEY
  pressed?

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Getting the Area Drawn

• Tell Windows what particular area of the window
  you want to be redrawn using InvalidateRect()
  function which calls the OnDraw() function
• void CDrawViewOnLButtonUp (UINT nFlags, CPoint
  point)
• // TODO Add your message handler code here
  and/or call default
• CViewOnLButtonUp(nFlags, point) //default
  call
• m_pt2 point //member of CDrawView
• RECT r m_pt1.x,m_pt1.y,m_pt2.x,m_pt2.y
• InvalidateRect(r)
• //InvalidateRect(0) invalidates the whole
  window

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Overview

• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Pressed, released
• Drawing the shape element
• When the mouse is released
• Drawing temporary shape element while the mouse
  is dragged
• When the mouse is released
• Keeping a list of the shape elements
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

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Drawing Shapes in OnDraw() (for now)
This code can draw ONE shape correctly it needs
to be changed/extended for your homework

• void CDrawViewOnDraw(CDC pDC)
• if (pDoc-gtm_shape LINE)
• pDC-gtMoveTo(m_firstpoint)
• pDC-gtLineTo(m_lastpoint)
• else if (pDoc-gtm_shape RECTANGLE)
• CRect enclosing_rect CRect(
  m_firstpoint.x,m_firstpoint.y,
• m_lastpoint.x, m_lastpoint.y)
• pDC-gtRectangle(enclosing_rect)
• else if (pDoc-gtm_shape CIRCLE)
• //alternatively you can draw around the center
• CRect enclosing_rect CRect ( m_firstpoint.x,
  m_firstpoint.y,
• 
  m_lastpoint.x, m_lastpoint.y)
• pDC-gtEllipse(enclosing_rect)

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Normalize Rectangle

• What if the user draws the mouse from
  bottom-right to top-left?
• Your shapes should still work, but it happens
  that the first point is no longer the top-left.
• You need to normalize your rectangle to always
  m_pt1 as the top-left!
• m_EnclosingRect CRect(Start, End)
• m_EnclosingRect.NormalizeRect()
• NormalizeRect makes sure that the enclosing
  rectangle is computed correctly, even if end is
  smaller than (closer to 0,0) than start.

This rectangle needs to be normalized
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What We Have Done with the Simple Draw
Program(so far using what you have learned in
Chp. 13-15)

• The program developed so far is a basic one
• there is no color, no pen thickness, no icons,
• you can move/cover your windows and shapes
  reappear when you come back
• but only the last one - what happens??

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the object list to be used in HW4

• Simple explanation, but details and even complete
  code can be found in Horton!

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Overview

• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Pressed, released
• Drawing the shape element
• When the mouse is released
• Keeping a list of the shape elements
• Drawing temporary shape element while the mouse
  is dragged
• When the mouse is released
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

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Objects being Redrawn

• When your client area is covered and uncovered,
  your application gets a WM_PAINT message, which
  calls the OnDraw() function
• currently, only the last element is redrawn!!
• In your homework, HW4, you will add all the
  objects to a shapelist (element list) so that
  they are not lost on the canvas when the canvas
  is erased (covered)
• Then, whenever OnDraw() is called, all the
  elements will be (re)drawn
• in particular, OnDraw() will be called
  automatically when your windows needs to be
  repaint (covered and uncovered)
• this will cause all the shapes to be redrawn, not
  just the last one
• As good OOP (Obj. Orient. Prog.) practice,
• you need to first write a shape (corresponding to
  element in Horton) class.

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Storing Drawn Shapes in a List

• Lets assume you now have a CElement class from
  which you will derive your particular shape
  classes.
• Now you will implement a list of elements, in
  order to keep all the shape elements that need to
  be redrawn if the window needs repainting
• You can use the list classes offered by MFC (this
  is suggested - because the code is given and
  everything will be compatible with MFC) or
• you can make your use list structure
• If you use the MFC list, your Document class will
  have the following variables (similarly if you
  use your own list)
• COLORREF m_Color
• WORD m_Element
• int m_PenWidth
• CTypedPtrListltCObList, CElementgt m_ElementList
  

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Storing Drawn Shapes in a List

• General form CTypedPtrListltBase Class, Typegt
• CTypedPtrList lt CObList, CElement
  gt m_ElementList
• With this definition, you will have an
  m_ElementList which is a list of pointers to
  CObject
• CObject and CObList are defined in MFC
• CElement is derived from CObject class hence it
  inherits all of its functionality
• see Chp. 16 - pp.657 for more info
• Member functions
• AddTail()
• IsEmpty()
• RemoveTail()

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Drawing Objects from the List

• Hence, OnLButtonUp, you will create the new
  element,
• then you will call InvalidteRect() which will
  cause Windows call OnDraw(),
• OnDraw() will in turn will draw all the elements
• void CDrawViewOnDraw(CDC pDC)
• CDrawDoc pDoc GetDocument()
• ASSERT_VALID(pDoc)
• // TODO add draw code for native data here
• POSITION current pDoc-gtGetListHeadPosition()
• //return the m_elementlists head
• CElement pElement 0
• while(current )
• pElement pDoc-gtGetNext(current ) //return
  the next list item
• //if the element is visible...
• if(pDC-gtRectVisible(pElement-gtGetBoundRect()))
• pElement-gtDraw(pDC) //draw it

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OnDraw

• Hence, before we call InvalidateRect(), we must
  have our element list updated
• - works both for drawing and deleting!
• Misc. Notes
• class CElement public Cobject
• must not be an abstract class (thought it is more
  appropriate that it is)
• because in order to save the elements, we will
  need that an instance of the element class be
  created (requirement of the MFC)
• AfxMessageBox(Some message,MB_OK)
• You may use this for debugging or to display
  error... messages

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Temporary Objects
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Overview

• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Pressed, released
• Drawing the shape element
• When the mouse is released
• Keeping a list of the shape elements
• Drawing temporary shape element while the mouse
  is dragged
• When the mouse is released
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

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Temporary Objects pp 635

• When you use a professional drawing program, as
  you move the mouse, you see a temporary shape
• if you are drawing a rectangle, you see it grow
  slowly from start to end
• this is so that you see visually what your object
  will look like
• In order to add this feature, you need to track
  the MOUSEMOVE event
• - at each new mouse coordinate, you need to
  draw the bigger shape
• - and erase the previous one

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Displaying the Temporary Object
As the cursor moves, you should erase the
previous shape object (smaller rect.) and display
the current shape object (solid rectangle).
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Temporary Objects pp 632-635

• void CDrawViewOnMouseMove(UINT nFlags, CPoint
  point)
• CClientDC aDC(this) //get a client Device
  Context
• //if left button is pressed and the window
  that captured the first mouse button is this
• if((nFlags MK_LBUTTON) (thisGetCapture()))
  
• m_SecondPoint point
• //Erase the temporary element
• //Redraw the new one using the two mouse
  points

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Temporary Objects pp 632-635

• void CDrawViewOnMouseMove(UINT nFlags, CPoint
  point)
• CClientDC aDC(this) //get a client Device
  Context
• aDC.SetROP2(R2_NOTXORPEN)
• if((nFlags MK_LBUTTON) (thisGetCapture()))
  
• m_SecondPoint point
• //Erase the temporary element
• if(m_pTempElement)
• m_pTempElement-gtDraw(aDC) //erases the old
  one due to NOTXOR
• delete m_pTempElement
• m_pTempElement0
• //Redraw the new one
• m_pTempElement CreateElement()
• m_pTempElement-gtDraw(aDC)
• //this is the actual code, you can plug this
  into your homework!!!

71
Drawing Modes Used in Temporary Objectspp. 632
Drawing the temp object under NotXor first time
will draw a red rectangle.
72
Drawing Modes Used in Temporary Objects
Drawing the temp object under NotXor second time
will draw a white rectangle effectively erasing
it.
73
Drawing Modes Used in Temporary Objectspp. 632
Shape drawn the first time Shape erased
the second time
What would happen with a different background
color? Same thing shape is drawn the first time
and erased (same as BG) the 2nd time.
74
Capturing WM Messages You may skip for now

• This is a less essential feature relating to what
  happens if you try to draw (finish) your shapes
  outside the current window. You may skip it for
  now and add few lines of code to handle this
  situation after the break once I go over this
  in detail.
• Windows send messages only to the window under
  the Cursor. So, if you finish your shape outside
  of the current Window, you wont get the WM
  messages
• You can use SetCapture() to receive all messages
• Ask to capture all further Mouse messages when
  you receive the first mouse message (LMouseDown)
• The function GetCapture() returns a pointer to
  the Window that issued the SetCapture() command
• You can check if you are that window using the
  following command, in other Mouse Message Handler
  functions
• if (this GetCapture())
• You will receive all messages until you call
  ReleaseCapture()
• Ask to no longer capture mouse messages (until
  you specifically ask to do so again, in
  LButtonDown) once you are done drawing your
  current shape
• You dont want to capture left button down
  messages done outside the current window

75
Multiple Views
76
Overview

• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Pressed, released
• Drawing the shape element
• When the mouse is released
• Keeping a list of the shape elements
• Drawing temporary shape element while the mouse
  is dragged
• When the mouse is released
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

77
Updating All the Views

• You can get another view of the document by
  Window/New Window
• Multiple views are a property of MDI applications
• For instance, one view can be a zoom view
• When you have multiple views, the shapes should
  be drawn in the other views as well
• Use UpdateAllViews() instead of InvalidateRect()
• Automatically calls OnUpdate()
• Add OnUpdate() to CDrawView class (ctrl-W)
• to catch the information sent to the
  UpdateAllViews()
• Calls InvalidateRect()
• See Horton pp. 670-673 for details.

78
Features not Shown

• These slides do not cover the following more
  advanced features covered in Horton
• Moving or Deleting Shapes
• Drawing curves
• Scrolling
• Scaling
• ...
• You can easily learn them by reading the
  appropriate parts of Horton.

79
Serialization

• Saving and Restoring the Document
• Horton Chp. 18

80
Overview

• Adding menu items and associated functionality
  (Chp. 14)
• Basic drawing on the screen (Chp. 15)
• Registering and handling mouse clicks (Chp. 15)
• Pressed, released
• Drawing the shape element
• When the mouse is released
• Keeping a list of the shape elements
• Drawing temporary shape element while the mouse
  is dragged
• When the mouse is released
• Updating all the views (Chp. 16)
• Serializing (saving) the document (Chp. 18)

81
Saving your document

• In order to restore the file you created (drawn)
  after you save and close it, you must write the
  complete specifications of the document
• shape elements created
• last selected pen etc (less important, but you
  should do it here)
• This operation is very easy due to the CArchive
  class of MFC.
• The engine that drives the serialization
  mechanism
• Provides MFC equivalent of C code to read and
  write to/from the keyboard and the screen...
• overloads the gtgt and ltlt operators

82
Saving/Restoring your document

• Call Serialize for the document to save document
  specific variables
• Call serialize for the shape element list for
  generic functionality
• This will call serialize for each element for
  variables specific for each element
• That elements shape, color, thickness
• Current pen
• Current shape
• (whatever you need to bring back the document as
  you left it)

83
Document Serialization

• void CDrawDocSerialize(CArchive
  ar) //automatically created and passed
• m_ElementList.Serialize(ar) //Serialize the
  element list
• if(ar.IsStoring()) //Serialize the rest
• //TODO Add storing code here
• else
• //TODO Add retrieving code here

84

• void CDrawDocSerialize (CArchive ar)
• m_ElementList.Serialize(ar) //Serialize the
  element list
• if(ar.IsStoring())
• ar ltlt m_Color //Store the current color
• ltlt m_Element //the current element type
• ltlt m_PenWidth //and the current pen
  width
• else
• ar gtgt m_Color //Retrieve the last used
  color
• gtgt m_Element //the last used element
  type
• gtgt m_PenWidth //and the last used pen
  width
• //this is the actual code you can use in your
  homework!

85
Serializing an Element

• No need to write the Serialization code for the
  ElementList which is already defined
• CTypedPtrListltCObList, CElementgt ElementList
• However, you need to write Serialization code for
  individual elements
• You must use the Serialization member function of
  the CObject class to store and retrieve
  information from an archive
• CElement must be derived from CObject

86
Element Class

• class CElement public CObject
• DECLARE_SERIAL(CElement) //why you need this
  macro here pp756
• protected
• COLORREF m_Color
• CRect m_EnclosingRect
• int m_Pen
• public
• virtual CElement()
• virtual void Draw(CDC pDC) const
• CRect GetBoundRect() const
• virtual void Serialize(CArchive ar)

87

• There are 3 levels of functionality available to
  your classes when derived from MFC class object
  (in increasing amount of functionality)
• DECLARE_DYNAMIC()
• DECLARE_DYNCREATE()
• DECLARE_SERIAL()
• DECLARE_SERIAL(CElement)
• Macro for MFC to provide support for run-time
  class information, dynamic object creation and
  serialization of objects.
• See page 756 for details.
• IMPLEMENT_SERIAL(CElement, CObject,
  VERSION_NUMBER)
• You must use this matching macro in the file
  containing class implementation see Horton Chp.
  18.

88
Serializing an Element

• void CElementSerialize(CArchive ar)
• CObjectSerialize(ar) //call the base class
  function to the the main job
• if(ar.IsStoring())
• ar ltlt m_Color //Store the objects color
• ltlt m_EnclosingRect //the enclosing
  rectangle
• ltlt m_Pen //and the objects pen width
• else
• ar gtgt m_Color //Retrieve the objects color
• gtgt m_EnclosingRect //the enclosing
  rectangle
• gtgt m_Pen //and the objects pen width
• //this is the actual code you can use in your
  homework!

89
Line Serialization

• void CLineSerialize(CArchive ar)
• CElementSerialize(ar)
• //store and retrieve line specific variables
• if(ar.IsStoring())
• ar ltlt m_StartPoint
• ltlt m_EndPoint
• else
• ar gtgt m_StartPoint
• gtgt m_EndPoint
• //this is the actual code you can use in your
  homework!

90

• You can also detect when a document is changed,
  so as to ask if the document should be saved when
  the user tries to exit.

91
HW4
92
HW4 Summary and highlights(see hw4-2005.doc for
exact specs.)

• Write a Draw program (similar to Sketcher in
  Horton) that works exactly like
• hw4-sample-draw.exe given under lectures/ (if it
  works better, thats FINE)
• If you cannot do all the functionality, see the
  hw definition to get partial credit
• but all parts of the code you should write is in
  the book, so you should have no problem! (but a
  little bit of work, yes)
• You are given the following files in
  hw4-starter.zip!
• ourconstants.h (use exactly)
• elements.h (use exactly)
• elements.cpp (few lines are erased so that you
  learn better)
• You can use these files, but of course this means
  that your data structures must be compatible with
  them. If you want to change something (say how
  circles are represented), you shd. change the
  corresponding part in these code as well, to work
  properly!
• You are also given a lot of the code in these
  slides (most of them will be used with no or
  almost no change)!
• If something isnt explained in the slides, you
  need to refer to Horton.

93
HW4 Summary and highlights(see hw4.doc for exact
specs.)

• So you need to
• complete elements.cpp (remember element means
  shape element)
• simple
• write the application using elements.h,cpp
• do so as we have done in class
• use the APP Wizard
• add buttons etc. slowly
• complete the projects unspecified parts (e.g.
  what should the document destructor do etc.)
• Suggestion You should start with just one or two
  shapes, and no color or pen thickness, and once
  they work, you can add the rest without having to
  change/relocate everything if you have a problem.
• Attention it is very difficult to change names
  of functions once you have added them since
  Windows ties macros with that name. You should
  restart building the project if you need major
  changes. Same thing if you change project base
  class etc.

94
HW4 Summary and highlights(see hw4-2005.doc for
exact specs.)

• The main change will be to modify the current
  code for LeftMouseButtonUp to
• - add the shape (element) to m_ElementList
• - requests for an update of all the views (pp.
  672) of the document
• - add OnUpdate() function as specified
• - change the OnDraw() function to what is given
  in the previous slides

95
What Else Could be Added to the Project

• A project like this would typically have other
  useful features (which you are not asked to do,
  but can find in Horton).
• Moving shapes
• Using brushes, using curves and freestyle drawing
• Making shapes non-opaque
• Scrolling views
• Printing functionality