1. Bitmap (Chapter 15)

2. CBrush with bitmap A Brush defines how to fill a region
Different kinds of the brush (by using different constructor)
Various Brushes
Example
Solid brush: filling with a color
CBrush brush(RGB(255, 0, 0));
Hatch brush: filling with a pattern
CBrush brush(HS_DIAGCROSS, RGB(255, 0, 0));
Bitmap brush: filling with an image
CBitmap bitmap;
bitmap.LoadBitmap(IDB_BITMAP1);
CBrush brush(&bitmap);

3. Bitmap?
Represent an image as a set of dots(pixels)

4. How to use Bitmap in Visual studio
Adding a bitmap in the resource view
Include the header file “resource.h” before using
#include "resource.h"

5. CBitmap CBitmap: a class for storing a bitmap Example: CBitmap bitmap;
Resource ID
CBitmap bitmap;
bitmap.LoadBitmap(IDB_BITMAP1);
CBrush brush(&bitmap);
dc.SelectObject(&brush);
dc.Rectangle(0,0,200,200);

6. CBitmap::GetBitmap( )
How to get the information about the bitmap:
int CBitmap::GetBitmap (BITMAP* pBitMap) ;
struct BITMAP {
int bmType;
int bmWidth; // width of the bitmap (pixel)
int bmHeight; // height of the bitmap (pixel)
int bmWidthBytes;
BYTE bmPlanes;
BYTE bmBitsPixel;
LPVOID bmBits; };

7. CBitmap::GetBitmap( )
Example:
CBitmap bitmap;
bitmap.LoadBitmap(IDB_BITMAP1);
BITMAP bmpinfo;
bitmap.GetBitmap(&bmpinfo);
CString str;
str.Format(_T(“width = %d, height = %d\n”),
bmpinfo.bmWidth, bmpinfo.bmHeight);
dc.TextOut(100,100,str);

8. Display the bitmap directly
Copy the image directly into the screen  Block Transfer
Process:
Original Device Context
Preparing one more device context
Draw image at the new DC
Copy the new DC into the original DC

9. Display the bitmap directly
Copy the image directly into the screen  Block Transfer
Process:
Original Device Context CPaintDC dc;
Preparing one more device context CDC memDc; CDC::CreateCompatibleDC(..);
Draw image at the new DC CDC::SelectObject(…);
Copy the new DC into the original DC dc.BitBlt(…);
Bit Block Transfer (BitBlt)

10. Example CPaintDC dc(this); CBitmap bitmap;
bitmap.LoadBitmap(IDB_BITMAP1);
BITMAP bmpInfo;
bitmap.GetBitmap(&bmpInfo);
CDC memDc;
memDc.CreateCompatibleDC(&dc);
memDc.SelectObject(&bitmap);
dc.BitBlt(100, 100, bmpInfo.bmWidth, bmpInfo.bmHeight,
&memDC, 0, 0, SRCCOPY);

11. (original device context) (new memory device context)
Bit Block Transfer
BitBlt
Parameter for copy:
SRCCOPY
BOOL BitBlt (int x, int y, int nWidth, int nHeight, CDC* pSrcDC, int xSrc, int ySrc, DWORD dwRop) ;
(original device context)
pSrcDC
(new memory device context) x y
nWidth
nHeight
xSrc
ySrc
nWidth
nHeight

12. Bit Block Transfer with stretching
StretchBlt:
BOOL StretchBlt (int x, int y, int nWidth, int nHeight, CDC* pSrcDC, int xSrc, int ySrc, int nSrcWidth, int nSrcHeight, DWORD dwRop) ;
pSrcDC
(new memory device context)
ySrc
nSrcWidth
xSrc
nSrcHeight
(original device context) y
nWidth x
nHeight

13. More Advanced Drawing: Double Buffering

14. The Problems: Image displays while drawing
Especially when using a slow computer
It is blinking when redrawing
When invalidating, it first erases the scene.

15. Double Buffering Using two Device Context
1. one for painting (Back Buffer)
2. the other for displaying (Front Screen Buffer)

16. Draw on Memory and Copy at once
Process:
1. making a memory dc (CreateCompatibleDC)
2. preparing a bitmap for storing the image (CreateCompatibleBitmap)
3. Selecting bitmap (SelectObject)
4. Drawing
5. Copy the image into the original DC (BitBlt)
 Draw on memory and Copy it at once: Double Buffering

17. Draw on Memory and Copy at once
CPaintDC dc(this);
CRect rect;
GetClientRect(&rect);
CDC memDC;
memDC.CreateCompatibleDC(&dc);
CBitmap bitmap;
bitmap.CreateCompatibleBitmap(&dc,rect.Width(),rect.Height());
memDC.SelectObject(&bitmap);
memDC.Rectangle(0,0,100,100);
dc.BitBlt(0, 0, rect.Width(), rect.Height(), &memDC,
0, 0, SRCCOPY);

18. Double Buffering using bitmap
Drawing is fast.
Still blinking
 Because it always erases when redrawing
 Do nothing at the message handler “Erase background”
Solution: Change the WM_ERASEBKGND message handler

19. WM_ERASEBKGND
WM_ERASEBKGND: when erasing the screen

20. WM_ERASEBKGND handler
WM_ERASEBKGND: when erasing the screen
Do nothing here but return true
BOOL CMainWindow::OnEraseBkgnd(CDC* pDC) {
// TODO: Add your message handler code here and/or call default
// return CWnd::OnEraseBkgnd(pDC);
return true; }

21. Announcement
Announcement about Homework #2 will be available at 9:00 PM TODAY
Check the our homepage
Due Date will be 2012/04/12 (Thursday)

22. Chapter 3 The mouse and the Keyboard

23. Getting input from the Mouse

24. Client-Area Mouse Messages
Sent When
WM_LBUTTONDOWN
The left mouse button is pressed
WM_LBUTTONUP
The left mouse button is released
WM_LBUTTONDBLCLK
The left mouse button is double-clicked
WM_MBUTTONDOWN
The middle mouse button is pressed
WM_MBUTTONUP
The middle mouse button is released
WM_MBUTTONDBLCLK
The middle mouse button is double-clicked
WM_RBUTTONDOWN
The right mouse button is pressed
WM_RBUTTONUP
The right mouse button is released
WM_RBUTTONDBLCLK
The right mouse button is double-clicked
WM_MOUSEMOVE
The cursor is moved over the client area

25. Client-Area Mouse Messages
Messages for Mouse Events
When clicking Left button
Clicking and Dragging
When moving
Double clicking
WM_MOUSEMOVE
WM_LBUTTONDOWN
WM_LBUTTONDOWN
WM_LBUTTONDOWN
WM_MOUSEMOVE
WM_LBUTTONUP
WM_MOUSEMOVE
WM_LBUTTONUP
WM_MOUSEMOVE
WM_MOUSEMOVE
WM_LBUTTONDBLCLK
WM_MOUSEMOVE
WM_MOUSEMOVE
WM_LBUTTONUP
WM_MOUSEMOVE
WM_LBUTTONUP

26. Client-Area Mouse Messages
Message-map macros and Message handlers
Message
WM_LBUTTONDOWN
WM_LBUTTONUP
WM_LBUTTONDBLCLK
WM_MBUTTONDOWN
WM_MBUTTONUP
WM_MBUTTONDBLCLK
WM_RBUTTONDOWN
WM_RBUTTONUP
WM_RBUTTONDBLCLK
WM_MOUSEMOVE
Message-Map Macro
ON_WM_LBUTTONDOWN()
ON_WM_LBUTTONUP()
ON_WM_LBUTTONDBLCLK()
ON_WM_MBUTTONDOWN()
ON_WM_MBUTTONUP()
ON_WM_MBUTTONDBLCLK()
ON_WM_RBUTTONDOWN()
ON_WM_RBUTTONUP()
ON_WM_RBUTTONDBLCLK()
ON_WM_MOUSEMOVE()
Handling function
OnLButtonDown
OnLButtonUp
OnLButtonDblClk
OnMButtonDown
OnMButtonUp
OnMButtonDblClk
OnRButtonDown
OnRButtonUp
OnRButtonDblClk
OnMouseMove

27. How to add the event handler
Using “Properties” window of CMainWindow

28. Mouse Message Handler Prototype of the Handler function: nFlags
Status of the mouse buttons and the Shift and Ct기 key at the time when the message was generated
afx_msg void On##### (UINT nFlags, CPoint point) ;
Bit Mask
Meaning
MK_CONTROL
Ctrl key is pressed
MK_SHIFT
Shift key is pressed
MK_LBUTTON
Mouse left button is pressed
MK_MBUTTON
Mouse middle button is pressed
MK_RBUTTON
Mouse right button is pressed

29. Mouse Message Handler Prototype of the Handler function: nFlags
afx_msg void On##### (UINT nFlags, CPoint point) ;
void CChildView::OnLButtonDown(UINT nFlags, CPoint point) {
if(nFlags & MK_SHIFT){
// if shift key is pressed }
if(nFlags & MK_RBUTTON){
// if right button is pressed at the same time
CWnd ::OnLButtonDown(nFlags, point);

30. Mouse Message Handler Prototype of the Handler function: point
Location of the cursor
afx_msg void On##### (UINT nFlags, CPoint point) ;
void CChildView::OnLButtonDown(UINT nFlags, CPoint point) {
CClientDC dc(this);
CPoint pt = point;
dc.Rectangle(pt.x-100, pt.y+100, pt.x+100, pt.y-100);
CWnd ::OnLButtonDown(nFlags, point); }

31. Coding practice: Line drawing 1
Draw lines by using mouse
Key Idea:
Remembering the beginning and ending position
When the mouse left button is down
Set the position as the beginning point
When the mouse left button is released
Set the position as the ending point
Drawing the line

32. Coding practice: Line drawing 2
Draw Lines by using Mouse
Show the lines even when dragging the mouse (rubber band effect)
Key Idea:
Remembering the beginning and ending position
When the mouse left button is down
Set the position as the beginning point
When dragging the mouse
Set the position as the ending point
Drawing the line
When the mouse left button is released

33. Any problem?
What happen when moving the mouse outside the window’s client area while dragging?

34. Capturing the mouse Mouse Capture: Related function:
Receiving mouse messages no matter where the mouse goes on the screen while dragging
Related function:
Function
Meaning
SetCapture()
Starting Mouse Capturing
ReleaseCapture()
Ending mouse Capturing
GetCapture()
Returns CWnd pointer that owns the capture

35. Nonclient-Area Mouse Messages
When the mouse is clicked or moved in a window’s nonclient area:
Message
Sent When
WM_NCLBUTTONDOWN
The left mouse button is pressed.
WM_NCLBUTTONUP
The left mouse button is released.
WM_NCLBUTTONDBLCLK
The left mouse button is double-clicked.
WM_NCMBUTTONDOWN
The middle mouse button is pressed.
WM_NCMBUTTONUP
The middle mouse button is released.
WM_NCMBUTTONDBLCLK
The middle mouse button is double-clicked.
WM_NCRBUTTONDOWN
The right mouse button is pressed.
WM_NCRBUTTONUP
The right mouse button is released.
WM_NCRBUTTONDBLCLK
The right mouse button is double-clicked.
WM_NCMOUSEMOVE
The cursor is moved over the window's nonclient area.

36. Nonclient-Area Mouse handlers
Massage-map Macros and Handlers
Message
Message-Map Macro
Handling Function
WM_NCLBUTTONDOWN
ON_WM_NCLBUTTONDOWN
OnNcLButtonDown
WM_NCLBUTTONUP
ON_WM_NCLBUTTONUP
OnNcLButtonUp
WM_NCLBUTTONDBLCLK
ON_WM_NCLBUTTONDBLCLK
OnNcLButtonDblClk
WM_NCMBUTTONDOWN
ON_WM_NCMBUTTONDOWN
OnNcMButtonDown
WM_NCMBUTTONUP
ON_WM_NCMBUTTONUP
OnNcMButtonUp
WM_NCMBUTTONDBLCLK
ON_WM_NCMBUTTONDBLCLK
OnNcMButtonDblClk
WM_NCRBUTTONDOWN
ON_WM_NCRBUTTONDOWN
OnNcRButtonDown
WM_NCRBUTTONUP
ON_WM_NCRBUTTONUP
OnNcRButtonUp
WM_NCRBUTTONDBLCLK
ON_WM_NCRBUTTONDBLCLK
OnNcRButtonDblClk
WM_NCMOUSEMOVE
ON_WM_NCMOUSEMOVE
OnNcMouseMove

37. Nonclient-Area Mouse handlers
Prototype of the handling function
nHitTest
A hit test code indicates where the event occurred.
point
Location at which the event occurred (in screen coordinate)
Use CWnd::ScreenToClient() function to convert screen coord to client coord.
afx_msg void OnNc* (UINT nHitTest, CPoint point) ;

38. Nonclient-Area Mouse Handlers
nHitTest
Value
Corresponding Location
HTCAPTION
The title bar
HTCLOSE
The close button
HTGROWBOX
The restore button (same as HTSIZE)
HTHSCROLL
The window's horizontal scroll bar
HTMENU
The menu bar
HTREDUCE
The minimize button
HTSIZE
The restore button (same as HTGROWBOX)
HTSYSMENU
The system menu box
HTVSCROLL
The window's vertical scroll bar
HTZOOM
The maximize button