patblt.cpp File Reference

#include <windows.h>

Include dependency graph for patblt.cpp:

Go to the source code of this file.

Functions
LRESULT CALLBACK	MainWndProc (HWND HWnd, UINT Msg, WPARAM WParam, LPARAM LParam)
int APIENTRY	WinMain (HINSTANCE HInstance, HINSTANCE, LPTSTR, int nCmdShow)
void	MapRect (IN HWND HWndFrom, IN HWND HWndTo, IN OUT RECT &RMap)
void	RenderTrackingRect (IN HDC HDestDC, IN const RECT &RRender)

Variables
HINSTANCE	HInst
const char *	WndClassName = "GMainWnd"
HDC	HMemDC = NULL
HBITMAP	HOldBmp = NULL
const char *	filename = "PENGUIN.BMP"
RECT	RImage = {225, 110, 225, 110}
bool	is_tracking = false
HDC	HScreenDC = NULL
POINT	PMouse = {0, 0}
RECT	RTrack = {0, 0, 0, 0}
const int	line_width = 5

Function Documentation

MainWndProc()

LRESULT CALLBACK MainWndProc	(	HWND	HWnd,
		UINT	Msg,
		WPARAM	WParam,
		LPARAM	LParam
	)

Definition at line 128 of file patblt.cpp.

{
   switch (Msg)
   {
      case WM_CREATE:
      {
         // create a memory DC
         HMemDC = CreateCompatibleDC(NULL);
         if (HMemDC)
         {
            // load the penguin bitmap
            HBITMAP HBmp = static_cast<HBITMAP>(
               LoadImage(HInst, filename, IMAGE_BITMAP, 0, 0,
                         LR_LOADFROMFILE | LR_DEFAULTSIZE)
               );
            if (HBmp)
            {
               // get the bitmap's dimensions
               BITMAP bmp;
               if (GetObject(HBmp, sizeof(BITMAP), &bmp))
               {
                  RImage.right += bmp.bmWidth;
                  RImage.bottom += bmp.bmHeight;
 
                  // realize the bitmap
                  HOldBmp = static_cast<HBITMAP>(
                     SelectObject(HMemDC, HBmp)
                     );
               }
               else DeleteObject(HBmp);
            }
         }
         break;
      }
      case WM_LBUTTONDOWN:
      {
         PMouse.x = LOWORD(LParam);
         PMouse.y = HIWORD(LParam);
 
         RECT RClient;
         if (PtInRect(&RImage, PMouse) &&
             GetClientRect(HWnd, &RClient))
         {
            MapRect(HWnd, HWND_DESKTOP, RClient);
            ClipCursor(&RClient);
 
            // grab a handle to the screen DC and clip
            // all output to the client area of our window
            HScreenDC = GetDC(NULL);
            HRGN HClipRgn = CreateRectRgnIndirect(&RClient);
            SelectClipRgn(HScreenDC, HClipRgn);
            DeleteObject(HClipRgn);
 
            CopyRect(&RTrack, &RImage);
            MapRect(HWnd, HWND_DESKTOP, RTrack);
 
            // render the first tracking rect
            RenderTrackingRect(HScreenDC, RTrack);
            is_tracking = true;
         }
         break;
      }
      case WM_MOUSEMOVE:
      {
         if (HScreenDC && is_tracking)
         {
            POINT PCurrent = {LOWORD(LParam), HIWORD(LParam)};
            const int dX = PCurrent.x - PMouse.x;
            const int dY = PCurrent.y - PMouse.y;
 
            // erase the previous rectangle
            RenderTrackingRect(HScreenDC, RTrack);
            // update the postion
            OffsetRect(&RTrack, dX, dY);
            // render the new tracking rectangle
            RenderTrackingRect(HScreenDC, RTrack);
 
            // update the mouse position
            memcpy(&PMouse, &PCurrent, sizeof(POINT));
         }
         break;
      }
      case WM_LBUTTONUP:
      {
         // clean up
         if (is_tracking)
         {
            is_tracking = false;
            SelectClipRgn(HScreenDC, NULL);
            ReleaseDC(NULL, HScreenDC);
 
            InvalidateRect(HWnd, &RImage, true);
            CopyRect(&RImage, &RTrack);
            MapRect(HWND_DESKTOP, HWnd, RImage);
            InvalidateRect(HWnd, &RImage, true);
 
            ClipCursor(NULL);
         }
         break;
      }
      case WM_PAINT:
      {
         PAINTSTRUCT ps;
         HDC Hdc = BeginPaint(HWnd, &ps);
         try
         {
            //
            // TODO: Add palette support...
            //
 
            // render the penguin
            BitBlt(Hdc, RImage.left, RImage.top,
                   RImage.right - RImage.left,
                   RImage.bottom - RImage.top,
                   HMemDC, 0, 0,
                   SRCCOPY);
         }
         catch (...)
         {
            EndPaint(HWnd, &ps);
         }
         EndPaint(HWnd, &ps);
         break;
      }
      case WM_DESTROY:
      {
         // clean up
         if (HOldBmp)
         {
            DeleteObject(SelectObject(HMemDC, HOldBmp));
         }
         if (HMemDC)
         {
            DeleteDC(HMemDC);
         }
         PostQuitMessage(0);
         return 0;
      }
   }
   return DefWindowProc(HWnd, Msg, WParam, LParam);
}

Referenced by WinMain().

MapRect()

void MapRect	(	IN HWND	HWndFrom,
		IN HWND	HWndTo,
		IN OUT RECT &	RMap
	)

Definition at line 85 of file patblt.cpp.

{
   MapWindowPoints(
      HWndFrom, HWndTo,
      reinterpret_cast<LPPOINT>(&RMap), 2
      );
}

Referenced by MainWndProc().

RenderTrackingRect()

void RenderTrackingRect	(	IN HDC	HDestDC,
		IN const RECT &	RRender
	)

Definition at line 97 of file patblt.cpp.

{
   const int width = RRender.right - RRender.left;
   const int height = RRender.bottom - RRender.top;
   const DWORD dwROP3 = DSTINVERT; // experiment with others
 
   // render top bar
   PatBlt(HDestDC,
          RRender.left, RRender.top,
          width, line_width,
          dwROP3);
   // render bottom bar
   PatBlt(HDestDC,
          RRender.left, RRender.bottom - line_width,
          width, line_width,
          dwROP3);
   // render left bar
   PatBlt(HDestDC,
          RRender.left, RRender.top + line_width,
          line_width, height - (2 * line_width),
          dwROP3);
   // render right bar
   PatBlt(HDestDC,
          RRender.right - line_width, RRender.top + line_width,
          line_width, height - (2 * line_width),
          dwROP3);
 
}

Referenced by MainWndProc().

WinMain()

int APIENTRY WinMain	(	HINSTANCE	HInstance,
		HINSTANCE	,
		LPTSTR	,
		int	nCmdShow
	)

Definition at line 25 of file patblt.cpp.

{
   HInst = HInstance;
 
   WNDCLASS wc;
   memset(&wc, 0, sizeof(WNDCLASS));
 
   wc.style = CS_VREDRAW | CS_HREDRAW;
   wc.lpszClassName = WndClassName;
   wc.lpfnWndProc = MainWndProc;
   wc.hInstance = HInstance;
   wc.hCursor = LoadCursor(NULL, IDC_ARROW);
   wc.hbrBackground = static_cast<HBRUSH>(
      GetStockObject(BLACK_BRUSH)
      );
 
   if (RegisterClass(&wc))
   {
      HWND HWnd =
         CreateWindow(WndClassName,
                      TEXT("PatBlt Tracking Rect Demo"),
                      WS_OVERLAPPEDWINDOW | WS_CAPTION |
                      WS_VISIBLE | WS_CLIPCHILDREN,
                      CW_USEDEFAULT, CW_USEDEFAULT, 640, 480,
                      NULL, NULL, HInst, NULL);
 
      if (HWnd)
      {
         ShowWindow(HWnd, nCmdShow);
         UpdateWindow(HWnd);
 
         MSG msg;
         while (GetMessage(&msg, NULL, 0, 0))
         {
             TranslateMessage(&msg);
             DispatchMessage(&msg);
         }
      }
    }
    return 0;
}

Variable Documentation

filename

const char* filename = "PENGUIN.BMP"

Definition at line 73 of file patblt.cpp.

HInst

HINSTANCE HInst

Definition at line 19 of file patblt.cpp.

Referenced by MainWndProc(), and WinMain().

HMemDC

HDC HMemDC = NULL

Definition at line 71 of file patblt.cpp.

Referenced by MainWndProc().

HOldBmp

HBITMAP HOldBmp = NULL

Definition at line 72 of file patblt.cpp.

Referenced by MainWndProc().

HScreenDC

HDC HScreenDC = NULL

Definition at line 78 of file patblt.cpp.

Referenced by MainWndProc().

is_tracking

bool is_tracking = false

Definition at line 77 of file patblt.cpp.

Referenced by MainWndProc().

line_width

const int line_width = 5

Definition at line 81 of file patblt.cpp.

Referenced by RenderTrackingRect().

PMouse

POINT PMouse = {0, 0}

Definition at line 79 of file patblt.cpp.

Referenced by MainWndProc().

RImage

RECT RImage = {225, 110, 225, 110}

Definition at line 74 of file patblt.cpp.

Referenced by MainWndProc().

RTrack

RECT RTrack = {0, 0, 0, 0}

Definition at line 80 of file patblt.cpp.

Referenced by MainWndProc().

WndClassName

const char* WndClassName = "GMainWnd"

Definition at line 20 of file patblt.cpp.

Referenced by WinMain().