main.c

JPEG基本系统的解码器

#include <windows.h>
#include <commdlg.h>
#include <string.h>
#include "jpeg.h"
////////////////////////////////////////////////////////////
int  PASCAL WinMain (HANDLE, HANDLE, LPSTR, int);
LRESULT CALLBACK MainWndProc(HWND , UINT,WPARAM, LPARAM);
extern void ScrollProc (HWND hWnd, int message, WORD wPos, WORD wScrollType);
extern void DisProc(HWND hWnd,HGLOBAL hbi);
//extern void SizeProc(HWND hWnd);
extern void GetJPGSize(char *fn);
extern void DecodeJPG(HWND ,char *,HGLOBAL *);
extern void FitNewSize (HWND hWnd);
void getopenname(HWND hWnd,char *openname);
////////////////////////////////////////////////////////////
HINSTANCE hinst;
HGLOBAL hbi;
HMENU   hMenu;
int     imgwidth,imgheight;
BOOL    HSCROLL,VSCROLL;
/*------------------------- WinMain() ------------------------*/
int PASCAL WinMain (HANDLE hInstance, HANDLE hPrevInstance,
		    LPSTR lpszCmdLine, int nCmdShow)
{
	MSG       msg;
  	HWND      hWnd;
   	WNDCLASS  wndclass;
    RECT rc;
    int       DesktopWidth,DesktopHeight,FrameLeft,FrameTop,FrameWidth,FrameHeight;
    
    hinst=hInstance;
   	if ( ! hPrevInstance )
    	{
     	wndclass.style = CS_HREDRAW | CS_VREDRAW;
     	wndclass.lpfnWndProc = MainWndProc;
     	wndclass.cbClsExtra = 0;
     	wndclass.cbWndExtra = 0;
     	wndclass.hInstance = hInstance;
     	wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION);
     	wndclass.hCursor = LoadCursor (NULL, IDC_ARROW);
     	wndclass.hbrBackground = GetStockObject (WHITE_BRUSH);
     	wndclass.lpszMenuName =  "FileMenu";
     	wndclass.lpszClassName = "JPEG Viewer";

     	if ( ! RegisterClass (&wndclass) )
       		return FALSE;
    	}
	hMenu = LoadMenu(hInstance,"FileMenu");
	
    GetWindowRect(GetDesktopWindow(),&rc);           
    DesktopWidth = rc.right - rc.left;
    DesktopHeight = rc.bottom - rc.top;
    FrameLeft = DesktopWidth / 10;
    FrameTop  = DesktopHeight /10;
    FrameWidth = FrameLeft*8;
    FrameHeight = FrameTop*8;
	
   	hWnd = CreateWindow (
						"JPEG Viewer",
						"JPEG Viewer",
						WS_OVERLAPPED|WS_CAPTION|WS_SYSMENU,//|WS_THICKFRAME, 
						FrameLeft,
						FrameTop,
						FrameWidth,
						FrameHeight,
						NULL,
						NULL,
						hInstance,
						NULL);
	if ( ! hWnd )
		return FALSE;
   
   	SetMenu(hWnd,hMenu);	

   	ShowWindow (hWnd, nCmdShow);
   	UpdateWindow (hWnd);

   	while ( GetMessage (&msg, NULL, 0, 0) )
    	{
      	TranslateMessage (&msg);
      	DispatchMessage (&msg);
    	}

   	return msg.wParam;
}

/*---------------------- WndProc() ---------------------------*/
LRESULT CALLBACK MainWndProc(HWND hWnd, UINT message,WPARAM wParam, LPARAM lParam)
{
	char openname[256];

	switch (message)
  		{
    	case WM_CREATE:
    		hbi=NULL;
    		imgheight=0;
    		imgwidth=0;
    		HSCROLL=VSCROLL=FALSE;
      		break;

	    case WM_COMMAND:
    		switch (wParam)
				{
	  			case IDM_OPEN:
	  				getopenname(hWnd,openname);
	  				if(openname[0]!='\0')
	  					{
	  					if(hbi!=NULL)
	  						{
	  						GlobalUnlock(hbi);
	  						GlobalFree(hbi);
	  						hbi=NULL;
	  						}
	  					imgheight=0;
	  					imgwidth=0; 
	  					GetJPGSize(openname);
	  					if((imgwidth!=0)&&(imgheight!=0))
	  						{
							//the InvalidateRect function is useful here
							HSCROLL=VSCROLL=FALSE;
							InvalidateRect(hWnd,NULL,TRUE);
							UpdateWindow(hWnd);
	  						FitNewSize(hWnd);
	  						DecodeJPG(hWnd,openname,&hbi);
	  						}
						}
	  				break;

			 	 case IDM_EXIT:
	    			SendMessage (hWnd, WM_CLOSE, 0, 0);
	    			return 0;
				}
      		break;

    	case WM_PAINT:
    		DisProc(hWnd,hbi);
			break;
		case WM_HSCROLL:
		case WM_VSCROLL:
			ScrollProc (hWnd, message, LOWORD (lParam), wParam);
			break;
				
    	case WM_DESTROY:
    		DestroyMenu(hMenu);
           	PostQuitMessage (0);
			return 0;

	    default:
    		break;
  		}

	return DefWindowProc (hWnd, message, wParam, lParam);
}                            
/*----------------------------GetOpenName()----------------------------*/
void getopenname(HWND hWnd,char *openname)
{
    OPENFILENAME ofn;
    char szFile[256],szFileTitle[256];
    char szFilter[40];
    int  len;
    
    strcpy(szFilter,"JPEG Image(*.jpg)|*.jpg|");
    
    len=strlen(szFilter);
    szFilter[len-1]='\0';
    szFilter[len-7]='\0';
    // set all struct members to zero
    memset(&ofn,0,sizeof(OPENFILENAME));
    //initialize the OPENFILENAME members.
    szFile[0] = '\0';
    ofn.lStructSize = sizeof(OPENFILENAME);
    ofn.hwndOwner = hWnd;    
    ofn.lpstrFilter = szFilter;
    ofn.lpstrFile = szFile;
    ofn.nMaxFile = sizeof(szFile);
    ofn.lpstrFileTitle = szFileTitle;
    ofn.nMaxFileTitle = sizeof(szFileTitle);
    ofn.lpstrInitialDir = NULL;
    ofn.Flags = OFN_OVERWRITEPROMPT;
    if (GetOpenFileName(&ofn))
    	lstrcpy(openname, ofn.lpstrFile);
    else 
        lstrcpy(openname,"\0");
}