//------------------------------------

//  VisualPng.C -- Shows a PNG image

//------------------------------------

// Copyright 2000, Willem van Schaik.  For conditions of distribution and

// use, see the copyright/license/disclaimer notice in png.h

// switches

// defines

#define PROGNAME  "VisualPng"

#define LONGNAME  "Win32 Viewer for PNG-files"

#define VERSION   "1.0 of 2000 June 07"

// constants

#define MARGIN 8

// standard includes

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <windows.h>

// application includes

#include "png.h"

#include "pngfile.h"

#include "resource.h"

// macros

// function prototypes

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM);

BOOL    CALLBACK AboutDlgProc (HWND, UINT, WPARAM, LPARAM) ;

BOOL CenterAbout (HWND hwndChild, HWND hwndParent);

BOOL BuildPngList (PTSTR pstrPathName, TCHAR **ppFileList, int *pFileCount,

        int *pFileIndex);

BOOL SearchPngList (TCHAR *pFileList, int FileCount, int *pFileIndex,

        PTSTR pstrPrevName, PTSTR pstrNextName);

BOOL LoadImageFile(HWND hwnd, PTSTR pstrPathName,

        png_byte **ppbImage, int *pxImgSize, int *pyImgSize, int *piChannels,

        png_color *pBkgColor);

BOOL DisplayImage (HWND hwnd, BYTE **ppDib,

        BYTE **ppDiData, int cxWinSize, int cyWinSize,

        BYTE *pbImage, int cxImgSize, int cyImgSize, int cImgChannels,

        BOOL bStretched);

BOOL InitBitmap (

        BYTE *pDiData, int cxWinSize, int cyWinSize);

BOOL FillBitmap (

        BYTE *pDiData, int cxWinSize, int cyWinSize,

        BYTE *pbImage, int cxImgSize, int cyImgSize, int cImgChannels,

        BOOL bStretched);

// a few global variables

static char *szProgName = PROGNAME;

static char *szAppName = LONGNAME;

static char *szIconName = PROGNAME;

static char szCmdFileName [MAX_PATH];

// MAIN routine

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,

                    PSTR szCmdLine, int iCmdShow)

{

    HACCEL   hAccel;

    HWND     hwnd;

    MSG      msg;

    WNDCLASS wndclass;

    int ixBorders, iyBorders;

    wndclass.style         = CS_HREDRAW | CS_VREDRAW;

    wndclass.lpfnWndProc   = WndProc;

    wndclass.cbClsExtra    = 0;

    wndclass.cbWndExtra    = 0;

    wndclass.hInstance     = hInstance;

    wndclass.hIcon         = LoadIcon (hInstance, szIconName) ;

    wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW);

    wndclass.hbrBackground = NULL; // (HBRUSH) GetStockObject (GRAY_BRUSH);

    wndclass.lpszMenuName  = szProgName;

    wndclass.lpszClassName = szProgName;

    if (!RegisterClass (&wndclass))

    {

        MessageBox (NULL, TEXT ("Error: this program requires Windows NT!"),

            szProgName, MB_ICONERROR);

        return 0;

    }

    // if filename given on commandline, store it

    if ((szCmdLine != NULL) && (*szCmdLine != '\0'))

        if (szCmdLine[0] == '"')

            strncpy (szCmdFileName, szCmdLine + 1, strlen(szCmdLine) - 2);

        else

            strcpy (szCmdFileName, szCmdLine);

    else

        strcpy (szCmdFileName, "");

    // calculate size of window-borders

    ixBorders = 2 * (GetSystemMetrics (SM_CXBORDER) +

                     GetSystemMetrics (SM_CXDLGFRAME));

    iyBorders = 2 * (GetSystemMetrics (SM_CYBORDER) +

                     GetSystemMetrics (SM_CYDLGFRAME)) +

                     GetSystemMetrics (SM_CYCAPTION) +

                     GetSystemMetrics (SM_CYMENUSIZE) +

                     1; /* WvS: don't ask me why? */

    hwnd = CreateWindow (szProgName, szAppName,

        WS_OVERLAPPEDWINDOW,

        CW_USEDEFAULT, CW_USEDEFAULT,

        512 + 2 * MARGIN + ixBorders, 384 + 2 * MARGIN + iyBorders,

//      CW_USEDEFAULT, CW_USEDEFAULT,

        NULL, NULL, hInstance, NULL);

    ShowWindow (hwnd, iCmdShow);

    UpdateWindow (hwnd);

    hAccel = LoadAccelerators (hInstance, szProgName);

    while (GetMessage (&msg, NULL, 0, 0))

    {

        if (!TranslateAccelerator (hwnd, hAccel, &msg))

        {

            TranslateMessage (&msg);

            DispatchMessage (&msg);

        }

    }

    return msg.wParam;

}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam,

        LPARAM lParam)

{

    static HINSTANCE          hInstance ;

    static HDC                hdc;

    static PAINTSTRUCT        ps;

    static HMENU              hMenu;

    static BITMAPFILEHEADER  *pbmfh;

    static BITMAPINFOHEADER  *pbmih;

    static BYTE              *pbImage;

    static int                cxWinSize, cyWinSize;

    static int                cxImgSize, cyImgSize;

    static int                cImgChannels;

    static png_color          bkgColor = {127, 127, 127};

    static BOOL               bStretched = TRUE;

    static BYTE              *pDib = NULL;

    static BYTE              *pDiData = NULL;

    static TCHAR              szImgPathName [MAX_PATH];

    static TCHAR              szTitleName [MAX_PATH];

    static TCHAR             *pPngFileList = NULL;

    static int                iPngFileCount;

    static int                iPngFileIndex;

    BOOL                      bOk;

    switch (message)

    {

    case WM_CREATE:

        hInstance = ((LPCREATESTRUCT) lParam)->hInstance ;

        PngFileInitialize (hwnd);

        strcpy (szImgPathName, "");

        // in case we process file given on command-line

        if (szCmdFileName[0] != '\0')

        {

            strcpy (szImgPathName, szCmdFileName);

            // read the other png-files in the directory for later

            // next/previous commands

            BuildPngList (szImgPathName, &pPngFileList, &iPngFileCount,

                          &iPngFileIndex);

            // load the image from file

            if (!LoadImageFile (hwnd, szImgPathName,

                &pbImage, &cxImgSize, &cyImgSize, &cImgChannels, &bkgColor))

                return 0;

            // invalidate the client area for later update

            InvalidateRect (hwnd, NULL, TRUE);

            // display the PNG into the DIBitmap

            DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,

                pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);

        }

        return 0;

    case WM_SIZE:

        cxWinSize = LOWORD (lParam);

        cyWinSize = HIWORD (lParam);

        // invalidate the client area for later update

        InvalidateRect (hwnd, NULL, TRUE);

        // display the PNG into the DIBitmap

        DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,

            pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);

        return 0;

    case WM_INITMENUPOPUP:

        hMenu = GetMenu (hwnd);

        if (pbImage)

            EnableMenuItem (hMenu, IDM_FILE_SAVE, MF_ENABLED);

        else

            EnableMenuItem (hMenu, IDM_FILE_SAVE, MF_GRAYED);

        return 0;

    case WM_COMMAND:

        hMenu = GetMenu (hwnd);

        switch (LOWORD (wParam))

        {

        case IDM_FILE_OPEN:

            // show the File Open dialog box

            if (!PngFileOpenDlg (hwnd, szImgPathName, szTitleName))

                return 0;

            // read the other png-files in the directory for later

            // next/previous commands

            BuildPngList (szImgPathName, &pPngFileList, &iPngFileCount,

                          &iPngFileIndex);

            // load the image from file

            if (!LoadImageFile (hwnd, szImgPathName,

                &pbImage, &cxImgSize, &cyImgSize, &cImgChannels, &bkgColor))

                return 0;

            // invalidate the client area for later update

            InvalidateRect (hwnd, NULL, TRUE);

            // display the PNG into the DIBitmap

            DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,

                pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);

            return 0;

        case IDM_FILE_SAVE:

            // show the File Save dialog box

            if (!PngFileSaveDlg (hwnd, szImgPathName, szTitleName))

                return 0;

            // save the PNG to a disk file

            SetCursor (LoadCursor (NULL, IDC_WAIT));

            ShowCursor (TRUE);

            bOk = PngSaveImage (szImgPathName, pDiData, cxWinSize, cyWinSize,

                  bkgColor);

            ShowCursor (FALSE);

            SetCursor (LoadCursor (NULL, IDC_ARROW));

            if (!bOk)

                MessageBox (hwnd, TEXT ("Error in saving the PNG image"),

                szProgName, MB_ICONEXCLAMATION | MB_OK);

            return 0;

        case IDM_FILE_NEXT:

            // read next entry in the directory

            if (SearchPngList (pPngFileList, iPngFileCount, &iPngFileIndex,

                NULL, szImgPathName))

            {

                if (strcmp (szImgPathName, "") == 0)

                    return 0;

                // load the image from file

                if (!LoadImageFile (hwnd, szImgPathName, &pbImage,

                        &cxImgSize, &cyImgSize, &cImgChannels, &bkgColor))

                    return 0;

                // invalidate the client area for later update

                InvalidateRect (hwnd, NULL, TRUE);

                // display the PNG into the DIBitmap

                DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,

                    pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);

            }

            return 0;

        case IDM_FILE_PREVIOUS:

            // read previous entry in the directory

            if (SearchPngList (pPngFileList, iPngFileCount, &iPngFileIndex,

                szImgPathName, NULL))

            {

                if (strcmp (szImgPathName, "") == 0)

                    return 0;

                // load the image from file

                if (!LoadImageFile (hwnd, szImgPathName, &pbImage, &cxImgSize,

                    &cyImgSize, &cImgChannels, &bkgColor))

                    return 0;

                // invalidate the client area for later update

                InvalidateRect (hwnd, NULL, TRUE);

                // display the PNG into the DIBitmap

                DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,

                    pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);

            }

            return 0;

        case IDM_FILE_EXIT:

            // more cleanup needed...

            // free image buffer

            if (pDib != NULL)

            {

                free (pDib);

                pDib = NULL;

            }

            // free file-list

            if (pPngFileList != NULL)

            {

                free (pPngFileList);

                pPngFileList = NULL;

            }

            // let's go ...

            exit (0);

            return 0;

        case IDM_OPTIONS_STRETCH:

            bStretched = !bStretched;

            if (bStretched)

                CheckMenuItem (hMenu, IDM_OPTIONS_STRETCH, MF_CHECKED);

            else

                CheckMenuItem (hMenu, IDM_OPTIONS_STRETCH, MF_UNCHECKED);

            // invalidate the client area for later update

            InvalidateRect (hwnd, NULL, TRUE);

            // display the PNG into the DIBitmap

            DisplayImage (hwnd, &pDib, &pDiData, cxWinSize, cyWinSize,

                pbImage, cxImgSize, cyImgSize, cImgChannels, bStretched);

            return 0;

        case IDM_HELP_ABOUT:

            DialogBox (hInstance, TEXT ("AboutBox"), hwnd, AboutDlgProc) ;

            return 0;

        } // end switch

        break;

    case WM_PAINT:

        hdc = BeginPaint (hwnd, &ps);

        if (pDib)

            SetDIBitsToDevice (hdc, 0, 0, cxWinSize, cyWinSize, 0, 0,

                0, cyWinSize, pDiData, (BITMAPINFO *) pDib, DIB_RGB_COLORS);

        EndPaint (hwnd, &ps);

        return 0;

    case WM_DESTROY:

        if (pbmfh)

        {

            free (pbmfh);

            pbmfh = NULL;

        }

        PostQuitMessage (0);

        return 0;

    }

    return DefWindowProc (hwnd, message, wParam, lParam);

}

BOOL CALLBACK AboutDlgProc (HWND hDlg, UINT message,

                            WPARAM wParam, LPARAM lParam)

{

     switch (message)

     {

     case WM_INITDIALOG :

          ShowWindow (hDlg, SW_HIDE);

          CenterAbout (hDlg, GetWindow (hDlg, GW_OWNER));

          ShowWindow (hDlg, SW_SHOW);

          return TRUE ;

     case WM_COMMAND :

          switch (LOWORD (wParam))

          {

          case IDOK :

          case IDCANCEL :

               EndDialog (hDlg, 0) ;

               return TRUE ;

          }

          break ;

     }

     return FALSE ;

}

//---------------

//  CenterAbout

//---------------

BOOL CenterAbout (HWND hwndChild, HWND hwndParent)

{

   RECT    rChild, rParent, rWorkArea;

   int     wChild, hChild, wParent, hParent;

   int     xNew, yNew;

   BOOL  bResult;

   // Get the Height and Width of the child window

   GetWindowRect (hwndChild, &rChild);

   wChild = rChild.right - rChild.left;

   hChild = rChild.bottom - rChild.top;

   // Get the Height and Width of the parent window

   GetWindowRect (hwndParent, &rParent);

   wParent = rParent.right - rParent.left;

   hParent = rParent.bottom - rParent.top;

   // Get the limits of the 'workarea'

   bResult = SystemParametersInfo(

      SPI_GETWORKAREA,  // system parameter to query or set

      sizeof(RECT),

      &rWorkArea,

      0);

   if (!bResult) {

      rWorkArea.left = rWorkArea.top = 0;

      rWorkArea.right = GetSystemMetrics(SM_CXSCREEN);

      rWorkArea.bottom = GetSystemMetrics(SM_CYSCREEN);

   }

   // Calculate new X position, then adjust for workarea

   xNew = rParent.left + ((wParent - wChild) /2);

   if (xNew < rWorkArea.left) {

      xNew = rWorkArea.left;

   } else if ((xNew+wChild) > rWorkArea.right) {

      xNew = rWorkArea.right - wChild;

   }

   // Calculate new Y position, then adjust for workarea

   yNew = rParent.top  + ((hParent - hChild) /2);

   if (yNew < rWorkArea.top) {

      yNew = rWorkArea.top;

   } else if ((yNew+hChild) > rWorkArea.bottom) {

      yNew = rWorkArea.bottom - hChild;

   }

   // Set it, and return

   return SetWindowPos (hwndChild, NULL, xNew, yNew, 0, 0, SWP_NOSIZE |

          SWP_NOZORDER);

}

//----------------

//  BuildPngList

//----------------

BOOL BuildPngList (PTSTR pstrPathName, TCHAR **ppFileList, int *pFileCount,

     int *pFileIndex)

{

    static TCHAR              szImgPathName [MAX_PATH];

    static TCHAR              szImgFileName [MAX_PATH];

    static TCHAR              szImgFindName [MAX_PATH];

    WIN32_FIND_DATA           finddata;

    HANDLE                    hFind;

    static TCHAR              szTmp [MAX_PATH];

    BOOL                      bOk;

    int                       i, ii;

    int                       j, jj;

    // free previous file-list

    if (*ppFileList != NULL)

    {

        free (*ppFileList);

        *ppFileList = NULL;

    }