rpng2-win.c

png图像文件格式开发包

    }

    if (!filename) {
        ++error;
    } else if (!(infile = fopen(filename, "rb"))) {
        fprintf(stderr, PROGNAME ":  can't open PNG file [%s]\n", filename);
        ++error;
    } else {
        incount = fread(inbuf, 1, INBUFSIZE, infile);
        if (incount < 8 || !readpng2_check_sig(inbuf, 8)) {
            fprintf(stderr, PROGNAME
              ":  [%s] is not a PNG file: incorrect signature\n",
              filename);
            ++error;
        } else if ((rc = readpng2_init(&rpng2_info)) != 0) {
            switch (rc) {
                case 2:
                    fprintf(stderr, PROGNAME
                      ":  [%s] has bad IHDR (libpng longjmp)\n",
                      filename);
                    break;
                case 4:
                    fprintf(stderr, PROGNAME ":  insufficient memory\n");
                    break;
                default:
                    fprintf(stderr, PROGNAME
                      ":  unknown readpng2_init() error\n");
                    break;
            }
            ++error;
        }
        if (error)
            fclose(infile);
    }


    /* usage screen */

    if (error) {
        int ch;

        fprintf(stderr, "\n%s %s:  %s\n\n", PROGNAME, VERSION, appname);
        readpng2_version_info();
        fprintf(stderr, "\n"
          "Usage:  %s [-gamma exp] [-bgcolor bg | -bgpat pat] [-timing]\n"
#if (defined(__i386__) || defined(_M_IX86))
          "        %*s [[-nommxfilters] [-nommxcombine] [-nommxinterlace] | -nommx]\n"
#endif
          "        %*s file.png\n\n"
          "    exp \ttransfer-function exponent (``gamma'') of the display\n"
          "\t\t  system in floating-point format (e.g., ``%.1f''); equal\n"
          "\t\t  to the product of the lookup-table exponent (varies)\n"
          "\t\t  and the CRT exponent (usually 2.2); must be positive\n"
          "    bg  \tdesired background color in 7-character hex RGB format\n"
          "\t\t  (e.g., ``#ff7700'' for orange:  same as HTML colors);\n"
          "\t\t  used with transparent images; overrides -bgpat option\n"
          "    pat \tdesired background pattern number (1-%d); used with\n"
          "\t\t  transparent images; overrides -bgcolor option\n"
          "    -timing\tenables delay for every block read, to simulate modem\n"
          "\t\t  download of image (~36 Kbps)\n"
#if (defined(__i386__) || defined(_M_IX86))
          "    -nommx*\tdisable optimized MMX routines for decoding row filters,\n"
          "\t\t  combining rows, and expanding interlacing, respectively\n"
#endif
          "\nPress Q, Esc or mouse button 1 after image is displayed to quit.\n"
          "Press Q or Esc to quit this usage screen. ",
          PROGNAME,
#if (defined(__i386__) || defined(_M_IX86))
          strlen(PROGNAME), " ",
#endif
          strlen(PROGNAME), " ", default_display_exponent, num_bgpat);
        fflush(stderr);
        do
            ch = _getch();
        while (ch != 'q' && ch != 'Q' && ch != 0x1B);
        exit(1);
    } else {
        fprintf(stderr, "\n%s %s:  %s\n", PROGNAME, VERSION, appname);
        fprintf(stderr,
          "\n   [console window:  closing this window will terminate %s]\n\n",
          PROGNAME);
        fflush(stderr);
    }


    /* set the title-bar string, but make sure buffer doesn't overflow */

    alen = strlen(appname);
    flen = strlen(filename);
    if (alen + flen + 3 > 1023)
        sprintf(titlebar, "%s:  ...%s", appname, filename+(alen+flen+6-1023));
    else
        sprintf(titlebar, "%s:  %s", appname, filename);


    /* set some final rpng2_info variables before entering main data loop */

    if (have_bg) {
        unsigned r, g, b;   /* this approach quiets compiler warnings */

        sscanf(bgstr+1, "%2x%2x%2x", &r, &g, &b);
        rpng2_info.bg_red   = (uch)r;
        rpng2_info.bg_green = (uch)g;
        rpng2_info.bg_blue  = (uch)b;
    } else
        rpng2_info.need_bgcolor = TRUE;

    rpng2_info.done = FALSE;
    rpng2_info.mainprog_init = rpng2_win_init;
    rpng2_info.mainprog_display_row = rpng2_win_display_row;
    rpng2_info.mainprog_finish_display = rpng2_win_finish_display;


    /* OK, this is the fun part:  call readpng2_decode_data() at the start of
     * the loop to deal with our first buffer of data (read in above to verify
     * that the file is a PNG image), then loop through the file and continue
     * calling the same routine to handle each chunk of data.  It in turn
     * passes the data to libpng, which will invoke one or more of our call-
     * backs as decoded data become available.  We optionally call Sleep() for
     * one second per iteration to simulate downloading the image via an analog
     * modem. */

    for (;;) {
        Trace((stderr, "about to call readpng2_decode_data()\n"))
        if (readpng2_decode_data(&rpng2_info, inbuf, incount))
            ++error;
        Trace((stderr, "done with readpng2_decode_data()\n"))
        if (error || feof(infile) || rpng2_info.done)
            break;
        if (timing)
            Sleep(1000L);
        incount = fread(inbuf, 1, INBUFSIZE, infile);
    }


    /* clean up PNG stuff and report any decoding errors */

    fclose(infile);
    Trace((stderr, "about to call readpng2_cleanup()\n"))
    readpng2_cleanup(&rpng2_info);

    if (error) {
        fprintf(stderr, PROGNAME ":  libpng error while decoding PNG image\n");
        exit(3);
    }


    /* wait for the user to tell us when to quit */

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


    /* we're done:  clean up all image and Windows resources and go away */

    Trace((stderr, "about to call rpng2_win_cleanup()\n"))
    rpng2_win_cleanup();

    return msg.wParam;
}





/* this function is called by readpng2_info_callback() in readpng2.c, which
 * in turn is called by libpng after all of the pre-IDAT chunks have been
 * read and processed--i.e., we now have enough info to finish initializing */

static void rpng2_win_init()
{
    ulg i;
    ulg rowbytes = rpng2_info.rowbytes;

    Trace((stderr, "beginning rpng2_win_init()\n"))
    Trace((stderr, "  rowbytes = %ld\n", rpng2_info.rowbytes))
    Trace((stderr, "  width  = %ld\n", rpng2_info.width))
    Trace((stderr, "  height = %ld\n", rpng2_info.height))

    rpng2_info.image_data = (uch *)malloc(rowbytes * rpng2_info.height);
    if (!rpng2_info.image_data) {
        readpng2_cleanup(&rpng2_info);
        return;
    }

    rpng2_info.row_pointers = (uch **)malloc(rpng2_info.height * sizeof(uch *));
    if (!rpng2_info.row_pointers) {
        free(rpng2_info.image_data);
        rpng2_info.image_data = NULL;
        readpng2_cleanup(&rpng2_info);
        return;
    }

    for (i = 0;  i < rpng2_info.height;  ++i)
        rpng2_info.row_pointers[i] = rpng2_info.image_data + i*rowbytes;

/*---------------------------------------------------------------------------
    Do the basic Windows initialization stuff, make the window, and fill it
    with the user-specified, file-specified or default background color.
  ---------------------------------------------------------------------------*/

    if (rpng2_win_create_window()) {
        readpng2_cleanup(&rpng2_info);
        return;
    }
}





static int rpng2_win_create_window()
{
    uch bg_red   = rpng2_info.bg_red;
    uch bg_green = rpng2_info.bg_green;
    uch bg_blue  = rpng2_info.bg_blue;
    uch *dest;
    int extra_width, extra_height;
    ulg i, j;
    WNDCLASSEX wndclass;
    RECT rect;


/*---------------------------------------------------------------------------
    Allocate memory for the display-specific version of the image (round up
    to multiple of 4 for Windows DIB).
  ---------------------------------------------------------------------------*/

    wimage_rowbytes = ((3*rpng2_info.width + 3L) >> 2) << 2;

    if (!(dib = (uch *)malloc(sizeof(BITMAPINFOHEADER) +
                              wimage_rowbytes*rpng2_info.height)))
    {
        return 4;   /* fail */
    }

/*---------------------------------------------------------------------------
    Initialize the DIB.  Negative height means to use top-down BMP ordering
    (must be uncompressed, but that's what we want).  Bit count of 1, 4 or 8
    implies a colormap of RGBX quads, but 24-bit BMPs just use B,G,R values
    directly => wimage_data begins immediately after BMP header.
  ---------------------------------------------------------------------------*/

    memset(dib, 0, sizeof(BITMAPINFOHEADER));
    bmih = (BITMAPINFOHEADER *)dib;
    bmih->biSize = sizeof(BITMAPINFOHEADER);
    bmih->biWidth = rpng2_info.width;
    bmih->biHeight = -((long)rpng2_info.height);
    bmih->biPlanes = 1;
    bmih->biBitCount = 24;
    bmih->biCompression = 0;
    wimage_data = dib + sizeof(BITMAPINFOHEADER);

/*---------------------------------------------------------------------------
    Fill window with the specified background color (default is black), but
    defer loading faked "background image" until window is displayed (may be
    slow to compute).  Data are in BGR order.
  ---------------------------------------------------------------------------*/

    if (bg_image) {   /* just fill with black for now */
        memset(wimage_data, 0, wimage_rowbytes*rpng2_info.height);
    } else {
        for (j = 0;  j < rpng2_info.height;  ++j) {
            dest = wimage_data + j*wimage_rowbytes;
            for (i = rpng2_info.width;  i > 0;  --i) {
                *dest++ = bg_blue;
                *dest++ = bg_green;
                *dest++ = bg_red;
            }
        }
    }

/*---------------------------------------------------------------------------
    Set the window parameters.
  ---------------------------------------------------------------------------*/

    memset(&wndclass, 0, sizeof(wndclass));

    wndclass.cbSize = sizeof(wndclass);
    wndclass.style = CS_HREDRAW | CS_VREDRAW;
    wndclass.lpfnWndProc = rpng2_win_wndproc;
    wndclass.hInstance = global_hInst;
    wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wndclass.hCursor = LoadCursor(NULL, IDC_ARROW);
    wndclass.hbrBackground = (HBRUSH)GetStockObject(DKGRAY_BRUSH);
    wndclass.lpszMenuName = NULL;
    wndclass.lpszClassName = progname;
    wndclass.hIconSm = LoadIcon(NULL, IDI_APPLICATION);

    RegisterClassEx(&wndclass);

/*---------------------------------------------------------------------------
    Finally, create the window.
  ---------------------------------------------------------------------------*/

    extra_width  = 2*(GetSystemMetrics(SM_CXBORDER) +
                      GetSystemMetrics(SM_CXDLGFRAME));
    extra_height = 2*(GetSystemMetrics(SM_CYBORDER) +
                      GetSystemMetrics(SM_CYDLGFRAME)) +
                      GetSystemMetrics(SM_CYCAPTION);

    global_hwnd = CreateWindow(progname, titlebar, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, CW_USEDEFAULT, rpng2_info.width+extra_width,
      rpng2_info.height+extra_height, NULL, NULL, global_hInst, NULL);

    ShowWindow(global_hwnd, global_showmode);
    UpdateWindow(global_hwnd);

/*---------------------------------------------------------------------------
    Now compute the background image and display it.  If it fails (memory
    allocation), revert to a plain background color.
  ---------------------------------------------------------------------------*/

    if (bg_image) {
        static const char *msg = "Computing background image...";
        int x, y, len = strlen(msg);
        HDC hdc = GetDC(global_hwnd);
        TEXTMETRIC tm;

        GetTextMetrics(hdc, &tm);
        x = (rpng2_info.width - len*tm.tmAveCharWidth)/2;
        y = (rpng2_info.height - tm.tmHeight)/2;
        SetBkMode(hdc, TRANSPARENT);
        SetTextColor(hdc, GetSysColor(COLOR_HIGHLIGHTTEXT));
        /* this can still begin out of bounds even if x is positive (???): */
        TextOut(hdc, ((x < 0)? 0 : x), ((y < 0)? 0 : y), msg, len);
        ReleaseDC(global_hwnd, hdc);

        rpng2_win_load_bg_image();   /* resets bg_image if fails */
    }

    if (!bg_image) {
        for (j = 0;  j < rpng2_info.height;  ++j) {
            dest = wimage_data + j*wimage_rowbytes;
            for (i = rpng2_info.width;  i > 0;  --i) {
                *dest++ = bg_blue;
                *dest++ = bg_green;
                *dest++ = bg_red;
            }
        }
    }

    rect.left = 0L;
    rect.top = 0L;
    rect.right = (LONG)rpng2_info.width;       /* possibly off by one? */
    rect.bottom = (LONG)rpng2_info.height;     /* possibly off by one? */
    InvalidateRect(global_hwnd, &rect, FALSE);
    UpdateWindow(global_hwnd);                 /* similar to XFlush() */

    return 0;

} /* end function rpng2_win_create_window() */





static int rpng2_win_load_bg_image()
{
    uch *src, *dest;
    uch r1, r2, g1, g2, b1, b2;
    uch r1_inv, r2_inv, g1_inv, g2_inv, b1_inv, b2_inv;
    int k, hmax, max;
    int xidx, yidx, yidx_max = (bgscale-1);
    int even_odd_vert, even_odd_horiz, even_odd;
    int invert_gradient2 = (bg[pat].type & 0x08);
    int invert_column;
    ulg i, row;

/*---------------------------------------------------------------------------
    Allocate buffer for fake background image to be used with transparent
    images; if this fails, revert to plain background color.
  ---------------------------------------------------------------------------*/

    bg_rowbytes = 3 * rpng2_info.width;
    bg_data = (uch *)malloc(bg_rowbytes * rpng2_info.height);
    if (!bg_data) {
        fprintf(stderr, PROGNAME
          ":  unable to allocate memory for background image\n");
        bg_image = 0;
        return 1;
    }

/*---------------------------------------------------------------------------
    Vertical gradients (ramps) in NxN squares, alternating direction and
    colors (N == bgscale).
  ---------------------------------------------------------------------------*/