rpng-x.c

教你如何简单显示一章TIFF位图,分析的很透彻,很适合出学者.希望能给你带来帮助!

    XGCValues gcvalues;
    XSetWindowAttributes attr;
    XSizeHints *size_hints;
    XTextProperty windowName, *pWindowName = &windowName;
    XTextProperty iconName, *pIconName = &iconName;
    XVisualInfo visual_info;
    XWMHints *wm_hints;


    bitmap_order = BitmapBitOrder(display);
    screen = DefaultScreen(display);
    depth = DisplayPlanes(display, screen);
    root = RootWindow(display, screen);

/* GRR:  add 8-bit support */
    if (/* depth != 8 && */ depth != 16 && depth != 24 && depth != 32) {
        fprintf(stderr,
          "screen depth %d not supported (only 16-, 24- or 32-bit TrueColor)\n",
          depth);
        return 2;
    }

    XMatchVisualInfo(display, screen, depth,
      (depth == 8)? PseudoColor : TrueColor, &visual_info);
    visual = visual_info.visual;

    RedMask   = visual->red_mask;
    GreenMask = visual->green_mask;
    BlueMask  = visual->blue_mask;

/* GRR:  add/check 8-bit support */
    if (depth == 8) {
        colormap = XCreateColormap(display, root, visual, AllocNone);
        if (!colormap) {
            fprintf(stderr, "XCreateColormap() failed\n");
            return 2;
        }
        have_colormap = TRUE;
    } else if (depth == 16) {
        RPixelShift = 15 - rpng_x_msb(RedMask);	/* these are right-shifts */
        GPixelShift = 15 - rpng_x_msb(GreenMask);
        BPixelShift = 15 - rpng_x_msb(BlueMask);
    } else /* if (depth > 16) */ {
        RPixelShift = rpng_x_msb(RedMask) - 7;	/* these are left-shifts */
        GPixelShift = rpng_x_msb(GreenMask) - 7;
        BPixelShift = rpng_x_msb(BlueMask) - 7;
    }

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

    attr.backing_store = Always;
    attr.event_mask = ExposureMask | KeyPressMask | ButtonPressMask;

    window = XCreateWindow(display, root, 0, 0, image_width, image_height,
      0, depth, InputOutput, visual, CWBackingStore | CWEventMask, &attr);

    if (window == None) {
        fprintf(stderr, "XCreateWindow() failed\n");
        return 2;
    } else
        have_window = TRUE;

    if (depth == 8)
        XSetWindowColormap(display, window, colormap);

    if (!XStringListToTextProperty(&window_name, 1, pWindowName))
        pWindowName = NULL;
    if (!XStringListToTextProperty(&icon_name, 1, pIconName))
        pIconName = NULL;

    /* OK if either hints allocation fails; XSetWMProperties() allows NULLs */

    if ((size_hints = XAllocSizeHints()) != NULL) {
        /* window will not be resizable */
        size_hints->flags = PMinSize | PMaxSize;
        size_hints->min_width = size_hints->max_width = image_width;
        size_hints->min_height = size_hints->max_height = image_height;
    }

    if ((wm_hints = XAllocWMHints()) != NULL) {
        wm_hints->initial_state = NormalState;
        wm_hints->input = True;
     /* wm_hints->icon_pixmap = icon_pixmap; */
        wm_hints->flags = StateHint | InputHint  /* | IconPixmapHint */ ;
    }

    XSetWMProperties(display, window, pWindowName, pIconName, NULL, 0,
      size_hints, wm_hints, NULL);

    XMapWindow(display, window);

    gc = XCreateGC(display, window, 0, &gcvalues);

/*---------------------------------------------------------------------------
    Fill window with the specified background color.
  ---------------------------------------------------------------------------*/

    if (depth == 24 || depth == 32) {
        bg_pixel = ((ulg)bg_red   << RPixelShift) |
                   ((ulg)bg_green << GPixelShift) |
                   ((ulg)bg_blue  << BPixelShift);
    } else if (depth == 16) {
        bg_pixel = ((((ulg)bg_red   << 8) >> RPixelShift) & RedMask)   |
                   ((((ulg)bg_green << 8) >> GPixelShift) & GreenMask) |
                   ((((ulg)bg_blue  << 8) >> BPixelShift) & BlueMask);
    } else /* depth == 8 */ {

        /* GRR:  add 8-bit support */

    }

    XSetForeground(display, gc, bg_pixel);
    XFillRectangle(display, window, gc, 0, 0, image_width, image_height);

/*---------------------------------------------------------------------------
    Wait for first Expose event to do any drawing, then flush.
  ---------------------------------------------------------------------------*/

    do
        XNextEvent(display, &e);
    while (e.type != Expose || e.xexpose.count);

    XFlush(display);

/*---------------------------------------------------------------------------
    Allocate memory for the X- and display-specific version of the image.
  ---------------------------------------------------------------------------*/

    if (depth == 24 || depth == 32) {
        xdata = (uch *)malloc(4*image_width*image_height);
        pad = 32;
    } else if (depth == 16) {
        xdata = (uch *)malloc(2*image_width*image_height);
        pad = 16;
    } else /* depth == 8 */ {
        xdata = (uch *)malloc(image_width*image_height);
        pad = 8;
    }

    if (!xdata) {
        fprintf(stderr, PROGNAME ":  unable to allocate image memory\n");
        return 4;
    }

    ximage = XCreateImage(display, visual, depth, ZPixmap, 0,
      (char *)xdata, image_width, image_height, pad, 0);

    if (!ximage) {
        fprintf(stderr, PROGNAME ":  XCreateImage() failed\n");
        free(xdata);
        return 3;
    }

    /* to avoid testing the bitmap_order every pixel (or doubling the size of
     * the drawing routine with a giant if-test), we arbitrarily set the byte
     * order to MSBFirst and let Xlib worry about inverting things on little-
     * endian machines (like Linux/x86, old VAXen, etc.)--this is not the most
     * efficient approach (the giant if-test would be better), but in the
     * interest of clarity, we take the easy way out... */

    ximage->byte_order = MSBFirst;

    return 0;

} /* end function rpng_x_create_window() */





static int rpng_x_display_image()
{
    uch *src, *dest;
    uch r, g, b, a;
    int ximage_rowbytes = ximage->bytes_per_line;
    ulg i, row, lastrow = 0;
    ulg pixel;


    Trace((stderr, "beginning display loop (image_channels == %d)\n",
      image_channels))
    Trace((stderr, "(width = %ld, rowbytes = %ld, ximage_rowbytes = %d)\n",
      image_width, image_rowbytes, ximage_rowbytes))

    if (depth == 24 || depth == 32) {
        ulg red, green, blue;

        for (lastrow = row = 0;  row < image_height;  ++row) {
            src = image_data + row*image_rowbytes;
            dest = ximage->data + row*ximage_rowbytes;
            if (image_channels == 3) {
                for (i = image_width;  i > 0;  --i) {
                    red   = *src++;
                    green = *src++;
                    blue  = *src++;
                    pixel = (red   << RPixelShift) |
                            (green << GPixelShift) |
                            (blue  << BPixelShift);
                    /* recall that we set ximage->byte_order = MSBFirst above */
                    *dest++ = ((uch *)&pixel)[3];
                    *dest++ = ((uch *)&pixel)[2];
                    *dest++ = ((uch *)&pixel)[1];
                    *dest++ = ((uch *)&pixel)[0];
                }
            } else /* if (image_channels == 4) */ {
                for (i = image_width;  i > 0;  --i) {
                    r = *src++;
                    g = *src++;
                    b = *src++;
                    a = *src++;
                    if (a == 255) {
                        red   = r;
                        green = g;
                        blue  = b;
                    } else if (a == 0) {
                        red   = bg_red;
                        green = bg_green;
                        blue  = bg_blue;
                    } else {
                        /* this macro (from png.h) composites the foreground
                         * and background values and puts the result into the
                         * first argument */
                        alpha_composite(red,   r, a, bg_red);
                        alpha_composite(green, g, a, bg_green);
                        alpha_composite(blue,  b, a, bg_blue);
                    }
                    pixel = (red   << RPixelShift) |
                            (green << GPixelShift) |
                            (blue  << BPixelShift);
                    /* recall that we set ximage->byte_order = MSBFirst above */
                    *dest++ = ((uch *)&pixel)[3];
                    *dest++ = ((uch *)&pixel)[2];
                    *dest++ = ((uch *)&pixel)[1];
                    *dest++ = ((uch *)&pixel)[0];
                }
            }
            /* display after every 16 lines */
            if (((row+1) & 0xf) == 0) {
                XPutImage(display, window, gc, ximage, 0, lastrow, 0, lastrow,
                  image_width, 16);
                XFlush(display);
                lastrow = row + 1;
            }
        }

    } else if (depth == 16) {
        ush red, green, blue;

        for (lastrow = row = 0;  row < image_height;  ++row) {
            src = image_data + row*image_rowbytes;
            dest = ximage->data + row*ximage_rowbytes;
            if (image_channels == 3) {
                for (i = image_width;  i > 0;  --i) {
                    red   = ((ush)(*src) << 8);
                    ++src;
                    green = ((ush)(*src) << 8);
                    ++src;
                    blue  = ((ush)(*src) << 8);
                    ++src;
                    pixel = ((red   >> RPixelShift) & RedMask)   |
                            ((green >> GPixelShift) & GreenMask) |
                            ((blue  >> BPixelShift) & BlueMask);
                    /* recall that we set ximage->byte_order = MSBFirst above */
                    *dest++ = ((uch *)&pixel)[1];
                    *dest++ = ((uch *)&pixel)[0];
                }
            } else /* if (image_channels == 4) */ {
                for (i = image_width;  i > 0;  --i) {
                    r = *src++;
                    g = *src++;
                    b = *src++;
                    a = *src++;
                    if (a == 255) {
                        red   = ((ush)r << 8);
                        green = ((ush)g << 8);
                        blue  = ((ush)b << 8);
                    } else if (a == 0) {
                        red   = ((ush)bg_red   << 8);
                        green = ((ush)bg_green << 8);
                        blue  = ((ush)bg_blue  << 8);
                    } else {
                        /* this macro (from png.h) composites the foreground
                         * and background values and puts the result back into
                         * the first argument (== fg byte here:  safe) */
                        alpha_composite(r, r, a, bg_red);
                        alpha_composite(g, g, a, bg_green);
                        alpha_composite(b, b, a, bg_blue);
                        red   = ((ush)r << 8);
                        green = ((ush)g << 8);
                        blue  = ((ush)b << 8);
                    }
                    pixel = ((red   >> RPixelShift) & RedMask)   |
                            ((green >> GPixelShift) & GreenMask) |
                            ((blue  >> BPixelShift) & BlueMask);
                    /* recall that we set ximage->byte_order = MSBFirst above */
                    *dest++ = ((uch *)&pixel)[1];
                    *dest++ = ((uch *)&pixel)[0];
                }
            }
            /* display after every 16 lines */
            if (((row+1) & 0xf) == 0) {
                XPutImage(display, window, gc, ximage, 0, lastrow, 0, lastrow,
                  image_width, 16);
                XFlush(display);
                lastrow = row + 1;
            }
        }

    } else /* depth == 8 */ {

        /* GRR:  add 8-bit support */

    }

    Trace((stderr, "calling final XPutImage()\n"))
    if (lastrow < image_height) {
        XPutImage(display, window, gc, ximage, 0, lastrow, 0, lastrow,
          image_width, image_height-lastrow);
        XFlush(display);
    }

    return 0;
}




static void rpng_x_cleanup()
{
    if (image_data) {
        free(image_data);
        image_data = NULL;
    }

    if (ximage) {
        if (ximage->data) {
            free(ximage->data);           /* we allocated it, so we free it */
            ximage->data = (char *)NULL;  /*  instead of XDestroyImage() */
        }
        XDestroyImage(ximage);
        ximage = NULL;
    }

    XFreeGC(display, gc);

    if (have_window)
        XDestroyWindow(display, window);

    if (have_colormap)
        XFreeColormap(display, colormap);
}





static int rpng_x_msb(ulg u32val)
{
    int i;

    for (i = 31;  i >= 0;  --i) {
        if (u32val & 0x80000000L)
            break;
        u32val <<= 1;
    }
    return i;
}