Re: AW: AW: Implementing PseudoColor support on TrueColor screens

[Sleep]

This should be slightly easier to read:

Display*        X_display = NULL;
Window          X_mainWindow;
Colormap        X_cmap;
Visual*         X_visual;
GC              X_gc;
int             X_screen;
XVisualInfo     X_visualinfo;
XImage*         image = NULL;
int             X_width;
int             X_height;
unsigned long st2d_8to24table[256];
int32_t  shiftmask_fl = 0;
int32_t  r_shift, g_shift, b_shift;
uint32_t r_mask, g_mask, b_mask;

//
// I_InitGraphics
//
// Creates and maps window
void I_InitGraphics (void)
{
    char* displayname = NULL;

    X_width = SCREENWIDTH;
    X_height = SCREENHEIGHT;

    // open the display
    X_display = XOpenDisplay(displayname);

    // use the default visual
    X_screen = DefaultScreen(X_display);
    XMatchVisualInfo(X_display, X_screen, 24, TrueColor, &X_visualinfo);
    X_visual = X_visualinfo.visual;

    // create the main window
    X_mainWindow = XCreateWindow(X_display,
                                 RootWindow(X_display, X_screen),
                                 0, 0,
                                 X_width, X_height,
                                 0, // borderwidth
                                 X_visualinfo.depth, // depth
                                 InputOutput,
                                 X_visual,
                                 0,
                                 0);

    // create the GC
    X_gc = XCreateGC(X_display,
                     X_mainWindow,
                     0,
                     NULL);

    // map the window
    XMapWindow(X_display, X_mainWindow);

    image = XCreateImage(X_display,
                         X_visual,
                         X_visualinfo.depth,
                         ZPixmap,
                         0,
                         malloc((X_width * 4) * X_height),
                         X_width, X_height,
                         32,
                         0);

    screens[0] = (byte *)image->data;
}

// Convert colors to 24 bits, called by I_FinishUpdate()
void st3_fixup (int width, int height)
{
    uint8_t *row_src;

    for (int y = 0; y < height; y++) {
        row_src = (uint8_t *)&image->data [y * image->bytes_per_line];
        for (int x = width-1; x >= 0; x--) {
            XPutPixel(image, x, y, st2d_8to24table[row_src[x]]);
        }
    }
}

// Called by xlib_rgb24()
void shiftmask_init (void)
{
    unsigned int x;

    r_mask = X_visual->red_mask;
    g_mask = X_visual->green_mask;
    b_mask = X_visual->blue_mask;

    for (r_shift = -8, x = 1; x < r_mask; x = x << 1)
        r_shift++;

    for (g_shift = -8, x = 1; x < g_mask; x = x << 1)
        g_shift++;

    for (b_shift = -8, x = 1; x < b_mask; x = x << 1)
        b_shift++;

    shiftmask_fl = 1;
}

// Called by UploadNewPalette()
unsigned long xlib_rgb24 (int r, int g, int b)
{
    unsigned long p;

    if (shiftmask_fl == 0)
        shiftmask_init();

    p = 0;

    if (r_shift > 0) {
        p = (r << (r_shift)) & r_mask;
    } else if (r_shift < 0) {
        p = (r >> (-r_shift)) & r_mask;
    } else p |= (r & r_mask);

    if (g_shift > 0) {
        p |= (g << (g_shift)) & g_mask;
    } else if (g_shift < 0) {
        p |= (g >> (-g_shift)) & g_mask;
    } else p |= (g & g_mask);

    if (b_shift > 0) {
        p |= (b << (b_shift)) & b_mask;
    } else if (b_shift < 0) {
        p |=(b >> (-b_shift)) & b_mask;
    } else p |= (b & b_mask);

    return p;
}

//
// Palette stuff.
//
void UploadNewPalette (Colormap cmap, byte *palette)
{
    (void)cmap; // UNUSED
    for (int i = 0; i < 256; i++)
    {
        st2d_8to24table[i] = xlib_rgb24(palette[i * 3], palette[i * 3 + 
1],palette[i * 3 + 2]);
    }
}

//
// I_SetPalette
//
void I_SetPalette (byte* palette)
{
    UploadNewPalette(X_cmap, palette);
}

//
// I_FinishUpdate
//
// Display the image on the window
void I_FinishUpdate (void)
{
    // Convert colors of the image to 24 bits color depth
    st3_fixup(X_width, X_height);

    // draw the image
    XPutImage(X_display,
              X_mainWindow,
              X_gc,
              image,
              0, 0,
              0, 0,
              X_width, X_height );

    // sync up with server
    XSync(X_display, False);
}

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