Added multiple colors schemes and CLI option to select them.

[screensavers] / hacks / NEDsim / NEDsim.c

diff --git a/hacks/NEDsim/NEDsim.c b/hacks/NEDsim/NEDsim.c
index 6778c2d..89a2090 100644 (file)
--- a/hacks/NEDsim/NEDsim.c
+++ b/hacks/NEDsim/NEDsim.c
@@ -9,72 +9,116 @@
 /* -------------------------------------------------------------------------- */
 
 struct NEDsim {
 /* -------------------------------------------------------------------------- */
 
 struct NEDsim {

-    /* Various X resources                                                    */
+    // Various X resources

     Display * dpy;
     Window    win;
     GC        gc;
 
     Display * dpy;
     Window    win;
     GC        gc;
 

-    // TODO: Explain these
+    // Tracks the width and height (in pixels) of 'win' on 'dpy'.

     int dpy_width, dpy_height;
 
     int dpy_width, dpy_height;
 

-    // TODO: Explain that this is created during init, then lights are populated/overwritten on each frame. 
+    // To ensure the NED display is always synchronized/valid, we
+    // double-buffer. This is that buffer.

     Pixmap panel;
 
     Pixmap panel;
 

-    /* Delay (in microseconds) between clock cycles in the NED CPU.           */
-    size_t delay;
-
+    // The front panel is defined in a fixed grid of 'cells' which are then
+    // scaled and projected onto the actual screen. This variable tracks the
+    // size of one 'cell' in screen pixels.

     int cell_size;
     int cell_size;

+    // Like above, this variable tracks the scaled size (in pixels) of cell
+    // borders when projecting them on the screen.

     int border_size;
     int border_size;

+
+    // Since the panel will be smaller than the display window, these two
+    // variable track the location (in pixels) of the upper left corner of the
+    // NED panel (pretending it didn't have rounded corners) relative to the
+    // display window's origin.

     int origin_x_offset, origin_y_offset;
     int origin_x_offset, origin_y_offset;

+
+    // Delay (in microseconds) between clock cycles in the NED CPU.
+    size_t delay;
+
+    // Since the heap and stack areas are resized to fit the display, this
+    // variable tracks their height.

     int num_data_rows;
 
     int num_data_rows;
 

+    // This is an index into the color_list[] array, selecting a color scheme.

     size_t color_index;
 
     size_t color_index;
 

+    // If the display is unsuitable (e.g. too small), this boolean is 'true'.
+    // With this, we blank the display but keep the simulation itself running,
+    // allowing the ongoing simulation to display when the situation is
+    // corrected, and allowing us to avoid boring the user with unnecessary
+    // simulation restarts.

     Bool suitable_display;
 
     Bool suitable_display;
 

+    // The font size is dynamically adjusted based on display size. This
+    // variable stores the full font description, including the correct font
+    // size, all in the X11 font specifier format. For example,
+    //             -*-helvetica-*-r-*-*-72-*-*-*-*-*-*-*
+    // if the display were using a 72 point helvetica font without emphasis.

     char * current_font;
 
     char * current_font;
 

-    // TODO: Explain that this contains all the actual state of the NED machine being simulated.
+    // This struct contains all machine state for the simulated NED computer.

     struct NEDstate * nedstate;
 };
 
 struct color_rgb {
     struct NEDstate * nedstate;
 };
 
 struct color_rgb {

-    // TODO: Explain why this is an unsigned short. Copy from WolframAutomata.
+    // The type 'unsigned short' comes from the XColor struct definition.
+    // The red, green, and blue values are always in the range 0 to 65535
+    // inclusive, independent of the number of bits actually used in the
+    // display hardware. The server scales these values to the range used
+    // by the hardware. Black is represented by (0,0,0), and white is
+    // represented by (65535,65535,65535).

     unsigned short red, green, blue;
 };
 
 struct color_scheme {
     unsigned short red, green, blue;
 };
 
 struct color_scheme {

-    // TODO: Explain all this.
+    // The following entries define a full color scheme for a NED panel.

     struct color_rgb
     struct color_rgb

-        panel_bg,
-        panel_fg,
-        light_on,
-        light_off,
-        error_on,
-        error_off,
-        primary,
-        secondary,
-        tertiary,
-        border,
-        text;
+        panel_bg,  // Empty screen space not taken up by the panel
+        panel_fg,  // Panel body/faceplate
+        light_on,  // Illuminated data indicator
+        light_off, // Non-illuminated data indicator
+        error_on,  // Illuminated error indicator
+        error_off, // Non-illuminated error indicator
+        primary,   // Primary panel color (see: logo background)
+        secondary, // Secondary panel color (see: "HALT" text background)
+        tertiary,  // Tertiary panel color (see: "subgeniuskitty.com" text background)
+        border,    // Cell borders
+        text;      // Panel text

 };
 
 };
 

+// All included color schemes for NEDsim are defined in this array. To select a
+// particular color scheme at runtime, use the `-color N` CLI option.

 static struct color_scheme color_list[] = {
 static struct color_scheme color_list[] = {

-    // TODO: Explain all this.
-    // TODO: Add other color schemes, like purple PDP-11/70.
-    // TODO: http://www.chdickman.com/pdp8/DECcolors/
-    {
+    { // This color scheme is inspired by the KI10 version of the PDP-10.
+      // Many RGB values came from: http://www.chdickman.com/pdp8/DECcolors/

         {63479,63479,63479}, // 092-XXXX-123
         { 5140, 2056, 5654}, // 092-XXXX-152
         {63479,63479,63479}, // 092-XXXX-123
         { 5140, 2056, 5654}, // 092-XXXX-152

-        {65535,11051,15677}, // 092-XXXX-139 - edit
-        {20000,13107,12850}, // 092-XXXX-154 - edit
-        {65535,13107,12850}, // homemade
-        {20000,13107,12850}, // 092-XXXX-154 - edit
+        {65535,11051,15677}, // homemade, derived from 092-XXXX-139
+        {20000,13107,12850}, // homemade, derived from 092-XXXX-154
+        {65535,13107,12850}, // homemade, derived from 092-XXXX-154
+        {20000,13107,12850}, // homemade, derived from 092-XXXX-154

         { 4112,12850,20046}, // 092-XXXX-145
         {12336,29555,37008}, // 092-XXXX-151
         {30326,24158, 6425}, // 092-XXXX-157
         {63479,63479,63479}, // 092-XXXX-123
         {63479,63479,63479}  // 092-XXXX-123
         { 4112,12850,20046}, // 092-XXXX-145
         {12336,29555,37008}, // 092-XXXX-151
         {30326,24158, 6425}, // 092-XXXX-157
         {63479,63479,63479}, // 092-XXXX-123
         {63479,63479,63479}  // 092-XXXX-123

+    },
+    { // This color scheme is (very loosely) inspired by the first version of the PDP-11/70.
+      // Many RGB values came from: http://www.chdickman.com/pdp8/DECcolors/
+        {63479,63479,63479}, // 092-XXXX-123
+        { 5140, 2056, 5654}, // 092-XXXX-152
+        {51400,34952,26682}, // homemade, derived from 092-XXXX-136
+        {20000,13107,12850}, // homemade, derived from 092-XXXX-154
+        {65535,13107,12850}, // homemade, derived from 092-XXXX-154
+        {20000,13107,12850}, // homemade, derived from 092-XXXX-154
+        {28270, 8995,19532}, // 092-XXXX-140
+        {40092,11051,15677}, // 092-XXXX-139
+        {15000,21000, 4000}, // homemade, derived from 092-XXXX-129
+        {63479,63479,63479}, // 092-XXXX-123
+        {63479,63479,63479}  // 092-XXXX-123

     }
 };
 
     }
 };
 


@@ -181,20 +225,20 @@ draw_rect_area(struct NEDsim * nedsim, size_t x_origin, size_t y_origin, size_t
     y_origin += nedsim->origin_y_offset;
     x_size *= nedsim->cell_size;
     y_size *= nedsim->cell_size;
     y_origin += nedsim->origin_y_offset;
     x_size *= nedsim->cell_size;
     y_size *= nedsim->cell_size;

-    XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, x_origin, y_origin, x_size, y_size);
+    XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc, x_origin, y_origin, x_size, y_size);

 
     set_color(nedsim, &color_list[nedsim->color_index].border);
     if (bord_top) {
 
     set_color(nedsim, &color_list[nedsim->color_index].border);
     if (bord_top) {

-        XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, x_origin, y_origin, x_size, nedsim->border_size);
+        XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc, x_origin, y_origin, x_size, nedsim->border_size);

     }
     if (bord_bottom) {
     }
     if (bord_bottom) {

-        XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, x_origin, (y_origin + y_size - nedsim->border_size), x_size, nedsim->border_size);
+        XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc, x_origin, (y_origin + y_size - nedsim->border_size), x_size, nedsim->border_size);

     }
     if (bord_left) {
     }
     if (bord_left) {

-        XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, x_origin, y_origin, nedsim->border_size, y_size);
+        XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc, x_origin, y_origin, nedsim->border_size, y_size);

     }
     if (bord_right) {
     }
     if (bord_right) {

-        XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, (x_origin + x_size - nedsim->border_size), y_origin, nedsim->border_size, y_size);
+        XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc, (x_origin + x_size - nedsim->border_size), y_origin, nedsim->border_size, y_size);

     }
 }
 
     }
 }
 


@@ -226,7 +270,7 @@ draw_circular_area(struct NEDsim * nedsim, size_t x, size_t y, double diameter)
     y -= (0.5 * nedsim->border_size);
 
     // Start angle 0 and ending angle 360*64 is one full circle in Xlib units.
     y -= (0.5 * nedsim->border_size);
 
     // Start angle 0 and ending angle 360*64 is one full circle in Xlib units.

-    XFillArc(nedsim->dpy, nedsim->win, nedsim->gc, x, y, diameter, diameter, 0, 360*64);
+    XFillArc(nedsim->dpy, nedsim->panel, nedsim->gc, x, y, diameter, diameter, 0, 360*64);

 }
 
 // TODO: Explain
 }
 
 // TODO: Explain


@@ -240,11 +284,11 @@ draw_panel(struct NEDsim * nedsim)
 
     // Draw background color over entire window.
     set_color(nedsim, &color_list[nedsim->color_index].panel_bg);
 
     // Draw background color over entire window.
     set_color(nedsim, &color_list[nedsim->color_index].panel_bg);

-    XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, 0, 0, nedsim->dpy_width, nedsim->dpy_height);
+    XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc, 0, 0, nedsim->dpy_width, nedsim->dpy_height);

 
     // Draw NED panel in foreground color.
     set_color(nedsim, &color_list[nedsim->color_index].panel_fg);
 
     // Draw NED panel in foreground color.
     set_color(nedsim, &color_list[nedsim->color_index].panel_fg);

-    XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset,
             nedsim->origin_y_offset,
             nedsim->cell_size * OVERALL_WIDTH_IN_CELLS,
             nedsim->origin_x_offset,
             nedsim->origin_y_offset,
             nedsim->cell_size * OVERALL_WIDTH_IN_CELLS,


@@ -253,25 +297,25 @@ draw_panel(struct NEDsim * nedsim)
 
     // Give the panel rounded corners by first deleting the four right-angle corners...
     set_color(nedsim, &color_list[nedsim->color_index].panel_bg);
 
     // Give the panel rounded corners by first deleting the four right-angle corners...
     set_color(nedsim, &color_list[nedsim->color_index].panel_bg);

-    XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset,
             nedsim->origin_y_offset,
             nedsim->cell_size,
             nedsim->cell_size
     );
             nedsim->origin_x_offset,
             nedsim->origin_y_offset,
             nedsim->cell_size,
             nedsim->cell_size
     );

-    XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset + (nedsim->cell_size * (OVERALL_WIDTH_IN_CELLS-1)),
             nedsim->origin_y_offset,
             nedsim->cell_size,
             nedsim->cell_size
     );
             nedsim->origin_x_offset + (nedsim->cell_size * (OVERALL_WIDTH_IN_CELLS-1)),
             nedsim->origin_y_offset,
             nedsim->cell_size,
             nedsim->cell_size
     );

-    XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset,
             nedsim->origin_y_offset + (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS - 1)),
             nedsim->cell_size,
             nedsim->cell_size
     );
             nedsim->origin_x_offset,
             nedsim->origin_y_offset + (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS - 1)),
             nedsim->cell_size,
             nedsim->cell_size
     );

-    XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset + (nedsim->cell_size * (OVERALL_WIDTH_IN_CELLS-1)),
             nedsim->origin_y_offset + (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS - 1)),
             nedsim->cell_size,
             nedsim->origin_x_offset + (nedsim->cell_size * (OVERALL_WIDTH_IN_CELLS-1)),
             nedsim->origin_y_offset + (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS - 1)),
             nedsim->cell_size,


@@ -279,25 +323,25 @@ draw_panel(struct NEDsim * nedsim)
     );
     // ...and then replacing them with filled arcs, forming rounded corners.
     set_color(nedsim, &color_list[nedsim->color_index].panel_fg);
     );
     // ...and then replacing them with filled arcs, forming rounded corners.
     set_color(nedsim, &color_list[nedsim->color_index].panel_fg);

-    XFillArc(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillArc(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset,
             nedsim->origin_y_offset,
             nedsim->cell_size * 2, nedsim->cell_size * 2,
             180*64, -90*64
     );
             nedsim->origin_x_offset,
             nedsim->origin_y_offset,
             nedsim->cell_size * 2, nedsim->cell_size * 2,
             180*64, -90*64
     );

-    XFillArc(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillArc(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset + (nedsim->cell_size * (OVERALL_WIDTH_IN_CELLS-2)),
             nedsim->origin_y_offset,
             nedsim->cell_size * 2, nedsim->cell_size * 2,
             0, 90*64
     );
             nedsim->origin_x_offset + (nedsim->cell_size * (OVERALL_WIDTH_IN_CELLS-2)),
             nedsim->origin_y_offset,
             nedsim->cell_size * 2, nedsim->cell_size * 2,
             0, 90*64
     );

-    XFillArc(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillArc(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset,
             nedsim->origin_y_offset + (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS - 2)),
             nedsim->cell_size * 2, nedsim->cell_size * 2,
             180*64, 90*64
     );
             nedsim->origin_x_offset,
             nedsim->origin_y_offset + (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS - 2)),
             nedsim->cell_size * 2, nedsim->cell_size * 2,
             180*64, 90*64
     );

-    XFillArc(nedsim->dpy, nedsim->win, nedsim->gc,
+    XFillArc(nedsim->dpy, nedsim->panel, nedsim->gc,

             nedsim->origin_x_offset + (nedsim->cell_size * (OVERALL_WIDTH_IN_CELLS-2)),
             nedsim->origin_y_offset + (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS - 2)),
             nedsim->cell_size * 2, nedsim->cell_size * 2,
             nedsim->origin_x_offset + (nedsim->cell_size * (OVERALL_WIDTH_IN_CELLS-2)),
             nedsim->origin_y_offset + (nedsim->cell_size * (HEADER_HEIGHT_IN_CELLS + nedsim->num_data_rows + FOOTER_HEIGHT_IN_CELLS - 2)),
             nedsim->cell_size * 2, nedsim->cell_size * 2,


@@ -328,7 +372,7 @@ draw_logo(struct NEDsim * nedsim)
     get_text_size(nedsim, "NED", &text_x_size, &text_y_size);
     int local_x_offset = ((LOGO_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((LOGO_NAME_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     get_text_size(nedsim, "NED", &text_x_size, &text_y_size);
     int local_x_offset = ((LOGO_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((LOGO_NAME_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (LOGO_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, (LOGO_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),

             ((LOGO_Y_OFFSET+LOGO_NAME_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "NED", 3);
 
     // And draw the 'subgeniuskitty.com' text in the bottom box.
             ((LOGO_Y_OFFSET+LOGO_NAME_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "NED", 3);
 
     // And draw the 'subgeniuskitty.com' text in the bottom box.


@@ -336,7 +380,7 @@ draw_logo(struct NEDsim * nedsim)
     get_text_size(nedsim, "subgeniuskitty.com", &text_x_size, &text_y_size);
     local_x_offset = ((LOGO_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     local_y_offset = ((LOGO_WEBSITE_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     get_text_size(nedsim, "subgeniuskitty.com", &text_x_size, &text_y_size);
     local_x_offset = ((LOGO_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     local_y_offset = ((LOGO_WEBSITE_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (LOGO_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, (LOGO_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),

             ((LOGO_Y_OFFSET+LOGO_NAME_HEIGHT+LOGO_WEBSITE_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "subgeniuskitty.com", 18);
 }
 
             ((LOGO_Y_OFFSET+LOGO_NAME_HEIGHT+LOGO_WEBSITE_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "subgeniuskitty.com", 18);
 }
 


@@ -362,7 +406,7 @@ draw_halt(struct NEDsim * nedsim)
     get_text_size(nedsim, "HALT", &text_x_size, &text_y_size);
     int local_x_offset = ((HALT_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((HALT_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     get_text_size(nedsim, "HALT", &text_x_size, &text_y_size);
     int local_x_offset = ((HALT_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((HALT_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (HALT_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, (HALT_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),

             ((HALT_Y_OFFSET+HALT_LIGHT_HEIGHT+HALT_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "HALT", 4);
 }
 
             ((HALT_Y_OFFSET+HALT_LIGHT_HEIGHT+HALT_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "HALT", 4);
 }
 


@@ -426,7 +470,7 @@ draw_pc(struct NEDsim * nedsim)
     get_text_size(nedsim, "PC", &text_x_size, &text_y_size);
     int local_x_offset = ((PC_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((PC_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     get_text_size(nedsim, "PC", &text_x_size, &text_y_size);
     int local_x_offset = ((PC_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((PC_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (PC_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, (PC_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),

             ((PC_Y_OFFSET+PC_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "PC", 2);
 }
 
             ((PC_Y_OFFSET+PC_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "PC", 2);
 }
 


@@ -452,7 +496,7 @@ draw_sc(struct NEDsim * nedsim)
     get_text_size(nedsim, "SC", &text_x_size, &text_y_size);
     int local_x_offset = ((SC_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((SC_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     get_text_size(nedsim, "SC", &text_x_size, &text_y_size);
     int local_x_offset = ((SC_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((SC_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (SC_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, (SC_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),

             ((SC_Y_OFFSET+SC_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "SC", 2);
 }
 
             ((SC_Y_OFFSET+SC_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "SC", 2);
 }
 


@@ -484,7 +528,7 @@ draw_psw(struct NEDsim * nedsim)
     get_text_size(nedsim, "N", &text_x_size, &text_y_size);
     int local_x_offset = ((PSW_LABEL_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((PSW_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     get_text_size(nedsim, "N", &text_x_size, &text_y_size);
     int local_x_offset = ((PSW_LABEL_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     int local_y_offset = ((PSW_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (PSW_N_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, (PSW_N_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),

             ((PSW_Y_OFFSET+PSW_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "N", 1);
 
     // Now draw the label text "Z".
             ((PSW_Y_OFFSET+PSW_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "N", 1);
 
     // Now draw the label text "Z".


@@ -492,7 +536,7 @@ draw_psw(struct NEDsim * nedsim)
     get_text_size(nedsim, "Z", &text_x_size, &text_y_size);
     local_x_offset = ((PSW_LABEL_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     local_y_offset = ((PSW_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     get_text_size(nedsim, "Z", &text_x_size, &text_y_size);
     local_x_offset = ((PSW_LABEL_WIDTH * nedsim->cell_size) - text_x_size) / 2;
     local_y_offset = ((PSW_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, (PSW_Z_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, (PSW_Z_X_OFFSET * nedsim->cell_size + nedsim->origin_x_offset + local_x_offset),

             ((PSW_Y_OFFSET+PSW_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "Z", 1);
 }
 
             ((PSW_Y_OFFSET+PSW_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "Z", 1);
 }
 


@@ -518,7 +562,7 @@ draw_stack(struct NEDsim * nedsim)
     int text_x_size, text_y_size;
     get_text_size(nedsim, "Stack Size:", &text_x_size, &text_y_size);
     int local_y_offset = ((STACK_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     int text_x_size, text_y_size;
     get_text_size(nedsim, "Stack Size:", &text_x_size, &text_y_size);
     int local_y_offset = ((STACK_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, ((STACK_X_OFFSET + 1) * nedsim->cell_size + nedsim->origin_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, ((STACK_X_OFFSET + 1) * nedsim->cell_size + nedsim->origin_x_offset),

             ((STACK_Y_OFFSET+STACK_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "Stack Size:", 11);
 }
 
             ((STACK_Y_OFFSET+STACK_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "Stack Size:", 11);
 }
 


@@ -546,7 +590,7 @@ draw_heap(struct NEDsim * nedsim)
     int text_x_size, text_y_size;
     get_text_size(nedsim, "RAM Base:", &text_x_size, &text_y_size);
     int local_y_offset = ((HEAP_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     int text_x_size, text_y_size;
     get_text_size(nedsim, "RAM Base:", &text_x_size, &text_y_size);
     int local_y_offset = ((HEAP_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, ((HEAP_X_OFFSET + 1) * nedsim->cell_size + nedsim->origin_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, ((HEAP_X_OFFSET + 1) * nedsim->cell_size + nedsim->origin_x_offset),

             ((HEAP_Y_OFFSET+HEAP_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "RAM Base:", 9);
 
     // Now draw the address text.
             ((HEAP_Y_OFFSET+HEAP_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), "RAM Base:", 9);
 
     // Now draw the address text.


@@ -555,7 +599,7 @@ draw_heap(struct NEDsim * nedsim)
     snprintf(address, sizeof(address), "0x%08X", HEAP_START_ADDRESS);
     get_text_size(nedsim, address, &text_x_size, &text_y_size);
     local_y_offset = ((HEAP_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     snprintf(address, sizeof(address), "0x%08X", HEAP_START_ADDRESS);
     get_text_size(nedsim, address, &text_x_size, &text_y_size);
     local_y_offset = ((HEAP_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, ((HEAP_X_OFFSET + 1 + (HEAP_WIDTH / 2)) * nedsim->cell_size + nedsim->origin_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, ((HEAP_X_OFFSET + 1 + (HEAP_WIDTH / 2)) * nedsim->cell_size + nedsim->origin_x_offset),

             ((HEAP_Y_OFFSET+HEAP_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), address, strlen(address));
 }
 
             ((HEAP_Y_OFFSET+HEAP_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), address, strlen(address));
 }
 


@@ -621,7 +665,7 @@ update_display(struct NEDsim * nedsim)
     int text_x_size, text_y_size;
     get_text_size(nedsim, stack_size, &text_x_size, &text_y_size);
     int local_y_offset = ((STACK_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;
     int text_x_size, text_y_size;
     get_text_size(nedsim, stack_size, &text_x_size, &text_y_size);
     int local_y_offset = ((STACK_LABEL_HEIGHT * nedsim->cell_size) - text_y_size) / 2;

-    XDrawString(nedsim->dpy, nedsim->win, nedsim->gc, ((STACK_X_OFFSET + 1 + (STACK_WIDTH / 2)) * nedsim->cell_size + nedsim->origin_x_offset),
+    XDrawString(nedsim->dpy, nedsim->panel, nedsim->gc, ((STACK_X_OFFSET + 1 + (STACK_WIDTH / 2)) * nedsim->cell_size + nedsim->origin_x_offset),

             ((STACK_Y_OFFSET+STACK_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), stack_size, strlen(stack_size));
 
     // Draw the heap lights.
             ((STACK_Y_OFFSET+STACK_LABEL_HEIGHT) * nedsim->cell_size + nedsim->origin_y_offset - local_y_offset), stack_size, strlen(stack_size));
 
     // Draw the heap lights.


@@ -654,6 +698,7 @@ NEDsim_free(Display * dpy, Window win, void * closure)
 
     // TODO: Replace all this with proper code to free everything related to the screensaver itself.
     XFreeGC(nedsim->dpy, nedsim->gc);
 
     // TODO: Replace all this with proper code to free everything related to the screensaver itself.
     XFreeGC(nedsim->dpy, nedsim->gc);

+    XFreePixmap(nedsim->dpy, nedsim->panel);

     free(nedsim);
 }
 
     free(nedsim);
 }
 


@@ -692,9 +737,17 @@ NEDsim_init(Display * dpy, Window win)
     }
 
     nedsim->gc = XCreateGC(nedsim->dpy, nedsim->win, GCForeground, &gcv);
     }
 
     nedsim->gc = XCreateGC(nedsim->dpy, nedsim->win, GCForeground, &gcv);

-
-    // TODO: Do this properly.
-    nedsim->color_index = 0;
+    nedsim->panel = XCreatePixmap(nedsim->dpy, nedsim->win, nedsim->dpy_width, nedsim->dpy_height, xgwa.depth);
+
+    // If the user specified a color, use it. Otherwise, select at random from
+    // the available color schemes.
+    nedsim->color_index = get_integer_resource(nedsim->dpy, "color", "Integer");
+    if (nedsim->color_index == -1) {
+        nedsim->color_index = random() % sizeof(color_list)/sizeof(color_list[0]);
+    } else if (nedsim->color_index >= sizeof(color_list)/sizeof(color_list[0])) {
+        fprintf(stderr, "WARNING: Color index out of range.\n");
+        nedsim->color_index = 0;
+    }

 
 // TODO: Save the GIMP reference diagram somewhere, along with notes about the size/spacing, and that each cell is 10 pixels across in the reference image.
 
 
 // TODO: Save the GIMP reference diagram somewhere, along with notes about the size/spacing, and that each cell is 10 pixels across in the reference image.
 


@@ -748,9 +801,11 @@ NEDsim_draw(Display * dpy, Window win, void * closure)
         update_display(nedsim);
     } else {
         set_color(nedsim, &color_list[nedsim->color_index].error_on);
         update_display(nedsim);
     } else {
         set_color(nedsim, &color_list[nedsim->color_index].error_on);

-        XFillRectangle(nedsim->dpy, nedsim->win, nedsim->gc, 0, 0, nedsim->dpy_width, nedsim->dpy_height);
+        XFillRectangle(nedsim->dpy, nedsim->panel, nedsim->gc, 0, 0, nedsim->dpy_width, nedsim->dpy_height);

     }
 
     }
 

+    XCopyArea(nedsim->dpy, nedsim->panel, nedsim->win, nedsim->gc, 0, 0, nedsim->dpy_width, nedsim->dpy_height, 0, 0);
+

     return nedsim->delay;
 }
 
     return nedsim->delay;
 }
 


@@ -773,12 +828,14 @@ NEDsim_reshape(Display * dpy, Window win, void * closure, unsigned int w, unsign
 
 static const char * NEDsim_defaults[] = {
     "*delay:              250",
 
 static const char * NEDsim_defaults[] = {
     "*delay:              250",

+    "*color:               -1",

     0
 };
 
 static XrmOptionDescRec NEDsim_options[] = {
     { "-delay",              ".delay",                  XrmoptionSepArg, 0      },
     { "-binary",             ".binary",                 XrmoptionSepArg, 0      },
     0
 };
 
 static XrmOptionDescRec NEDsim_options[] = {
     { "-delay",              ".delay",                  XrmoptionSepArg, 0      },
     { "-binary",             ".binary",                 XrmoptionSepArg, 0      },

+    { "-color",              ".color",                  XrmoptionSepArg, 0      },

     { 0, 0, 0, 0 }
 };
 
     { 0, 0, 0, 0 }
 };