dw_style.c

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         min = green;
      else
         min = blue;
   } else {
      if (green > blue)
         max = green;
      else
         max = blue;

      if (red < blue)
         min = red;
      else
         min = blue;
   }

   l = (max + min) / 2;
   s = 0;
   h = 0;

   if (max != min) {
      if (l <= 0.5)
         s = (max - min) / (max + min);
      else
         s = (max - min) / (2 - max - min);

      delta = max -min;
      if (red == max)
         h = (green - blue) / delta;
      else if (green == max)
         h = 2 + (blue - red) / delta;
      else if (blue == max)
         h = 4 + (red - green) / delta;

      h *= 60;
      if (h < 0.0)
         h += 360;
   }

   *r = h;
   *g = l;
   *b = s;
}

/*
 * Copied from gtkstyle.c.
 * Convert HLS into RGB.
 */
static void Dw_style_hls_to_rgb (gdouble *h,
                                 gdouble *l,
                                 gdouble *s)
{
   gdouble hue;
   gdouble lightness;
   gdouble saturation;
   gdouble m1, m2;
   gdouble r, g, b;

   lightness = *l;
   saturation = *s;

   if (lightness <= 0.5)
      m2 = lightness * (1 + saturation);
   else
      m2 = lightness + saturation - lightness * saturation;
   m1 = 2 * lightness - m2;

   if (saturation == 0) {
      *h = lightness;
      *l = lightness;
      *s = lightness;
   } else {
      hue = *h + 120;
      while (hue > 360)
         hue -= 360;
      while (hue < 0)
         hue += 360;

      if (hue < 60)
            r = m1 + (m2 - m1) * hue / 60;
      else if (hue < 180)
         r = m2;
      else if (hue < 240)
         r = m1 + (m2 - m1) * (240 - hue) / 60;
      else
         r = m1;

      hue = *h;
      while (hue > 360)
         hue -= 360;
      while (hue < 0)
         hue += 360;

      if (hue < 60)
         g = m1 + (m2 - m1) * hue / 60;
      else if (hue < 180)
         g = m2;
      else if (hue < 240)
         g = m1 + (m2 - m1) * (240 - hue) / 60;
      else
         g = m1;

      hue = *h - 120;
      while (hue > 360)
         hue -= 360;
      while (hue < 0)
         hue += 360;

      if (hue < 60)
         b = m1 + (m2 - m1) * hue / 60;
      else if (hue < 180)
         b = m2;
      else if (hue < 240)
         b = m1 + (m2 - m1) * (240 - hue) / 60;
      else
         b = m1;

      *h = r;
      *l = g;
      *s = b;
   }
}


/*
 * Create the necessary recources (GdkColor, GdkGC).
 * k is a factor the color is multiplied with before, this is needed
 * for shaded colors.
 */
static void Dw_style_color_create (gint color_val,
                                   GdkWindow *window,
                                   GdkColor *color,
                                   GdkGC **gc,
                                   gint d)
{
   gint red, green, blue;
   gdouble hue, lightness, saturation;

   red = (color_val >> 16) & 255;
   green = (color_val >> 8) & 255;
   blue = color_val & 255;

   if (d) {
      hue = (gdouble)red / 255;
      lightness = (gdouble)green / 255;
      saturation = (gdouble)blue / 255;

      DEBUG_MSG (1, "Shaded by %1.3g: (%1.3g, %1.3g, %1.3g) -> ",
                 k, hue, lightness, saturation);
      Dw_style_rgb_to_hls (&hue, &lightness, &saturation);

      if (lightness > 0.8) {
         if (d > 0)
            lightness -= 0.2;
         else
            lightness -= 0.4;
      } else if (lightness < 0.2) {
         if (d > 0)
            lightness += 0.4;
         else
            lightness += 0.2;
      } else
         lightness += d * 0.2;

      Dw_style_hls_to_rgb (&hue, &lightness, &saturation);
      DEBUG_MSG (1, "(%1.3g, %1.3g, %1.3g)\n", hue, lightness, saturation);

      red = hue * 255;
      green = lightness * 255;
      blue = saturation * 255;
   }

   blue |= blue << 8;
   red |= red << 8;
   green |= green << 8;

   color->red = red;
   color->green = green;
   color->blue = blue;
   gdk_color_alloc (gdk_window_get_colormap (window), color);

   *gc = gdk_gc_new (window);
   gdk_gc_set_foreground (*gc, color);
}

/*
   Return a new or already existing color. color_val has the form
   0xrrggbb.
 */
DwStyleColor* a_Dw_style_color_new (gint color_val,
                                    GdkWindow *window)
{
   DwStyleColor *color;

   color = g_hash_table_lookup (colors_table, GINT_TO_POINTER (color_val));
   if (color == NULL) {
      color = g_new (DwStyleColor, 1);
      color->ref_count = 0;
      color->color_val = color_val;

      Dw_style_color_create (color_val, window,
                             &color->color, &color->gc, 0);
      Dw_style_color_create (color_val ^ 0xffffff, window,
                             &color->inverse_color, &color->inverse_gc, 0);
      g_hash_table_insert (colors_table, GINT_TO_POINTER (color_val), color);
      g_hash_table_insert (colors_table, GINT_TO_POINTER (color_val), color);
   }

   return color;
}

/*
 * Remove a color (called when ref_count == 0).
 */
static void Dw_style_color_remove (DwStyleColor *color)
{
   g_hash_table_remove (colors_table, GINT_TO_POINTER (color->color_val));
   gdk_gc_destroy (color->gc);
   gdk_gc_destroy (color->inverse_gc);
   g_free (color);
}


/*
 * Return a new or already existing shaded color. color_val has the
 * form 0xrrggbb.
 */
DwStyleShadedColor* a_Dw_style_shaded_color_new (gint color_val,
                                                 GdkWindow *window)
{
   DwStyleShadedColor *color;

   color =
      g_hash_table_lookup (shaded_colors_table, GINT_TO_POINTER (color_val));
   if (color == NULL) {
      color = g_new (DwStyleShadedColor, 1);
      color->ref_count = 0;
      color->color_val = color_val;

      Dw_style_color_create (color_val, window,
                             &color->color, &color->gc, 0);
      Dw_style_color_create (color_val ^ 0xffffff, window,
                             &color->inverse_color, &color->inverse_gc, 0);
      Dw_style_color_create (color_val, window,
                             &color->color_dark, &color->gc_dark, -1);
      Dw_style_color_create (color_val, window,
                             &color->color_light, &color->gc_light, +1);
      g_hash_table_insert (shaded_colors_table,
                           GINT_TO_POINTER (color_val), color);
   }

   return color;
}

/*
 * Remove a shaded color (called when ref_count == 0).
 */
static void Dw_style_shaded_color_remove (DwStyleShadedColor *color)
{
   g_hash_table_remove (shaded_colors_table,
                        GINT_TO_POINTER (color->color_val));
   gdk_gc_destroy (color->gc);
   gdk_gc_destroy (color->gc_dark);
   gdk_gc_destroy (color->gc_light);
   g_free (color);
}

/*
 * This function returns whether something may change its size, when
 * its style changes from style1 to style2. It is mainly for
 * optimizing style changes where only colors etc change (where FALSE
 * would be returned), in some cases it may return TRUE, although a
 * size change does not actually happen (e.g. when in a certain
 * context a particular attribute is ignored).
 */
gboolean a_Dw_style_size_diffs (DwStyle *style1,
                                DwStyle *style2)
{
   /* todo: Should for CSS implemented properly. Currently, size
    * changes are not needed, so always FALSE is returned. See also
    * a_Dw_widget_set_style(). */
   return FALSE;
}


/* ----------------------------------------------------------------------
 *
 *    Drawing functions
 *
 * ----------------------------------------------------------------------
 */

/*
 * Draw a part of a border.
 */
static void Dw_style_draw_polygon (GdkDrawable *drawable,
                                   GdkGC *gc,
                                   gint32 x1, gint32 y1, gint32 x2, gint32 y2,
                                   gint32 width, gint32 w1, gint32 w2)
{
   GdkPoint points[4];

   if (width != 0) {
      if (width == 1) {
         if (x1 == x2)
            gdk_draw_line (drawable, gc, x1, y1, x2, y2 - 1);
         else
            gdk_draw_line (drawable, gc, x1, y1, x2 - 1, y2);
      } else if (width == -1) {
         if (x1 == x2)
            gdk_draw_line (drawable, gc, x1 - 1, y1, x2 - 1, y2 - 1);
         else
            gdk_draw_line (drawable, gc, x1, y1 - 1, x2 - 1, y2 - 1);
      } else {
         points[0].x = x1;
         points[0].y = y1;
         points[1].x = x2;
         points[1].y = y2;

         if (x1 == x2) {
            points[2].x = x1 + width;
            points[2].y = y2 + w2;
            points[3].x = x1 + width;
            points[3].y = y1 + w1;
         } else {
            points[2].x = x2 + w2;
            points[2].y = y1 + width;
            points[3].x = x1 + w1;
            points[3].y = y1 + width;
         }

         gdk_draw_polygon (drawable, gc, TRUE, points, 4);
      }
   }
}


/*
 * Draw the border of a region in window, according to style. Used by
 * Dw_widget_draw_box and Dw_widget_draw_widget_box.
 */

#define LIMIT(v)    if ((v) < -30000) v = -30000; \
                    if ((v) > 30000) v = 30000

void p_Dw_style_draw_border (GdkWindow *window,
                             GdkRectangle *area,
                             gint32 vx,
                             gint32 vy,
                             gint32 x,
                             gint32 y,
                             gint32 width,
                             gint32 height,
                             DwStyle *style,
                             gboolean inverse)
{
   /* todo: a lot! */
   GdkGC *dark_gc, *light_gc, *normal_gc;
   GdkGC *top_gc, *right_gc, *bottom_gc, *left_gc;
   gint32 xb1, yb1, xb2, yb2, xp1, yp1, xp2, yp2;

   if (style->border_style.top == DW_STYLE_BORDER_NONE)
      return;

   xb1 = x + style->margin.left - vx;
   yb1 = y + style->margin.top - vy;
   xb2 = xb1 + width - style->margin.left - style->margin.right;
   yb2 = yb1 + height - style->margin.top - style->margin.bottom;

   xp1 = xb1 + style->border_width.top;
   yp1 = yb1 + style->border_width.left;
   xp2 = xb2 + style->border_width.bottom;
   yp2 = yb2 + style->border_width.right;

   /* Make sure that we pass 16-bit values to Gdk functions. */
   LIMIT (xb1);
   LIMIT (xb2);
   LIMIT (yb1);
   LIMIT (yb2);

   light_gc = inverse ? style->border_color.top->gc_dark :
      style->border_color.top->gc_light;
   dark_gc = inverse ? style->border_color.top->gc_light :
      style->border_color.top->gc_dark;
   normal_gc = inverse ? style->border_color.top->inverse_gc :
      style->border_color.top->gc;

   switch (style->border_style.top) {
   case DW_STYLE_BORDER_INSET:
      top_gc = left_gc = dark_gc;
      right_gc = bottom_gc = light_gc;
      break;

   case DW_STYLE_BORDER_OUTSET:
      top_gc = left_gc = light_gc;
      right_gc = bottom_gc = dark_gc;
      break;

   default:
      top_gc = right_gc = bottom_gc = left_gc = normal_gc;
      break;
   }

   Dw_style_draw_polygon (window, top_gc, xb1, yb1, xb2, yb1,
                          style->border_width.top,
                          style->border_width.left,
                          - style->border_width.right);
   Dw_style_draw_polygon (window, right_gc, xb2, yb1, xb2, yb2,
                          - style->border_width.right,
                          style->border_width.top,
                          - style->border_width.bottom);
   Dw_style_draw_polygon (window, bottom_gc, xb1, yb2, xb2, yb2,
                          - style->border_width.bottom,
                          style->border_width.left,
                          - style->border_width.right);
   Dw_style_draw_polygon (window, left_gc, xb1, yb1, xb1, yb2,
                          style->border_width.left,
                          style->border_width.top,
                          - style->border_width.bottom);
}


/*
 * Draw the background (content plus padding) of a region in window,
 * according to style. Used by Dw_widget_draw_box and
 * Dw_widget_draw_widget_box.
 */
void p_Dw_style_draw_background (GdkWindow *window,
                                 GdkRectangle *area,
                                 gint32 vx,
                                 gint32 vy,
                                 gint32 x,
                                 gint32 y,
                                 gint32 width,
                                 gint32 height,
                                 DwStyle *style,
                                 gboolean inverse)
{
   DwRectangle dw_area, bg_area, intersection;

   if (style->background_color) {
      dw_area.x = area->x + vx;
      dw_area.y = area->y + vy;
      dw_area.width = area->width;
      dw_area.height = area->height;

      bg_area.x = x + style->margin.left + style->border_width.left;
      bg_area.y = y + style->margin.top + style->border_width.top;
      bg_area.width =
         width - style->margin.left - style->border_width.left -
         style->margin.right - style->border_width.right;
      bg_area.height =
         height - style->margin.top - style->border_width.top -
         style->margin.bottom - style->border_width.bottom;

      if (p_Dw_rectangle_intersect (&dw_area, &bg_area, &intersection))
         gdk_draw_rectangle (window,
                             inverse ? style->background_color->inverse_gc :
                             style->background_color->gc,
                             TRUE, intersection.x - vx, intersection.y - vy,
                             intersection.width, intersection.height);
   }
}


/*
 * Convert a number into a string, in a given style. Used for ordered lists.
 */
void a_Dw_style_numtostr (gint num,
                          gchar *buf,
                          gint buflen,
                          DwStyleListStyleType list_style_tyle)
{
   int i3, i2, i1, i0;
   gboolean low = FALSE;

   switch(list_style_tyle){
   case DW_STYLE_LIST_STYLE_TYPE_LOWER_ALPHA:
      low = TRUE;
   case DW_STYLE_LIST_STYLE_TYPE_UPPER_ALPHA:
      i0 = num - 1;
      i1 = i0/26; i2 = i1/26;
      i0 %= 26;   i1 %= 26;
      if (i2 > 26) /* more than 26*26*26=17576 elements ? */
         sprintf(buf, "****.");
      else if (i2)
         sprintf(buf, "%c%c%c.", 'A'+i2-1,'A'+i1-1,'A'+i0);
      else if (i1)
         sprintf(buf, "%c%c.", 'A'+i1-1,'A'+i0);
      else
         sprintf(buf, "%c.", 'A'+i0);
      if (low)
         g_strdown(buf);
      break;
   case DW_STYLE_LIST_STYLE_TYPE_LOWER_ROMAN:
      low = TRUE;
   case DW_STYLE_LIST_STYLE_TYPE_UPPER_ROMAN:
      i0 = num - 1;
      i1 = i0/10; i2 = i1/10; i3 = i2/10;
      i0 %= 10;   i1 %= 10;   i2 %= 10;
      if (i3 > 4) /* more than 4999 elements ? */
         sprintf(buf, "****.");
      else if (i3)
         sprintf(buf, "%s%s%s%s.", roman_I3[i3-1], roman_I2[i2-1],
                 roman_I1[i1-1], roman_I0[i0]);
      else if (i2)
         sprintf(buf, "%s%s%s.", roman_I2[i2-1],
                 roman_I1[i1-1], roman_I0[i0]);
      else if (i1)
         sprintf(buf, "%s%s.", roman_I1[i1-1], roman_I0[i0]);
      else
         sprintf(buf, "%s.", roman_I0[i0]);
      if (low)
         g_strdown(buf);
      break;
   case DW_STYLE_LIST_STYLE_TYPE_DECIMAL:
   default:
      g_snprintf(buf, buflen, "%d.", num);
      break;
   }
}