WIP Lightning Magic tool

UI, icon, sfx working; not actually rendering the bolt yet.

docs/AUTHORS.txt

@@ -6,11 +6,7 @@ Copyright (c) 2002-2021
 Various contributors (see below, and CHANGES.txt)
 http://www.tuxpaint.org/
 
-
-June 17, 2002 - September 17, 2021
-
-$Id$
-
+June 17, 2002 - September 26, 2021
 
 * Design and Coding:
 
@@ -482,6 +478,11 @@ $Id$
     http://soundbible.com/633-Snowing.html
     Creative Commons Attribution 3.0
 
+  * lightning.ogg
+    Jonathan Hunt, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>
+    via Wikimedia Commons
+    https://commons.wikimedia.org/wiki/File:Thunder_Claps.ogg
+
 * Translations
 
   * Acholi translation

docs/CHANGES.txt

@@ -11,6 +11,9 @@ $Id$
 2021.September.26 (0.9.27)
   * New Magic Tools:
     ----------------
+    * WIP "Lightning" - Draws a bolt of lightning striking between
+      the start and end positions of a line.
+
     * "Opposite" -- Change parts of the picture to their complementary
       colors.  (Similar to "Negative", but instead of inverting the
       Red, Green, and Blue components, it rotates the Hue 180 degrees

magic/src/lightning.c

@@ -0,0 +1,168 @@
+/* lightning.c
+
+   Draws a lightning strike between the click
+   and drag+release positions.
+
+   Last modified: 2021.09.26
+*/
+
+#include <stdio.h>
+#include <string.h>
+#include <libintl.h>
+
+#include "tp_magic_api.h"
+#include "SDL_image.h"
+#include "SDL_mixer.h"
+
+Mix_Chunk *snd_effect;
+Uint8 lightning_r, lightning_g, lightning_b;
+int sx, sy;
+
+
+void lightning_drag(magic_api * api, int which, SDL_Surface * canvas,
+                    SDL_Surface * snapshot, int ox, int oy, int x, int y, SDL_Rect * update_rect);
+void lightning_line_callback_drag(void *ptr, int which, SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y);
+void lightning_line_callback_release(void *ptr, int which, SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y);
+
+
+Uint32 lightning_api_version(void)
+{
+  return (TP_MAGIC_API_VERSION);
+}
+
+int lightning_init(magic_api * api)
+{
+  char fname[1024];
+
+  snprintf(fname, sizeof(fname), "%s/sounds/magic/lightning.ogg", api->data_directory);
+  snd_effect = Mix_LoadWAV(fname);
+
+  return (1);
+}
+
+int lightning_get_tool_count(magic_api * api)
+{
+  return (1);
+}
+
+
+SDL_Surface *lightning_get_icon(magic_api * api, int which)
+{
+  char fname[1024];
+
+  snprintf(fname, sizeof(fname), "%s/images/magic/lightning.png", api->data_directory);
+
+  return (IMG_Load(fname));
+}
+
+char *lightning_get_name(magic_api * api, int which)
+{
+  return strdup(gettext("Lightning"));
+}
+
+int lightning_get_group(magic_api * api, int which)
+{
+  return MAGIC_TYPE_ARTISTIC;
+}
+
+char *lightning_get_description(magic_api * api, int which, int mode)
+{
+  return strdup(gettext("Click, drag, and release to a lightning bolt between two points."));
+}
+
+int lightning_requires_colors(magic_api * api, int which)
+{
+  return 1;
+}
+
+int lightning_modes(magic_api * api, int which)
+{
+  return MODE_PAINT;
+}
+
+void lightning_shutdown(magic_api * api)
+{
+  if (snd_effect != NULL)
+    Mix_FreeChunk(snd_effect);
+}
+
+
+void
+lightning_click(magic_api * api, int which, int mode,
+              SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y, SDL_Rect * update_rect)
+{
+  sx = x;
+  sy = y;
+  lightning_drag(api, which, canvas, snapshot, x, y, x, y, update_rect);
+}
+
+
+void
+lightning_drag(magic_api * api, int which, SDL_Surface * canvas,
+             SDL_Surface * snapshot, int ox, int oy, int x, int y, SDL_Rect * update_rect)
+{
+  /* FIXME: This could be made more efficient
+     (only blit and update between (sx,sy) and (x,y), though
+     it should also cover the area extending to (ox,oy),
+     to avoid leaving trails */
+  update_rect->x = 0;
+  update_rect->y = 0;
+  update_rect->w = canvas->w;
+  update_rect->h = canvas->h;
+
+  SDL_BlitSurface(snapshot, update_rect, canvas, update_rect);
+
+  api->line((void *)api, which, canvas, snapshot, sx, sy, x, y, 1, lightning_line_callback_drag);
+}
+
+
+void
+lightning_release(magic_api * api, int which,
+                SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y, SDL_Rect * update_rect)
+{
+  /* FIXME: This could be made more efficient
+     (only blit and update between (sx,sy) and (x,y), though
+     it should also cover the area extending to (ox,oy),
+     to avoid leaving trails */
+  update_rect->x = 0;
+  update_rect->y = 0;
+  update_rect->w = canvas->w;
+  update_rect->h = canvas->h;
+
+  SDL_BlitSurface(snapshot, update_rect, canvas, update_rect);
+
+  api->line((void *)api, which, canvas, snapshot, sx, sy, x, y, 1, lightning_line_callback_release);
+  api->stopsound();
+  api->playsound(snd_effect, (x * 255) / canvas->w, 255);
+}
+
+void lightning_set_color(magic_api * api, Uint8 r, Uint8 g, Uint8 b)
+{
+  lightning_r = r;
+  lightning_g = g;
+  lightning_b = b;
+}
+
+
+void lightning_line_callback_drag(void *ptr, int which, SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y)
+{
+  magic_api *api = (magic_api *) ptr;
+
+  api->xorpixel(canvas, x, y);
+}
+
+void lightning_line_callback_release(void *ptr, int which, SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y)
+{
+  magic_api *api = (magic_api *) ptr;
+
+  // FIXME
+  api->putpixel(canvas, x, y, SDL_MapRGB(canvas->format, lightning_r, lightning_g, lightning_b));
+}
+
+void lightning_switchin(magic_api * api, int which, int mode, SDL_Surface * canvas)
+{
+}
+
+void lightning_switchout(magic_api * api, int which, int mode, SDL_Surface * canvas)
+{
+}