tuxpaint-pencil-sharpener/docs/es_ES.UTF-8/html/tp_magic_example.c

/* tp_magic_example.c

   An example of a "Magic" tool plugin for Tux Paint
   octubre 18, 2022
*/


/* Inclusion of header files */
/* ---------------------------------------------------------------------- */

#include <stdio.h>
#include <string.h>        // For "strdup()"
#include <libintl.h>       // For "gettext()"

#include "tp_magic_api.h"  // Tux Paint "Magic" tool API header
#include "SDL_image.h"     // For IMG_Load(), to load our PNG icon
#include "SDL_mixer.h"     // For Mix_LoadWAV(), to load our sound effects


/* Tool Enumerations: */
/* ---------------------------------------------------------------------- */

/* What tools we contain: */


enum
{
  TOOL_ONE, // Becomes '0'
  TOOL_ONE, // Becomes '1'
  NUM_TOOLS // Becomes '2'
};


/* A list of filenames for sounds and icons to load at startup: */

const char *sound_filenames[NUM_TOOLS] = {
  "tool_one.wav",
  "tool_two.wav"
};

const char *icon_filenames[NUM_TOOLS] = {
  "tool_one.png",
  "tool_two.png"
};


/*
NOTE: We use a macro called "gettext_noop()" below in some arrays of
strings (char *'s) that hold the names and descriptions of our "Magic"
tools.  This allows the strings to be localized into other languages.
*/


/* A list of names for the tools */

const char *tool_names[NUM_TOOLS] = {
  gettext_noop("A tool"),
  gettext_noop("Another tool")
};


/* How to group the tools with other similar tools, within the 'Magic' selector: */

const int tool_groups[$NUM_TOOLS] = {
  MAGIC_TYPE_PAINTING,
  MAGIC_TYPE_DISTORTS
};


/* A list of descriptions of the tools */

const char *tool_descriptions[NUM_TOOLS] = {
  gettext_noop("This is example tool number 1."),
  gettext_noop("This is example tool number 2.")
};



/* Our global variables: */
/* ---------------------------------------------------------------------- */

/* Sound effects: */
Mix_Chunk *sound_effects[NUM_TOOLS];

/* The current color (an "RGB" -- red, green, blue -- value) the user has selected in Tux Paint: */
Uint8 example_r, $example_g, $example_b;


/* Our local function prototypes: */
/* ---------------------------------------------------------------------- */

/*
These functions are called by other functions within our plugin, so we
provide a 'prototype' of them, so the compiler knows what they accept and
return.  This lets us use them in other functions that are declared
_before_ them.
*/

void example_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 example_line_callback(void *pointer, int which, SDL_Surface * canvas,
                           SDL_Surface * snapshot, int x, int y);


/* Setup Functions: */
/* ---------------------------------------------------------------------- */

/*
API Version check

The running copy of Tux Paint that has loaded us first asks us what version
of the Tux Paint 'Magic' tool plugin API we were built against.  If it
deems us compatible, we'll be used!

All we need to do here is return "TP_MAGIC_API_VERSION", which is defined
(#define) in the header file "tp_magic_api.h".
*/

Uint32 example_api_version(void)
{
  return (TP_MAGIC_API_VERSION);
}


/*
Initialization

This happens once, when Tux Paint starts up and is loading all of the
'Magic' tool plugins.  (Assuming what we returned from api_version was
acceptable!)

All we're doing in this example is loading our sound effects, which we'll
use later (in example_click(), example_drag(), and example_release()) when
the user is using our Magic tools.

The memory we allocate here to store the sounds will be freed (aka
released, aka deallocated) when the user quits Tux Paint, when our
example_shutdown() function is called.
*/

int example_init(magic_api * api)
{
  int i;
  char filename[1024];

  for (i = 0; i < NUM_TOOLS; i++)
  {
    /*
    Assemble the filename from the "sound_filenames[]" array into a full path
    to a real file.

    Use "api->data_directory" to figure out where our sounds should be. (The
    "tp-magic-config --dataprefix" command would have told us when we installed
    our plugin and its data.)

    snprintf(filename, sizeof(filename), "%s/sounds/magic/%s", api->data_directory,
             sound_filenames[i]);

    printf("Trying to load %s sound file\n", filename);

    // Try to load the file!
    sound_effects[i] = Mix_LoadWAV(filename);
  }

  return (1);
}


// Report our tool count
// 
// Tux Paint needs to know how many "Magic" tools we'll be providing.
// Return that number here.  (We simply grab the value of "NUM_TOOLS"
// from our 'enum' above!)
// 
// When Tux Paint is starting up and loading plugins, it will call
// some of the following setup functions once for each tool we report.

int example_get_tool_count(magic_api * api)
{
  return (NUM_TOOLS);
}


// Load icons
//
// When Tux Paint is starting up and loading plugins, it asks us to
// provide icons for the "Magic" tool buttons.

SDL_Surface *example_get_icon(magic_api * api, int which)
{
  char fname[1024];

  // Assemble the filename from the "icon_filenames[]" array into
  // a full path to a real file.
  //
  // Use "api->data_directory" to figure out where our sounds should be.
  // (The "tp-magic-config --dataprefix" command would have told us when
  // we installed our plugin and its data.)
  //
  // We use 'which' (which of our tools Tux Paint is asking about)
  // as an index into the array.

  snprintf(fname, sizeof(fname), "%s/images/magic/%s.png",
           api->data_directory, icon_filenames[which]);


  // Try to load the image, and return the results to Tux Paint:

  return (IMG_Load(fname));
}


// Report our "Magic" tool names
//
// When Tux Paint is starting up and loading plugins, it asks us to
// provide names (labels) for the "Magic" tool buttons.

char *example_get_name(magic_api * api, int which)
{
  const char *our_name_english;
  const char *our_name_localized;

  // Get our name from the "names[]" array.
  //
  // We use 'which' (which of our tools Tux Paint is asking about)
  // as an index into the array.

  our_name_english = names[which];


  // Return a localized (aka translated) version of our name,
  // if possible.
  //
  // We send "gettext()" the English version of the name from our array.

  our_name_localized = gettext(our_name_english);


  // Finally, duplicate the string into a new section of memory, and
  // send it to Tux Paint.  (Tux Paint keeps track of the string and
  // will free it for us, so we have one less thing to keep track of.)

  return (strdup(our_name_localized));
}


/*
Report our 'Magic' tool groups

When Tux Paint is starting up and loading plugins, it asks us to specify
where the tool should be grouped.
*/
int example_get_group(magic_api * api, int which)
{
  /*
  Return our group, found in the "tool_groups[]" array.

  We use 'which' (which of our tools Tux Paint is asking about) as an index
  into the array.
  */
  return (tool_groups[which]);
}


/*
Report our 'Magic' tool descriptions

When Tux Paint is starting up and loading plugins, it asks us to provide
descriptions of each 'Magic' tool.
*/
char *example_get_description(magic_api * api, int which, int mode)
{
  const char *our_desc_english;
  const char *our_desc_localized;

  /*
  Get our description from the "tool_descriptions[]" array.

  We use 'which' (which of our tools Tux Paint is asking about) as an index
  into the array.
  */
  our_desc_english = tool_descriptions[which];


  /*
  Return a localized (aka translated) version of our description, if
  possible.

  We send "gettext" the English version of the description from our array.
  */
  our_desc_localized = gettext(our_desc_english);


  /*
  Finally, duplicate the string into a new section of memory, and send it to
  Tux Paint.  (Tux Paint keeps track of the string and will free it for us,
  so we have one less thing to keep track of.)
  */

  return (strdup(our_desc_localized));
}

// Report whether we accept colors

int example_requires_colors(magic_api * api, int which)
{
  // Both of our tools accept colors, so we're always returning '1' (for 'true')

  return 1;
}


// Report what modes we work in

int example_modes(magic_api * api, int which)
{
  // Both of our tools are painted (neither affect the full-screen), so we're
always returning 'MODE_PAINT'

  return MODE_PAINT;
}


/*
Shut down

Tux Paint is quitting.  When it quits, it asks all of the plugins to 'clean
up' after themselves.  We, for example, loaded some sound effects at
startup (in our example_init() function), so we should free the memory used
by them now.
*/
void example_shutdown(magic_api * api)
{
  int i;

  /*
  Free (aka release, aka deallocate) the memory used to store the sound
  effects that we loaded during example_init():
  */
  for (i = 0; i < NUM_TOOLS; i++)
    Mix_FreeChunk(sound_effects[i]);
}


/* Functions that respond to events in Tux Paint: */
/* ---------------------------------------------------------------------- */

// Affect the canvas on click:

void
example_click(magic_api * api, int which, int mode,
              SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y,
              SDL_Rect * update_rect)
{
  // In our case, a single click (which is also the start of a drag!)
  // is identical to what dragging does, but just at one point, rather
  // than across a line.
  // 
  // So we 'cheat' here, by calling our draw() function with
  // (x,y) for both the beginning and end points of a line.

  example_drag(api, which, canvas, snapshot, x, y, x, y, update_rect);
}


// Affect the canvas on drag:

void
example_drag(magic_api * api, int which, SDL_Surface * canvas,
             SDL_Surface * snapshot, int ox, int oy, int x, int y,
             SDL_Rect * update_rect)
{
  // Call Tux Paint's "line()" function.
  //
  // It will calculate a straight line between (ox,ox) and (x,y).
  // Every N steps along that line (in this case, N is '1'), it
  // will call _our_ function, "example_line_callback()", and send
  // the current X,Y coordinates along the line, as well as other
  // useful things (which of our "Magic" tools is being used and
  // the current and snapshot canvases).

  api->line((void *) api, which, canvas, snapshot, ox, oy, x, y, 1,
            example_line_callback);


  // If we need to, swap the X and/or Y values, so that
  // (ox,oy) is always the top left, and (x,y) is always the bottom right,
  // so the values we put inside "update_rect" make sense:

  if (ox > x)
  {
    int tmp = ox;

    ox = x;
    x = tmp;
  }
  if (oy > y)
  {
    int tmp = oy;

    oy = y;
    y = tmp;
  }


  // Fill in the elements of the "update_rect" SDL_Rect structure
  // that Tux Paint is sharing with us.

  update_rect->x = ox - 4;
  update_rect->y = oy - 4;
  update_rect->w = (x + 4) - update_rect->x;
  update_rect->h = (y + 4) - update_rect->h;


  // Play the appropriate sound effect
  //
  // We're calculating a value between 0-255 for where the mouse is
  // across the canvas (0 is the left, ~128 is the center, 255 is the right).
  //
  // These are the exact values Tux Paint's "playsound()" wants,
  // to determine what speaker to play the sound in.
  // (So the sound will pan from speaker to speaker as you drag the
  // mouse around the canvas!)

  api->playsound(snd_effect[which], (x * 255) / canvas->w,      // pan
                 255);          // distance
}


// Affect the canvas on release:

void
example_release(magic_api * api, int which,
                SDL_Surface * canvas, SDL_Surface * snapshot, int x, int y,
                SDL_Rect * update_rect)
{
  // Neither of our effects do anything special when the mouse is released
  // from a click or click-and-drag, so there's no code here...
}


// Accept colors
//
// When any of our "Magic" tools are activated by the user,
// if that tool accepts colors, the current color selection is sent to us.
//
// Additionally, if one of our color-accepting tools is active when the
// user changes colors, we'll be informed of that, as well.
// 
// The color comes in as RGB values.

void example_set_color(magic_api * api, Uint8 r, Uint8 g, Uint8 b)
{
  // We simply store the RGB values in the global variables we
  // declared at the top of this file.

  example_r = r;
  example_g = g;
  example_b = b;
}


/* The Magic Effect Routines! */
/* ---------------------------------------------------------------------- */

// Our "callback" function
//
// We do the 'work' in this callback.  Our plugin file has just one.
// Some "Magic" tool plugins may have more, depending on the tools they're
// providing.  Some have none (since they're not click-and-drag
// painting-style tools).
//
// Our callback function gets called once for every point along a line between
// the mouse's previous and current position, as it's being dragged.
//
// It pays attention to 'which' to determine which of our plugin's tools
// is currently selected.

void example_line_callback(void *ptr, int which, SDL_Surface * canvas,
                           SDL_Surface * snapshot, int x, int y)
{
  // For technical reasons, we can't accept a pointer to the "magic_api"
  // struct, like the other functions do.
  //
  // Instead, we receive a 'generic' pointer (a "void *").
  // The line below declares a local "magic_api" pointer variable called "api",
  // and then assigns it to the value of the 'generic' pointer we received.
  // 
  // (The "(magic_api *)" casts the generic pointer into the 'type' of
  // pointer we want, a pointer to a "magic_api".)
  magic_api *api = (magic_api *) ptr;
  int xx, yy;


  // This function handles both of our tools, so we need to check which
  // is being used right now.  We compare the 'which' argument that
  // Tux Paint sends to us with the values we enumerated above.

  if (which == TOOL_ONE)
  {
    // Tool number 1 simply draws a single pixel at the (x,y) location.
    // It's a 1x1 pixel brush

    api->putpixel(canvas, x, y,
                  SDL_MapRGB(canvas->format, example_r, example_g,
                             example_b));

    // We use "SDL_MapRGB()" to convert the RGB value we receive from Tux Paint
    // for the user's current color selection to a 'Uint32' pixel value
    // we can send to Tux Paint's "putpixel()" function.
  }
  else if (which == TOOL_TWO)
  {
    // Tool number 2 copies an 8x8 square of pixels from the opposite side
    // of the canvas and puts it under the cursor

    for (yy = -4; yy < 4; yy++)
    {
      for (xx = -4; xx < 4; xx++)
      {
        api->putpixel(canvas, x + xx, y + yy,
                      api->getpixel(snapshot, canvas->w - x - xx,
                                    canvas->h - y - yy));

        // We simply use Tux Paint's "getpixel()" routine to pull pixel
        // values from the 'snapshot', and then "putpixel()" to draw them
        // right into the 'canvas'.

        // Note: putpixel() and getpixel() are safe to use, even if your
        // X,Y values are outside of the SDL surface (e.g., negative, or
        // greater than the surface's width or height).
      }
    }
  }
}

// Switch-In event
//
// This happens whenever a Magic tool is enabled, either because the
// user just selected it, or they just came back to "Magic" after using
// another tool (e.g., Brush or Text), and this was the most-recently
// selected Magic tool.
// 
// (This also applies to momentary tools, like
// Undo and Redo, and image-changing tools such as New and Open.)
// 
// It also happens when a Magic tool's mode changes (it first
// receives a 'switchout()', below, for the old mode).
//
// Our example doesn't do anything when we switch to, or away from, our
// Magic tools, so we just do nothing here.

void example_switchin(magic_api * api, int which, int mode,
                      SDL_Surface * canvas)
{
}

// Switch-Out event
//
// This happens whenever a Magic tool is disabled, either because the
// user selected a different Magic tool, or they selected a completely
// different tool (e.g., Brush or Text).
// 
// (This also applies to momentary tools, like Undo and Redo, and
// image-changing tools such as New and Open, in which case the
// switchin() function will be called moments later.)
//
// It also happens when a Magic tool's mode changes (it then
// receives a 'switchin()', above, for the new mode).
// 
// Our example doesn't do anything when we switch to, or away from, our
// Magic tools, so we just do nothing here.

void example_switchout(magic_api * api, int which, int mode,
                       SDL_Surface * canvas)
{
}