text: /*
   * drawing.c: Intermediary between the drawing interface as
   * presented to the back end, and that implemented by the front
   * end.
   * 
   * Mostly just looks up calls in a vtable and passes them through
   * unchanged. However, on the printing side it tracks print colours
   * so the front end API doesn't have to.
   * 
   * FIXME:
   * 
   *  - I'd _like_ to do automatic draw_updates, but it's a pain for
   *    draw_text in particular. I'd have to invent a front end API
   *    which retrieved the text bounds.
   *     + that might allow me to do the alignment centrally as well?
   * 	  * perhaps not, because PS can't return this information,
   * 	    so there would have to be a special case for it.
   *     + however, that at least doesn't stand in the way of using
   * 	 the text bounds for draw_update, because PS doesn't need
   * 	 draw_update since it's printing-only. Any _interactive_
   * 	 drawing API couldn't get away with refusing to tell you
   * 	 what parts of the screen a text draw had covered, because
   * 	 you would inevitably need to erase it later on.
   */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <assert.h>
  #include <math.h>
  
  #include "puzzles.h"
  
  struct print_colour {
      int hatch;
      int hatch_when;		       /* 0=never 1=only-in-b&w 2=always */
      float r, g, b;
      float grey;
  };
  
  struct drawing {
      const drawing_api *api;
      void *handle;
      struct print_colour *colours;
      int ncolours, coloursize;
      float scale;
      /* `me' is only used in status_bar(), so print-oriented instances of
       * this may set it to NULL. */
      midend *me;
      char *laststatus;
  };
  
  drawing *drawing_new(const drawing_api *api, midend *me, void *handle)
  {
      drawing *dr = snew(drawing);
      dr->api = api;
      dr->handle = handle;
      dr->colours = NULL;
      dr->ncolours = dr->coloursize = 0;
      dr->scale = 1.0F;
      dr->me = me;
      dr->laststatus = NULL;
      return dr;
  }
  
  void drawing_free(drawing *dr)
  {
      sfree(dr->laststatus);
      sfree(dr->colours);
      sfree(dr);
  }
  
  void draw_text(drawing *dr, int x, int y, int fonttype, int fontsize,
                 int align, int colour, const char *text)
  {
      dr->api->draw_text(dr->handle, x, y, fonttype, fontsize, align,
  		       colour, text);
  }
  
  void draw_rect(drawing *dr, int x, int y, int w, int h, int colour)
  {
      dr->api->draw_rect(dr->handle, x, y, w, h, colour);
  }
  
  void draw_line(drawing *dr, int x1, int y1, int x2, int y2, int colour)
  {
      dr->api->draw_line(dr->handle, x1, y1, x2, y2, colour);
  }
  
  void draw_thick_line(drawing *dr, float thickness,
  		     float x1, float y1, float x2, float y2, int colour)
  {
      if (thickness < 1.0)
          thickness = 1.0;
      if (dr->api->draw_thick_line) {
  	dr->api->draw_thick_line(dr->handle, thickness,
  				 x1, y1, x2, y2, colour);
      } else {
  	/* We'll fake it up with a filled polygon.  The tweak to the
  	 * thickness empirically compensates for rounding errors, because
  	 * polygon rendering uses integer coordinates.
  	 */
  	float len = sqrt((x2 - x1)*(x2 - x1) + (y2 - y1)*(y2 - y1));
  	float tvhatx = (x2 - x1)/len * (thickness/2 - 0.2);
  	float tvhaty = (y2 - y1)/len * (thickness/2 - 0.2);
  	int p[8];
  
  	p[0] = x1 - tvhaty;
  	p[1] = y1 + tvhatx;
  	p[2] = x2 - tvhaty;
  	p[3] = y2 + tvhatx;
  	p[4] = x2 + tvhaty;
  	p[5] = y2 - tvhatx;
  	p[6] = x1 + tvhaty;
  	p[7] = y1 - tvhatx;
  	dr->api->draw_polygon(dr->handle, p, 4, colour, colour);
      }
  }
  
  void draw_polygon(drawing *dr, const int *coords, int npoints,
                    int fillcolour, int outlinecolour)
  {
      dr->api->draw_polygon(dr->handle, coords, npoints, fillcolour,
  			  outlinecolour);
  }
  
  void draw_circle(drawing *dr, int cx, int cy, int radius,
                   int fillcolour, int outlinecolour)
  {
      dr->api->draw_circle(dr->handle, cx, cy, radius, fillcolour,
  			 outlinecolour);
  }
  
  void draw_update(drawing *dr, int x, int y, int w, int h)
  {
      if (dr->api->draw_update)
  	dr->api->draw_update(dr->handle, x, y, w, h);
  }
  
  void clip(drawing *dr, int x, int y, int w, int h)
  {
      dr->api->clip(dr->handle, x, y, w, h);
  }
  
  void unclip(drawing *dr)
  {
      dr->api->unclip(dr->handle);
  }
  
  void start_draw(drawing *dr)
  {
      dr->api->start_draw(dr->handle);
  }
  
  void end_draw(drawing *dr)
  {
      dr->api->end_draw(dr->handle);
  }
  
  char *text_fallback(drawing *dr, const char *const *strings, int nstrings)
  {
      int i;
  
      /*
       * If the drawing implementation provides one of these, use it.
       */
      if (dr && dr->api->text_fallback)
  	return dr->api->text_fallback(dr->handle, strings, nstrings);
  
      /*
       * Otherwise, do the simple thing and just pick the first string
       * that fits in plain ASCII. It will then need no translation
       * out of UTF-8.
       */
      for (i = 0; i < nstrings; i++) {
  	const char *p;
  
  	for (p = strings[i]; *p; p++)
  	    if (*p & 0x80)
  		break;
  	if (!*p)
  	    return dupstr(strings[i]);
      }
  
      /*
       * The caller was responsible for making sure _some_ string in
       * the list was in plain ASCII.
       */
      assert(!"Should never get here");
      return NULL;		       /* placate optimiser */
  }
  
  void status_bar(drawing *dr, const char *text)
  {
      char *rewritten;
  
      if (!dr->api->status_bar)
  	return;
  
      assert(dr->me);
  
      rewritten = midend_rewrite_statusbar(dr->me, text);
      if (!dr->laststatus || strcmp(rewritten, dr->laststatus)) {
  	dr->api->status_bar(dr->handle, rewritten);
  	sfree(dr->laststatus);
  	dr->laststatus = rewritten;
      } else {
  	sfree(rewritten);
      }
  }
  
  blitter *blitter_new(drawing *dr, int w, int h)
  {
      return dr->api->blitter_new(dr->handle, w, h);
  }
  
  void blitter_free(drawing *dr, blitter *bl)
  {
      dr->api->blitter_free(dr->handle, bl);
  }
  
  void blitter_save(drawing *dr, blitter *bl, int x, int y)
  {
      dr->api->blitter_save(dr->handle, bl, x, y);
  }
  
  void blitter_load(drawing *dr, blitter *bl, int x, int y)
  {
      dr->api->blitter_load(dr->handle, bl, x, y);
  }
  
  void print_begin_doc(drawing *dr, int pages)
  {
      dr->api->begin_doc(dr->handle, pages);
  }
  
  void print_begin_page(drawing *dr, int number)
  {
      dr->api->begin_page(dr->handle, number);
  }
  
  void print_begin_puzzle(drawing *dr, float xm, float xc,
  			float ym, float yc, int pw, int ph, float wmm,
  			float scale)
  {
      dr->scale = scale;
      dr->ncolours = 0;
      dr->api->begin_puzzle(dr->handle, xm, xc, ym, yc, pw, ph, wmm);
  }
  
  void print_end_puzzle(drawing *dr)
  {
      dr->api->end_puzzle(dr->handle);
      dr->scale = 1.0F;
  }
  
  void print_end_page(drawing *dr, int number)
  {
      dr->api->end_page(dr->handle, number);
  }
  
  void print_end_doc(drawing *dr)
  {
      dr->api->end_doc(dr->handle);
  }
  
  void print_get_colour(drawing *dr, int colour, bool printing_in_colour,
  		      int *hatch, float *r, float *g, float *b)
  {
      assert(colour >= 0 && colour < dr->ncolours);
      if (dr->colours[colour].hatch_when == 2 ||
  	(dr->colours[colour].hatch_when == 1 && !printing_in_colour)) {
  	*hatch = dr->colours[colour].hatch;
      } else {
  	*hatch = -1;
  	if (printing_in_colour) {
  	    *r = dr->colours[colour].r;
  	    *g = dr->colours[colour].g;
  	    *b = dr->colours[colour].b;
  	} else {
  	    *r = *g = *b = dr->colours[colour].grey;
  	}
      }
  }
  
  static int print_generic_colour(drawing *dr, float r, float g, float b,
  				float grey, int hatch, int hatch_when)
  {
      if (dr->ncolours >= dr->coloursize) {
  	dr->coloursize = dr->ncolours + 16;
  	dr->colours = sresize(dr->colours, dr->coloursize,
  			      struct print_colour);
      }
      dr->colours[dr->ncolours].hatch = hatch;
      dr->colours[dr->ncolours].hatch_when = hatch_when;
      dr->colours[dr->ncolours].r = r;
      dr->colours[dr->ncolours].g = g;
      dr->colours[dr->ncolours].b = b;
      dr->colours[dr->ncolours].grey = grey;
      return dr->ncolours++;
  }
  
  int print_mono_colour(drawing *dr, int grey)
  {
      return print_generic_colour(dr, grey, grey, grey, grey, -1, 0);
  }
  
  int print_grey_colour(drawing *dr, float grey)
  {
      return print_generic_colour(dr, grey, grey, grey, grey, -1, 0);
  }
  
  int print_hatched_colour(drawing *dr, int hatch)
  {
      return print_generic_colour(dr, 0, 0, 0, 0, hatch, 2);
  }
  
  int print_rgb_mono_colour(drawing *dr, float r, float g, float b, int grey)
  {
      return print_generic_colour(dr, r, g, b, grey, -1, 0);
  }
  
  int print_rgb_grey_colour(drawing *dr, float r, float g, float b, float grey)
  {
      return print_generic_colour(dr, r, g, b, grey, -1, 0);
  }
  
  int print_rgb_hatched_colour(drawing *dr, float r, float g, float b, int hatch)
  {
      return print_generic_colour(dr, r, g, b, 0, hatch, 1);
  }
  
  void print_line_width(drawing *dr, int width)
  {
      /*
       * I don't think it's entirely sensible to have line widths be
       * entirely relative to the puzzle size; there is a point
       * beyond which lines are just _stupidly_ thick. On the other
       * hand, absolute line widths aren't particularly nice either
       * because they start to feel a bit feeble at really large
       * scales.
       * 
       * My experimental answer is to scale line widths as the
       * _square root_ of the main puzzle scale. Double the puzzle
       * size, and the line width multiplies by 1.4.
       */
      dr->api->line_width(dr->handle, (float)sqrt(dr->scale) * width);
  }
  
  void print_line_dotted(drawing *dr, bool dotted)
  {
      dr->api->line_dotted(dr->handle, dotted);
  }
  