puzzles: refactor and resync with upstream

This brings puzzles up-to-date with upstream revision
2d333750272c3967cfd5cd3677572cddeaad5932, though certain changes made
by me, including cursor-only Untangle and some compilation fixes
remain. Upstream code has been moved to its separate subdirectory and
future syncs can be done by simply copying over the new sources.

Change-Id: Ia6506ca5f78c3627165ea6791d38db414ace0804

1 files changed, 680 insertions, 0 deletions

diff --git a/apps/plugins/puzzles/src/puzzles.h b/apps/plugins/puzzles/src/puzzles.h
new file mode 100644
index 0000000000..03af2ca186
--- /dev/null
+++ b/apps/plugins/puzzles/src/puzzles.h
@@ -0,0 +1,680 @@
+/*
+ * puzzles.h: header file for my puzzle collection
+ */
+
+#ifndef PUZZLES_PUZZLES_H
+#define PUZZLES_PUZZLES_H
+
+#include <stdio.h>  /* for FILE */
+#include <stdlib.h> /* for size_t */
+#include <limits.h> /* for UINT_MAX */
+
+#ifndef TRUE
+#define TRUE 1
+#endif
+#ifndef FALSE
+#define FALSE 0
+#endif
+
+#define PI 3.141592653589793238462643383279502884197169399
+
+#define lenof(array) ( sizeof(array) / sizeof(*(array)) )
+
+#define STR_INT(x) #x
+#define STR(x) STR_INT(x)
+
+/* NB not perfect because they evaluate arguments multiple times. */
+#ifndef max
+#define max(x,y) ( (x)>(y) ? (x) : (y) )
+#endif /* max */
+#ifndef min
+#define min(x,y) ( (x)<(y) ? (x) : (y) )
+#endif /* min */
+
+enum {
+    LEFT_BUTTON = 0x0200,
+    MIDDLE_BUTTON,
+    RIGHT_BUTTON,
+    LEFT_DRAG,
+    MIDDLE_DRAG,
+    RIGHT_DRAG,
+    LEFT_RELEASE,
+    MIDDLE_RELEASE,
+    RIGHT_RELEASE,
+    CURSOR_UP,
+    CURSOR_DOWN,
+    CURSOR_LEFT,
+    CURSOR_RIGHT,
+    CURSOR_SELECT,
+    CURSOR_SELECT2,
+    
+    /* made smaller because of 'limited range of datatype' errors. */
+    MOD_CTRL       = 0x1000,
+    MOD_SHFT       = 0x2000,
+    MOD_NUM_KEYPAD = 0x4000,
+    MOD_MASK       = 0x7000 /* mask for all modifiers */
+};
+
+#define IS_MOUSE_DOWN(m) ( (unsigned)((m) - LEFT_BUTTON) <= \
+                               (unsigned)(RIGHT_BUTTON - LEFT_BUTTON))
+#define IS_MOUSE_DRAG(m) ( (unsigned)((m) - LEFT_DRAG) <= \
+                               (unsigned)(RIGHT_DRAG - LEFT_DRAG))
+#define IS_MOUSE_RELEASE(m) ( (unsigned)((m) - LEFT_RELEASE) <= \
+                               (unsigned)(RIGHT_RELEASE - LEFT_RELEASE))
+#define IS_CURSOR_MOVE(m) ( (m) == CURSOR_UP || (m) == CURSOR_DOWN || \
+                            (m) == CURSOR_RIGHT || (m) == CURSOR_LEFT )
+#define IS_CURSOR_SELECT(m) ( (m) == CURSOR_SELECT || (m) == CURSOR_SELECT2)
+
+/*
+ * Flags in the back end's `flags' word.
+ */
+/* Bit flags indicating mouse button priorities */
+#define BUTTON_BEATS(x,y) ( 1 << (((x)-LEFT_BUTTON)*3+(y)-LEFT_BUTTON) )
+/* Flag indicating that Solve operations should be animated */
+#define SOLVE_ANIMATES ( 1 << 9 )
+/* Pocket PC: Game requires right mouse button emulation */
+#define REQUIRE_RBUTTON ( 1 << 10 )
+/* Pocket PC: Game requires numeric input */
+#define REQUIRE_NUMPAD ( 1 << 11 )
+/* end of `flags' word definitions */
+
+#ifdef _WIN32_WCE
+  /* Pocket PC devices have small, portrait screen that requires more vivid colours */
+  #define SMALL_SCREEN
+  #define PORTRAIT_SCREEN
+  #define VIVID_COLOURS
+  #define STYLUS_BASED
+#endif
+
+#define IGNOREARG(x) ( (x) = (x) )
+
+typedef struct frontend frontend;
+typedef struct config_item config_item;
+typedef struct midend midend;
+typedef struct random_state random_state;
+typedef struct game_params game_params;
+typedef struct game_state game_state;
+typedef struct game_ui game_ui;
+typedef struct game_drawstate game_drawstate;
+typedef struct game game;
+typedef struct blitter blitter;
+typedef struct document document;
+typedef struct drawing_api drawing_api;
+typedef struct drawing drawing;
+typedef struct psdata psdata;
+
+#define ALIGN_VNORMAL 0x000
+#define ALIGN_VCENTRE 0x100
+
+#define ALIGN_HLEFT   0x000
+#define ALIGN_HCENTRE 0x001
+#define ALIGN_HRIGHT  0x002
+
+#define FONT_FIXED    0
+#define FONT_VARIABLE 1
+
+/* For printing colours */
+#define HATCH_SLASH     1
+#define HATCH_BACKSLASH 2
+#define HATCH_HORIZ     3
+#define HATCH_VERT      4
+#define HATCH_PLUS      5
+#define HATCH_X         6
+
+/*
+ * Structure used to pass configuration data between frontend and
+ * game
+ */
+enum { C_STRING, C_CHOICES, C_BOOLEAN, C_END };
+struct config_item {
+    /*
+     * `name' is never dynamically allocated.
+     */
+    char *name;
+    /*
+     * `type' contains one of the above values.
+     */
+    int type;
+    /*
+     * For C_STRING, `sval' is always dynamically allocated and
+     * non-NULL. For C_BOOLEAN and C_END, `sval' is always NULL.
+     * For C_CHOICES, `sval' is non-NULL, _not_ dynamically
+     * allocated, and contains a set of option strings separated by
+     * a delimiter. The delimeter is also the first character in
+     * the string, so for example ":Foo:Bar:Baz" gives three
+     * options `Foo', `Bar' and `Baz'.
+     */
+    char *sval;
+    /*
+     * For C_BOOLEAN, this is TRUE or FALSE. For C_CHOICES, it
+     * indicates the chosen index from the `sval' list. In the
+     * above example, 0==Foo, 1==Bar and 2==Baz.
+     */
+    int ival;
+};
+
+/*
+ * Structure used to communicate the presets menu from midend to
+ * frontend. In principle, it's also used to pass the same information
+ * from game to midend, though games that don't specify a menu
+ * hierarchy (i.e. most of them) will use the simpler fetch_preset()
+ * function to return an unstructured list.
+ *
+ * A tree of these structures always belongs to the midend, and only
+ * the midend should ever need to free it. The front end should treat
+ * them as read-only.
+ */
+struct preset_menu_entry {
+    char *title;
+    /* Exactly one of the next two fields is NULL, depending on
+     * whether this entry is a submenu title or an actual preset */
+    game_params *params;
+    struct preset_menu *submenu;
+    /* Every preset menu entry has a number allocated by the mid-end,
+     * so that midend_which_preset() can return a value that
+     * identifies an entry anywhere in the menu hierarchy. The values
+     * will be allocated reasonably densely from 1 upwards (so it's
+     * reasonable for the front end to use them as array indices if it
+     * needs to store GUI state per menu entry), but no other
+     * guarantee is given about their ordering.
+     *
+     * Entries containing submenus have ids too - not only the actual
+     * presets are numbered. */
+    int id;
+};
+struct preset_menu {
+    int n_entries;             /* number of entries actually in use */
+    int entries_size;          /* space currently allocated in this array */
+    struct preset_menu_entry *entries;
+};
+/* For games which do want to directly return a tree of these, here
+ * are convenience routines (in midend.c) for constructing one. These
+ * assume that 'title' and 'encoded_params' are already dynamically
+ * allocated by the caller; the resulting preset_menu tree takes
+ * ownership of them. */
+struct preset_menu *preset_menu_new(void);
+struct preset_menu *preset_menu_add_submenu(struct preset_menu *parent,
+                                            char *title);
+void preset_menu_add_preset(struct preset_menu *menu,
+                            char *title, game_params *params);
+/* Helper routine front ends can use for one of the ways they might
+ * want to organise their preset menu usage */
+game_params *preset_menu_lookup_by_id(struct preset_menu *menu, int id);
+
+/*
+ * Platform routines
+ */
+
+/* We can't use #ifdef DEBUG, because Cygwin defines it by default. */
+#ifdef DEBUGGING
+#define debug(x) (debug_printf x)
+void debug_printf(char *fmt, ...);
+#else
+#define debug(x)
+#endif
+
+void fatal(char *fmt, ...);
+void frontend_default_colour(frontend *fe, float *output);
+void deactivate_timer(frontend *fe);
+void activate_timer(frontend *fe);
+void get_random_seed(void **randseed, int *randseedsize);
+
+/*
+ * drawing.c
+ */
+drawing *drawing_new(const drawing_api *api, midend *me, void *handle);
+void drawing_free(drawing *dr);
+void draw_text(drawing *dr, int x, int y, int fonttype, int fontsize,
+               int align, int colour, char *text);
+void draw_rect(drawing *dr, int x, int y, int w, int h, int colour);
+void draw_line(drawing *dr, int x1, int y1, int x2, int y2, int colour);
+void draw_polygon(drawing *dr, int *coords, int npoints,
+                  int fillcolour, int outlinecolour);
+void draw_circle(drawing *dr, int cx, int cy, int radius,
+                 int fillcolour, int outlinecolour);
+void draw_thick_line(drawing *dr, float thickness,
+                     float x1, float y1, float x2, float y2, int colour);
+void clip(drawing *dr, int x, int y, int w, int h);
+void unclip(drawing *dr);
+void start_draw(drawing *dr);
+void draw_update(drawing *dr, int x, int y, int w, int h);
+void end_draw(drawing *dr);
+char *text_fallback(drawing *dr, const char *const *strings, int nstrings);
+void status_bar(drawing *dr, char *text);
+blitter *blitter_new(drawing *dr, int w, int h);
+void blitter_free(drawing *dr, blitter *bl);
+/* save puts the portion of the current display with top-left corner
+ * (x,y) to the blitter. load puts it back again to the specified
+ * coords, or else wherever it was saved from
+ * (if x = y = BLITTER_FROMSAVED). */
+void blitter_save(drawing *dr, blitter *bl, int x, int y);
+#define BLITTER_FROMSAVED (-1)
+void blitter_load(drawing *dr, blitter *bl, int x, int y);
+void print_begin_doc(drawing *dr, int pages);
+void print_begin_page(drawing *dr, int number);
+void print_begin_puzzle(drawing *dr, float xm, float xc,
+                        float ym, float yc, int pw, int ph, float wmm,
+                        float scale);
+void print_end_puzzle(drawing *dr);
+void print_end_page(drawing *dr, int number);
+void print_end_doc(drawing *dr);
+void print_get_colour(drawing *dr, int colour, int printing_in_colour,
+                      int *hatch, float *r, float *g, float *b);
+int print_mono_colour(drawing *dr, int grey); /* 0==black, 1==white */
+int print_grey_colour(drawing *dr, float grey);
+int print_hatched_colour(drawing *dr, int hatch);
+int print_rgb_mono_colour(drawing *dr, float r, float g, float b, int mono);
+int print_rgb_grey_colour(drawing *dr, float r, float g, float b, float grey);
+int print_rgb_hatched_colour(drawing *dr, float r, float g, float b,
+                             int hatch);
+void print_line_width(drawing *dr, int width);
+void print_line_dotted(drawing *dr, int dotted);
+
+/*
+ * midend.c
+ */
+midend *midend_new(frontend *fe, const game *ourgame,
+                   const drawing_api *drapi, void *drhandle);
+void midend_free(midend *me);
+const game *midend_which_game(midend *me);
+void midend_set_params(midend *me, game_params *params);
+game_params *midend_get_params(midend *me);
+void midend_size(midend *me, int *x, int *y, int user_size);
+void midend_reset_tilesize(midend *me);
+void midend_new_game(midend *me);
+void midend_restart_game(midend *me);
+void midend_stop_anim(midend *me);
+int midend_process_key(midend *me, int x, int y, int button);
+void midend_force_redraw(midend *me);
+void midend_redraw(midend *me);
+float *midend_colours(midend *me, int *ncolours);
+void midend_freeze_timer(midend *me, float tprop);
+void midend_timer(midend *me, float tplus);
+struct preset_menu *midend_get_presets(midend *me, int *id_limit);
+int midend_which_preset(midend *me);
+int midend_wants_statusbar(midend *me);
+enum { CFG_SETTINGS, CFG_SEED, CFG_DESC, CFG_FRONTEND_SPECIFIC };
+config_item *midend_get_config(midend *me, int which, char **wintitle);
+char *midend_set_config(midend *me, int which, config_item *cfg);
+char *midend_game_id(midend *me, char *id);
+char *midend_get_game_id(midend *me);
+char *midend_get_random_seed(midend *me);
+int midend_can_format_as_text_now(midend *me);
+char *midend_text_format(midend *me);
+char *midend_solve(midend *me);
+int midend_status(midend *me);
+int midend_can_undo(midend *me);
+int midend_can_redo(midend *me);
+void midend_supersede_game_desc(midend *me, char *desc, char *privdesc);
+char *midend_rewrite_statusbar(midend *me, char *text);
+void midend_serialise(midend *me,
+                      void (*write)(void *ctx, void *buf, int len),
+                      void *wctx);
+char *midend_deserialise(midend *me,
+                         int (*read)(void *ctx, void *buf, int len),
+                         void *rctx);
+char *identify_game(char **name, int (*read)(void *ctx, void *buf, int len),
+                    void *rctx);
+void midend_request_id_changes(midend *me, void (*notify)(void *), void *ctx);
+/* Printing functions supplied by the mid-end */
+char *midend_print_puzzle(midend *me, document *doc, int with_soln);
+int midend_tilesize(midend *me);
+
+/*
+ * malloc.c
+ */
+void *smalloc(size_t size);
+void *srealloc(void *p, size_t size);
+void sfree(void *p);
+char *dupstr(const char *s);
+#define snew(type) \
+    ( (type *) smalloc (sizeof (type)) )
+#define snewn(number, type) \
+    ( (type *) smalloc ((number) * sizeof (type)) )
+#define sresize(array, number, type) \
+    ( (type *) srealloc ((array), (number) * sizeof (type)) )
+
+/*
+ * misc.c
+ */
+void free_cfg(config_item *cfg);
+void obfuscate_bitmap(unsigned char *bmp, int bits, int decode);
+
+/* allocates output each time. len is always in bytes of binary data.
+ * May assert (or just go wrong) if lengths are unchecked. */
+char *bin2hex(const unsigned char *in, int inlen);
+unsigned char *hex2bin(const char *in, int outlen);
+
+/* Sets (and possibly dims) background from frontend default colour,
+ * and auto-generates highlight and lowlight colours too. */
+void game_mkhighlight(frontend *fe, float *ret,
+                      int background, int highlight, int lowlight);
+/* As above, but starts from a provided background colour rather
+ * than the frontend default. */
+void game_mkhighlight_specific(frontend *fe, float *ret,
+                               int background, int highlight, int lowlight);
+
+/* Randomly shuffles an array of items. */
+void shuffle(void *array, int nelts, int eltsize, random_state *rs);
+
+/* Draw a rectangle outline, using the drawing API's draw_line. */
+void draw_rect_outline(drawing *dr, int x, int y, int w, int h,
+                       int colour);
+
+/* Draw a set of rectangle corners (e.g. for a cursor display). */
+void draw_rect_corners(drawing *dr, int cx, int cy, int r, int col);
+
+void move_cursor(int button, int *x, int *y, int maxw, int maxh, int wrap);
+
+/* Used in netslide.c and sixteen.c for cursor movement around edge. */
+int c2pos(int w, int h, int cx, int cy);
+int c2diff(int w, int h, int cx, int cy, int button);
+void pos2c(int w, int h, int pos, int *cx, int *cy);
+
+/* Draws text with an 'outline' formed by offsetting the text
+ * by one pixel; useful for highlighting. Outline is omitted if -1. */
+void draw_text_outline(drawing *dr, int x, int y, int fonttype,
+                       int fontsize, int align,
+                       int text_colour, int outline_colour, char *text);
+
+/* Copies text left-justified with spaces. Length of string must be
+ * less than buffer size. */
+void copy_left_justified(char *buf, size_t sz, const char *str);
+
+/*
+ * dsf.c
+ */
+int *snew_dsf(int size);
+
+void print_dsf(int *dsf, int size);
+
+/* Return the canonical element of the equivalence class containing element
+ * val.  If 'inverse' is non-NULL, this function will put into it a flag
+ * indicating whether the canonical element is inverse to val. */
+int edsf_canonify(int *dsf, int val, int *inverse);
+int dsf_canonify(int *dsf, int val);
+int dsf_size(int *dsf, int val);
+
+/* Allow the caller to specify that two elements should be in the same
+ * equivalence class.  If 'inverse' is TRUE, the elements are actually opposite
+ * to one another in some sense.  This function will fail an assertion if the
+ * caller gives it self-contradictory data, ie if two elements are claimed to
+ * be both opposite and non-opposite. */
+void edsf_merge(int *dsf, int v1, int v2, int inverse);
+void dsf_merge(int *dsf, int v1, int v2);
+void dsf_init(int *dsf, int len);
+
+/*
+ * tdq.c
+ */
+
+/*
+ * Data structure implementing a 'to-do queue', a simple
+ * de-duplicating to-do list mechanism.
+ *
+ * Specification: a tdq is a queue which can hold integers from 0 to
+ * n-1, where n was some constant specified at tdq creation time. No
+ * integer may appear in the queue's current contents more than once;
+ * an attempt to add an already-present integer again will do nothing,
+ * so that that integer is removed from the queue at the position
+ * where it was _first_ inserted. The add and remove operations take
+ * constant time.
+ *
+ * The idea is that you might use this in applications like solvers:
+ * keep a tdq listing the indices of grid squares that you currently
+ * need to process in some way. Whenever you modify a square in a way
+ * that will require you to re-scan its neighbours, add them to the
+ * list with tdq_add; meanwhile you're constantly taking elements off
+ * the list when you need another square to process. In solvers where
+ * deductions are mostly localised, this should prevent repeated
+ * O(N^2) loops over the whole grid looking for something to do. (But
+ * if only _most_ of the deductions are localised, then you should
+ * respond to an empty to-do list by re-adding everything using
+ * tdq_fill, so _then_ you rescan the whole grid looking for newly
+ * enabled non-local deductions. Only if you've done that and emptied
+ * the list again finding nothing new to do are you actually done.)
+ */
+typedef struct tdq tdq;
+tdq *tdq_new(int n);
+void tdq_free(tdq *tdq);
+void tdq_add(tdq *tdq, int k);
+int tdq_remove(tdq *tdq);        /* returns -1 if nothing available */
+void tdq_fill(tdq *tdq);         /* add everything to the tdq at once */
+
+/*
+ * laydomino.c
+ */
+int *domino_layout(int w, int h, random_state *rs);
+void domino_layout_prealloc(int w, int h, random_state *rs,
+                            int *grid, int *grid2, int *list);
+/*
+ * version.c
+ */
+extern char ver[];
+
+/*
+ * random.c
+ */
+random_state *random_new(const char *seed, int len);
+random_state *random_copy(random_state *tocopy);
+unsigned long random_bits(random_state *state, int bits);
+unsigned long random_upto(random_state *state, unsigned long limit);
+void random_free(random_state *state);
+char *random_state_encode(random_state *state);
+random_state *random_state_decode(const char *input);
+/* random.c also exports SHA, which occasionally comes in useful. */
+#if __STDC_VERSION__ >= 199901L
+#include <stdint.h>
+typedef uint32_t uint32;
+#elif UINT_MAX >= 4294967295L
+typedef unsigned int uint32;
+#else
+typedef unsigned long uint32;
+#endif
+typedef struct {
+    uint32 h[5];
+    unsigned char block[64];
+    int blkused;
+    uint32 lenhi, lenlo;
+} SHA_State;
+void SHA_Init(SHA_State *s);
+void SHA_Bytes(SHA_State *s, const void *p, int len);
+void SHA_Final(SHA_State *s, unsigned char *output);
+void SHA_Simple(const void *p, int len, unsigned char *output);
+
+/*
+ * printing.c
+ */
+document *document_new(int pw, int ph, float userscale);
+void document_free(document *doc);
+void document_add_puzzle(document *doc, const game *game, game_params *par,
+                         game_state *st, game_state *st2);
+void document_print(document *doc, drawing *dr);
+
+/*
+ * ps.c
+ */
+psdata *ps_init(FILE *outfile, int colour);
+void ps_free(psdata *ps);
+drawing *ps_drawing_api(psdata *ps);
+
+/*
+ * combi.c: provides a structure and functions for iterating over
+ * combinations (i.e. choosing r things out of n).
+ */
+typedef struct _combi_ctx {
+  int r, n, nleft, total;
+  int *a;
+} combi_ctx;
+
+combi_ctx *new_combi(int r, int n);
+void reset_combi(combi_ctx *combi);
+combi_ctx *next_combi(combi_ctx *combi); /* returns NULL for end */
+void free_combi(combi_ctx *combi);
+
+/*
+ * divvy.c
+ */
+/* divides w*h rectangle into pieces of size k. Returns w*h dsf. */
+int *divvy_rectangle(int w, int h, int k, random_state *rs);
+
+/*
+ * findloop.c
+ */
+struct findloopstate;
+struct findloopstate *findloop_new_state(int nvertices);
+void findloop_free_state(struct findloopstate *);
+/*
+ * Callback provided by the client code to enumerate the graph
+ * vertices joined directly to a given vertex.
+ *
+ * Semantics: if vertex >= 0, return one of its neighbours; if vertex
+ * < 0, return a previously unmentioned neighbour of whatever vertex
+ * was last passed as input. Write to 'ctx' as necessary to store
+ * state. In either case, return < 0 if no such vertex can be found.
+ */
+typedef int (*neighbour_fn_t)(int vertex, void *ctx);
+/*
+ * Actual function to find loops. 'ctx' will be passed unchanged to
+ * the 'neighbour' function to query graph edges. Returns FALSE if no
+ * loop was found, or TRUE if one was.
+ */
+int findloop_run(struct findloopstate *state, int nvertices,
+                 neighbour_fn_t neighbour, void *ctx);
+/*
+ * Query whether an edge is part of a loop, in the output of
+ * find_loops.
+ *
+ * Due to the internal storage format, if you pass u,v which are not
+ * connected at all, the output will be TRUE. (The algorithm actually
+ * stores an exhaustive list of *non*-loop edges, because there are
+ * fewer of those, so really it's querying whether the edge is on that
+ * list.)
+ */
+int findloop_is_loop_edge(struct findloopstate *state, int u, int v);
+
+/*
+ * Data structure containing the function calls and data specific
+ * to a particular game. This is enclosed in a data structure so
+ * that a particular platform can choose, if it wishes, to compile
+ * all the games into a single combined executable rather than
+ * having lots of little ones.
+ */
+struct game {
+    const char *name;
+    const char *winhelp_topic, *htmlhelp_topic;
+    game_params *(*default_params)(void);
+    int (*fetch_preset)(int i, char **name, game_params **params);
+    struct preset_menu *(*preset_menu)(void);
+    void (*decode_params)(game_params *, char const *string);
+    char *(*encode_params)(const game_params *, int full);
+    void (*free_params)(game_params *params);
+    game_params *(*dup_params)(const game_params *params);
+    int can_configure;
+    config_item *(*configure)(const game_params *params);
+    game_params *(*custom_params)(const config_item *cfg);
+    char *(*validate_params)(const game_params *params, int full);
+    char *(*new_desc)(const game_params *params, random_state *rs,
+                      char **aux, int interactive);
+    char *(*validate_desc)(const game_params *params, const char *desc);
+    game_state *(*new_game)(midend *me, const game_params *params,
+                            const char *desc);
+    game_state *(*dup_game)(const game_state *state);
+    void (*free_game)(game_state *state);
+    int can_solve;
+    char *(*solve)(const game_state *orig, const game_state *curr,
+                   const char *aux, char **error);
+    int can_format_as_text_ever;
+    int (*can_format_as_text_now)(const game_params *params);
+    char *(*text_format)(const game_state *state);
+    game_ui *(*new_ui)(const game_state *state);
+    void (*free_ui)(game_ui *ui);
+    char *(*encode_ui)(const game_ui *ui);
+    void (*decode_ui)(game_ui *ui, const char *encoding);
+    void (*changed_state)(game_ui *ui, const game_state *oldstate,
+                          const game_state *newstate);
+    char *(*interpret_move)(const game_state *state, game_ui *ui,
+                            const game_drawstate *ds, int x, int y, int button);
+    game_state *(*execute_move)(const game_state *state, const char *move);
+    int preferred_tilesize;
+    void (*compute_size)(const game_params *params, int tilesize,
+                         int *x, int *y);
+    void (*set_size)(drawing *dr, game_drawstate *ds,
+                     const game_params *params, int tilesize);
+    float *(*colours)(frontend *fe, int *ncolours);
+    game_drawstate *(*new_drawstate)(drawing *dr, const game_state *state);
+    void (*free_drawstate)(drawing *dr, game_drawstate *ds);
+    void (*redraw)(drawing *dr, game_drawstate *ds, const game_state *oldstate,
+                   const game_state *newstate, int dir, const game_ui *ui,
+                   float anim_time, float flash_time);
+    float (*anim_length)(const game_state *oldstate,
+                         const game_state *newstate, int dir, game_ui *ui);
+    float (*flash_length)(const game_state *oldstate,
+                          const game_state *newstate, int dir, game_ui *ui);
+    int (*status)(const game_state *state);
+    int can_print, can_print_in_colour;
+    void (*print_size)(const game_params *params, float *x, float *y);
+    void (*print)(drawing *dr, const game_state *state, int tilesize);
+    int wants_statusbar;
+    int is_timed;
+    int (*timing_state)(const game_state *state, game_ui *ui);
+    int flags;
+};
+
+/*
+ * Data structure containing the drawing API implemented by the
+ * front end and also by cross-platform printing modules such as
+ * PostScript.
+ */
+struct drawing_api {
+    void (*draw_text)(void *handle, int x, int y, int fonttype, int fontsize,
+                      int align, int colour, char *text);
+    void (*draw_rect)(void *handle, int x, int y, int w, int h, int colour);
+    void (*draw_line)(void *handle, int x1, int y1, int x2, int y2,
+                      int colour);
+    void (*draw_polygon)(void *handle, int *coords, int npoints,
+                         int fillcolour, int outlinecolour);
+    void (*draw_circle)(void *handle, int cx, int cy, int radius,
+                        int fillcolour, int outlinecolour);
+    void (*draw_update)(void *handle, int x, int y, int w, int h);
+    void (*clip)(void *handle, int x, int y, int w, int h);
+    void (*unclip)(void *handle);
+    void (*start_draw)(void *handle);
+    void (*end_draw)(void *handle);
+    void (*status_bar)(void *handle, char *text);
+    blitter *(*blitter_new)(void *handle, int w, int h);
+    void (*blitter_free)(void *handle, blitter *bl);
+    void (*blitter_save)(void *handle, blitter *bl, int x, int y);
+    void (*blitter_load)(void *handle, blitter *bl, int x, int y);
+    void (*begin_doc)(void *handle, int pages);
+    void (*begin_page)(void *handle, int number);
+    void (*begin_puzzle)(void *handle, float xm, float xc,
+                         float ym, float yc, int pw, int ph, float wmm);
+    void (*end_puzzle)(void *handle);
+    void (*end_page)(void *handle, int number);
+    void (*end_doc)(void *handle);
+    void (*line_width)(void *handle, float width);
+    void (*line_dotted)(void *handle, int dotted);
+    char *(*text_fallback)(void *handle, const char *const *strings,
+                           int nstrings);
+    void (*draw_thick_line)(void *handle, float thickness,
+                            float x1, float y1, float x2, float y2,
+                            int colour);
+};
+
+/*
+ * For one-game-at-a-time platforms, there's a single structure
+ * like the above, under a fixed name. For all-at-once platforms,
+ * there's a list of all available puzzles in array form.
+ */
+#ifdef COMBINED
+extern const game *gamelist[];
+extern const int gamecount;
+#else
+extern const game thegame;
+#endif
+
+/* A little bit of help to lazy developers */
+#define DEFAULT_STATUSBAR_TEXT "Use status_bar() to fill this in."
+
+#endif /* PUZZLES_PUZZLES_H */