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f37913002a
This changes the drawing API so that implementations receive a
`drawing *` pointer with each call, instead of a `void *` pointer as
they did previously. The `void *` context pointer has been moved to be
a member of the `drawing` structure (which has been made public), from
which it can be retrieved via the new `GET_HANDLE_AS_TYPE()` macro. To
signal this breaking change to downstream front end authors, I've
added a version number to the `drawing_api` struct, which will
hopefully force them to notice.
The motivation for this change is the upcoming introduction of a
draw_polygon_fallback() function, which will use a series of calls to
draw_line() to perform software polygon rasterization on platforms
without a native polygon fill primitive. This function is fairly
large, so I desired that it not be included in the binary
distribution, except on platforms which require it (e.g. my Rockbox
port). One way to achieve this is via link-time optimization (LTO,
a.k.a. "interprocedural optimization"/IPO), so that the code is
unconditionally compiled (preventing bit-rot) but only included in the
linked executable if it is actually referenced from elsewhere.
Practically, this precludes the otherwise straightforward route of
including a run-time check of the `draw_polygon` pointer in the
drawing.c middleware. Instead, Simon recommended that a front end be
able to set its `draw_polygon` field to point to
draw_polygon_fallback(). However, the old drawing API's semantics of
passing a `void *` pointer prevented this from working in practice,
since draw_polygon_fallback(), implemented in middleware, would not be
able to perform any drawing operations without a `drawing *` pointer;
with the new API, this restriction is removed, clearing the way for
that function's introduction.
This is a breaking change for front ends, which must update their
implementations of the drawing API to conform. The migration process
is fairly straightforward: every drawing API function which previously
took a `void *` context pointer should be updated to take a `drawing *`
pointer in its place. Then, where each such function would have
previously casted the `void *` pointer to a meaningful type, they now
instead retrieve the context pointer from the `handle` field of the
`drawing` structure. To make this transition easier, the
`GET_HANDLE_AS_TYPE()` macro is introduced to wrap the context pointer
retrieval (see below for usage).
As an example, an old drawing API function implementation would have
looked like this:
void frontend_draw_func(void *handle, ...)
{
frontend *fe = (frontend *)handle;
/* do stuff with fe */
}
After this change, that function would be rewritten as:
void frontend_draw_func(drawing *dr, ...)
{
frontend *fe = GET_HANDLE_AS_TYPE(dr, frontend);
/* do stuff with fe */
}
I have already made these changes to all the in-tree front ends, but
out-of-tree front ends will need to follow the procedure outlined
above.
Simon pointed out that changing the drawing API function pointer
signatures to take `drawing *` instead of `void *` results only in a
compiler warning, not an outright error. Thus, I've introduced a
version field to the beginning of the `drawing_api` struct, which will
cause a compilation error and hopefully force front ends to notice
this. This field should be set to 1 for now. Going forward, it will
provide a clear means of communicating future breaking API changes.
79 lines
2.9 KiB
C
79 lines
2.9 KiB
C
/*
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* nullfe.c: Null front-end code containing a bunch of boring stub
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* functions. Used to ensure successful linking when building the
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* various stand-alone solver binaries.
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*/
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#include <stdarg.h>
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#include "puzzles.h"
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void frontend_default_colour(frontend *fe, float *output) {}
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void get_random_seed(void **randseed, int *randseedsize)
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{ char *c = snewn(1, char); *c = 0; *randseed = c; *randseedsize = 1; }
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void deactivate_timer(frontend *fe) {}
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void activate_timer(frontend *fe) {}
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drawing *drawing_new(const drawing_api *api, midend *me, void *handle)
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{ return snew(drawing); }
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void drawing_free(drawing *dr) { sfree(dr); }
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void draw_text(drawing *dr, int x, int y, int fonttype, int fontsize,
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int align, int colour, const char *text) {}
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void draw_rect(drawing *dr, int x, int y, int w, int h, int colour) {}
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void draw_line(drawing *dr, int x1, int y1, int x2, int y2, int colour) {}
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void draw_thick_line(drawing *dr, float thickness,
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float x1, float y1, float x2, float y2, int colour) {}
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void draw_polygon(drawing *dr, const int *coords, int npoints,
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int fillcolour, int outlinecolour) {}
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void draw_circle(drawing *dr, int cx, int cy, int radius,
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int fillcolour, int outlinecolour) {}
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char *text_fallback(drawing *dr, const char *const *strings, int nstrings)
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{ return dupstr(strings[0]); }
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void clip(drawing *dr, int x, int y, int w, int h) {}
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void unclip(drawing *dr) {}
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void start_draw(drawing *dr) {}
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void draw_update(drawing *dr, int x, int y, int w, int h) {}
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void end_draw(drawing *dr) {}
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struct blitter { char dummy; };
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blitter *blitter_new(drawing *dr, int w, int h) { return snew(blitter); }
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void blitter_free(drawing *dr, blitter *bl) { sfree(bl); }
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void blitter_save(drawing *dr, blitter *bl, int x, int y) {}
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void blitter_load(drawing *dr, blitter *bl, int x, int y) {}
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int print_mono_colour(drawing *dr, int grey) { return 0; }
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int print_grey_colour(drawing *dr, float grey) { return 0; }
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int print_hatched_colour(drawing *dr, int hatch) { return 0; }
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int print_rgb_mono_colour(drawing *dr, float r, float g, float b, int grey)
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{ return 0; }
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int print_rgb_grey_colour(drawing *dr, float r, float g, float b, float grey)
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{ return 0; }
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int print_rgb_hatched_colour(drawing *dr, float r, float g, float b, int hatch)
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{ return 0; }
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void print_line_width(drawing *dr, int width) {}
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void print_line_dotted(drawing *dr, bool dotted) {}
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void status_bar(drawing *dr, const char *text) {}
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void document_add_puzzle(document *doc, const game *game, game_params *par,
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game_ui *ui, game_state *st, game_state *st2) {}
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void fatal(const char *fmt, ...)
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{
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va_list ap;
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fprintf(stderr, "fatal error: ");
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va_start(ap, fmt);
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vfprintf(stderr, fmt, ap);
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va_end(ap);
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fprintf(stderr, "\n");
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exit(1);
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}
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#ifdef DEBUGGING
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void debug_printf(const char *fmt, ...)
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{
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va_list ap;
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va_start(ap, fmt);
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vfprintf(stdout, fmt, ap);
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va_end(ap);
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}
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#endif
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