From d4a1dfb3d9a6a8f89d5f543ba1ad2eea091c813c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 7 Sep 2011 14:37:47 -0700 Subject: [PATCH] Fix up horribly broken cairo scaling The way cairo does scaling is really really inconvenient, and one of the things in cairo that is fundamentally mis-designed. Cairo scaling always affects both coordinates and object sizes, and the two can apparently never be split apart. Which is very much not what we want: we want just coordinate scaling. So we cannot use 'cairo_scale()' to scale our canvas, because that screws up lines and text size too. And no, you cannot "fix" that by de-scaling the line size etc - because line size is one-dimensional, so you can't undo the (different) scaling in X/Y. Sad. I realize that often you do want to scale object size with coordinate transformation, but quite often you *don't* want to. Yeah, we could do random context save/restore in odd places etc, but that's just a sign of the bad design of cairo scaling. Work around it by introducing our own graphics context with scaling, which does it right. I don't like this, but it seems to be better than the alternatives. Signed-off-by: Linus Torvalds --- profile.c | 215 ++++++++++++++++++++++++++++++------------------------ 1 file changed, 120 insertions(+), 95 deletions(-) diff --git a/profile.c b/profile.c index 7c72d0b..280a7fa 100644 --- a/profile.c +++ b/profile.c @@ -9,6 +9,33 @@ int selected_dive = 0; +/* + * Cairo scaling really is horribly horribly mis-designed. + * + * Which is sad, because I really like Cairo otherwise. But + * the fact that the line width is scaled with the same scale + * as the coordinate system is a f*&%ing disaster. So we + * can't use it, and instead have this butt-ugly wrapper thing.. + */ +struct graphics_context { + cairo_t *cr; + double maxx, maxy; + double scalex, scaley; +}; + +/* Scale to 0,0 -> maxx,maxy */ +#define SCALE(gc,x,y) (x)*gc->maxx/gc->scalex,(y)*gc->maxy/gc->scaley + +static void move_to(struct graphics_context *gc, double x, double y) +{ + cairo_move_to(gc->cr, SCALE(gc, x, y)); +} + +static void line_to(struct graphics_context *gc, double x, double y) +{ + cairo_line_to(gc->cr, SCALE(gc, x, y)); +} + #define ROUND_UP(x,y) ((((x)+(y)-1)/(y))*(y)) /* @@ -34,10 +61,12 @@ typedef struct { enum {CENTER,LEFT} allign; } text_render_options_t; -static void plot_text(cairo_t *cr, text_render_options_t *tro, +static void plot_text(struct graphics_context *gc, text_render_options_t *tro, double x, double y, const char *fmt, ...) { + cairo_t *cr = gc->cr; cairo_text_extents_t extents; + double dx, dy; char buffer[80]; va_list args; @@ -46,17 +75,21 @@ static void plot_text(cairo_t *cr, text_render_options_t *tro, va_end(args); cairo_text_extents(cr, buffer, &extents); - + dx = 0; if (tro->allign == CENTER) - x -= extents.width/2 + extents.x_bearing; - y += extents.height * 1.2; + dx = -(extents.width/2 + extents.x_bearing); + dy = extents.height * 1.2; + + move_to(gc, x, y); + cairo_rel_move_to(cr, dx, dy); - cairo_move_to(cr, x, y); cairo_text_path(cr, buffer); cairo_set_source_rgb(cr, 0, 0, 0); cairo_stroke(cr); - cairo_move_to(cr, x, y); + move_to(gc, x, y); + cairo_rel_move_to(cr, dx, dy); + cairo_set_source_rgb(cr, tro->r, tro->g, tro->b); cairo_show_text(cr, buffer); } @@ -113,12 +146,7 @@ static struct sample *next_minmax(struct sample *sample, struct sample *end, int return result; } -/* Scale to 0,0 -> maxx,maxy */ -#define SCALE(x,y) (x)*maxx/scalex,(y)*maxy/scaley - -void plot_text_samples(struct dive *dive, cairo_t *cr, - double maxx, double maxy, - double scalex, double scaley, +void plot_text_samples(struct dive *dive, struct graphics_context *gc, struct sample *a, struct sample *b) { struct sample *max, *min; @@ -137,12 +165,12 @@ void plot_text_samples(struct dive *dive, cairo_t *cr, double d; min = next_minmax(max, b, 0); - plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, a, max); + plot_text_samples(dive, gc, a, max); if (min) { - plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, max, min); - plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, min, b); + plot_text_samples(dive, gc, max, min); + plot_text_samples(dive, gc, min, b); } else - plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, max, b); + plot_text_samples(dive, gc, max, b); switch (output_units.length) { case METERS: @@ -155,27 +183,24 @@ void plot_text_samples(struct dive *dive, cairo_t *cr, break; } - plot_text(cr, &tro, SCALE(sec, depth.mm), fmt, d); + plot_text(gc, &tro, sec, depth.mm, fmt, d); return; } } -static void plot_depth_text(struct dive *dive, cairo_t *cr, - double maxx, double maxy) +static void plot_depth_text(struct dive *dive, struct graphics_context *gc) { struct sample *sample, *end; - double scalex, scaley; int maxtime, maxdepth; /* Get plot scaling limits */ maxtime = round_seconds_up(dive->duration.seconds); maxdepth = round_depth_up(dive->maxdepth); - scalex = maxtime; - scaley = maxdepth; + gc->scalex = maxtime; + gc->scaley = maxdepth; - cairo_set_font_size(cr, 14); - cairo_set_source_rgb(cr, 1, 0.2, 0.2); + cairo_set_font_size(gc->cr, 14); /* * We never take the last sample into account. @@ -185,13 +210,12 @@ static void plot_depth_text(struct dive *dive, cairo_t *cr, sample = dive->sample; end = dive->sample + dive->samples - 1; - plot_text_samples(dive, cr, maxx, maxy, scalex, scaley, sample, end); + plot_text_samples(dive, gc, sample, end); } -static void plot_depth_profile(struct dive *dive, cairo_t *cr, - double maxx, double maxy) +static void plot_depth_profile(struct dive *dive, struct graphics_context *gc) { - double scalex, scaley; + cairo_t *cr = gc->cr; int begins, sec, depth; int i, samples; struct sample *sample; @@ -201,23 +225,23 @@ static void plot_depth_profile(struct dive *dive, cairo_t *cr, if (!samples) return; - cairo_set_line_width(cr, 2); + cairo_set_line_width(gc->cr, 2); /* Get plot scaling limits */ maxtime = round_seconds_up(dive->duration.seconds); maxdepth = round_depth_up(dive->maxdepth); /* Time markers: every 5 min */ - scalex = maxtime; - scaley = 1.0; + gc->scalex = maxtime; + gc->scaley = 1.0; for (i = 5*60; i < maxtime; i += 5*60) { - cairo_move_to(cr, SCALE(i, 0)); - cairo_line_to(cr, SCALE(i, 1)); + move_to(gc, i, 0); + line_to(gc, i, 1); } /* Depth markers: every 30 ft or 10 m*/ - scalex = 1.0; - scaley = maxdepth; + gc->scalex = 1.0; + gc->scaley = maxdepth; switch (output_units.length) { case METERS: marker = 10000; break; case FEET: marker = 9144; break; /* 30 ft */ @@ -225,34 +249,34 @@ static void plot_depth_profile(struct dive *dive, cairo_t *cr, cairo_set_source_rgba(cr, 1, 1, 1, 0.5); for (i = marker; i < maxdepth; i += marker) { - cairo_move_to(cr, SCALE(0, i)); - cairo_line_to(cr, SCALE(1, i)); + move_to(gc, 0, i); + line_to(gc, 1, i); } cairo_stroke(cr); /* Show mean depth */ cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.40); - cairo_move_to(cr, SCALE(0, dive->meandepth.mm)); - cairo_line_to(cr, SCALE(1, dive->meandepth.mm)); + move_to(gc, 0, dive->meandepth.mm); + line_to(gc, 1, dive->meandepth.mm); cairo_stroke(cr); - scalex = maxtime; + gc->scalex = maxtime; sample = dive->sample; cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.80); begins = sample->time.seconds; - cairo_move_to(cr, SCALE(sample->time.seconds, sample->depth.mm)); + move_to(gc, sample->time.seconds, sample->depth.mm); for (i = 1; i < dive->samples; i++) { sample++; sec = sample->time.seconds; if (sec <= maxtime) { depth = sample->depth.mm; - cairo_line_to(cr, SCALE(sec, depth)); + line_to(gc, sec, depth); } } - scaley = 1.0; - cairo_line_to(cr, SCALE(MIN(sec,maxtime), 0)); - cairo_line_to(cr, SCALE(begins, 0)); + gc->scaley = 1.0; + line_to(gc, MIN(sec,maxtime), 0); + line_to(gc, begins, 0); cairo_close_path(cr); cairo_set_source_rgba(cr, 1, 0.2, 0.2, 0.20); cairo_fill_preserve(cr); @@ -261,13 +285,13 @@ static void plot_depth_profile(struct dive *dive, cairo_t *cr, } /* gets both the actual start and end pressure as well as the scaling factors */ -static int get_cylinder_pressure_range(struct dive *dive, double *scalex, double *scaley, - pressure_t *startp, pressure_t *endp) +static int get_cylinder_pressure_range(struct dive *dive, struct graphics_context *gc, + pressure_t *startp, pressure_t *endp) { int i; int min, max; - *scalex = round_seconds_up(dive->duration.seconds); + gc->scalex = round_seconds_up(dive->duration.seconds); max = 0; min = 5000000; @@ -295,22 +319,20 @@ static int get_cylinder_pressure_range(struct dive *dive, double *scalex, double endp->mbar = min; if (!max) return 0; - *scaley = max * 1.5; + gc->scaley = max * 1.5; return 1; } -static void plot_cylinder_pressure(struct dive *dive, cairo_t *cr, - double maxx, double maxy) +static void plot_cylinder_pressure(struct dive *dive, struct graphics_context *gc) { int i, sec = -1; - double scalex, scaley; - if (!get_cylinder_pressure_range(dive, &scalex, &scaley, NULL, NULL)) + if (!get_cylinder_pressure_range(dive, gc, NULL, NULL)) return; - cairo_set_source_rgba(cr, 0.2, 1.0, 0.2, 0.80); + cairo_set_source_rgba(gc->cr, 0.2, 1.0, 0.2, 0.80); - cairo_move_to(cr, SCALE(0, dive->cylinder[0].start.mbar)); + move_to(gc, 0, dive->cylinder[0].start.mbar); for (i = 1; i < dive->samples; i++) { int mbar; struct sample *sample = dive->sample + i; @@ -320,15 +342,15 @@ static void plot_cylinder_pressure(struct dive *dive, cairo_t *cr, continue; sec = sample->time.seconds; if (sec <= dive->duration.seconds) - cairo_line_to(cr, SCALE(sec, mbar)); + line_to(gc, sec, mbar); } /* * We may have "surface time" events, in which case we don't go * back to dive duration */ if (sec < dive->duration.seconds) - cairo_line_to(cr, SCALE(dive->duration.seconds, dive->cylinder[0].end.mbar)); - cairo_stroke(cr); + line_to(gc, dive->duration.seconds, dive->cylinder[0].end.mbar); + cairo_stroke(gc->cr); } /* @@ -355,8 +377,7 @@ static double calculate_airuse(struct dive *dive) return airuse; } -static void plot_info(struct dive *dive, cairo_t *cr, - double maxx, double maxy) +static void plot_info(struct dive *dive, struct graphics_context *gc) { text_render_options_t tro = {0.2, 1.0, 0.2, LEFT}; const double liters_per_cuft = 28.317; @@ -377,24 +398,21 @@ static void plot_info(struct dive *dive, cairo_t *cr, airuse /= liters_per_cuft; break; } - plot_text(cr, &tro, maxx*0.8, maxy*0.8, "vol: %4.2f %s", airuse, unit); + plot_text(gc, &tro, 0.8, 0.8, "vol: %4.2f %s", airuse, unit); if (dive->duration.seconds) { double pressure = 1 + (dive->meandepth.mm / 10000.0); double sac = airuse / pressure * 60 / dive->duration.seconds; - plot_text(cr, &tro, maxx*0.8, maxy*0.85, "SAC: %4.2f %s/min", sac, unit); + plot_text(gc, &tro, 0.8, 0.85, "SAC: %4.2f %s/min", sac, unit); } } -static void plot_cylinder_pressure_text(struct dive *dive, cairo_t *cr, - double maxx, double maxy) +static void plot_cylinder_pressure_text(struct dive *dive, struct graphics_context *gc) { - double scalex, scaley; pressure_t startp, endp; - cairo_set_font_size(cr, 10); + cairo_set_font_size(gc->cr, 10); - if (get_cylinder_pressure_range(dive, &scalex, &scaley, - &startp, &endp)) { + if (get_cylinder_pressure_range(dive, gc, &startp, &endp)) { int start, end; const char *unit = "bar"; @@ -417,65 +435,72 @@ static void plot_cylinder_pressure_text(struct dive *dive, cairo_t *cr, } text_render_options_t tro = {0.2, 1.0, 0.2, LEFT}; - plot_text(cr, &tro, SCALE(0, startp.mbar), "%d %s", start, unit); - plot_text(cr, &tro, SCALE(dive->duration.seconds, endp.mbar), + plot_text(gc, &tro, 0, startp.mbar, "%d %s", start, unit); + plot_text(gc, &tro, dive->duration.seconds, endp.mbar, "%d %s", end, unit); } } -static void plot(cairo_t *cr, int w, int h, struct dive *dive) +static void plot(struct graphics_context *gc, int w, int h, struct dive *dive) { - double topx, topy, maxx, maxy; - double scalex, scaley; + double topx, topy; topx = w / 20.0; topy = h / 20.0; - maxx = (w - 2*topx); - maxy = (h - 2*topy); - cairo_translate(cr, topx, topy); + cairo_translate(gc->cr, topx, topy); + + /* + * We can use "cairo_translate()" because that doesn't + * scale line width etc. But the actual scaling we need + * do set up ourselves.. + * + * Snif. What a pity. + */ + gc->maxx = (w - 2*topx); + gc->maxy = (h - 2*topy); /* Cylinder pressure plot */ - plot_cylinder_pressure(dive, cr, maxx, maxy); + plot_cylinder_pressure(dive, gc); /* Depth profile */ - plot_depth_profile(dive, cr, maxx, maxy); + plot_depth_profile(dive, gc); /* Text on top of all graphs.. */ - plot_depth_text(dive, cr, maxx, maxy); - plot_cylinder_pressure_text(dive, cr, maxx, maxy); + plot_depth_text(dive, gc); + plot_cylinder_pressure_text(dive, gc); /* And info box in the lower right corner.. */ - plot_info(dive, cr, maxx, maxy); + gc->scalex = gc->scaley = 1.0; + plot_info(dive, gc); /* Bounding box last */ - scalex = scaley = 1.0; - cairo_set_source_rgb(cr, 1, 1, 1); - cairo_move_to(cr, SCALE(0,0)); - cairo_line_to(cr, SCALE(0,1)); - cairo_line_to(cr, SCALE(1,1)); - cairo_line_to(cr, SCALE(1,0)); - cairo_close_path(cr); - cairo_stroke(cr); + cairo_set_source_rgb(gc->cr, 1, 1, 1); + move_to(gc, 0, 0); + line_to(gc, 0, 1); + line_to(gc, 1, 1); + line_to(gc, 1, 0); + cairo_close_path(gc->cr); + cairo_stroke(gc->cr); } static gboolean expose_event(GtkWidget *widget, GdkEventExpose *event, gpointer data) { struct dive *dive = current_dive; - cairo_t *cr; + struct graphics_context gc; int w,h; w = widget->allocation.width; h = widget->allocation.height; - cr = gdk_cairo_create(widget->window); - cairo_set_source_rgb(cr, 0, 0, 0); - cairo_paint(cr); + gc.cr = gdk_cairo_create(widget->window); + cairo_set_source_rgb(gc.cr, 0, 0, 0); + cairo_paint(gc.cr); if (dive) - plot(cr, w, h, dive); + plot(&gc, w, h, dive); - cairo_destroy(cr); + cairo_destroy(gc.cr); return FALSE; } -- 2.45.2