X-Git-Url: https://git.cworth.org/git?a=blobdiff_plain;f=acre.c;h=a01dbe5c2f1275c0c4f77b049844c8220b2c69e8;hb=5897f1f7f868e2fdfa51fc8e3bb9e02d49171b2b;hp=5949a96a1a38ccc37fe48397b0cb3ea3d755e046;hpb=256fd062ba200c24faab99c2e773744f33770c1c;p=acre diff --git a/acre.c b/acre.c index 5949a96..a01dbe5 100644 --- a/acre.c +++ b/acre.c @@ -17,10 +17,15 @@ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ +#define _ISOC99_SOURCE /* for round() */ +#define _XOPEN_SOURCE 500 +#define _GNU_SOURCE /* for asprintf() */ + #include "acre.h" #include "xmalloc.h" #include +#include #include typedef struct _acre_data_point_2d { @@ -53,6 +58,7 @@ struct _acre { /* Data for drawing. */ cairo_t *cr; + PangoFontDescription *font; /* Total size including labels. */ int width; @@ -84,6 +90,11 @@ acre_create (void) acre->data_size = 0; acre->num_data = 0; + acre->chart.x = 0; + acre->chart.y = 0; + acre->chart.width = 0; + acre->chart.height = 0; + return acre; } @@ -152,13 +163,80 @@ acre_add_data (acre_t *acre, acre_data_t *data) #define ACRE_TITLE_FONT_SIZE 32 #define ACRE_PAD (ACRE_FONT_SIZE) #define ACRE_TICK_SIZE 6 +#define ACRE_X_TICK_VALUE_PAD 2 +#define ACRE_Y_TICK_VALUE_PAD 4 + +static PangoLayout * +_create_layout (acre_t *acre, const char *text) +{ + PangoLayout *layout; + + layout = pango_cairo_create_layout (acre->cr); + pango_layout_set_font_description (layout, acre->font); + pango_layout_set_text (layout, text, -1); + pango_layout_set_alignment (layout, PANGO_ALIGN_CENTER); + + return layout; +} + +#define PRINTF_FORMAT(fmt_index, va_index) __attribute__ ((__format__(__printf__, fmt_index, va_index))) + +static PangoLayout * +_create_layout_vprintf (acre_t *acre, const char *fmt, va_list ap) +{ + PangoLayout *layout; + char *text; + + vasprintf (&text, fmt, ap); + + layout = _create_layout (acre, text); + + free (text); + + return layout; +} + +static PangoLayout * +_create_layout_printf (acre_t *acre, const char *fmt, ...) + PRINTF_FORMAT (2, 3); + +static PangoLayout * +_create_layout_printf (acre_t *acre, const char *fmt, ...) +{ + va_list ap; + PangoLayout *layout; + + va_start (ap, fmt); + + layout = _create_layout_vprintf (acre, fmt, ap); + + va_end (ap); + + return layout; +} + +static void +_destroy_layout (PangoLayout *layout) +{ + g_object_unref (layout); +} + +static void +_show_layout (cairo_t *cr, PangoLayout *layout) +{ + pango_cairo_show_layout (cr, layout); + + _destroy_layout (layout); +} static void _draw_title_and_labels (acre_t *acre) { cairo_t *cr = acre->cr; - PangoFontDescription *acre_font, *title_font; + PangoFontDescription *title_font; PangoLayout *title_layout, *x_axis_layout, *y_axis_layout; + PangoLayout *min_y, *max_y; + int min_y_width, max_y_width, y_axis_value_width; int title_width, title_height; int x_axis_width, x_axis_height; int y_axis_width, y_axis_height; @@ -166,9 +244,9 @@ _draw_title_and_labels (acre_t *acre) cairo_save (cr); - acre_font = pango_font_description_new (); - pango_font_description_set_family (acre_font, ACRE_FONT_FAMILY); - pango_font_description_set_absolute_size (acre_font, + acre->font = pango_font_description_new (); + pango_font_description_set_family (acre->font, ACRE_FONT_FAMILY); + pango_font_description_set_absolute_size (acre->font, ACRE_FONT_SIZE * PANGO_SCALE); title_font = pango_font_description_new (); @@ -176,29 +254,28 @@ _draw_title_and_labels (acre_t *acre) pango_font_description_set_absolute_size (title_font, ACRE_TITLE_FONT_SIZE * PANGO_SCALE); - title_layout = pango_cairo_create_layout (cr); + title_layout = _create_layout (acre, acre->title); pango_layout_set_font_description (title_layout, title_font); - pango_layout_set_text (title_layout, acre->title, -1); - pango_layout_set_alignment (title_layout, PANGO_ALIGN_CENTER); - x_axis_layout = pango_cairo_create_layout (cr); - pango_layout_set_font_description (x_axis_layout, acre_font); - pango_layout_set_text (x_axis_layout, acre->x_axis.label, -1); - pango_layout_set_alignment (x_axis_layout, PANGO_ALIGN_CENTER); + x_axis_layout = _create_layout (acre, acre->x_axis.label); + y_axis_layout = _create_layout (acre, acre->y_axis.label); + + min_y = _create_layout_printf (acre, "%g", + round (acre->y_axis.min)); + max_y = _create_layout_printf (acre, "%g", + round (acre->y_axis.max)); + + pango_layout_get_pixel_size (min_y, &min_y_width, NULL); + pango_layout_get_pixel_size (max_y, &max_y_width, NULL); + y_axis_value_width = MAX (min_y_width, max_y_width); - y_axis_layout = pango_cairo_create_layout (cr); - pango_layout_set_font_description (y_axis_layout, acre_font); - pango_layout_set_text (y_axis_layout, acre->y_axis.label, -1); - pango_layout_set_alignment (y_axis_layout, PANGO_ALIGN_CENTER); + _destroy_layout (min_y); + _destroy_layout (max_y); /* Iterate with the layout of the title and axis labels until they * are stable, (this requires iteration since we don't know what * to set their widths to in advance due to the wrapping of the * other elements). */ - acre->chart.x = 0; - acre->chart.y = 0; - acre->chart.width = acre->width; - acre->chart.height = acre->height; while (1) { pango_layout_set_width (title_layout, acre->chart.width * PANGO_SCALE); pango_layout_set_width (x_axis_layout, acre->chart.width * PANGO_SCALE); @@ -209,11 +286,13 @@ _draw_title_and_labels (acre_t *acre) pango_layout_get_pixel_size (y_axis_layout, &y_axis_width, &y_axis_height); new_chart.x = ACRE_PAD + y_axis_height + - ACRE_PAD + ACRE_FONT_SIZE; + ACRE_PAD + y_axis_value_width + ACRE_Y_TICK_VALUE_PAD; new_chart.width = acre->width - acre->chart.x - ACRE_PAD; new_chart.y = ACRE_PAD + title_height + ACRE_PAD; - new_chart.height = acre->height - acre->chart.y - (ACRE_FONT_SIZE + ACRE_PAD + x_axis_height + ACRE_PAD); + new_chart.height = acre->height - acre->chart.y - + (ACRE_X_TICK_VALUE_PAD + ACRE_FONT_SIZE + + ACRE_PAD + x_axis_height + ACRE_PAD); if (new_chart.x == acre->chart.x && new_chart.y == acre->chart.y && @@ -232,31 +311,115 @@ _draw_title_and_labels (acre_t *acre) cairo_set_source_rgb (cr, 0, 0, 0); cairo_move_to (cr, acre->chart.x, ACRE_PAD); - pango_cairo_show_layout (cr, title_layout); + _show_layout (cr, title_layout); cairo_save (cr); { cairo_translate (cr, ACRE_PAD, acre->chart.y + acre->chart.height); cairo_rotate (cr, - M_PI / 2.0); cairo_move_to (cr, 0, 0); - pango_cairo_show_layout (cr, y_axis_layout); + _show_layout (cr, y_axis_layout); } cairo_restore (cr); cairo_move_to (cr, acre->chart.x, acre->chart.y + acre->chart.height + ACRE_FONT_SIZE + ACRE_PAD); - pango_cairo_show_layout (cr, x_axis_layout); + _show_layout (cr, x_axis_layout); cairo_restore (cr); } +/* For a given axis range, compute a step size (in data space) to + * generate a suitable number of ticks (5 or so). */ +static double +_step_for_range (double range) +{ + double step, scale_factor; + + /* We want roughly 5 major ticks for the chart. */ + step = range / 5; + + /* Normalize the step so we can easily snap it to a desirable + * value. */ + scale_factor = pow (10.0, floor (log10 (step))); + step /= scale_factor; + + /* We want increments of 1, 2.5, 5, or 10 (times some power of + * 10). The threshold values between these are computed + * logarithmically. */ + if (step < 3.535533905932738) { + if (step < 1.58113883008419) + step = 1.0; + else + step = 2.5; + } else { + if (step < 7.071067811865475) + step = 5.0; + else + step = 10.0; + } + + /* Un-normalize and we now have the data value that we want to + * step at. */ + return step * scale_factor; +} + +/* Given an axis range, we can compute a desired data-space step + * amount for the major ticks (see _step_for_range). To get + * nice-looking pixel-snapped ticks we want to expand the range + * slightly. */ +static void +_expand_range_for_width (double *axis_min, double *axis_max, int pixel_size) +{ + double range, new_range, step, pixel_step; + + range = *axis_max - *axis_min; + + step = _step_for_range (range); + pixel_step = step * pixel_size / range; + + /* We expand the range by the ratio of the pixel step to the floor + * of the pixel_step. + */ + new_range = range * pixel_step / floor (pixel_step); + + /* And spread the increase out on either side of the range. */ + *axis_min -= (new_range - range) / 2.0; + *axis_max += (new_range - range) / 2.0; +} + +/* Setup a transformation in acre->cr such that data values plotted + * will appear where they should within the chart. + */ +static void +_set_transform_to_data_space (acre_t *acre) +{ + cairo_t *cr = acre->cr; + + cairo_translate (cr, + acre->chart.x, + acre->chart.y + acre->chart.height); + cairo_scale (cr, + acre->chart.width / (acre->x_axis.max - acre->x_axis.min), + - acre->chart.height /(acre->y_axis.max - acre->y_axis.min)); + cairo_translate (cr, -acre->x_axis.min, -acre->y_axis.min); +} + static void _compute_axis_ranges (acre_t *acre) { unsigned int d, i; acre_data_t *data; + double x_adjust, y_adjust; + cairo_t *cr = acre->cr; + + acre->x_axis.min = acre->data[0]->points[0].x; + acre->x_axis.max = acre->data[0]->points[0].x; + acre->y_axis.min = acre->data[0]->points[0].y; + acre->y_axis.min = acre->data[0]->points[0].y; + /* First, simply find the extrema of the data. */ for (d = 0; d < acre->num_data; d++) { data = acre->data[d]; for (i = 0; i < data->num_points; i++) { @@ -271,23 +434,39 @@ _compute_axis_ranges (acre_t *acre) acre->y_axis.max = data->points[i].y; } } -} -/* Setup a transformation in acre->cr such that data values plotted - * will appear where they should within the chart. - */ -static void -_set_transform_to_data_space (acre_t *acre) -{ - cairo_t *cr = acre->cr; + /* Next, increase the axis ranges just enough so that the step + * sizes for the ticks will be integers. + */ + _expand_range_for_width (&acre->x_axis.min, + &acre->x_axis.max, + acre->chart.width); - cairo_translate (cr, - acre->chart.x + 0.5, - acre->chart.y + acre->chart.height - 0.5); - cairo_scale (cr, - acre->chart.width / (acre->x_axis.max - acre->x_axis.min), - - acre->chart.height /(acre->y_axis.max - acre->y_axis.min)); - cairo_translate (cr, -acre->x_axis.min, -acre->y_axis.min); + _expand_range_for_width (&acre->y_axis.min, + &acre->y_axis.max, + acre->chart.height); + + /* Finally, we also translate the axis ranges slightly so that the + * ticks land on half-integer device-pixel positions. + */ + cairo_save (cr); + { + _set_transform_to_data_space (acre); + + x_adjust = 0.0; + y_adjust = 0.0; + cairo_user_to_device (cr, &x_adjust, &y_adjust); + x_adjust = (round (x_adjust + 0.5) - 0.5) - x_adjust; + y_adjust = (round (y_adjust + 0.5) - 0.5) - y_adjust; + cairo_device_to_user_distance (cr, &x_adjust, &y_adjust); + + acre->x_axis.min -= x_adjust; + acre->x_axis.max -= x_adjust; + + acre->y_axis.min -= y_adjust; + acre->y_axis.max -= y_adjust; + } + cairo_restore (cr); } static void @@ -323,89 +502,91 @@ _draw_data (acre_t *acre) cairo_restore (cr); } -static double -_step_for_range (double range) +typedef enum _ticks { ACRE_TICKS_X, ACRE_TICKS_Y } acre_ticks_t; + +static void +_draw_ticks (acre_t *acre, + double axis_min, double axis_max, + acre_ticks_t ticks) { - double step, scale_factor; + cairo_t *cr = acre->cr; + double i, step; - /* We want roughly 5 major ticks for the chart. */ - step = range / 5; + cairo_save (cr); - /* Normalize the step so we can easily snap it to a desirable - * value. */ - scale_factor = pow (10.0, floor (log10 (step))); - step /= scale_factor; + _set_transform_to_data_space (acre); - /* We want increments of 1, 2.5, 5, or 10 (times some power of - * 10). The threshold values between these are computed - * logarithmically. */ - if (step < 3.535533905932738) { - if (step < 1.58113883008419) - step = 1.0; - else - step = 2.5; - } else { - if (step < 7.071067811865475) - step = 5.0; + step = _step_for_range (axis_max - axis_min); + i = (floor (axis_min / step) + 1) * step; + + while (i <= axis_max) { + if (ticks == ACRE_TICKS_X) + cairo_move_to (cr, i, acre->y_axis.min); else - step = 10.0; + cairo_move_to (cr, acre->x_axis.min, i); + + /* tick */ + cairo_save (cr); + { + cairo_identity_matrix (cr); + if (ticks == ACRE_TICKS_X) { + cairo_rel_line_to (cr, 0, 0.5); + cairo_rel_line_to (cr, 0, -ACRE_TICK_SIZE-0.5); + } else { + cairo_rel_line_to (cr, -0.5, 0); + cairo_rel_line_to (cr, ACRE_TICK_SIZE+0.5, 0); + } + cairo_set_line_width (cr, 1.0); + cairo_stroke (cr); + } + cairo_restore (cr); + + /* label */ + cairo_save (cr); + { + PangoLayout *layout; + int width, height; + + layout = _create_layout_printf (acre, "%g", i); + + if (ticks == ACRE_TICKS_X) + cairo_move_to (cr, i, acre->y_axis.min); + else + cairo_move_to (cr, acre->x_axis.min, i); + + cairo_identity_matrix (cr); + pango_layout_get_pixel_size (layout, &width, &height); + + if (ticks == ACRE_TICKS_X) + cairo_rel_move_to (cr, -width / 2, ACRE_X_TICK_VALUE_PAD); + else + cairo_rel_move_to (cr, -width - ACRE_Y_TICK_VALUE_PAD, + -height/2); + + _show_layout (cr, layout); + } + cairo_restore (cr); + + i += step; } - /* Un-normalize and we now have the data value that we want to - * step at. */ - return step * scale_factor; + cairo_restore (cr); } static void _draw_frame_and_ticks (acre_t *acre) { cairo_t *cr = acre->cr; - double step, x, y; cairo_save (cr); cairo_set_source_rgb (cr, 0, 0, 0); /* black */ - /* First the ticks within data space. */ - cairo_save (cr); - { - _set_transform_to_data_space (acre); + /* ticks */ + _draw_ticks (acre, acre->x_axis.min, acre->x_axis.max, ACRE_TICKS_X); + _draw_ticks (acre, acre->y_axis.min, acre->y_axis.max, ACRE_TICKS_Y); - step = _step_for_range (acre->x_axis.max -acre->x_axis.min); - x = (floor (acre->x_axis.min / step) + 1) * step; - while (x <= acre->x_axis.max) { - cairo_move_to (cr, x, acre->y_axis.min); - cairo_save (cr); - { - cairo_identity_matrix (cr); - cairo_rel_line_to (cr, 0, 0.5); - cairo_rel_line_to (cr, 0, -ACRE_TICK_SIZE); - cairo_set_line_width (cr, 1.0); - cairo_stroke (cr); - } - cairo_restore (cr); - x += step; - } - - step = _step_for_range (acre->y_axis.max -acre->y_axis.min); - y = (floor (acre->y_axis.min / step) + 1) * step; - while (y <= acre->y_axis.max) { - cairo_move_to (cr, acre->x_axis.min, y); - cairo_save (cr); - { - cairo_identity_matrix (cr); - cairo_rel_line_to (cr, -0.5, 0); - cairo_rel_line_to (cr, ACRE_TICK_SIZE, 0); - cairo_set_line_width (cr, 1.0); - cairo_stroke (cr); - } - cairo_restore (cr); - y += step; - } - } - cairo_restore (cr); - - /* Then the frame drawn in pixel space. */ + /* frame */ cairo_rectangle (cr, acre->chart.x - 0.5, acre->chart.y - 0.5, acre->chart.width + 1.0, acre->chart.height + 1.0); @@ -424,17 +605,25 @@ void acre_draw (acre_t *acre, cairo_t *cr, int width, int height) { acre->cr = cr; + acre->width = width; acre->height = height; + acre->chart.width = width; + acre->chart.height = height; + cairo_save (cr); cairo_set_source_rgb (cr, 1, 1, 1); - cairo_paint (cr); + /* We compute the axis ranges before doing label layout so that we + * can account for the width of the y-axis value labels. */ + _compute_axis_ranges (acre); _draw_title_and_labels (acre); + /* And we recompute the axis ranges now that the title and axis + * label space is all measured and accounted for. */ _compute_axis_ranges (acre); _draw_data (acre);