* 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 <string.h>
+#include <stdarg.h>
#include <math.h>
typedef struct _acre_data_point_2d {
/* Data for drawing. */
cairo_t *cr;
+ PangoFontDescription *font;
/* Total size including labels. */
int width;
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;
}
#define ACRE_FONT_SIZE 12
#define ACRE_TITLE_FONT_SIZE 32
#define ACRE_PAD (ACRE_FONT_SIZE)
-#define ACRE_TICK_SIZE 6
+#define ACRE_TICK_MAJOR_SIZE 6
+#define ACRE_TICK_MINOR_SIZE 3
+#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;
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 ();
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);
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 &&
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)
+_step_for_range (double range, int *minor_divisions)
{
double step, scale_factor;
* 10). The threshold values between these are computed
* logarithmically. */
if (step < 3.535533905932738) {
- if (step < 1.58113883008419)
+ if (step < 1.58113883008419) {
step = 1.0;
- else
+ *minor_divisions = 4;
+ } else {
step = 2.5;
+ *minor_divisions = 5;
+ }
} else {
- if (step < 7.071067811865475)
+ if (step < 7.071067811865475) {
step = 5.0;
- else
+ *minor_divisions = 5;
+ } else {
step = 10.0;
+ *minor_divisions = 4;
+ }
}
/* Un-normalize and we now have the data value that we want to
* amount for the major ticks (see _step_for_range). To get
* nice-looking pixel-snapped ticks we want to expand the range
* slightly. */
-static double
-_expand_range (double data_range, int pixel_size)
+static void
+_expand_range_for_width (double *axis_min, double *axis_max, int pixel_range)
{
- double step, pixel_step;
+ double range, new_range, step, step_minor, pixel_step;
+ int minor_divisions;
+
+ range = *axis_max - *axis_min;
- step = _step_for_range (data_range);
- pixel_step = step * pixel_size / data_range;
+ step = _step_for_range (range, &minor_divisions);
+ step_minor = step / minor_divisions;
+
+ pixel_step = step_minor * (pixel_range / range);
/* We expand the range by the ratio of the pixel step to the floor
* of the pixel_step.
*/
- return data_range * pixel_step / floor (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
{
unsigned int d, i;
acre_data_t *data;
- double x_range, new_x_range;
- double y_range, new_y_range;
+ 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++) {
}
}
- /* Next, increase the axis ranges just enough so that the step
+ /* Next, we want to ensure that the data never collides with the
+ * ticks. So we expand each axis on its minimum side as needed. */
+ cairo_save (cr);
+ {
+ double x, y;
+
+ _set_transform_to_data_space (acre);
+
+ x = ACRE_TICK_MAJOR_SIZE + 2.0;
+ y = ACRE_TICK_MAJOR_SIZE + 2.0;
+ cairo_device_to_user_distance (cr, &x, &y);
+
+ acre->x_axis.min -= x;
+ acre->y_axis.min += y;
+ }
+ cairo_restore (cr);
+
+ /* Then, increase the axis ranges just enough so that the step
* sizes for the ticks will be integers.
*/
- x_range = acre->x_axis.max - acre->x_axis.min;
- new_x_range = _expand_range (x_range, acre->chart.width);
+ _expand_range_for_width (&acre->x_axis.min,
+ &acre->x_axis.max,
+ acre->chart.width);
- y_range = acre->y_axis.max - acre->y_axis.min;
- new_y_range = _expand_range (y_range, acre->chart.height);
+ _expand_range_for_width (&acre->y_axis.min,
+ &acre->y_axis.max,
+ acre->chart.height);
- /* And spread the increase out on either side of the range. */
- acre->x_axis.min -= (new_x_range - x_range) / 2.0;
- acre->x_axis.max += (new_x_range - x_range) / 2.0;
+ /* 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);
- acre->y_axis.min -= (new_y_range - y_range) / 2.0;
- acre->y_axis.max += (new_y_range - y_range) / 2.0;
-}
+ 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);
-/* 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;
+ acre->x_axis.min -= x_adjust;
+ acre->x_axis.max -= x_adjust;
- 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);
+ acre->y_axis.min -= y_adjust;
+ acre->y_axis.max -= y_adjust;
+ }
+ cairo_restore (cr);
}
static void
cairo_restore (cr);
}
+typedef enum _ticks { ACRE_TICKS_X, ACRE_TICKS_Y } acre_ticks_t;
+
static void
-_draw_frame_and_ticks (acre_t *acre)
+_draw_ticks (acre_t *acre,
+ double axis_min, double axis_max,
+ acre_ticks_t ticks)
{
cairo_t *cr = acre->cr;
- double step, x, y;
+ double t, step, sub_step;
+ int minor_divisions;
cairo_save (cr);
- cairo_set_source_rgb (cr, 0, 0, 0); /* black */
+ _set_transform_to_data_space (acre);
- /* First the ticks within data space. */
- cairo_save (cr);
+ step = _step_for_range (axis_max - axis_min, &minor_divisions);
+ sub_step = step / minor_divisions;
+
+ for (t = (floor (axis_min / sub_step) + 1) * sub_step;
+ t <= axis_max;
+ t += sub_step)
{
- _set_transform_to_data_space (acre);
+ int tick_size;
+ if (fabs((t / step) - (int) (t / step)) < 0.5 * (sub_step / step))
+ tick_size = ACRE_TICK_MAJOR_SIZE;
+ else
+ tick_size = ACRE_TICK_MINOR_SIZE;
- 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);
+ /* tick */
+ cairo_save (cr);
+ {
+ if (ticks == ACRE_TICKS_X)
+ cairo_move_to (cr, t, acre->y_axis.min);
+ else
+ cairo_move_to (cr, acre->x_axis.min, t);
+
+ 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);
- cairo_set_line_width (cr, 1.0);
- cairo_stroke (cr);
+ cairo_rel_line_to (cr, 0, -tick_size - 0.5);
+ } else {
+ cairo_rel_line_to (cr, -0.5, 0);
+ cairo_rel_line_to (cr, tick_size + 0.5, 0);
}
- cairo_restore (cr);
- x += step;
+
+ cairo_set_line_width (cr, 1.0);
+ cairo_stroke (cr);
}
+ cairo_restore (cr);
+
+ /* label */
+ if (tick_size == ACRE_TICK_MAJOR_SIZE)
+ {
+ PangoLayout *layout;
+ int width, height;
- 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);
- }
+
+ layout = _create_layout_printf (acre, "%g", t);
+
+ if (ticks == ACRE_TICKS_X)
+ cairo_move_to (cr, t, acre->y_axis.min);
+ else
+ cairo_move_to (cr, acre->x_axis.min, t);
+
+ 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);
- y += step;
}
}
+
cairo_restore (cr);
+}
+
+static void
+_draw_frame_and_ticks (acre_t *acre)
+{
+ cairo_t *cr = acre->cr;
+
+ cairo_save (cr);
+
+ cairo_set_source_rgb (cr, 0, 0, 0); /* black */
- /* Then the frame drawn in pixel space. */
+ /* 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);
+
+ /* frame */
cairo_rectangle (cr,
acre->chart.x - 0.5, acre->chart.y - 0.5,
acre->chart.width + 1.0, acre->chart.height + 1.0);
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);