+ _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, int *minor_divisions)
+{
+ 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;
+ *minor_divisions = 4;
+ } else {
+ step = 2.5;
+ *minor_divisions = 5;
+ }
+ } else {
+ if (step < 7.071067811865475) {
+ step = 5.0;
+ *minor_divisions = 5;
+ } else {
+ step = 10.0;
+ *minor_divisions = 4;
+ }
+ }
+
+ /* 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_range)
+{
+ double range, new_range, step, step_minor, pixel_step;
+ int minor_divisions;
+
+ range = *axis_max - *axis_min;
+
+ 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.
+ */
+ 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.view_max - acre->x_axis.view_min),
+ - acre->chart.height /(acre->y_axis.view_max - acre->y_axis.view_min));
+ cairo_translate (cr, -acre->x_axis.view_min, -acre->y_axis.view_min);
+}
+
+static void
+_find_x_range_given_y_range (acre_t *acre,
+ double *x_min, double *x_max,
+ double y_min, double y_max)
+{
+ acre_data_t *data;
+ unsigned d, i;
+ bool first;
+
+ first = true;
+
+ for (d = 0; d < acre->num_data; d++) {
+ data = acre->data[d];
+ for (i = 0; i < data->num_points; i++) {
+ if (data->points[i].y >= y_min &&
+ data->points[i].y <= y_max)
+ {
+ if (first) {
+ *x_min = data->points[i].x;
+ *x_max = data->points[i].x;
+ first = false;
+ } else {
+ if (data->points[i].x < *x_min)
+ *x_min = data->points[i].x;
+ if (data->points[i].x > *x_max)
+ *x_max = data->points[i].x;
+ }
+ }
+ }
+ }
+
+ /* If nothing is visible, punt to full X data range. */
+ if (first) {
+ *x_min = acre->x_axis.data_min;
+ *x_max = acre->x_axis.data_max;
+ }
+}
+
+static void
+_find_y_range_given_x_range (acre_t *acre,
+ double *y_min, double *y_max,
+ double x_min, double x_max)
+{
+ acre_data_t *data;
+ unsigned d, i;
+ bool first;
+
+ first = true;
+
+ for (d = 0; d < acre->num_data; d++) {
+ data = acre->data[d];
+
+ /* Never mess with the Y range for timeline data. */
+ if (data->style == ACRE_STYLE_TIMELINE)
+ continue;
+
+ for (i = 0; i < data->num_points; i++) {
+ if (data->points[i].x >= x_min &&
+ data->points[i].x <= x_max)
+ {
+ if (first) {
+ *y_min = data->points[i].y;
+ *y_max = data->points[i].y;
+ first = false;
+ } else {
+ if (data->points[i].y < *y_min)
+ *y_min = data->points[i].y;
+ if (data->points[i].y > *y_max)
+ *y_max = data->points[i].y;
+ }
+ }
+ }
+ }
+
+ /* If nothing is visible, punt to full Y data range. */
+ if (first) {
+ *y_min = acre->y_axis.data_min;
+ *y_max = acre->y_axis.data_max;
+ }
+}
+
+static void
+_compute_axis_ranges (acre_t *acre)
+{
+ double x_adjust, y_adjust;
+ cairo_t *cr = acre->cr;
+
+ /* If neither view range is set, set both to data ranges. */
+ if (! acre->x_axis.view_range_set && ! acre->y_axis.view_range_set)
+ {
+ acre->x_axis.view_min = acre->x_axis.data_min;
+ acre->x_axis.view_max = acre->x_axis.data_max;
+
+ acre->y_axis.view_min = acre->y_axis.data_min;
+ acre->y_axis.view_max = acre->y_axis.data_max;
+ } else {
+ /* Otherwise, auto-fit unset range based on data. */
+ if (acre->x_axis.view_range_set && ! acre->y_axis.view_range_set) {
+ _find_y_range_given_x_range (acre,
+ &acre->y_axis.view_min,
+ &acre->y_axis.view_max,
+ acre->x_axis.view_min,
+ acre->x_axis.view_max);
+ }
+ else if (acre->y_axis.view_range_set && ! acre->x_axis.view_range_set) {
+ _find_x_range_given_y_range (acre,
+ &acre->x_axis.view_min,
+ &acre->x_axis.view_max,
+ acre->y_axis.view_min,
+ acre->y_axis.view_max);
+ }
+ }
+
+ /* Then, increase the axis ranges just enough so that the step
+ * sizes for the ticks will be integers.
+ */
+ _expand_range_for_width (&acre->x_axis.view_min,
+ &acre->x_axis.view_max,
+ acre->chart.width);
+
+ _expand_range_for_width (&acre->y_axis.view_min,
+ &acre->y_axis.view_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.view_min -= x_adjust;
+ acre->x_axis.view_max -= x_adjust;
+
+ acre->y_axis.view_min -= y_adjust;
+ acre->y_axis.view_max -= y_adjust;
+ }
+ cairo_restore (cr);
+}
+
+static void
+_choose_colors (acre_t *acre)
+{
+ cmsHPROFILE lab_profile, srgb_profile;
+ cmsHTRANSFORM lab_to_srgb;
+ int i;
+ double theta, radius, srgb[3];
+ cmsCIELab lab;
+
+ lab_profile = cmsCreateLabProfile (NULL); /* D50 */
+ srgb_profile = cmsCreate_sRGBProfile ();
+
+ lab_to_srgb = cmsCreateTransform (lab_profile, TYPE_Lab_DBL,
+ srgb_profile, TYPE_RGB_DBL,
+ INTENT_PERCEPTUAL, 0);
+
+ acre->num_colors = acre->num_data;
+
+ if (acre->num_colors > acre->colors_size) {
+ acre->colors_size = acre->num_colors;
+ acre->colors = xrealloc (acre->colors,
+ acre->colors_size * sizeof (acre_color_t));
+ }
+
+ lab.L = 36;
+ radius = 130;
+ for (i = 0; i < acre->num_colors; i++) {
+ theta = 0.713 + 2 * M_PI * (double) i / acre->num_colors;
+ lab.a = radius * cos (theta);
+ lab.b = radius * sin (theta);
+
+ cmsDoTransform (lab_to_srgb, &lab, srgb, 1);
+
+ acre->colors[i].red = srgb[0];
+ acre->colors[i].green = srgb[1];
+ acre->colors[i].blue = srgb[2];
+ }
+
+ cmsDeleteTransform (lab_to_srgb);
+ cmsCloseProfile (lab_profile);
+ cmsCloseProfile (srgb_profile);
+}
+
+/* Draw the given dataset as a line. */
+static void
+_draw_data_line (acre_t *acre, acre_data_t *data)
+{
+ unsigned i;
+ cairo_t *cr = acre->cr;
+
+ cairo_save (cr);
+
+ cairo_new_path (cr);
+
+ for (i = 0; i < data->num_points; i++) {
+ cairo_line_to (cr,
+ data->points[i].x,
+ data->points[i].y);
+ }
+
+ cairo_identity_matrix (cr);
+ cairo_set_line_width (cr, 1.0);
+ cairo_stroke (cr);
+
+ cairo_restore (cr);
+}
+
+#define BARS_WIDTH 0.8
+
+/* Draw the given dataset as bars if there is room for that.
+ *
+ * Or, if the bars would run into each other, use a line instead.
+ */
+static void
+_draw_data_bars_or_line (acre_t *acre, acre_data_t *data)
+{
+ unsigned i;
+ cairo_t *cr = acre->cr;
+ double ignored, width;
+
+ /* Check device-space width available for inter-bad padding. */
+ width = 1.0 - BARS_WIDTH;
+ ignored = 0.0;
+ cairo_user_to_device_distance (cr, &width, &ignored);
+
+ /* If padding is less than two pixels, draw with a line instead. */
+ if (width < 2.0) {
+ _draw_data_line (acre, data);
+
+ return;
+ }
+
+ cairo_save (cr);
+
+ cairo_new_path (cr);
+
+ for (i = 0; i < data->num_points; i++) {
+ cairo_rectangle (cr,
+ data->points[i].x - BARS_WIDTH / 2.0, 0.0,
+ BARS_WIDTH, data->points[i].y);
+ }
+
+ cairo_identity_matrix (cr);
+ cairo_set_line_width (cr, 1.0);
+ cairo_stroke (cr);
+
+ cairo_restore (cr);
+}
+
+#define TIMELINE_BAR_HEIGHT 0.6
+
+/* Draw the given dataset as a timeline. Each (X,Y) point (potentially
+ * with a name) specifies the (start,stop) of a single timeline bar.
+ *
+ * Each independent timeline dataset in the chart is given its own
+ * vertical position, as specified by 'y_position'.
+ */
+static void
+_draw_data_timeline (acre_t *acre, acre_data_t *data, int y_position)
+{
+ unsigned i;
+ cairo_t *cr = acre->cr;
+ PangoLayout *timeline_label_layout;
+ double ignored, label_offset;
+ int labels_within_bar;
+
+ cairo_save (cr);
+
+ timeline_label_layout = _create_layout (acre, "Timeline");
+ pango_layout_set_font_description (timeline_label_layout, acre->font);
+
+ ignored = 0.0;
+ label_offset = ACRE_FONT_SIZE;
+ cairo_device_to_user_distance (cr, &ignored, &label_offset);
+
+ labels_within_bar = TIMELINE_BAR_HEIGHT / fabs (label_offset);
+
+ for (i = 0; i < data->num_points; i++) {
+ cairo_rectangle (cr,
+ data->points[i].x,
+ y_position - TIMELINE_BAR_HEIGHT / 2.0,
+ data->points[i].y - data->points[i].x,
+ TIMELINE_BAR_HEIGHT);
+
+ cairo_save (cr);
+ cairo_identity_matrix (cr);
+ cairo_set_line_width (cr, 1.0);
+ cairo_stroke_preserve (cr);
+ cairo_restore (cr);
+
+ cairo_new_path (cr);
+
+ if (i <= data->num_names && data->names[i]) {
+ cairo_save (cr);
+
+ cairo_move_to (cr, data->points[i].x,
+ y_position + TIMELINE_BAR_HEIGHT / 2.0 +
+ (i % labels_within_bar) * label_offset);
+ pango_layout_set_text (timeline_label_layout, data->names[i], -1);
+ cairo_identity_matrix (cr);
+ pango_cairo_show_layout (cr, timeline_label_layout);
+
+ cairo_restore (cr);
+ } else {
+ cairo_new_path (cr);
+ }
+
+ }
+
+ _destroy_layout (timeline_label_layout);
+
+ cairo_restore (cr);
+}
+
+/* Draw all the datasets of the chart. */
+static void
+_draw_data (acre_t *acre)
+{
+ cairo_t *cr = acre->cr;
+ unsigned int i;
+ acre_data_t *data;
+
+ cairo_save (cr);
+
+ cairo_rectangle (cr,
+ acre->chart.x, acre->chart.y,
+ acre->chart.width, acre->chart.height);
+ cairo_clip (cr);
+
+ cairo_set_source_rgb (cr, 0, 0, 0);
+
+ _set_transform_to_data_space (acre);
+
+ for (i = 0; i < acre->num_data; i++) {
+ int color = i % acre->num_colors;
+ cairo_set_source_rgb (cr,
+ acre->colors[color].red,
+ acre->colors[color].green,
+ acre->colors[color].blue);
+ data = acre->data[i];
+
+ switch (data->style) {
+ case ACRE_STYLE_LINE:
+ _draw_data_line (acre, data);
+ break;
+ case ACRE_STYLE_BARS_OR_LINE:
+ _draw_data_bars_or_line (acre, data);
+ break;
+ case ACRE_STYLE_TIMELINE:
+ /* Position the timeline bars top-down */
+ _draw_data_timeline (acre, data, acre->num_data - 1 - i);
+ break;
+ }
+ }
+
+ cairo_restore (cr);
+}
+
+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)
+{
+ cairo_t *cr = acre->cr;
+ double t, step, sub_step;
+ int minor_divisions;
+
+ cairo_save (cr);
+
+ _set_transform_to_data_space (acre);
+
+ 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)
+ {
+ int tick_size;
+ if (fabs((t / step) - round (t / step)) < 0.5 * (sub_step / step))
+ tick_size = ACRE_TICK_MAJOR_SIZE;
+ else
+ tick_size = ACRE_TICK_MINOR_SIZE;
+
+ /* tick */
+ cairo_save (cr);
+ {
+ if (ticks == ACRE_TICKS_X)
+ cairo_move_to (cr, t, acre->y_axis.view_min);
+ else
+ cairo_move_to (cr, acre->x_axis.view_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, -tick_size - 0.5);
+ } else {
+ cairo_rel_line_to (cr, -0.5, 0);
+ cairo_rel_line_to (cr, tick_size + 0.5, 0);
+ }
+
+ 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;
+ double label_value;
+
+ cairo_save (cr);
+
+ label_value = t;
+ if (fabs (label_value) < (sub_step / 1000.))
+ label_value = 0.0;
+ layout = _create_layout_printf (acre, "%g", label_value);
+
+ if (ticks == ACRE_TICKS_X)
+ cairo_move_to (cr, t, acre->y_axis.view_min);
+ else
+ cairo_move_to (cr, acre->x_axis.view_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);
+ }
+ }
+
+ cairo_restore (cr);
+}
+
+static void
+_draw_legend (acre_t *acre)
+{
+ PangoLayout *layout;
+ int label_width, max_label_width = 0;
+ int width, height;
+ unsigned int i;
+ cairo_t *cr = acre->cr;
+
+ cairo_save (cr);
+
+ for (i = 0; i < acre->num_data; i++) {
+ layout = _create_layout (acre, acre->data[i]->name);
+ pango_layout_get_pixel_size (layout, &label_width, NULL);
+ _destroy_layout (layout);
+ if (label_width > max_label_width)
+ max_label_width = label_width;
+ }
+
+ width = ACRE_LEGEND_PAD + ACRE_LEGEND_LINE_SIZE + ACRE_LEGEND_PAD +
+ max_label_width + ACRE_LEGEND_PAD;
+ height = ACRE_LEGEND_PAD +
+ acre->num_data * (ACRE_FONT_SIZE + ACRE_LEGEND_PAD);
+
+ cairo_translate (cr, acre->chart.x, acre->chart.y);
+
+ cairo_translate (cr,
+ acre->chart.width - ACRE_LEGEND_PAD - width,
+ ACRE_LEGEND_PAD);
+
+ cairo_rectangle (cr, -0.5, -0.5, width + 1.0, height + 1.0);
+ cairo_set_source_rgb (cr, 0, 0, 0);
+ cairo_set_line_width (cr, 1.0);
+ cairo_stroke (cr);
+
+ cairo_translate (cr, ACRE_LEGEND_PAD, ACRE_LEGEND_PAD);
+
+ for (i = 0; i < acre->num_data; i++) {
+ cairo_rectangle (cr,
+ 0, ACRE_LEGEND_LINE_SIZE / 2,
+ ACRE_LEGEND_LINE_SIZE, ACRE_LEGEND_LINE_SIZE / 2);
+ cairo_set_source_rgb (cr,
+ acre->colors[i % acre->num_colors].red,
+ acre->colors[i % acre->num_colors].green,
+ acre->colors[i % acre->num_colors].blue);
+ cairo_fill (cr);
+
+ layout = _create_layout (acre, acre->data[i]->name);
+ cairo_move_to (cr, ACRE_LEGEND_LINE_SIZE + ACRE_LEGEND_PAD, 0);
+ cairo_set_source_rgb (cr, 0, 0, 0);
+ _show_layout (cr, layout);
+
+ cairo_translate (cr, 0, ACRE_LEGEND_PAD + ACRE_FONT_SIZE);
+ }
+
+ 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 */
+
+ /* ticks */
+ _draw_ticks (acre, acre->x_axis.view_min, acre->x_axis.view_max, ACRE_TICKS_X);
+ _draw_ticks (acre, acre->y_axis.view_min, acre->y_axis.view_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);
+ cairo_set_line_width (cr, 1.0);
+ cairo_stroke (cr);
+
+ cairo_restore (cr);