X-Git-Url: https://git.cworth.org/git?a=blobdiff_plain;f=acre.c;h=35d0541d9c4b14bc58eef0da4d86bc61121be27a;hb=4df04fc13a5b7411dbdba561528e18f234a5364d;hp=6cd3a0b3c309fef4d49d5bffc05601e76f520e99;hpb=4a5a4c8bad866e53298a1cdf47104c2711c139df;p=acre

diff --git a/acre.c b/acre.c
index 6cd3a0b..35d0541 100644
--- a/acre.c
+++ b/acre.c
@@ -59,6 +59,8 @@ struct _acre {
     /* Data for drawing. */
     cairo_t *cr;
     PangoFontDescription *font;
+    struct { double r; double g; double b;} colors[3];
+    int num_colors;
 
     /* Total size including labels. */
     int width;
@@ -160,12 +162,14 @@ acre_add_data (acre_t *acre, acre_data_t *data)
 
 #define ACRE_FONT_FAMILY "sans"
 #define ACRE_FONT_SIZE 12
-#define ACRE_TITLE_FONT_SIZE 32
+#define ACRE_TITLE_FONT_SIZE 20
 #define ACRE_PAD (ACRE_FONT_SIZE)
 #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
+#define ACRE_LEGEND_PAD 4
+#define ACRE_LEGEND_LINE_SIZE 10
 
 static PangoLayout *
 _create_layout (acre_t *acre, const char *text)
@@ -334,7 +338,7 @@ _draw_title_and_labels (acre_t *acre)
 /* 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;
 
@@ -350,15 +354,21 @@ _step_for_range (double range)
      * 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
@@ -371,14 +381,17 @@ _step_for_range (double range)
  * 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)
+_expand_range_for_width (double *axis_min, double *axis_max, int pixel_range)
 {
-    double range, new_range, step, pixel_step;
+    double range, new_range, step, step_minor, pixel_step;
+    int minor_divisions;
 
     range = *axis_max - *axis_min;
 
-    step = _step_for_range (range);
-    pixel_step = step * pixel_size / 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.
@@ -436,7 +449,24 @@ _compute_axis_ranges (acre_t *acre)
 	}
     }
 
-    /* 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.
      */
     _expand_range_for_width (&acre->x_axis.min,
@@ -470,6 +500,26 @@ _compute_axis_ranges (acre_t *acre)
     cairo_restore (cr);
 }
 
+static void
+_choose_colors (acre_t *acre)
+{
+    /* XXX: Should choose N, equally-spaced colors from a perceptually
+     * linear space here. */
+    acre->num_colors = 3;
+
+    acre->colors[0].r = 1;
+    acre->colors[0].g = 0;
+    acre->colors[0].b = 0;
+
+    acre->colors[1].r = 0;
+    acre->colors[1].g = 1;
+    acre->colors[1].b = 0;
+
+    acre->colors[2].r = 0;
+    acre->colors[2].g = 0;
+    acre->colors[2].b = 1;
+}
+
 static void
 _draw_data (acre_t *acre)
 {
@@ -484,6 +534,11 @@ _draw_data (acre_t *acre)
     _set_transform_to_data_space (acre);
 
     for (d = 0; d < acre->num_data; d++) {
+	int color = d % acre->num_colors;
+	cairo_set_source_rgb (cr,
+			      acre->colors[color].r,
+			      acre->colors[color].g,
+			      acre->colors[color].b);
 	data = acre->data[d];
 	cairo_new_path (cr);
 	for (i = 0; i < data->num_points; i++) {
@@ -512,13 +567,13 @@ _draw_ticks (acre_t *acre,
 {
     cairo_t *cr = acre->cr;
     double t, step, sub_step;
-    int minor_divisions = 5;
+    int minor_divisions;
 
     cairo_save (cr);
 
     _set_transform_to_data_space (acre);
 
-    step = _step_for_range (axis_max - axis_min);
+    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;
@@ -526,7 +581,7 @@ _draw_ticks (acre_t *acre,
 	 t += sub_step)
     {
 	int tick_size;
-	if (fabs((t / step) - (int) (t / step)) < 0.5 * (sub_step / step))
+	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;
@@ -587,6 +642,63 @@ _draw_ticks (acre_t *acre,
     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_move_to (cr, 0, ACRE_FONT_SIZE / 2 + 0.5);
+	cairo_rel_line_to (cr, ACRE_LEGEND_LINE_SIZE, 0);
+	cairo_set_source_rgb (cr,
+			      acre->colors[i % acre->num_colors].r,
+			      acre->colors[i % acre->num_colors].g,
+			      acre->colors[i % acre->num_colors].b);
+	cairo_stroke (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)
 {
@@ -630,6 +742,8 @@ acre_draw (acre_t *acre, cairo_t *cr, int width, int height)
 
     cairo_set_source_rgb (cr, 1, 1, 1);
 
+    _choose_colors (acre);
+
     /* 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);
@@ -642,6 +756,9 @@ acre_draw (acre_t *acre, cairo_t *cr, int width, int height)
 
     _draw_data (acre);
 
+    if (acre->num_data > 1)
+	_draw_legend (acre);
+
     _draw_frame_and_ticks (acre);
 }