From: Carl Worth <cworth@cworth.org>
Date: Tue, 27 Jan 2009 17:57:35 +0000 (-0800)
Subject: Adjust axis ranges so data doesn't collide with ticks.
X-Git-Url: https://git.cworth.org/git?p=acre;a=commitdiff_plain;h=9f7a70910ddcb7e29103a293e2ae6f056adcf45a

Adjust axis ranges so data doesn't collide with ticks.

There. I think I'm done making the ticks and frame look nice now.
I'm totally happy with the result.
---

diff --git a/acre.c b/acre.c
index e91248c..1ca0505 100644
--- a/acre.c
+++ b/acre.c
@@ -377,15 +377,17 @@ _step_for_range (double range, int *minor_divisions)
  * 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, &minor_divisions);
-    pixel_step = step * pixel_size / 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.
@@ -443,7 +445,24 @@ _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,