X-Git-Url: https://git.cworth.org/git?a=blobdiff_plain;f=acre.c;h=3ddf14382a880a7db7edebff34512040e34fb1e3;hb=573652f264c7fc92e985d118b1f3dc64a5c6c9fc;hp=cec8a2f2532a528ffdc32e6b1a9c0c227d1df68d;hpb=3c7d4a2c642dea29982dadd700542549ac09be14;p=acre

diff --git a/acre.c b/acre.c
index cec8a2f..3ddf143 100644
--- a/acre.c
+++ b/acre.c
@@ -162,7 +162,8 @@ acre_add_data (acre_t *acre, acre_data_t *data)
 #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
 
@@ -333,7 +334,7 @@ _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;
 
@@ -349,15 +350,21 @@ _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
@@ -370,14 +377,17 @@ _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.
@@ -435,7 +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,
@@ -502,95 +529,104 @@ _draw_data (acre_t *acre)
     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) - round (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);
-	    {
-		/* tick */
-		cairo_save (cr);
-		{
-		    cairo_identity_matrix (cr);
-		    cairo_rel_line_to (cr, 0, 0.5);
-		    cairo_rel_line_to (cr, 0, -ACRE_TICK_SIZE-0.5);
-		    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", x);
-		    cairo_move_to (cr, x, acre->y_axis.min);
-		    cairo_identity_matrix (cr);
-		    pango_layout_get_pixel_size (layout, &width, &height);
-		    cairo_rel_move_to (cr, -width / 2, ACRE_X_TICK_VALUE_PAD);
-		    _show_layout (cr, layout);
-		}
-		cairo_restore (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, -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);
-	    {
-		/* tick */
-		cairo_save (cr);
-		{
-		    cairo_identity_matrix (cr);
-		    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", y);
-		    cairo_move_to (cr, acre->x_axis.min, y);
-		    cairo_identity_matrix (cr);
-		    pango_layout_get_pixel_size (layout, &width, &height);
-		    cairo_rel_move_to (cr, -width - ACRE_Y_TICK_VALUE_PAD,
-				       -height/2);
-		    _show_layout (cr, layout);
-		}
-		cairo_restore (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 */
+
+    /* 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);
 
-    /* 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);