Fix a couple of crashes with empty matrices. Some small optimisations.

Correctly handle descenders on text when plotting labels.  Minor layout
improvements.  Add some drawings of what's going on in the port matrix
so that I don't keep losing them.


git-svn-id: svn://localhost/ardour2/branches/3.0@6319 d708f5d6-7413-0410-9779-e7cbd77b26cf

1 files changed, 28 insertions, 24 deletions

diff --git a/gtk2_ardour/port_matrix_column_labels.cc b/gtk2_ardour/port_matrix_column_labels.cc
index 2aeb084b9f..c10bb01a2b 100644
--- a/gtk2_ardour/port_matrix_column_labels.cc
+++ b/gtk2_ardour/port_matrix_column_labels.cc
@@ -45,10 +45,6 @@ PortMatrixColumnLabels::compute_dimensions ()
 	_longest_bundle_name = 0;
 	/* width of the longest channel name */
 	_longest_channel_name = 0;
-	/* height of highest bit of text (apart from group names) */
-	_highest_text = 0;
-	/* width of the whole thing */
-	_width = 0;
 
 	/* Compute dimensions using all port groups, so that we allow for the largest and hence
 	   we can change between visible groups without the size of the labels jumping around.
@@ -64,10 +60,6 @@ PortMatrixColumnLabels::compute_dimensions ()
 				_longest_bundle_name = ext.width;
 			}
 
-			if (ext.height > _highest_text) {
-				_highest_text = ext.height;
-			}
-
 			for (uint32_t k = 0; k < j->bundle->nchannels (); ++k) {
 
 				cairo_text_extents (
@@ -79,14 +71,21 @@ PortMatrixColumnLabels::compute_dimensions ()
 				if (ext.width > _longest_channel_name) {
 					_longest_channel_name = ext.width;
 				}
-
-				if (ext.height > _highest_text) {
-					_highest_text = ext.height;
-				}
 			}
 		}
+	}
 
-		_width += group_size (*i) * grid_spacing ();
+	/* height metrics */
+	cairo_text_extents_t ext;
+	cairo_text_extents (cr, X_("AQRjpy"), &ext);
+	_text_height = ext.height;
+	_descender_height = ext.height + ext.y_bearing;
+
+	/* width of the whole thing */
+	if (_matrix->visible_columns()) {
+		_width = group_size (_matrix->visible_columns()) * grid_spacing ();
+	} else {
+		_width = 0;
 	}
 
 	cairo_destroy (cr);
@@ -99,7 +98,7 @@ PortMatrixColumnLabels::compute_dimensions ()
 		a += _longest_channel_name;
 	}
 
-	_height =  a * sin (angle()) + _highest_text * cos (angle());
+	_height =  a * sin (angle()) + _text_height * cos (angle());
 	_overhang = _height / tan (angle ());
 	_width += _overhang;
 }
@@ -108,7 +107,7 @@ double
 PortMatrixColumnLabels::basic_text_x_pos (int) const
 {
 	return grid_spacing() / 2 +
-		_highest_text / (2 * sin (angle ()));
+		_text_height / (2 * sin (angle ()));
 }
 
 void
@@ -278,6 +277,8 @@ PortMatrixColumnLabels::render_bundle_name (
 
 	set_source_rgb (cr, text_colour());
 
+	double const q = ((grid_spacing() * sin (angle())) - _text_height) / 2 + _descender_height;
+
 	if (_matrix->arrangement() == PortMatrix::TOP_TO_RIGHT) {
 
 		double rl = 0;
@@ -288,16 +289,16 @@ PortMatrixColumnLabels::render_bundle_name (
 		}
 		cairo_move_to (
 			cr,
-			xoff + basic_text_x_pos (0) + rl * cos (angle()),
-			yoff + _height - rl * sin (angle())
+			xoff + grid_spacing() - q * sin (angle ()) + rl * cos (angle()),
+			yoff + _height - q * cos (angle ()) - rl * sin (angle())
 			);
 
 	} else {
 
 		cairo_move_to (
 			cr,
-			xoff + basic_text_x_pos (0) + name_pad() * cos (angle ()),
-			yoff + _height - name_pad() * sin (angle())
+			xoff + grid_spacing() - q * sin (angle ()),
+			yoff + _height - q * cos (angle ())
 			);
 	}
 
@@ -328,21 +329,24 @@ PortMatrixColumnLabels::render_channel_name (
 
 	set_source_rgb (cr, text_colour());
 
+	double const q = ((grid_spacing() * sin (angle())) - _text_height) / 2 + _descender_height;
+
 	if (_matrix->arrangement() == PortMatrix::TOP_TO_RIGHT) {
 
 		cairo_move_to (
 			cr,
-			xoff + basic_text_x_pos(bc.channel),
-			yoff + _height - name_pad() * sin (angle())
+			xoff + grid_spacing() - q * sin (angle ()),
+			yoff + _height - q * cos (angle ())
 			);
+				
 
 	} else {
 
 		double const rl = 3 * name_pad() + _longest_bundle_name;
 		cairo_move_to (
 			cr,
-			xoff + basic_text_x_pos(bc.channel) + rl * cos (angle ()),
-			yoff + _height - rl * sin (angle())
+			xoff + grid_spacing() - q * sin (angle ()) + rl * cos (angle ()),
+			yoff + _height - q * cos (angle ()) - rl * sin (angle())
 			);
 	}
 
@@ -453,7 +457,7 @@ PortMatrixColumnLabels::motion (double x, double y)
 		return;
 	}
 
-	uint32_t const bh = _longest_channel_name * sin (angle ()) + _highest_text / cos (angle ());
+	uint32_t const bh = _longest_channel_name * sin (angle ()) + _text_height / cos (angle ());
 
 	if (
 		(_matrix->arrangement() == PortMatrix::LEFT_TO_BOTTOM && y > bh) ||