Revision history for Perl extension Bio::Graphics.
 
2.18
     - Made handling of min/max scale calculations consistent across all xyplot glyphs and their derivatives.
     - Added following autoscale options to wiggle_xyplot and wiggle_whiskers: "z-score" to rescale data such
       that mean is zero and values are standard deviation-fold change; and "clipped_global" to scale to
       global mean +/- some number of standard deviations indicated by "z_score_bounds".
     - Added "z_score_bounds" option to wiggle_xyplot and wiggle_whiskers to control how many standard
       deviations to show.
       

2.17
     - In segments glyph, fixed bleedover of "deletion" color when a deletion is followed by an insertion.
     - In segments glyph, fixed the display of inserted bases such that they will not bleed into a
       preceding deletion.
     - In segments glyph, fixed the mismatch color highlighting when the alignment is to the negative
       strand.
     - In segments glyph, fixed the default colors for mismatch, insertion and deletion.
     - In segments glyph, fixed treatment of soft clipping as an "insertion"; this will avoid the insertion
       color from appearing at the ends of soft-clipped reads.
     - In gene glyph, fixed occasional linking of two neighboring transcripts.
     
2.16
     - Distinguish between "chromosome" and "global" autoscaling in the xyplot and density glyphs.
       Global autoscaling only works when underlying database is bigwig.
     - Regularized options which select glyph subtypes with an option named "glyph_subtype".

2.15
     - Fixed documentation bug: sort_order options to sort by feature length should be
       "longest" and "shortest" rather than "longer and "shorter".
     - Improved layout algorithm, achieving speedup of ~4x on busy tracks.
     - Fixed font color problems when displaying multiple alignments at DNA level in
       the segments glyph.
     - Fixed problem of DNA alignment indels disappearing from view when they span entire region.
     - Fixed problem of mismatch and indel colors leaking off ends of feature arrows.

2.14
     - Fixes to the way that "fast bump" works so that tracks never fast bump.
       This fixes problems when using groups to simulate subtracks, and the
       groups are of different heights.
     - The group glyph will now add the group labels to the list of track keys
       stored in the panel and retrieved from the call to $panel->key_boxes().

2.13
     - Changed default namespace for callbacks to make them portable across freeze/thaw
       cycles.

2.12 Tue Aug 31 10:42:06 EDT 2010
     - Created a read_pairs glyph that contains the settings most often used for SAM paired end reads/mate pairs;
       this fixes the mate-pairs overlap bug.
     - xyplot glyph now obeys "flip" setting.

2.11 Tue Jun 29 15:37:03 EDT 2010
     - Cleaned up stylesheet-based rendering of features when the main glyph has a type of
     "hat" and subfeatures overlap with each other.  This occurred when rendering certain
     DAS sources.

2.10 Mon May 24 13:58:26 PDT 2010
     - Fixed a long-standing but rarely-seen bug in layout algorithm that
       caused some features to be displaced downward further than they should
       be.
     - Added support for labeling groups (on the left side). This is used by
       GBrowse to create subtracks.

2.09 Fri May 14 11:46:51 EDT 2010
     - Fixed Bio::Graphics::FeatureFile cached callbacks so that they are evaluated
       in the same package as they were when the file was originally evaluated and cached.

2.08 Thu May 13 17:06:29 EDT 2010
     - Fixed Bio::Graphics::FeatureFile init_code so that it is reinvoked when retrieving a 
       cached copy of parsed featurefiles.

2.07 Sun May  9 11:56:10 EDT 2010
     - Added FeatureFile->cachedir argument to help with GBrowse tests.

2.06 Wed May  5 00:51:00 EDT 2010
     - Segments glyph now displays correct mismatch color for sequences that begin or end with soft clips.
     - Indels displayed in correct color when indel begins or ends outside current visible region.

2.05 Identical to 2.04.

2.04 Sun Apr 18 17:26:01 EDT 2010
     - Segments glyph now smarter about fetching reference sequence; this improves performance
       on multiple alignments.
     - -show_mismatch option now takes following arguments: 0 (false), "always", "base level" (draw only
       when DNA is in view), or a number, in which case mismatches will only be drawn when the length
       of the window is <= that number. For compatibility, a value of "1" is the same as "base level."
     - Fixed display of protein sequence in genes when -draw_protein is true.
     - Fixed display of long deletions in segments glyph base-pair alignments to avoid drop-out of
       sequence from the right end of the alignment following deleted region.
     - Fixed display of insertions in segments glyph base-pair alignments so that the length
       of the deletion is displayed when there is more than one digit of length.
     - Fixed Wiggle loader routine to handle statistics on chromosomes that have a 
       combination of fixed and variable step declarations.

2.03 Fri Mar 26 16:32:02 EDT 2010
     - Bad CPAN upload. Do not use.

2.02 Sun Mar 14 18:44:04 EDT 2010
     - Added a wiggle_whiskers glyph that works nicely with BigWig and
       BigBed data.
     - Fixed processed_transcript (and gene) glyphs so that thin UTRs are more attractive.
     - Fixed the behavior of transcript arrows to be more customizable and not to get
       too large.
     - Segments glyph now shows mismatches when zoomed out and -show_mismatches is true.
     - Added an -indel_color option to segments glyph to show indels in a different color
       from simple nucleotide substitutions.
     - Added a -mismatch_only option to segments glyph that only shows mismatching base
       pairs when zoomed in.

2.01 Thu Feb 25 16:46:08 EST 2010
     - Fixed display of alignments that have hard-clipping in their CIGAR strings.

2.00 Wed Jan 20 11:12:13 EST 2010
     - Added the "cross" glyph for DAS compatibility.
     - Fixed the triangle glyph so that DAS stylesheets can set orientation
       properly.	
     - Fixed wiggle_xyplot/density documentation of smoothing options.  
     - Turn off sampling from wiggle loader by default (turn it on with --sample option).
     - Multiple sequence alignment code in the segments glyph has been updated to deal with
       the Samtools case of both reference DNA and target reporting minus strand alignments.
     - It felt like time to go to 2.00.

1.995 Wed Jan  6 10:06:17 EST 2010
      - Fixed the gene glyph so that non-SO genes (gene=>exon without an intervening transcript)
        display properly. Otherwise the exons were bumping.
      - Added support for "featureRGB" and "featureScore" special color names. This provides
        an additional level of UCSC graphics compatibility.

1.994 Thu Dec 10 10:07:19 EST 2009
      - The GFF3 Gap attribute (which contains a CIGAR string) is now supported in the segments
      glyph. Set -split_on_cigar=>1 when creating the track in order to activate this feature.

1.993 Thu Dec  3 06:36:06 EST 2009
      - Fixed issue which caused GD::SVG rendering of xyplot glyph to show scale
      but no values under some circumstances.

1.992 Wed Nov 18 13:06:07 EST 2009
      - Fixed issue in which the connector vanishes when zoomed in to
        the region between two parts (such as the region between two
        exons)

1.991 Mon Nov 16 09:20:18 EST 2009
      - CPAN upload failed due to lack of $VERSION in hybrid_plot. Uploaded again.
1.99 Mon Nov 16 08:15:23 EST 2009  
     - Segments glyph now handles indels for features that have CIGAR strings.
1.982 Wed Aug 26 17:57:43 EDT 2009
     - Fixed DAS stylesheet support so that Ensembl and Dazzle sources both work
       properly.	 
1.981 Wed Aug 19 15:21:31 EDT 2009
     - Peter Ruzanov fixed bug in wiggle_xyplot that caused histogram to go to background
       color under some circumstances.
1.98 Mon Jul  6 09:48:58 EDT 2009
     - Documented -feature_limit in the Panel docs as well as in Glyph.
     - Fixed bug in wiggle_xyplot that caused an ugly 1-pixel rectangle to be drawn
       in the case of a zero-height data value.
1.97 Thu Jul  2 15:22:21 EDT 2009
     - Added "feature_limit" option to put a cap on the maximum number of features that a 
     track will attempt to display. This only works correctly if features are added one at a
     time with add_feature().
1.96 Thu Jun  4 17:49:57 EDT 2009
     - Added "hat" and "hidden" glyphs, and changed way that the "line" glyph works in order to
     support DAS 1.5.
1.95 Sat May 30 18:07:21 EDT 2009
     - In the substitution pattern rules, $id is replaced with the
     output of either the feature_id or primary_id methods depending 
     on which one is implemented.
     - The image.pm glyph will now render into SVG if a sufficiently-current
     GD::SVG module is available.
     - Some fixes to the segments glyph to work better with Bio::DB::Bam
     rendering at the base pair level.
     - The glyph_help.pl script can now create SVGs.
1.94 Wed Apr 29 05:59:02 EDT 2009
     - Added a "fast" bumping option suitable for very dense tracks in which
       all features have identical height. Activate it using -bump=>3 or
       -bump=>'fast'.
     - Fixed division by zero error in xyplot glyph when min_score==max_score.
1.93 Thu Apr  2 18:20:35 EDT 2009
     - Many fixes to ideograph glyph to be more stable.
     - Fixed minor display issues involving bumping and directional arrows.
     - Continued documenting glyphs. About 75% done.
1.92 Tue Mar 31 00:38:16 EDT 2009
     - Added documentation system for glyphs, but only half the glyphs are documented this way so far.
     - Bug fixes for GBrowse on Windows.
1.91 Tue Mar 17 09:54:02 EDT 2009
     - wiggle_density now supports local scaling
     - wiggle loader now defaults to clipping at 2 stdev
     - adjusted default smoothing parameters to do less smoothing
1.90 Sun Mar 15 01:11:28 EDT 2009
     - Optimized Bio::Graphics::Wiggle to sample directly from disk when the desired visualization
       size is significantly (less than 100 fold) smaller than the length of the region to
       be sampled.
1.88 Sat Mar 14 23:31:46 EDT 2009
     -Cleaned up calculation of min and max values for scaling and introduced the "autoscale" option.
1.87 Sat Mar 14 20:56:47 EDT 2009
     -Fixed bug in xyplot visualization.
1.86 Sat Mar 14 12:22:50 EDT 2009
     -Improved performance of wiggle xyplot drawing about 5-fold
     -Added minor ticks to xyplots
1.83 Fri Jan  9 20:44:41 MST 2009
     - Made #include directive case-insensitive.
1.80 December 2008
     - Split off from Bio::Perl after a 6-year hiatus.
1.05 Fri Apr 12 20:53:42 EDT 2002
	- Version 1.04 had a fatal bug.  Do not use.  1.05 fixes this
	and is identical to BioPerl 1.01.
1.04 Fri Apr 12 08:20:35 EDT 2002
	- Take advantage of optimizations in Bio::DB::GFF::Feature so don't
	have to retrieve subfeatures at low magnifications (when you can't
	see 'em anyway).
1.03 Fri Apr 12 00:26:12 EDT 2002
	- Fixes to handle case of a transcript glyph that is zoomed in so
	far that only an intron shows (no exons).
1.02 Sun Mar 31 16:19:35 EST 2002
	- Make the Bio::Graphics::Feature objects more-or-less compatible with
		Bio::SeqFeatureI and Bio::LocationI.  Slightly difficult because
		this is a moving target.
	- Minor bugfixes to support Generic Genome browser version 1.37
	
0.98 Fri Feb 22 14:02:11 EST 2002
	-Fixed up the scale so that numbers don't (or shouldn't)
	overlap.

0.97 Mon Feb 18 22:04:57 EST 2002
	-Added the "dna" glyph, which supports display of raw DNA and a GC
	content histogram.

0.96 Fri Jan 11 13:23:03 EST 2002
	-Added support for displaying heterogeneous features, such as WABA similarities.

0.95 Thu Jan  3 08:50:01 EST 2002  (LS)
	-Removed generic genome browser from project, it is now part of
	 Generic-Genome-Browser.

0.92 Sat Dec  8 23:28:19 EST 2001  (LS)
	-Fixed up key glyph so that it correctly tracks what appears on screen
	-Fixed wormbase_transcript glyph so that it uses the skinny arrow when 
	 there isn't enough room to show the filled arrow.

0.91 Sun Nov 18 22:59:14 EST 2001  (LS)
	-Modified Feature.pm to accept vanilla GFF format.
	-Fixed Panel.pm so that empty tracks (height zero) do not take
	 up space in the map.

0.90  Sun Nov 18 21:46:46 EST 2001  (LS)
	- Added the gbrowse genome browser script and supporting files
	- Added a wormbase_transcript glyph for Wormbase's curated/uncurated genes.

0.85  Mon Oct  1 16:41:57 EDT 2001  (LS)
	- Changed all instances of stop() to end() so that BioSeqFeatureI is supported
	  correctly.

0.82  Fri Jul 20 10:36:57 EDT 2001  (LS)
	- Removed perl 5.6'isms.
	- Added appropriate documentation to Feature.

0.81  Tue Jun 12 09:30:10 EDT 2001  (LS)
	- Messed up sourceforge upload, so bumping version no
		to clean up.

0.80  Tue Jun 12 09:10:15 EDT 2001  (LS)
	- Basically functional
	- examples in eg/
	- Bio::Graphics::Panel documentation complete,
		other documentation incomplete

0.01  Tue Jun  5 07:26:52 2001  (LS)
	- original version; created by h2xs 1.20 with options
		-n Bio::Graphics -A

