Remove images display mode and even the displayMode option generally

bin/upgrade-database-to-utf8mb4.pl

@@ -19,7 +19,7 @@ =head1 SYNOPSIS
                               be the defaults for webwork.  This pass is not run
                               by default.
     -n|--upgrade-non-native   Upgrade the non-native tables
-                              (locations, location_addresses, depths)
+                              (locations, location_addresses, etc.)
     --no-backup               Do not backup the database before making changes
                               to the database. (Not recommended)
     -b|--backup-file [file]   Filename for the database backup file.

conf/defaults.config

@@ -321,10 +321,6 @@ $webworkURLs{htdocs} = "$webwork_htdocs_url";
 $webworkDirs{htdocs_temp} = "$webworkDirs{htdocs}/tmp";
 $webworkURLs{htdocs_temp} = "$webworkURLs{htdocs}/tmp";
 
-# Location of cached equation images.
-$webworkDirs{equationCache} = "$webworkDirs{htdocs_temp}/equations";
-$webworkURLs{equationCache} = "$webworkURLs{htdocs_temp}/equations";
-
 # Location of theme templates.
 $webworkDirs{themes} = "$webworkDirs{htdocs}/themes";
 
@@ -460,13 +456,6 @@ $courseLinks{Student_Orientation} =
 # Location of this file.
 $webworkFiles{environment} = "$webworkDirs{conf}/defaults.conf";
 
-# Flat-file database used to protect against MD5 hash collisions. TeX equations
-# are hashed to determine the name of the image file. There is a tiny chance of
-# a collision between two TeX strings. This file allows for that. However, this
-# is slow, so most people chose not to worry about it. Set this to "" if you
-# don't want to use the equation cache file.
-$webworkFiles{equationCacheDB} = "";    # "$webworkDirs{DATA}/equationcache";
-
 ################################################################################
 # Hardcopy Theme
 ################################################################################
@@ -1026,21 +1015,9 @@ $caliper{enabled} = 0;
 # PG subsystem options
 ################################################################################
 
-# List of enabled screen display modes. Comment out any modes you don't wish to
-# make available for use.
-# The first uncommented option is the default for instructors rendering problems
-# in the homework sets editor.
-$pg{displayModes} = [
-	"MathJax",    # render TeX math expressions on the client side using
-				  # MathJax; we strongly recommend people install and use
-				  # MathJax, and it is required if you want to use MathView
-	"images",     # display math expressions as images generated by dvipng
-
-	#"plainText",  # display raw TeX for math expressions
-];
-
-# List of additional display modes for the PG editor only.
-$pg{additionalPGEditorDisplayModes} = [
+# List of display modes that can be selected in the PG editor.
+$pg{PGEditorDisplayModes} = [
+	"MathJax",    # render TeX math expressions using MathJax
 	"tex",        # display tex code for a rendered problem
 	"PTX",        # display static PreTeXt XML for a rendered problem
 ];
@@ -1075,9 +1052,6 @@ $options{PGCodeMirror} = 1;
 #### coloring of answer blanks and the numeric display of entered answers.
 ###########################################################################################
 
-# Default display mode. Should be listed above (uncomment only one).
-$pg{options}{displayMode} = "MathJax";
-
 # The default grader to use, if a problem doesn't specify.
 $pg{options}{grader} = "avg_problem_grader";
 
@@ -1116,23 +1090,6 @@ $pg{options}{showEvaluatedAnswers} = 1;
 # propagate to the main process.  So this really should never be set to 0.
 $pg{options}{catchWarnings} = 1;
 
-##### Settings for various display modes
-
-# "images" mode has several settings:
-$pg{displayModeOptions}{images} = {
-	# Determines the method used to align images in output. Can be any valid value for the css vertical-align rule such
-	# as 'baseline' or 'middle'.
-	dvipng_align => 'baseline',
-
-	# If dbsource is set to a nonempty value, then this database connection information will be used to store dvipng
-	# depths.  It is assumed that the 'depths' table exists in the database.
-	dvipng_depth_db => {
-		dbsource => $database_dsn,
-		user     => $database_username,
-		passwd   => $database_password,
-	},
-};
-
 ##### Directories used by PG
 
 # The root of the PG directory tree (from pg_dir set in conf/webwork2.mojolicious.yml).
@@ -1202,8 +1159,8 @@ $pg{specialPGEnvironmentVars}{convertFullWidthCharacters} = 0;
 
 # Strings to insert at the start and end of the body of a problem
 #  (at beginproblem() and ENDDOCUMENT) in various modes.  More display modes
-#  can be added if different behaviours are desired (e.g., HTML_dpng,
-#  HTML_asciimath, etc.).  These parts are not used in the Library browser.
+#  can be added if different behaviours are desired.  These parts are not used
+#  in the Library browser.
 
 $pg{specialPGEnvironmentVars}{problemPreamble}  = { TeX => '', HTML => '' };
 $pg{specialPGEnvironmentVars}{problemPostamble} = { TeX => '', HTML => '' };