Beautify MacVim's dmg installer background and volume icon

src/MacVim/Credits.rtf

@@ -1,4 +1,4 @@
-{\rtf1\ansi\ansicpg1252\cocoartf2709
+{\rtf1\ansi\ansicpg1252\cocoartf2821
 \cocoascreenfonts1\cocoatextscaling0\cocoaplatform0{\fonttbl\f0\fswiss\fcharset0 Helvetica-Bold;\f1\fswiss\fcharset0 Helvetica;\f2\fswiss\fcharset0 Helvetica-Oblique;
 }
 {\colortbl;\red255\green255\blue255;}
@@ -51,15 +51,10 @@ Dmitry Vazhov\
 \f1\i0 \cf0 \
 ...and many others who have helped by reporting bugs etc.\
 \
-\
-Thank you to {\field{\*\fldinst{HYPERLINK "http://www.positivespinmedia.com"}}{\fldrslt Positive Spin Media}} for the PSMTabBarControl Framework.\
-\
+\pard\tx566\tx1133\tx1700\tx2267\tx2834\tx3401\tx3968\tx4535\tx5102\tx5669\tx6236\tx6803\pardirnatural\partightenfactor0
+\cf0 The MacVim icon was designed by {\field{\*\fldinst{HYPERLINK "https://jasonlong.me/"}}{\fldrslt Jason Long}}.\
+\pard\tx566\tx1133\tx1700\tx2267\tx2834\tx3401\tx3968\tx4535\tx5102\tx5669\tx6236\tx6803\pardirnatural\partightenfactor0
+\cf0 \
 Thank you to {\field{\*\fldinst{HYPERLINK "https://whomwah.github.io/qlstephen/"}}{\fldrslt Duncan Robertson}} for the QLStephen QuickLook plugin.\
 \
-Toolbar icons by {\field{\*\fldinst{HYPERLINK "http://www.mattballdesign.com/"}}{\fldrslt Matt Ball}} (free Developer Icons), {\field{\*\fldinst{HYPERLINK "http://www.jonasraskdesign.com/"}}{\fldrslt Jonas Rask}} (Danish Royalty Free icon set), and {\field{\*\fldinst{HYPERLINK "http://www.everaldo.com"}}{\fldrslt Everaldo Coelho}} (Crystal Project Icons, released under LGPL license).\
-\
-Revamped MacVim icon by RIC.\
-\
-Thanks to Andy Matuschak for {\field{\*\fldinst{HYPERLINK "http://sparkle-project.org"}}{\fldrslt Sparkle}}.\
-\
-Thanks to Damien Guard for {\field{\*\fldinst{HYPERLINK "http://damieng.com/blog/2008/05/26/envy-code-r-preview-7-coding-font-released"}}{\fldrslt Envy Code R}} (used in MacVim's 16x16 document icons).}
+Thanks to Andy Matuschak and the Sparkle Project for {\field{\*\fldinst{HYPERLINK "http://sparkle-project.org"}}{\fldrslt Sparkle}}.}

src/MacVim/scripts/create_icns

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+# Utility script to create an icns file from an iconset folder. It will handle
+# duplicating the necessary images for 1x/2x use so we don't have to commit
+# identical images to the repository.
+
+if [[ $# == 0 || $# == 1 || $# == 2 ]]; then
+    echo "Usage: create_icns <folder> <output_folder> <icns_name>"
+    exit -1
+fi
+
+set -e
+
+icons_folder=$1
+output_folder=$2
+output_name=$3
+
+cp -R "$icons_folder" "$output_folder/$output_name.iconset"
+
+cd "$output_folder/$output_name.iconset"
+
+cp icon_32x32@1x.png icon_16x16@2x.png
+cp icon_64x64@1x.png icon_32x32@2x.png
+cp icon_128x128@1x.png icon_64x64@2x.png
+cp icon_256x256@1x.png icon_128x128@2x.png
+cp icon_512x512@1x.png icon_256x256@2x.png
+
+cd ..
+iconutil --convert icns $output_name.iconset --out $output_name.icns

src/Makefile

@@ -3744,21 +3744,31 @@ macvim-dmg-legacy: DMGFILESYSTEM = HFS+
 macvim-dmg-legacy: DMGFORMAT = UDZO
 macvim-dmg-legacy: macvim-dmg
 
+# Build the dmg installer.
+# First, create 1x/2x versions of backgorund images and volume icons.
+# Second, use create-dmg to create the image.
+# - Note: Background is 472 pt high, but the macOS title bar is an additional
+#   28. Add them up (472+28=500) so the window can show the entire image
+#   without being clipped. Note that if the user has "Show Path Bar" set in
+#   Finder this will still clip the bottom but there's nothing we can do about
+#   that.
 macvim-dmg:
 	rm -rf $(DMGDIR)
 	mkdir -p $(DMGDIR)
 	cp -a $(RELEASEDIR)/MacVim.app $(DMGDIR)/
+	tiffutil -cathidpicheck MacVim/dmg/background@1x.png MacVim/dmg/background@2x.png -out $(DMGDIR)/background.tiff
+	MacVim/scripts/create_icns MacVim/dmg/volume_icons $(DMGDIR) volume
 	rm -rf $(RELEASEDIR)/$(DMGFILE)
 	MacVim/create-dmg/create-dmg \
 		--filesystem "$(DMGFILESYSTEM)" \
 		--format "$(DMGFORMAT)" \
 		--volname "MacVim" \
-		--volicon MacVim/icons/MacVim.icns \
-		--background MacVim/dmg/background.png \
-		--window-size 650 470 \
-		--icon-size 80 \
-		--icon MacVim.app 240 320 \
-		--app-drop-link 410 320 \
+		--volicon $(DMGDIR)/volume.icns \
+		--background $(DMGDIR)/background.tiff \
+		--window-size 650 500 \
+		--icon-size 128 \
+		--icon MacVim.app 210 290 \
+		--app-drop-link 440 290 \
 		$(CREATEDMG_FLAGS) $(RELEASEDIR)/$(DMGFILE) $(DMGDIR)
 
 macvimclean: