From 3135e82b798b03d2424cc105f203988908d1cb3c Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@datawire.io>
Date: Fri, 3 May 2019 13:29:58 -0400
Subject: X11: Better DPI handling

---
 .../user/X11@.target.wants/fix-dpi@.service        |  1 +
 .../user/X11@.target.wants/xresources-dpi@.service |  1 -
 .config/systemd/user/fix-dpi@.service              | 15 ++++++
 .config/systemd/user/xresources-dpi@.service       | 15 ------
 .local/bin/fix-dpi                                 | 53 ++++++++++++++++++++++
 .local/bin/xrdb-set-dpi                            |  3 --
 6 files changed, 69 insertions(+), 19 deletions(-)
 create mode 120000 .config/systemd/user/X11@.target.wants/fix-dpi@.service
 delete mode 120000 .config/systemd/user/X11@.target.wants/xresources-dpi@.service
 create mode 100644 .config/systemd/user/fix-dpi@.service
 delete mode 100644 .config/systemd/user/xresources-dpi@.service
 create mode 100755 .local/bin/fix-dpi
 delete mode 100755 .local/bin/xrdb-set-dpi

diff --git a/.config/systemd/user/X11@.target.wants/fix-dpi@.service b/.config/systemd/user/X11@.target.wants/fix-dpi@.service
new file mode 120000
index 0000000..af1d134
--- /dev/null
+++ b/.config/systemd/user/X11@.target.wants/fix-dpi@.service
@@ -0,0 +1 @@
+../fix-dpi@.service
\ No newline at end of file
diff --git a/.config/systemd/user/X11@.target.wants/xresources-dpi@.service b/.config/systemd/user/X11@.target.wants/xresources-dpi@.service
deleted file mode 120000
index f3b5a4c..0000000
--- a/.config/systemd/user/X11@.target.wants/xresources-dpi@.service
+++ /dev/null
@@ -1 +0,0 @@
-../xresources-dpi@.service
\ No newline at end of file
diff --git a/.config/systemd/user/fix-dpi@.service b/.config/systemd/user/fix-dpi@.service
new file mode 100644
index 0000000..d248cf2
--- /dev/null
+++ b/.config/systemd/user/fix-dpi@.service
@@ -0,0 +1,15 @@
+[Unit]
+Description=Rectify all DPI settings on X display %I
+Documentation=man:xrdb(1)
+Before=X11@%i.target
+Requisite=X11@%i.target
+
+[Service]
+Environment=DISPLAY=%I
+
+Type=oneshot
+ExecStart=/usr/bin/env flock %t/x11-xrdb@%I -c fix-dpi
+SyslogIdentifier=fix-dpi
+
+[Install]
+WantedBy=X11@%i.target
diff --git a/.config/systemd/user/xresources-dpi@.service b/.config/systemd/user/xresources-dpi@.service
deleted file mode 100644
index c9d23cc..0000000
--- a/.config/systemd/user/xresources-dpi@.service
+++ /dev/null
@@ -1,15 +0,0 @@
-[Unit]
-Description=Set the X Resources DataBase DPI to match the display DPI on X display %I
-Documentation=man:xrdb(1)
-Before=X11@%i.target
-Requisite=X11@%i.target
-
-[Service]
-Environment=DISPLAY=%I
-
-Type=oneshot
-ExecStart=/usr/bin/env flock %t/x11-xrdb@%I -c xrdb-set-dpi
-SyslogIdentifier=xrdb-set-dpi
-
-[Install]
-WantedBy=X11@%i.target
diff --git a/.local/bin/fix-dpi b/.local/bin/fix-dpi
new file mode 100755
index 0000000..90019c2
--- /dev/null
+++ b/.local/bin/fix-dpi
@@ -0,0 +1,53 @@
+#!/usr/bin/env bash
+# Copyright 2019  Luke Shumaker
+
+# env-var: MAX_DPI: integer
+# env-var: DRY_RUN: empty/non-empty
+
+( # Phase 1: Probe outputs
+	export LC_ALL=C
+	xrandr | sed -rn -e 's@(.*) connected( .*)? ([0-9]+)x([0-9]+)\+([0-9]+)\+([0-9]+)( .*)? ([0-9]+)mm x ([0-9]+)mm( .*)?@\1 \3 \4 \8 \9@p' -e 's@^   ([0-9]+)x([0-9]+)i? .*\*.*@ \1 \2@p' | sed '/^\S/{ N; s/\n//; }'
+	#                      1             2      3        4         5         6       7      8            9         10                                 1        2
+	#                      `-outputName  |      `-fb_xpx `-fb_ypx  `-fb_xoff `-fb_yoff      `- hw_xmm    `- hw_ymm |                                  `-hw_xpx `-hw_ypx
+	#                                    `-discard                                  `- discard                     `- discard
+) | ( # Phase 2: Translate that to a set of actions to perform
+	max_xdpi=${MAX_DPI:-96}
+	max_ydpi=${MAX_DPI:-96}
+
+	dpi=$(xrdb -query|sed -n 's/^Xft\.dpi:\s*//p')
+	xdpi=${dpi%%x*}
+	ydpi=${dpi#*x}
+	if (( xdpi > max_xdpi )); then
+		max_xdpi=$xdpi
+	fi
+	if (( ydpi > max_ydpi )); then
+		max_ydpi=$ydpi
+	fi
+
+	declare -A outputs
+	while read -r output fb_xpx fb_ypx hw_xmm hw_ymm hw_xpx hw_ypx; do
+		xdpi=$(bc <<<"($hw_xpx*25.4)/$hw_xmm")
+		ydpi=$(bc <<<"($hw_ypx*25.4)/$hw_ymm")
+		if (( xdpi > max_xdpi )); then
+			max_xdpi=$xdpi
+		fi
+		if (( ydpi > max_ydpi )); then
+			max_ydpi=$ydpi
+		fi
+		outputs["$output"]="$xdpi $ydpi"
+	done
+	echo 'xrandr \'
+	printf '  --dpi %q \\\n' "${max_xdpi}x${max_ydpi}"
+	for output in "${!outputs[@]}"; do
+		read -r xdpi ydpi <<<"${outputs[$output]}"
+		printf '  --output %q --scale %q \\\n' "$output" "$(bc <<<"scale=5; $max_xdpi/$xdpi")x$(bc <<<"scale=5; $max_ydpi/$ydpi")"
+	done
+	echo
+	printf "xrdb -merge <<<'Xft.dpi: %s'\n" "${max_xdpi}x${max_ydpi}"
+) | ( # Phase 3: Apply those actions
+	if [[ -z "$DRY_RUN" ]]; then
+		bash -v
+	else
+		cat
+	fi
+)
diff --git a/.local/bin/xrdb-set-dpi b/.local/bin/xrdb-set-dpi
deleted file mode 100755
index a87627e..0000000
--- a/.local/bin/xrdb-set-dpi
+++ /dev/null
@@ -1,3 +0,0 @@
-#!/usr/bin/env bash
-dpi=$(LC_ALL=C xdpyinfo|sed -rn 's/^\s*resolution:\s*(.*) dots per inch$/\1/p')
-xrdb -merge <<<"Xft.dpi: ${dpi}"
-- 
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