Text vertical alignment is not static for chscale != 1.0

[UtkarshVerma]

I have noticed that commits bd37022 and a8e2af0 have caused misalignment of text vertically when chscale is not 1.0.

I believe it can be reproduced by enabling ligatures and setting chscale to 1.1. Here's a video showing the bug:

2023-02-12_13.57.33.mp4

[bakkeby]

Hmm, if so then this should be reproducible with the latest ligatures patch on the suckless page and a chscale config change.

I wasn't directly able to reproduce this as I don't have that kind of command prediction / suggestion in place.

I grabbed a couple of frames from your video and placed them on top of each other in gimp. What I found was that the misalignment is exactly the that of the underline. So I was wondering didn't you expose a config option in your build to control the offset of that underline and could that be what is causing the misalignment here?

[UtkarshVerma]

I created a branch on my fork for reproducing this with master.

https://github.com/UtkarshVerma/st-flexipatch/tree/alignment-bug

Here are the changes:

diff --git a/config.mk b/config.
index 36e98ce..dde2dc9 100644
--- a/config.mk
+++ b/config.mk
@@ -19,10 +19,10 @@ PKG_CONFIG =
 #XCURSOR = -lXcursor

 # Uncomment the lines below for
-#LIGATURES_C = hb.c
-#LIGATURES_H = hb.h
-#LIGATURES_INC = `$(PKG_CONFIG)
-#LIGATURES_LIBS = `$(PKG_CONFIG
+LIGATURES_C = hb.c
+LIGATURES_H = hb.h
+LIGATURES_INC = `$(PKG_CONFIG)
+LIGATURES_LIBS = `$(PKG_CONFIG)

 # Uncomment this for the SIXEL
 #SIXEL_C = sixel.c sixel_hls.c

~/.local/src/st alignment-bug !1 ❯ diff patches.def.h patches.h
228c228
< #define LIGATURES_PATCH 0
---
> #define LIGATURES_PATCH 1
375c375
< #define UNDERCURL_PATCH 0
---
> #define UNDERCURL_PATCH 1
400c400
< #define VERTCENTER_PATCH 0
---
> #define VERTCENTER_PATCH 1
448c448
< #define XRESOURCES_PATCH 0
---
> #define XRESOURCES_PATCH 1
~/.local/src/st alignment-bug !1 ❯ diff config.def.h config.h
64c64
< static float chscale = 1.0;
---
> static float chscale = 1.1;