Terminal font alignment regression when GPU acceleration used

[jryans]

Type: Bug

VS Code 1.86 seems to have regressed terminal font alignment compared to 1.85 for me. When terminal GPU acceleration is used, the terminal text is placed slightly lower than expected and the cursor is taller than expected.

Context

• macOS 13.6.4
• Terminal font: Source Code Pro

All terminal-related settings

  "terminal.integrated.fontFamily": "Source Code Pro",
  "terminal.integrated.fontSize": 14,
  "workbench.colorCustomizations": {
    "terminal.background": "#1D1F21",
    "terminal.foreground": "#C5C8C6",
    "terminalCursor.background": "#C5C8C6",
    "terminalCursor.foreground": "#C5C8C6",
    "terminal.ansiBlack": "#1D1F21",
    "terminal.ansiBlue": "#86aec0",
    "terminal.ansiCyan": "#92bfb8",
    "terminal.ansiGreen": "#a5b474",
    "terminal.ansiMagenta": "#b28dad",
    "terminal.ansiRed": "#b05c57",
    "terminal.ansiWhite": "#C5C8C6",
    "terminal.ansiYellow": "#f0cb91",
    "terminal.ansiBrightBlack": "#969896",
    "terminal.ansiBrightBlue": "#86aec0",
    "terminal.ansiBrightCyan": "#92bfb8",
    "terminal.ansiBrightGreen": "#a5b474",
    "terminal.ansiBrightMagenta": "#b28dad",
    "terminal.ansiBrightRed": "#b05c57",
    "terminal.ansiBrightWhite": "#FFFFFF",
    "terminal.ansiBrightYellow": "#f0cb91",
  },
  "terminal.integrated.tabs.enabled": false,
  "terminal.integrated.copyOnSelection": true,
  "terminal.integrated.minimumContrastRatio": 1,
  "terminal.integrated.scrollback": 10000,
  "terminal.integrated.persistentSessionScrollback": 1000,
  "terminal.integrated.shellIntegration.enabled": false,
  "terminal.integrated.shellIntegration.decorationsEnabled": "never",

With terminal acceleration

terminal.integrated.gpuAcceleration: auto

This is the default acceleration value and what I normally use, but it produces bad font metrics in 1.86 for me:

In particular, the text is placed too low and the descenders of letters like "j" and "g" on the last line are cut off. Also, notice that the top of cursor block sticks out quite high and pokes up into the line above.

Without terminal acceleration

terminal.integrated.gpuAcceleration: off

With GPU acceleration off, the text metrics look correct to me:

All descenders on the last line are visible, and the cursor block is vertically aligned with the current line of text.

VS Code version: Code 1.86.0 (0504748, 2024-01-31T10:29:15.765Z)
OS version: Darwin x64 22.6.0
Modes:

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz (12 x 2600)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: disabled_off direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled webgpu: enabled
Load (avg)	6, 4, 4
Memory (System)	32.00GB (0.25GB free)
Process Argv	--crash-reporter-id f154a3a4-d518-4bd8-a55f-e21f7dcfdcd2
Screen Reader	no
VM	0%

Extensions (45)

Extension	Author (truncated)	Version
language-x86-64-assembly	13x	3.1.4
vscode-ron	a5h	0.11.0
chez-scheme-vscode	abh	0.1.4
mercury	bre	0.0.1
autotrim	chr	1.1.1
vscode-eslint	dba	2.4.2
xml	Dot	2.5.1
vscode-wasm	dts	1.4.1
gitlens	eam	14.5.0
magic-racket	evz	0.6.6
rest-client	hum	0.25.1
latex-workshop	Jam	9.15.7
svg	joc	1.5.3
llvm	jry	0.0.1
vsc-fennel	kon	0.1.3
beancount	Len	0.10.0
mercury-ls	lil	0.0.8
vscode-mlir	llv	0.0.11
autoconf	mae	0.2.0
Kotlin	mat	1.7.1
file-downloader	min	1.0.13
isort	ms-	2023.10.1
python	ms-	2023.20.0
vscode-pylance	ms-	2023.11.13
jupyter	ms-	2023.10.1100000000
jupyter-keymap	ms-	1.1.2
jupyter-renderers	ms-	1.0.17
vscode-jupyter-cell-tags	ms-	0.1.8
vscode-jupyter-slideshow	ms-	0.1.5
cpptools	ms-	1.18.5
hexeditor	ms-	1.9.12
vscode-json-editor	nic	0.3.0
vscode-yaml	red	1.14.0
rust-analyzer	rus	0.3.1730
partial-diff	ryu	1.4.3
dot	Ste	0.0.1
rewrap	stk	1.16.3
code-spell-checker	str	3.0.1
even-better-toml	tam	0.19.2
open-in-browser	tec	2.0.0
graphviz-interactive-preview	tin	0.3.5
latex-support	tor	3.10.0
cmake	twx	0.0.17
vim	vsc	1.27.0
markdown-all-in-one	yzh	3.5.1

(1 theme extensions excluded)

A/B Experiments

vsliv368cf:30146710
vspor879:30202332
vspor708:30202333
vspor363:30204092
vscoreces:30445986
vscod805cf:30301675
binariesv615:30325510
vsaa593cf:30376535
py29gd2263:30899288
vscaat:30438848
c4g48928:30535728
azure-dev_surveyone:30548225
962ge761:30951796
pythongtdpath:30769146
welcomedialogc:30910334
pythonidxpt:30866567
pythonnoceb:30805159
asynctok:30898717
pythontestfixt:30902429
pythonregdiag2:30936856
pyreplss1:30897532
pythonmypyd1:30879173
pythoncet0:30885854
pythontbext0:30879054
accentitlementsc:30887149
dsvsc016:30899300
dsvsc017:30899301
dsvsc018:30899302
dsvsc019b:30953937
3ef8e399:30949928
bg6jg535:30956215

[jryans]

In case it's relevant here, my default external monitor is a low DPI / non-retina monitor (devicePixelRatio == 1).

[jryans]

Just retested with the internal retina monitor, looks the same there, so I guess that's not a factor here.

[towo]

Same here, w/ Arch Linux and Ubuntu 22.04 and e.g. "SauceCodePro Nerd Font", native and via Citrix.
As a weird side effect, the angled brackets of the prompt are correctly aligned when using "terminal.integrated.customGlyphs": true, and not so when false. Sample attached.

[Tyriar]

We've always had a problem with Linux in particular about certain fonts not giving us the right font metrics AFAICT. Source Code Pro on mac seems to have the same problem. To look into this we should try reproduce it and look into the text metrics/bounding box/origin being calaculated in xterm.js

[Tyriar]

Tracking upstream: xtermjs/xterm.js#5257