Correct font size calculation for Terminal in multi-monitor setups

[HeikoKlare]

The StyleMap of the Terminal implementation uses a GC to calculate the extents of strings to be rendered. This GC is created on the current Display instance, which does not incorporate the zoom of the current usage context (i.e., the monitor on which the Terminal is displayed). But the monitor zoom has an effect on the effective font size, as font sizes in pixels are always integers such that the logical SWT point value can be rounded differently depending on the zoom. An effect of this are cut-off texts on secondary monitors on Windows, because without taking the zoom of the usage context into account the terminal font is erroneously not identified as a monospace font.

This change adapts the implementation of StyleMap and its callers to create a GC for text extent calculations for the actual usage context. It makes the Terminal font being properly identified as a monospace font, such that individual characters are rendered and texts are not cut off.

Contributes to #2295

Additional information

This change further improves and is thus only benefical in combination with:

• Enable anti-aliasing for Terminal text #2463

To test this change, you should have two monitors on a Windows system with different zooms. Open a terminal on the secondary monitor. For example, the following screenshots are taken on the secondary monitor of a setup with 100% primary monitor zoom and 125% secondary monitor zoom.

With current master state:

With #2463:

With #2463 and this:

[github-actions]

Test Results

 1 980 files  ±0   1 980 suites  ±0   1h 34m 6s ⏱️ - 1m 0s
 4 750 tests ±0   4 726 ✅ ±0   24 💤 ±0  0 ❌ ±0 
14 250 runs  ±0  14 068 ✅ ±0  182 💤 ±0  0 ❌ ±0 

Results for commit f9644cc. ± Comparison against base commit ce5c9cc.

♻️ This comment has been updated with latest results.

[eclipse-platform-bot]

This pull request changes some projects for the first time in this development cycle.
Therefore the following files need a version increment:

terminal/tests/org.eclipse.terminal.test/META-INF/MANIFEST.MF

Warning

🚧 This PR cannot be modified by maintainers because edits are disabled or it is created from an organization repository. To obtain the required changes apply the git patch manually as an additional commit.

Git patch

From 41a90d4a30a9f4dadcb8016850d1773dc4ec1600 Mon Sep 17 00:00:00 2001
From: Eclipse Platform Bot <platform-bot@eclipse.org>
Date: Tue, 3 Mar 2026 19:40:55 +0000
Subject: [PATCH] Version bump(s) for 4.40 stream


diff --git a/terminal/tests/org.eclipse.terminal.test/META-INF/MANIFEST.MF b/terminal/tests/org.eclipse.terminal.test/META-INF/MANIFEST.MF
index 0fbd569bef..f741529424 100644
--- a/terminal/tests/org.eclipse.terminal.test/META-INF/MANIFEST.MF
+++ b/terminal/tests/org.eclipse.terminal.test/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.terminal.test;singleton:=true
-Bundle-Version: 1.1.0.qualifier
+Bundle-Version: 1.1.100.qualifier
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
 Require-Bundle: org.eclipse.core.runtime;bundle-version="[3.33.0,4)",
-- 
2.53.0

Further information are available in Common Build Issues - Missing version increments.