Prevent pixman warnings by validating rectangle dimensions before region creation

[Copilot]

Pixman emits warnings when cairo_region_create_rectangle receives rectangles with zero or negative dimensions, which occurs when widgets are resized to minimal dimensions or when GTK returns invalid GdkRectangle values.

Changes

• Added validation: isValid() method in cairo_rectangle_int_t checks width > 0 && height > 0
• Protected region creation: Added validation before all cairo_region_create_rectangle calls:
  • GC.java: cairoClipRegion() and copyArea()
  • Control.java: drawBackground() and cairoClipRegion()
  • Canvas.java: scroll()
  • TextLayout.java: Two text rendering paths

When invalid rectangles are detected, methods return early or skip region operations, preventing the warning while maintaining correct rendering behavior (region clipping is skipped, operations proceed without the invalid region).

cairo_rectangle_int_t cairoRect = new cairo_rectangle_int_t();
cairoRect.convertFromGdkRectangle(rect);
if (!cairoRect.isValid()) return;  // Skip instead of creating invalid region
long actualRegion = Cairo.cairo_region_create_rectangle(cairoRect);

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• repo.eclipse.org
  • Triggering command: /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/21.0.10-7/x64/bin/java /opt/hostedtoolcache/Java_Temurin-Hotspot_jdk/21.0.10-7/x64/bin/java --enable-native-access=ALL-UNNAMED -classpath /opt/hostedtoolcache/maven/3.9.12/x64/boot/plexus-classworlds-2.9.0.jar -Dclassworlds.conf=/opt/hostedtoolcache/maven/3.9.12/x64/bin/m2.conf -Dmaven.home=/opt/hostedtoolcache/maven/3.9.12/x64 -Dlibrary.jansi.path=/opt/hostedtoolcache/maven/3.9.12/x64/lib/jansi-native -Dmaven.multiModuleProjectDirectory=/home/REDACTED/work/eclipse.platform.swt/eclipse.platform.swt org.codehaus.plexus.classworlds.launcher.Launcher clean compile -DskipTests -pl bundles/org.eclipse.swt -am (dns block)
• www.cairographics.org
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

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This section details on the original issue you should resolve

<issue_title>Pixman Invalid rectangle warning in console</issue_title>
<issue_description>Running SWT (most notably Eclipse ) sometimes prints
*** BUG ***
In pixman_region32_init_rect: Invalid rectangle passed
Set a breakpoint on '_pixman_log_error' to debug</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Pixman Invalid rectangle warning in console #82

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