Apply gamma during realtime override

[DedeHai]

partial fix for #5661

Summary by CodeRabbit

• Bug Fixes
  • Refined gamma correction application for improved color rendering consistency in real-time display modes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 9bac4860-d9f9-4200-9910-73d207a014a4

📥 Commits

Reviewing files that changed from the base of the PR and between be264fb and a73b3ee.

📒 Files selected for processing (1)

• wled00/FX_fcn.cpp

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Walkthrough

The PR refines gamma correction application in the pixel painting loop of WS2812FX::show() by introducing a local useGammaCorrection boolean that consolidates gammaCorrectCol with realtime-override and disable-gamma exceptions, then uses this flag to conditionally apply gamma32() per-pixel instead of the previous simpler realtime-based check.

Changes

Gamma Correction Logic

Layer / File(s)	Summary
Gamma correction conditional gating wled00/FX_fcn.cpp	A local useGammaCorrection flag is computed from gammaCorrectCol combined with arlsDisableGammaCorrection and realtimeOverride checks, then replaces the previous realtime-only condition in the per-pixel gamma-correction if statement.

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

• wled/WLED#5225: Fixes gammaCorrectCol initialization in cfg.cpp; the main PR's gamma-correction behavior in show() depends on this flag's correct defaults.
• wled/WLED#4722: Adds inverseGamma32 to adjust gamma-corrected colors; both PRs refine the gamma-correction pipeline by conditioning behavior on gammaCorrectCol.

Suggested labels

bug, Awaiting testing

Suggested reviewers

• blazoncek
• softhack007

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: applying gamma correction during realtime override mode, which directly matches the code modification in WS2812FX::show().
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 Infer (1.2.0)

wled00/FX_fcn.cpp

In file included from wled00/FX_fcn.cpp:12:
wled00/wled.h:77:10: fatal error: 'Arduino.h' file not found
77 | #include <Arduino.h>
| ^~~~~~~~~~~
1 error generated.
Error: the following clang command did not run successfully:
/opt/infer-linux-x86_64-v1.2.0/lib/infer/facebook-clang-plugins/clang/install/bin/clang-18
@/tmp/coderabbit-infer/a73b3ee71e067ae0e5af0acdaa53e0808de7cf43-f109c58280734613/tmp/clang_command_.tmp.07cff5.txt
++Contents of '/tmp/coderabbit-infer/a73b3ee71e067ae0e5af0acdaa53e0808de7cf43-f109c58280734613/tmp/clang_command_.tmp.07cff5.txt':
"-cc1" "-load"
"/opt/infer-linux-x86_64-v1.2.0/lib/infer/infer/bin/../../facebook-clang-plugins/libtooling/build/FacebookClangPlugin.dylib"
"-add-plugin" "BiniouASTExporter" "-plugin-arg-BiniouASTExporter" "-"
"-plugin-arg-BiniouASTExporter" "PREPEND_CURRENT_DIR=1"
"-plugin-arg-BiniouASTExporter" "MAX_STRING_SIZE=65535" "-cc1" "-triple"
"x86_64-unknown-linux-gnu" "-emit-obj" "-mrelax

... [truncated 1074 characters] ...

ins/clang/install/lib/clang/18/include"
"-internal-isystem" "/usr/local/include" "-internal-isystem"
"/usr/lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
"-internal-externc-isystem" "/usr/include/x86_64-linux-gnu"
"-internal-externc-isystem" "/include" "-internal-externc-isystem"
"/usr/include" "-Wno-ignored-optimization-argument" "-Wno-everything"
"-fdeprecated-macro" "-ferror-limit" "19" "-fgnuc-version=4.2.1"
"-fskip-odr-check-in-gmf" "-fcxx-exceptions" "-fexceptions"
"-D__GCC_HAVE_DWARF2_CFI_ASM=1" "-o"
"/tmp/coderabbit-infer/f109c58280734613/file.o" "-x" "c++"
"wled00/FX_fcn.cpp" "-O0" "-fno-builtin" "-include"
"/opt/infer-linux-x86_64-v1.2.0/lib/infer/infer/bin/../lib/clang_wrappers/global_defines.h"
"-Wno-everything"

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[softhack007]

very good, i like the idea to move the checking outside of the pixel loop 👍

[DedeHai]

very good, i like the idea to move the checking outside of the pixel loop 👍

the compiler might have optimized that already, but better be explicit.
I also wanted to remove the double-checking of gammaCorrectCol inside the gamma functions but then I remembered that the table is also used by brightness-gamma. Could still remove it from Correct32(uint32_t color) as that is only used once - and is inlined so the compiler might take care of it if it is that clever.