Harden graphical scrollbar rendering

[forntoh]

Summary

• Clear the graphical scrollbar track before drawing the handle.
• Clamp scrollbar track and scroll range math to avoid underflow/division edge cases.
• Add focused renderer coverage for scrollbar track clearing.

Checks

• git diff --check
• pio run -e esp32

Notes

• Unrelated local diagram.json, wokwi.toml, bin/, and docs/source/reference/samples/ changes were not included.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch gd/09-renderer-layout-parity

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[github-actions]

Memory usage change @ 4990f16

Board	flash	%	RAM for global variables	%
STMicroelectronics:stm32:GenF1:pnum=BLUEPILL_F103C8	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:avr:uno	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino:samd:mkr1000	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
esp32:esp32:esp32	🔺 0 - +60	0.0 - 0.0	0 - 0	0.0 - 0.0
esp8266:esp8266:huzzah	N/A	N/A	N/A	N/A

Click for full report table

Board	examples/Basic flash	%	examples/Basic RAM for global variables	%	examples/ButtonAdapter flash	%	examples/ButtonAdapter RAM for global variables	%	examples/Callbacks flash	%	examples/Callbacks RAM for global variables	%	examples/InputRotary flash	%	examples/InputRotary RAM for global variables	%	examples/IntFloatValues flash	%	examples/IntFloatValues RAM for global variables	%	examples/KeyboardAdapter flash	%	examples/KeyboardAdapter RAM for global variables	%	examples/List flash	%	examples/List RAM for global variables	%	examples/SimpleRotary flash	%	examples/SimpleRotary RAM for global variables	%	examples/SSD1803A_I2C flash	%	examples/SSD1803A_I2C RAM for global variables	%	examples/UseByRef flash	%	examples/UseByRef RAM for global variables	%	examples/DynamicMenu flash	%	examples/DynamicMenu RAM for global variables	%	examples/Widgets flash	%	examples/Widgets RAM for global variables	%	examples/RTOS flash	%	examples/RTOS RAM for global variables	%	examples/ST7920_SPI flash	%	examples/ST7920_SPI RAM for global variables	%
STMicroelectronics:stm32:GenF1:pnum=BLUEPILL_F103C8	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:avr:uno	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino:samd:mkr1000	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
esp32:esp32:esp32	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	60	0.0	0	0.0
esp8266:esp8266:huzzah	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A

Click for full report CSV

Board,examples/Basic<br>flash,%,examples/Basic<br>RAM for global variables,%,examples/ButtonAdapter<br>flash,%,examples/ButtonAdapter<br>RAM for global variables,%,examples/Callbacks<br>flash,%,examples/Callbacks<br>RAM for global variables,%,examples/InputRotary<br>flash,%,examples/InputRotary<br>RAM for global variables,%,examples/IntFloatValues<br>flash,%,examples/IntFloatValues<br>RAM for global variables,%,examples/KeyboardAdapter<br>flash,%,examples/KeyboardAdapter<br>RAM for global variables,%,examples/List<br>flash,%,examples/List<br>RAM for global variables,%,examples/SimpleRotary<br>flash,%,examples/SimpleRotary<br>RAM for global variables,%,examples/SSD1803A_I2C<br>flash,%,examples/SSD1803A_I2C<br>RAM for global variables,%,examples/UseByRef<br>flash,%,examples/UseByRef<br>RAM for global variables,%,examples/DynamicMenu<br>flash,%,examples/DynamicMenu<br>RAM for global variables,%,examples/Widgets<br>flash,%,examples/Widgets<br>RAM for global variables,%,examples/RTOS<br>flash,%,examples/RTOS<br>RAM for global variables,%,examples/ST7920_SPI<br>flash,%,examples/ST7920_SPI<br>RAM for global variables,%
STMicroelectronics:stm32:GenF1:pnum=BLUEPILL_F103C8,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:avr:uno,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino:samd:mkr1000,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,,,,
esp32:esp32:esp32,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,60,0.0,0,0.0
esp8266:esp8266:huzzah,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,N/A,,,,,,,,