Text color selection for watermark

[saikumarjetti]

Description

This PR addresses Feature Request #369 by adding the ability for users to select a custom text color for watermarks in PDF documents.

Key Changes

WatermarkController.java

• Added customColor support in the addWatermark method.
• Updated logic to apply the custom color to watermark text.

AddWatermarkRequest.java

Introduced customColor field with a default value of #d3d3d3.

Localization

Added watermark.customColor key to all existing Localization files with values matching addWatermarkRequest.customColor to ensure consistency across languages.

add-watermark.html

• Included a color picker for customColor in the UI.
• Added JavaScript to update the color picker’s background based on user selection.

Closes #369

Checklist

• I have read the Contribution Guidelines
• I have performed a self-review of my own code
• I have attached images of the change if it is UI based
• I have commented my code, particularly in hard-to-understand areas
• If my code has heavily changed functionality I have updated relevant docs on Stirling-PDFs doc repo
• My changes generate no new warnings
• I have read the section Add New Translation Tags (for new translation tags only)

[github-actions]

🚀 Translation Verification Summary

🔄 Reference Branch: pr-branch

📃 File Check: messages_ar_AR.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_az_AZ.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_bg_BG.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_ca_CA.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_cs_CZ.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_da_DK.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_de_DE.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_el_GR.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_en_US.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_es_ES.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_eu_ES.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_fr_FR.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_ga_IE.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_hi_IN.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_hr_HR.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_hu_HU.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_id_ID.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_it_IT.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_ja_JP.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_ko_KR.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_nl_NL.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_no_NB.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_pl_PL.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_pt_BR.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_pt_PT.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_ro_RO.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_ru_RU.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_sk_SK.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_sr_LATN_RS.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_sv_SE.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_th_TH.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_tr_TR.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_uk_UA.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_vi_VN.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_zh_CN.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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📃 File Check: messages_zh_TW.properties

1. Test Status: ✅ Passed
2. Test Status: ✅ Passed

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✅ Overall Check Status: Success

Thanks @saikumarjetti for your help in keeping the translations up to date.