Bug 157549 - Shadow transparency in Impress table borders is inconsistent when cell background is set to None
Summary: Shadow transparency in Impress table borders is inconsistent when cell backgr...
Status: RESOLVED NOTABUG
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Impress (show other bugs)
Version:
(earliest affected)
7.6.0.3 release
Hardware: All All
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks: ImpressDraw-Tables
  Show dependency treegraph
 
Reported: 2023-10-01 23:16 UTC by Rafael Lima
Modified: 2025-04-29 07:28 UTC (History)
4 users (show)

See Also:
Crash report or crash signature:


Attachments
Example file with similar settings in PP and Impress (107.35 KB, image/png)
2025-04-29 07:17 UTC, Gabor Kelemen (allotropia)
Details
Example file in PP and Impress with white bg table (77.37 KB, image/png)
2025-04-29 07:20 UTC, Gabor Kelemen (allotropia)
Details
Similar settings made in PP, saved as pptx (34.52 KB, application/vnd.openxmlformats-officedocument.presentationml.presentation)
2025-04-29 07:24 UTC, Gabor Kelemen (allotropia)
Details

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Description Rafael Lima 2023-10-01 23:16:00 UTC
This is a follow up after bug 150557 was fixed.

Open attachment 181975 [details] from bug 150557. It has 2 tables formatted with borders using Transparency = 0%.

The cells in the table on the left have background color set to "Color" and "white". The table has shadow using Red color and transparency set to 0%. Notice that the shadows are indeed consistent with 0% transparency.

The table on the right is a copy of the table on the left, but the cell background was set to None. Notice that now the shadows are fainter and are not consistent with 0% transparency. It appears that some transparency is still being applied, even though transparency is set to 0%.

To reproduce this issue:
1) Select all cells in the table on the left
2) Using the toolbar, set the color to None
3) Notice that the shadow now has some transparency (although transparency is set to 0%)
4) To check that, right-click the table, go to Table Properties - Shadow

System info

Version: 7.6.2.1 (X86_64) / LibreOffice Community
Build ID: 60(Build:1)
CPU threads: 16; OS: Linux 6.2; UI render: default; VCL: kf5 (cairo+xcb)
Locale: pt-BR (pt_BR.UTF-8); UI: en-US
Ubuntu package version: 4:7.6.2~rc1-0ubuntu0.23.04.1~lo1
Calc: threaded

Also present in

Version: 24.2.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 1cf500366e8de4c1c89c1f9235629d2efeaa89af
CPU threads: 16; OS: Linux 6.2; UI render: default; VCL: kf5 (cairo+xcb)
Locale: pt-BR (pt_BR.UTF-8); UI: en-US
Calc: CL threaded
Comment 1 m_a_riosv 2023-10-02 00:16:38 UTC
Reproducible with
Version: 24.2.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 506fb766885f147a40f09ffca803b4e31b14b1e1
CPU threads: 16; OS: Windows 10.0 Build 22621; UI render: Skia/Raster; VCL: win
Locale: es-ES (es_ES); UI: en-US Calc: CL threaded Jumbo

In the help talks only about the object. May should be a request for enhancement.
https://help.libreoffice.org/24.2/en-US/text/shared/01/05210600.html?System=WIN&DbPAR=IMPRESS&HID=cui/ui/shadowtabpage/ShadowTabPage#bm_id3150620
Comment 2 Gabor Kelemen (allotropia) 2025-04-29 07:17:45 UTC
Created attachment 200595 [details]
Example file with similar settings in PP and Impress

Applying the same(-ish) settings on a table in PP however gives the same result as we see in Impress.
If we apply none background and similar shadow settings, we get the same pink blurred shadow in both.
Comment 3 Gabor Kelemen (allotropia) 2025-04-29 07:20:33 UTC
Created attachment 200596 [details]
Example file in PP and Impress with white bg table

If the background is white and shadow settings are similar(-ish), we get a more defined red shadow, in both.
Comment 4 Gabor Kelemen (allotropia) 2025-04-29 07:24:47 UTC
Created attachment 200597 [details]
Similar settings made in PP, saved as pptx

For reference, this PP-made file looks the same in Impress. So the logic to apply blurred shadow, with 0% transparency (entirely visible) seems to be reliably working.
Comment 5 Gabor Kelemen (allotropia) 2025-04-29 07:28:21 UTC
With all the above, I think this behavior can be considered reasonable. Looking into the example file and the description, I think this was a misunderstanding:

3) Notice that the shadow now has some transparency (although transparency is set to 0%)

-> the shadow here has a Blur value set, this is why it is a pink blur. 
0% Transparency means it should be visible, 100% means it should not be visible.