What does alpha val="0" mean?

Question

Hi all;

In the DOCX spec it says that alpha val="50%" means 50% alpha. So I have two questions:

First is 0 fully transparent, or no transparency?

Second, Word is not writing the %. Inside a shape (that holds a textbox) it has:

<a:solidFill>
  <a:schemeClr val="bg1">
    <a:alpha val="0"/>
  </a:schemeClr>
</a:solidFill>

Is "0" assuming "0%"? And when we write out a docx should we also drop the %?

thanks - dave

Answer 1

Hi Dave,

MS-OI29500 does discuss this:

2.1.1217 Part 1 Section 20.1.2.3.1, alpha (Alpha)
a. The standard states that the val attribute specifies the opacity as expressed by a percentage
value.
Office uses the val attribute to specify a percentage value for several elements.
b. The standard states that ST_PositiveFixedPercentage is read and written as a floating point value
with a trailing percent sign.
Office will read in percentages formatted as floating point value with a trailing percent sign or as
an integer 1000th of a percent without trailing percent sign, but only write out percentages as the
latter.

And higher percentage or value indicates more transparency.

Does that help?

Best regards,
Tom Jebo
Sr Escalation Engineer
Microsoft Open Specifications