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Implementation of non-centered path gradients?

    Question

  • Greetings.  I am trying to understand PowerPoint 2010's implementation of non-centered path gradients.  Please take a look at this test case:

    http://home.comcast.net/~bellert/path_grad.pptx

    There are three slides in this test case with three different non-centered path gradients.  The cross-hair of the dashed lines indicate the approximate location of the gradient center point.  There are also two rays on each gradient leaving the gradient center and ending on the shape edge.  The pixel colors along these two rays are different within the same shape.  For one ray the gradient is smooth across the length of the ray whereas for the other ray the gradient seems to be applied twice.

    I wish to better understand how PowerPoint is rendering these path gradients.  The OOXML specification is utterly useless in trying to divine exactly how PowerPoint decides to generate these gradients.  Why does one ray get a smooth color change but another get a discontinuity?  How does PowerPoint decide this?  What is the algorithm?  Is PowerPoint even rendering these correct?  One could argue that PowerPoint's implementation of non-centered path gradients is incorrect.  I would argue that the path gradient rendered on slide 3 is wrong.  Why the discontinuity in the upper left quadrant of the cross-hairs?

    Monday, July 29, 2013 2:55 PM

All replies

  • Hi,

    This is a quick note to let you know that I'm trying to involve someone familiar with this topic to further look.


    Max Meng
    TechNet Community Support

    Tuesday, July 30, 2013 8:17 AM
    Moderator
  • PowerPoint path gradients is a shape fill that gradually changes from one color to another across the surface of the shape and is done by design. We don't have details about how it is decided by PowerPoint or what the algorithm is.
    Tuesday, July 30, 2013 2:50 PM