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Documentation of class 'ImageReader::EnforcedImageTypeQuery':

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Class: EnforcedImageTypeQuery (private in ImageReader

This class is only visible from within ImageReader.

Inheritance:

   Object
   |
   +--GenericException
      |
      +--Notification
         |
         +--Query
            |
            +--ImageReader::EnforcedImageTypeQuery

Package:
stx:libview
Category:
Graphics-Images-Readers
Owner:
ImageReader
Author:
cg

Description:


consider this a hack (but a not too bad one):

with pngReader (and maybe others), we may want to read an image file,
but ignore the alpha channel.
I.e. read it as an rgb image although the image file is actually rgba formatted.
This is useful, if the image contains invalid alpha information anyway,
as when asking appium for a screen shot 
(there are no transparent pixels on the screen - at least not until we get glass-plate displays...)

Instead of passing this information down through all the possible image and image reader interfaces,
this query is asked by some readers (currently only pngReader) and
can be answered high above by a caller to answer #rgb.

The default answer (nil) leads to the old behavior in that the file itself determines the format.
Please take a look at the concrete image reader documentation for which answers are valid and useful.


[instance variables:]

[class variables:]


Related information:




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