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Weekly Meeting Virtual User Interface (VUI) Team
Table of Contents 1 Action Items 2 Accessibility: Handling UI bitmaps in high contrast (HC) mode
1 Action Items
2 Accessibility: Handling UI bitmaps in high contrast modeCJ: Confirmed that Stella Schulze will draw a high contrast version of all of our used bitmaps. We discussed if VCL can handle this extra bitmapsfor us. MBA stated that toolboxes will handles this inside VCL, but we needed a solution for other controls and handmade ui elements. We agreed that it should be no resource problem if we have both the standard and high contrast bitmap available in memory at the same time for dialogs. CL raised the question if we can add references to the high contrast bitmaps next to the definitions of the standard bitmaps in the resource files. We mostly agree that this would be a good design but all the work, including changing the resource manager, had to be done by SSA who is already on tight schedule. MBA started with the idea that the ui developer should overload
the StateChange method at theire ui classes and set the correct
bitmaps themself after a change to/from high contrast mode. We found
out that it is not sufficient to do this in the StateChange method
only since we have to test on dialog construction if where already in
high contrast mode. FS suggested a virtual method for tabpages to
switch between the modes to have a common interface and to share the
StateChange implementation. Our solution was to have the VCL controls store two bitmaps, one standard and an optional bitmap for high contrast mode. If that is set, the control handles the state changes to/from high contrast mode themself. For not having another special interface for just the high contrast mode, we agreed on having a SetModeBitmap method which takes a bitmap and an enum that definine for which mode this bitmap will be used. So this can be used for future additions like a true color mode f.e . So the dialogs must set the bitmaps for high contrast mode only once after creation. CJ informed us about a special handling in the white high contrast mode. There we will use the default bitmaps but do a special painting for pressed images where we have to replace some colors using a table provided by CJ. KA will add a function to do this replacement for images and image lists. The replacement will be handled in the paint method, so we need a new paintflag for this. VCL will detect itself which paintmode has to be used. MT informed us that high contrast bitmaps should also be used if the luminance of the background color falls below a fixed value. SSA will add a method at our color class where we can verify this. For handmade ui controls, we have to use our background color and check it against that method to see if we need to use the high contrast bitmap.This raised an issue that MBA needs two different image lists for toolboxes and menus, since they can have different background colors.
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