[Mono-winforms-list] What ImageList bugs do we need?

Kornél Pál kornelpal at hotmail.com
Sat Oct 22 21:08:18 EDT 2005


Now ImageList should be functionally compatible with MS.NET. The only thing
it cannot support is a native image list handle.

But MS.NET ImageList seems to be poorly designed and in addition has a lot
of bugs.

There are three bugs that are so critical that I have corrected them:

1) MS.NET 1.x shares the same HIMAGELIST between ImageLists that were
initialized from the same ImageListStreamer and doesn't update ImageSize and
ColorDepth that are treated as bugs and MS.NET 2.0 behavior is implemented.

2) MS.NET 2.0 initializes TransparentColor to Color.Transparent in
constructors but ResetTransparentColor and ShouldSerializeTransparentColor
default to Color.LightGray that is treated as a bug.

3) MS.NET 2.0 does not clear keys when handle is destroyed that is treated
as a bug.

And there are some other bug that I implemented as feature:

4) Image strips are counted as a single item in the return value of Add and
AddStrip until handle is created.

5) When ImageSize was changed after adding image strips Count will return
invalid values based on old ImageSize but when creating handle either
ArgumentException will be thrown or image strip will be added according to
the new ImageSize. This can result in image count difference that can result
in exceptions in methods that use Count before creating handle. In addition
this can result in the loss of sync with keys. When doing the same after
handle was created there are no problems as handle will be recreated after
changing ImageSize that results in the loss of images added previously.

6) When last IndexOfKey was successful and the same key was assigned to an
image with a lower index than the last result and the key of the last result
equals to key argument the last result is returned.

And ImageList has some other poorly designed methods that aren't bugs but
their behavior is documented as comments in source code.

Bug 1) can causes defective behavior particulary because thread safety
Bug 2) prevents Color.LightGray from being used as TransparentColor.
Bug 3) makes keys useless after handle recreation.
Bug 4) makes return value of Add methods useless.
Bug 5) makes ImageSize changing incompatible with image strips and can cause
very defective behavior when using image strips.
Bug 6) makes IndexOfKey behavior inconsistent.

All the above bugs can cause extreme ImageList behavior but who know whether
some people are assume this behavior.

My questions is that do we need any of these bugs as features? And do you
mind if I correct bugs 4-6?


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