How to host an IContextMenu, part 4 - Key context
Another of the bugs you may have noticed in
our first attempt at displaying the context menu to the user
is that the Delete command doesn't alter its behavior depending
on whether you hold the shift key. Recall that
holding the shift key changes the behavior of the Delete command,
causing it to delete a file immediately instead of moving it
to the Recycle Bin.
But in our sample program, it always offers to move the file
to the Recycle Bin, even if you have the shift key down.
(You can see the difference in the wording of the dialog
and in the icon. If the operation is to move the item into the
Recycle Bin, you get a Recycle Bin icon and the text asks you
to confirm sending the item to the Recycle Bin. If the operation
will delete the item permanently, then you get an icon that shows
a file and a folder fading away and the text asks you to confirm
deleting the item.)
To convey this information to the context menu, you need to
pass the key states in
the CMINVOKECOMMANDINFOEX structure.
CMINVOKECOMMANDINFOEX info = { 0 };
info.cbSize = sizeof(info);
info.fMask = CMIC_MASK_UNICODE | CMIC_MASK_PTINVOKE;
if (GetKeyState(VK_CONTROL) < 0) {
info.fMask |= CMIC_MASK_CONTROL_DOWN;
}
if (GetKeyState(VK_SHIFT) < 0) {
info.fMask |= CMIC_MASK_SHIFT_DOWN;
}
Make this change and observe that the dialogs you get from
the Delete option now respect your shift key state.
Warning: Before playing with this, make sure that
you have enabled delete confirmation warnings or you will end up
deleting your clock.avi file for real!
If you want to play around with the Delete option, you may want
to tweak the program so it operates on a file you don't mind losing.
Exercise: There's another place where key
context influences the context menu, namely the convention that
holding the shift key while right-clicking enables
"extended verbs". These are verbs that are lesser-used and
therefore do not appear on the conventional context menu to
avoid creating clutter. For homework, incorporate the
extended verb convention into the sample program.
[Sorry today's entries are late. Had problems connecting to the
blog server.]
