James Chandler Jr napsal(a):
Hi Tom
Hi,
Thanks for adding the Carbon SetCursorPos patch.
Wome feedback on your comment: "Thanks. It's only pitty that it does
not produce mouse events."
I could be mistaken, and appreciate correction, but think that
SetCursorPos SHOULD NOT send mouse events (on any platform).
That is from my use of SetCursorPos but perhaps there are other uses
which would want to generate mouse events.
For instance, a favorite control is what I call a TextSlider-- It
displays a Text value, and when you click-drag the control, it tracks
like a vertical slider, but rather than the text control moving
on-screen, the number in the text control just changes in response to
vertical mouse movement. This kind of control has been common in music
programs since the 1980's. Many round knob controls work similarly.
I hilite the textbox and hide the cursor (and pin the hidden cursor on
the textbox), or alternately leave the cursor visible and move it to
the right of the textbox and 'pin' its location, so that vertical
drags cannot move long distances on the screen. If the TextSlider
control is near the top of the screen and the user wants to drag the
value from 10 to 1000, the value drag would stop when the cursor hits
the top of the screen, limiting the amount that the user could drag in
a single movement.
In that kind usage, it would be undesirable if SetCursorPos would send
mouse events. If my OnMouseMove notices that the user dragged up 5
pixels, and then adds 5 to the control's value and updates the screen,
and does SetCursorPos to move the cursor back to its original location
for further user dragging--
If the control's OnMouseMove SetCursorPos generates a mouse move down
event, then that new event would trigger OnMouseMove again, and 'undo'
the user's drag, subtracting 5 from the control value and returning
the control back to the original value.
Haven't traced the code, but am pretty sure that the PC Delphi and PC
Lazarus SetCursorPos does not generate mouse move events, otherwise my
mouse-tracking controls which use that trick, would never work.
Apple strongly disapproves programmatically moving the cursor, and I
read somewhere that they supplied the WarpCursorPos function to coddle
video game programs, which also need to keep the cursor on-screen for
similar reasons that my controls need. It is doubtful that game
programmers would want mouse-move events, for the same reasons I don't
want em. It could 'undo' the purpose of the SetCursorPos.
Sorry for such a boring message. Just wanted to point out that adding
a mouse move event to SetCursorPos might be undesirable.
Thanks for such great work!
That's allright, I comprehend that generating mouse events is sometimes
undesirable. I have been following behaviour of SetCursorPos in Lazarus
on Windows platform and Delphi (5), where SetCursorPos generates
OnMouseMove events. I will add a note on Wiki about this.
Tom
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