How to make the TScollBox automatically scroll when DragMode is dmAutomatic?












1















I have a ScrollBox in which I have a GridPanel in which I have Buttons.
I set DragMode to dmAutomatic for all buttons so I can move the buttons around (drag and drop).



But I have a problem: because the GridPanel is larger than the ScrollBox, the ScrollBox has the vertical scrollbar visible. I want to make the ScrollBar to automatically scroll down so I can drop a bottom from the visible (top) rows into the inaccessible rows at the bottom (this is typical behavior for all Windows programs, right?)



I have simple code that is doing this: In MouseMove I detect when the mouse is getting close to the bottom of the ScrollBox and I adjust ScrollBox.VertScrollBa.Position to scroll down. This works ONLY if I am NOT in "drag and drop" mode (if I am not dragging a button).



If I start a drag and drop operation NO mouse events are fired.



What can I do to receive MouseMove event even if I am in "drag and drop" mode?

A solution would be not to use dmAutomatic and implement my own drag and drop alternative (based on mousedown, mousemove, mouseup). Is these a quicker fix?










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  • 1





    If I remember correctly a TDragObject will receive and handle the mouse messages during Drag&Drop. But you should then get e.g. DragOver events instead.

    – nil
    Nov 22 '18 at 16:14











  • @nil - I think I get the idea: "move the code from MouseMove to DragOver". I will try it. thanks!

    – Rigel
    Nov 22 '18 at 16:15













  • Maybe, if it's true that you receive MouseMove when not dragging and DragOver when dragging.

    – nil
    Nov 22 '18 at 16:19











  • @nil - it works. can you post your comment as an answer so I can accept it? 1.5 million thanks.

    – Rigel
    Nov 22 '18 at 16:25








  • 1





    "What can I do to receive MouseMove event even if I am in "drag and drop" mode?" - Nothing... you can't. See documentation for SetCapture on MSDN for explanation. Called from TDragObject.Capture.

    – Sertac Akyuz
    Nov 22 '18 at 16:39
















1















I have a ScrollBox in which I have a GridPanel in which I have Buttons.
I set DragMode to dmAutomatic for all buttons so I can move the buttons around (drag and drop).



But I have a problem: because the GridPanel is larger than the ScrollBox, the ScrollBox has the vertical scrollbar visible. I want to make the ScrollBar to automatically scroll down so I can drop a bottom from the visible (top) rows into the inaccessible rows at the bottom (this is typical behavior for all Windows programs, right?)



I have simple code that is doing this: In MouseMove I detect when the mouse is getting close to the bottom of the ScrollBox and I adjust ScrollBox.VertScrollBa.Position to scroll down. This works ONLY if I am NOT in "drag and drop" mode (if I am not dragging a button).



If I start a drag and drop operation NO mouse events are fired.



What can I do to receive MouseMove event even if I am in "drag and drop" mode?

A solution would be not to use dmAutomatic and implement my own drag and drop alternative (based on mousedown, mousemove, mouseup). Is these a quicker fix?










share|improve this question




















  • 1





    If I remember correctly a TDragObject will receive and handle the mouse messages during Drag&Drop. But you should then get e.g. DragOver events instead.

    – nil
    Nov 22 '18 at 16:14











  • @nil - I think I get the idea: "move the code from MouseMove to DragOver". I will try it. thanks!

    – Rigel
    Nov 22 '18 at 16:15













  • Maybe, if it's true that you receive MouseMove when not dragging and DragOver when dragging.

    – nil
    Nov 22 '18 at 16:19











  • @nil - it works. can you post your comment as an answer so I can accept it? 1.5 million thanks.

    – Rigel
    Nov 22 '18 at 16:25








  • 1





    "What can I do to receive MouseMove event even if I am in "drag and drop" mode?" - Nothing... you can't. See documentation for SetCapture on MSDN for explanation. Called from TDragObject.Capture.

    – Sertac Akyuz
    Nov 22 '18 at 16:39














1












1








1








I have a ScrollBox in which I have a GridPanel in which I have Buttons.
I set DragMode to dmAutomatic for all buttons so I can move the buttons around (drag and drop).



But I have a problem: because the GridPanel is larger than the ScrollBox, the ScrollBox has the vertical scrollbar visible. I want to make the ScrollBar to automatically scroll down so I can drop a bottom from the visible (top) rows into the inaccessible rows at the bottom (this is typical behavior for all Windows programs, right?)



I have simple code that is doing this: In MouseMove I detect when the mouse is getting close to the bottom of the ScrollBox and I adjust ScrollBox.VertScrollBa.Position to scroll down. This works ONLY if I am NOT in "drag and drop" mode (if I am not dragging a button).



If I start a drag and drop operation NO mouse events are fired.



What can I do to receive MouseMove event even if I am in "drag and drop" mode?

A solution would be not to use dmAutomatic and implement my own drag and drop alternative (based on mousedown, mousemove, mouseup). Is these a quicker fix?










share|improve this question
















I have a ScrollBox in which I have a GridPanel in which I have Buttons.
I set DragMode to dmAutomatic for all buttons so I can move the buttons around (drag and drop).



But I have a problem: because the GridPanel is larger than the ScrollBox, the ScrollBox has the vertical scrollbar visible. I want to make the ScrollBar to automatically scroll down so I can drop a bottom from the visible (top) rows into the inaccessible rows at the bottom (this is typical behavior for all Windows programs, right?)



I have simple code that is doing this: In MouseMove I detect when the mouse is getting close to the bottom of the ScrollBox and I adjust ScrollBox.VertScrollBa.Position to scroll down. This works ONLY if I am NOT in "drag and drop" mode (if I am not dragging a button).



If I start a drag and drop operation NO mouse events are fired.



What can I do to receive MouseMove event even if I am in "drag and drop" mode?

A solution would be not to use dmAutomatic and implement my own drag and drop alternative (based on mousedown, mousemove, mouseup). Is these a quicker fix?







delphi mouseevent c++builder onmouseover






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edited Nov 22 '18 at 16:13







Rigel

















asked Nov 22 '18 at 16:02









RigelRigel

10k14111223




10k14111223








  • 1





    If I remember correctly a TDragObject will receive and handle the mouse messages during Drag&Drop. But you should then get e.g. DragOver events instead.

    – nil
    Nov 22 '18 at 16:14











  • @nil - I think I get the idea: "move the code from MouseMove to DragOver". I will try it. thanks!

    – Rigel
    Nov 22 '18 at 16:15













  • Maybe, if it's true that you receive MouseMove when not dragging and DragOver when dragging.

    – nil
    Nov 22 '18 at 16:19











  • @nil - it works. can you post your comment as an answer so I can accept it? 1.5 million thanks.

    – Rigel
    Nov 22 '18 at 16:25








  • 1





    "What can I do to receive MouseMove event even if I am in "drag and drop" mode?" - Nothing... you can't. See documentation for SetCapture on MSDN for explanation. Called from TDragObject.Capture.

    – Sertac Akyuz
    Nov 22 '18 at 16:39














  • 1





    If I remember correctly a TDragObject will receive and handle the mouse messages during Drag&Drop. But you should then get e.g. DragOver events instead.

    – nil
    Nov 22 '18 at 16:14











  • @nil - I think I get the idea: "move the code from MouseMove to DragOver". I will try it. thanks!

    – Rigel
    Nov 22 '18 at 16:15













  • Maybe, if it's true that you receive MouseMove when not dragging and DragOver when dragging.

    – nil
    Nov 22 '18 at 16:19











  • @nil - it works. can you post your comment as an answer so I can accept it? 1.5 million thanks.

    – Rigel
    Nov 22 '18 at 16:25








  • 1





    "What can I do to receive MouseMove event even if I am in "drag and drop" mode?" - Nothing... you can't. See documentation for SetCapture on MSDN for explanation. Called from TDragObject.Capture.

    – Sertac Akyuz
    Nov 22 '18 at 16:39








1




1





If I remember correctly a TDragObject will receive and handle the mouse messages during Drag&Drop. But you should then get e.g. DragOver events instead.

– nil
Nov 22 '18 at 16:14





If I remember correctly a TDragObject will receive and handle the mouse messages during Drag&Drop. But you should then get e.g. DragOver events instead.

– nil
Nov 22 '18 at 16:14













@nil - I think I get the idea: "move the code from MouseMove to DragOver". I will try it. thanks!

– Rigel
Nov 22 '18 at 16:15







@nil - I think I get the idea: "move the code from MouseMove to DragOver". I will try it. thanks!

– Rigel
Nov 22 '18 at 16:15















Maybe, if it's true that you receive MouseMove when not dragging and DragOver when dragging.

– nil
Nov 22 '18 at 16:19





Maybe, if it's true that you receive MouseMove when not dragging and DragOver when dragging.

– nil
Nov 22 '18 at 16:19













@nil - it works. can you post your comment as an answer so I can accept it? 1.5 million thanks.

– Rigel
Nov 22 '18 at 16:25







@nil - it works. can you post your comment as an answer so I can accept it? 1.5 million thanks.

– Rigel
Nov 22 '18 at 16:25






1




1





"What can I do to receive MouseMove event even if I am in "drag and drop" mode?" - Nothing... you can't. See documentation for SetCapture on MSDN for explanation. Called from TDragObject.Capture.

– Sertac Akyuz
Nov 22 '18 at 16:39





"What can I do to receive MouseMove event even if I am in "drag and drop" mode?" - Nothing... you can't. See documentation for SetCapture on MSDN for explanation. Called from TDragObject.Capture.

– Sertac Akyuz
Nov 22 '18 at 16:39












1 Answer
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During drag-and-drop operations the VCL will create a TDragObject to manage said drag-and-drop operation. This TDragObject - or a derived class - will start receiving and handling mouse events as long as dragging lasts. In turn, it will generate drag-and-drop specific events like OnDragOver and OnDragDrop which can be handled by - potential target - controls under current mouse position.



This will allow you to handle OnMouseMove whenever no drag-and-drop is happening. In addition handle OnDragOver in a similar way to catch mouse movements when currently dragging.






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    During drag-and-drop operations the VCL will create a TDragObject to manage said drag-and-drop operation. This TDragObject - or a derived class - will start receiving and handling mouse events as long as dragging lasts. In turn, it will generate drag-and-drop specific events like OnDragOver and OnDragDrop which can be handled by - potential target - controls under current mouse position.



    This will allow you to handle OnMouseMove whenever no drag-and-drop is happening. In addition handle OnDragOver in a similar way to catch mouse movements when currently dragging.






    share|improve this answer






























      4














      During drag-and-drop operations the VCL will create a TDragObject to manage said drag-and-drop operation. This TDragObject - or a derived class - will start receiving and handling mouse events as long as dragging lasts. In turn, it will generate drag-and-drop specific events like OnDragOver and OnDragDrop which can be handled by - potential target - controls under current mouse position.



      This will allow you to handle OnMouseMove whenever no drag-and-drop is happening. In addition handle OnDragOver in a similar way to catch mouse movements when currently dragging.






      share|improve this answer




























        4












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        4







        During drag-and-drop operations the VCL will create a TDragObject to manage said drag-and-drop operation. This TDragObject - or a derived class - will start receiving and handling mouse events as long as dragging lasts. In turn, it will generate drag-and-drop specific events like OnDragOver and OnDragDrop which can be handled by - potential target - controls under current mouse position.



        This will allow you to handle OnMouseMove whenever no drag-and-drop is happening. In addition handle OnDragOver in a similar way to catch mouse movements when currently dragging.






        share|improve this answer















        During drag-and-drop operations the VCL will create a TDragObject to manage said drag-and-drop operation. This TDragObject - or a derived class - will start receiving and handling mouse events as long as dragging lasts. In turn, it will generate drag-and-drop specific events like OnDragOver and OnDragDrop which can be handled by - potential target - controls under current mouse position.



        This will allow you to handle OnMouseMove whenever no drag-and-drop is happening. In addition handle OnDragOver in a similar way to catch mouse movements when currently dragging.







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Nov 22 '18 at 16:55

























        answered Nov 22 '18 at 16:44









        nilnil

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