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TppViewer and mouse scroll wheel

ReportBuilder 20.04
Delphi 7

A client has requested the mouse wheel be able to scroll reports. So far I have not got it working.

Currently the preview form is based on an rb example preview form code, with the main difference being the addition of a pagecontrol, with the first tabsheet containing the original controls/layout.

The scroll wheel works on other controls within the form but not the Viewer, and if i click on the scroll bar for the report, it will scroll very slowly using the wheel.

I see that support was added for mouse wheel from RB 7.04 and revised in RB14.

MouseMode property is vmmScroll (if that is in any way related).

I have also tried adding the below event as a test, and if i place a breakpoint, within, it never triggers, so still not working.

procedure TmySearchPrintPreview.FormMouseWheel(Sender: TObject;
Shift: TShiftState; WheelDelta: Integer; MousePos: TPoint;
var Handled: Boolean);
ppViewer1.VerticalScroll(WheelDelta div 5);
Handled := True;


  • Hi Steven,

    The issue with mousewheel in the preview is focus. The previewer consists of numerous controls, all gaining and loosing focus as a user interacts with them. The OnMouseWheel event will only fire for the "focused" control when implemented.

    To work around this, RB uses a "KeyCatcher" control. This is essentially an invisible TEdit control that is constantly given focus once something is done inside the previewer. This way when a key is pressed or the mousewheel is moved, the TEdit events are always fired and the correct action is taken in the previewer.

    I suggest implementing something similar in your preview plugin (or create a new preview plugin that descends from the current TppPreview class). See the FKeyCatcher property of the TppPreview class for how we go about it.

    Best Regards,

    Nico Cizik
    Digital Metaphors
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