Delphi Mouse wheel event in component
I'm wanting to write a component that uses the mouse wheel to zoom something similar to Google earth.
I have a component using onMouseWheel and I have properties MaxZoom MinZoom and Zoom there is a better option that StretchDraw with the bitmap I'm trying to get the location of the components area in the form
What I understand I have to find each parent until I find the tCustomform and add all Component's top and components left to get the objects location to find my objects location. is there a better way
once I have the location I can zoom a Map from the mouse cursor location if the mouse is over my object and where to zoom from.
has any one seen any code please 开发者_运维问答
If you are writing a component then you should try overriding these 2 methods in your component:
function DoMouseWheelDown( Shift :TShiftState; MousePos :TPoint ) :Boolean; override; function DoMouseWheelUp( Shift :TShiftState; MousePos :TPoint ) :Boolean; override;
which are protected dynamic methods of TControl. They get called whenever the mouse wheel is rotated.
It depends on what kind of content you are going to zoom ; I will only Post here how to get how long the wheel has moved
on private declaration
private
{ Private declarations }
procedure FormMouseWheel(Sender: TObject; Shift: TShiftState;
WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
on create or any other starting procedure
OnMouseWheel := formMouseWheel; // depends on you
The FormMouseWheel comes like this
procedure FormMouseWheel(Sender: TObject; Shift: TShiftState;
WheelDelta: Integer; MousePos: TPoint; var Handled: Boolean);
begin
// your code here
// WheelDelta returns you - or + values (in my computer -120 and + 120 ;
// It depends on control panel mouse wheel settings)
// If it is a font make the font size bigger or
// if it is a image
// strech := true;
// increase width and height of the Timage
//and put them inside a scrollbox
//
end;
I checked it using vcl form (not inside component ), If You want to zoom post us what kind of content you want to zoom
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