Capturing vertical and horizontal scroll from mousewheel - delphi

Question

I need to capture mousewheel events in my application to move the view area like modern UI's since my application will run mostly on laptops.
I have looked into Windows messages and apparently only controls inherited from TWinControl can recieve mousewheel messages.
I'm using TApplicationEvents, that can also capture those mesagges. I tried handling the WM_MOUSEWHEEL message, but it works only for vertical scrolling. I also tried handling WM_HSCROLL and WM_HSCROLLCLIPBOARD messages, but they were not captured at all.
How can I capture both vertical and especially horizontal mousewheel messages and use them in my software?

Answer 1

You simply need to respond to WM_MOUSEHWHEEL messages. For instance, here's an extract from a class of mine which adds horizontal mouse wheel scrolling to a scroll box:
procedure TMyScrollBox.WndProc(var Message: TMessage);
begin
if Message.Msg=WM_MOUSEHWHEEL then begin
(* For some reason using a message handler for WM_MOUSEHWHEEL doesn't work.
The messages don't always arrive. It seems to occur when both scroll bars
are active. Strangely, if we handle the message here, then the messages
all get through. Go figure! *)
if TWMMouseWheel(Message).Keys=0 then begin
HorzScrollBar.Position := HorzScrollBar.Position
+ TWMMouseWheel(Message).WheelDelta;
Message.Result := 0;
end else begin
Message.Result := 1;
end;
end else begin
inherited;
end;
end;

Answer 2

First you need to handle the message WM_MOUSEHWHEEL.
Notice that the letter "H" is in there (WM_MOUSE H WHEEL).
I added a TApplicationEvent componenet and added the following code
to the OnMessage event:
uses VCL.Controls;
.....
procedure TForm1.ApplicationEvents1Message(var Msg: tagMSG; var Handled: Boolean);
var ctrl: TWinControl;
begin
ctrl := FindVCLWindow(Mouse.CursorPos); //first I need to find the control under the mouse
if ctrl is T3DWorldViewerComponent then //then I need to make sure
//that the control under the mouse
//is the 3D World Viewer contains my graphics
if msg.message = WM_MOUSEHWHEEL then //then I need to make sure that I want to scroll Horizontally
begin
if msg.wParam=4287102976 then //this indicates that I'm scrolling to the left
world.CameraMoveTo(MyCamera.Position.X+0.03, MyCamera.Position.Y, MyCamera.Position.Z)
else
if msg.wParam=7864320 then //and this indicates that I'm scrolling to the right
world.CameraMoveTo(MyCamera.Position.X-0.03, MyCamera.Position.Y, MyCamera.Position.Z);
end;
end;
Done!