How to display dynamic text with the mouse cursor

Question

While the user is reformatting the form, in XE2 I would like to display the current size of the form next to the current mouse cursor. I would use the OnResize event.

In other words: I need ideas on how to display dynamic text (e.g. x, y coordinates, such as 300, 250 in the image below) with the mouse cursor when the user moves his mouse.

One approach is to layout the .cur file and assign it to the cursor in OnResize. This seems cumbersome and can be quite slow (and I still don't know what the contents of the file are)

Another idea would be to display some transparent text (which component could do this?) That I installed .Top, .Left in the OnResize event.

One of the problems I ran into is how I discovered when the recalibration operation is complete so that I can return to the standard mouse cursor.

Any suggestions aimed at continuing?

Answer 1

Update:

Here is an updated version in which part of the tooltip animation was removed (since I feel you need to immediately display the tooltip for your purpose) and where double buffering was added (due to frequent tooltip updates) to prevent flicker and also decent alpha -mixing (just for curiosity).

Thanks to @NGLN, the missing assignment of a help window variable has been fixed!

unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TAlphaHintWindow = class(THintWindow) private procedure CMTextChanged(var Message: TMessage); message CM_TEXTCHANGED; protected procedure CreateParams(var Params: TCreateParams); override; procedure CreateWindowHandle(const Params: TCreateParams); override; public constructor Create(AOwner: TComponent); override; procedure ActivateHint(Rect: TRect; const AHint: string); override; end; type TForm1 = class(TForm) private FSizeMove: Boolean; FHintWindow: TAlphaHintWindow; procedure WMEnterSizeMove(var AMessage: TMessage); message WM_ENTERSIZEMOVE; procedure WMSize(var AMessage: TWMSize); message WM_SIZE; procedure WMExitSizeMove(var AMessage: TMessage); message WM_EXITSIZEMOVE; public { Public declarations } end; var Form1: TForm1; implementation {$R *.dfm} { TAlphaHintWindow } constructor TAlphaHintWindow.Create(AOwner: TComponent); begin inherited Create(AOwner); // window might be updated quite frequently, so enable double buffer DoubleBuffered := True; end; procedure TAlphaHintWindow.CreateParams(var Params: TCreateParams); begin inherited CreateParams(Params); // include the layered window style (for alpha blending) Params.ExStyle := Params.ExStyle or WS_EX_LAYERED; end; procedure TAlphaHintWindow.CreateWindowHandle(const Params: TCreateParams); begin inherited CreateWindowHandle(Params); // value of 220 here is the alpha (the same as form AlphaBlendValue) SetLayeredWindowAttributes(Handle, ColorToRGB(clNone), 220, LWA_ALPHA); end; procedure TAlphaHintWindow.ActivateHint(Rect: TRect; const AHint: string); var Monitor: TMonitor; begin // from here was just stripped the animation part and fixed one bug // (setting a hint window top position when going off screen; it is // at least in Delphi 2009 with the most recent updates) Caption := AHint; Inc(Rect.Bottom, 4); UpdateBoundsRect(Rect); Monitor := Screen.MonitorFromPoint(Point(Rect.Left, Rect.Top)); if Width > Monitor.Width then Width := Monitor.Width; if Height > Monitor.Height then Height := Monitor.Height; if Rect.Top + Height > Monitor.Top + Monitor.Height then Rect.Top := (Monitor.Top + Monitor.Height) - Height; if Rect.Left + Width > Monitor.Left + Monitor.Width then Rect.Left := (Monitor.Left + Monitor.Width) - Width; if Rect.Left < Monitor.Left then Rect.Left := Monitor.Left; if Rect.Top < Monitor.Top then Rect.Top := Monitor.Top; ParentWindow := Application.Handle; SetWindowPos(Handle, HWND_TOPMOST, Rect.Left, Rect.Top, Width, Height, SWP_NOACTIVATE); ShowWindow(Handle, SW_SHOWNOACTIVATE); Invalidate; end; procedure TAlphaHintWindow.CMTextChanged(var Message: TMessage); begin // do exactly nothing, because we're adjusting the size by ourselves // and the ancestor would just autosize the window by the text; text // or if you want Caption, is updated only by calling ActivateHint end; { TForm1 } procedure TForm1.WMEnterSizeMove(var AMessage: TMessage); begin inherited; FSizeMove := True; end; procedure TForm1.WMSize(var AMessage: TWMSize); var CurPos: TPoint; begin inherited; if FSizeMove and GetCursorPos(CurPos) then begin if not Assigned(FHintWindow) then FHintWindow := TAlphaHintWindow.Create(nil); FHintWindow.ActivateHint( Rect(CurPos.X + 20, CurPos.Y - 20, CurPos.X + 120, CurPos.Y + 30), 'Current size' + sLineBreak + 'Width: ' + IntToStr(Width) + sLineBreak + 'Height: ' + IntToStr(Height)); end; end; procedure TForm1.WMExitSizeMove(var AMessage: TMessage); begin inherited; FHintWindow.Free; FHintWindow := nil; FSizeMove := False; end; end. 

And the result when filling out the form (quite transparent for my taste :-)

Answer 2

Do I need to be transparent? Keep in mind that text can be difficult to read on certain backgrounds.

Instead, consider displaying a tooltip window. Create a THintWindow element, set its title and position and show it.

When you receive the wm_ExitSizeMove message, wm_ExitSizeMove or destroy the window.