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Languages :: Delphi :: Problems writing a component
By: stab Sweden  Date: 23/08/2008 22:25:34  English  Points: 20 Status: Open
Hi all,

I'm trying to write a component that, dropped on a form and activated will cause every control on the form to resize together with the form.

Looked at the example in article at About Delphi Programming:

How to Detect the Start Move/Resize, Move and Stop Move/Resize events of a Form

and it worked when used on a form but I can't detect the corresponding windows messages in my component . My component contains a TApplicationEvents object and uses event: OnMessage to enter procedure ResizeAndReposition. The component enters ResizeAndReposition, but it doesn't detect WM_EXITSIZEMOVE that would cause the actual resizing.

Can anyone explain way this doesn't work?

Code as follows:

unit SBResizer;

interface

uses
Windows, Messages, SysUtils, Classes, Controls, Forms, StdCtrls, ExtCtrls, TypInfo, AppEvnts;

type
TSBResizer = class(TObject)
private
{ Private declarations }
FAOwner : TForm;
FApplicationEvent : TApplicationEvents;
FEnabled: boolean;
FCurrentHeight : integer;
FCurrentWidth : integer;
FCurrentFontSize : integer;

procedure ResizeAndReposition(var Msg: TMsg; var Handled: Boolean);
procedure SetEnabled(const Value: boolean);
protected
{ Protected declarations }
public
{ Public declarations }
constructor Create(AOwner : TForm);
destructor Destroy; override;

published
{ Published declarations }
property Enabled : boolean read FEnabled write SetEnabled;
end;

//procedure Register;

implementation

uses TwinklePanelTestMain;

{procedure Register;
begin
RegisterComponents('Festina Lente', [TSBResizer]);
end;}

{ TSBResizer }

constructor TSBResizer.Create(AOwner: TForm);
begin
inherited Create;

FAOwner := AOwner;

FCurrentHeight := FAOwner.Height;
FCurrentWidth := FAOwner.Width;
FCurrentFontSize := FAOwner.Font.Size;

FApplicationEvent := TApplicationEvents.Create(FAOwner);
FApplicationEvent.OnMessage := ResizeAndReposition;
// FApplicationEvent.
end;

destructor TSBResizer.Destroy;
begin
FreeAndNil(FApplicationEvent);

inherited;
end;

procedure TSBResizer.ResizeAndReposition(var Msg: TMsg; var Handled: Boolean);
var
i : integer;
control : TControl;
winControl : TWinControl;
component : TComponent;
fH, fW, fF : double;

procedure ResizeComponent(parentComponent : TComponent);
var
i : integer;
component : TComponent;
begin
i := 0;
while i < parentComponent.componentCount do
begin
component := parentComponent.components;
Resizecomponent(component);

i := i + 1;
end;

if parentComponent is TControl then
begin
TControl(parentComponent).Left := Round(fW * TControl(parentComponent).Left);
TControl(parentComponent).Top := Round(fH * TControl(parentComponent).Top);
TControl(parentComponent).Height := Round(fH * TControl(parentComponent).Height);
TControl(parentComponent).Width := Round(fW * TControl(parentComponent).Width);

with parentComponent do
begin
if GetPropInfo(ClassInfo, 'font') <> nil then
begin
if abs(fH - 1) > abs(fW - 1) then
TEdit(parentComponent).Font.Size := Round(fH * FCurrentFontSize)
else
TEdit(parentComponent).Font.Size := Round(fW * FCurrentFontSize);
end;
end;
end;
end;

begin
if not FEnabled then Exit;

if Msg.message = WM_EXITSIZEMOVE then
begin
fH := (1.0 - 1.0 + FAOwner.Height) / FCurrentHeight;
fW := (1.0 - 1.0 + FAOwner.Width) / FCurrentWidth;
if abs(fH - 1) > abs(fW - 1) then
FAOwner.Font.Size := Round(fH * FCurrentFontSize)
else
FAOwner.Font.Size := Round(fW * FCurrentFontSize);

i := 0;
while i < FAOwner.ComponentCount do
begin
component := FAOwner.Components;
ResizeComponent(component);

i := i + 1;
end;

FCurrentHeight := FAOwner.Height;
FCurrentWidth := FAOwner.Width;
FCurrentFontSize := FAOwner.Font.Size;

Handled := True;
end;
end;

procedure TSBResizer.SetEnabled(const Value: boolean);
begin
FEnabled := Value;
end;

end.



Regards

stab
By: VGR Date: 23/08/2008 23:27:56 English  Type : Comment
Probably TApplicationEvents is either not handling that event or is a third-party component not available in source, right ?

Then you could perhaps add this to your TForm descendant (FAOwner) :
procedure WMExitSizeMove(var Message: TMessage) ; message WM_EXITSIZEMOVE;

and call TSBResizer.ResizeAndReposition()

HTH

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