Fade all other windows of an application when a dialog is shown? - delphi

Question

How to dim / fade all other windows of an application in Delphi 2009.
Form has an AlphaBlend property, but it controls only transparency level. But it would be nice if we can have something like this
(Concentrated window) . Even stackoverflow.com does that, when we try to insert a link/ image etc in the post.
How can we achieve this in a delphi application?

Answer 1

Here is a unit I just knocked together for you.
To use this unit drop a TApplication component on your main form and in the OnModalBegin call _GrayForms and then in the OnModalEnd call the _NormalForms method.
This is a very simple example and could be made to be more complex very easily. Checking for multiple call levels etc....
For things like system (open, save, etc) dialogs you can wrap the dialog execute method in a try...finally block calling the appropriate functions to get a similar reaction.
This unit should work on Win2k, WinXP, Vista and should even work on Win7.
Ryan.
unit GrayOut;
interface
procedure _GrayForms;
procedure _GrayDesktop;
procedure _NormalForms;
implementation
uses windows, classes, forms, Contnrs, Types, Graphics, sysutils;
var
gGrayForms : TComponentList;
procedure _GrayDesktop;
var
loop : integer;
wScrnFrm : TForm;
wForm : TForm;
wPoint : TPoint;
begin
if not assigned(gGrayForms) then
begin
gGrayForms := TComponentList.Create;
gGrayForms.OwnsObjects := true;
for loop := 0 to Screen.MonitorCount - 1 do
begin
wForm := TForm.Create(nil);
gGrayForms.Add(wForm);
wForm.Position := poDesigned;
wForm.AlphaBlend := true;
wForm.AlphaBlendValue := 64;
wForm.Color := clBlack;
wForm.BorderStyle := bsNone;
wForm.Enabled := false;
wForm.BoundsRect := Screen.Monitors[loop].BoundsRect;
SetWindowPos(wForm.handle, HWND_TOP, 0,0,0,0, SWP_NOSIZE or SWP_NOMOVE);
wForm.Visible := true;
end;
end;
end;
procedure _GrayForms;
var
loop : integer;
wScrnFrm : TForm;
wForm : TForm;
wPoint : TPoint;
wScreens : TList;
begin
if not assigned(gGrayForms) then
begin
gGrayForms := TComponentList.Create;
gGrayForms.OwnsObjects := true;
wScreens := TList.create;
try
for loop := 0 to Screen.FormCount - 1 do
wScreens.Add(Screen.Forms[loop]);
for loop := 0 to wScreens.Count - 1 do
begin
wScrnFrm := wScreens[loop];
if wScrnFrm.Visible then
begin
wForm := TForm.Create(wScrnFrm);
gGrayForms.Add(wForm);
wForm.Position := poOwnerFormCenter;
wForm.AlphaBlend := true;
wForm.AlphaBlendValue := 64;
wForm.Color := clBlack;
wForm.BorderStyle := bsNone;
wForm.Enabled := false;
wForm.BoundsRect := wScrnFrm.BoundsRect;
SetWindowLong(wForm.Handle, GWL_HWNDPARENT, wScrnFrm.Handle);
SetWindowPos(wForm.handle, wScrnFrm.handle, 0,0,0,0, SWP_NOSIZE or SWP_NOMOVE);
wForm.Visible := true;
end;
end;
finally
wScreens.free;
end;
end;
end;
procedure _NormalForms;
begin
FreeAndNil(gGrayForms);
end;
initialization
gGrayForms := nil;
end.

Answer 2

I have done something similar for showing a modal form trying to keep the implementation as simple as possible. I don't know if this will fit your needs, but here it is:
function ShowModalDimmed(Form: TForm; Centered: Boolean = true): TModalResult;
var
Back: TForm;
begin
Back := TForm.Create(nil);
try
Back.Position := poDesigned;
Back.BorderStyle := bsNone;
Back.AlphaBlend := true;
Back.AlphaBlendValue := 192;
Back.Color := clBlack;
Back.SetBounds(0, 0, Screen.Width, Screen.Height);
Back.Show;
if Centered then begin
Form.Left := (Back.ClientWidth - Form.Width) div 2;
Form.Top := (Back.ClientHeight - Form.Height) div 2;
end;
result := Form.ShowModal;
finally
Back.Free;
end;
end;

Answer 3

I'm not sure about the "right" way to do it, but in order to "fade-to-white", what you can do is place your form in another completely white form (white background color, no controls).
So when your form is in 0% transparency, it will show as a regular form, but when it's in 50% transparency it will be faded to white. You can obviously choose other colors as your background.
I'm looking forward to seeing other answers...
EDIT: after seeing your "Jedi Concentrate" link, it seems that a dark-gray background will mimic the Expose effect better.

Answer 4

One way to do this is to place another form behind your dialog, this form would have no borders, and would contain a single image. This image would be a capture of the entire desktop from just before the dialog popped up, then run through a transform to lower the luminosity of each pixel by 50%. One trick that works quite well here is to use a black form, and to only include ever other pixel. If you know for certain that you will have theme support, you can optionally use a completely black form and use the alphablend and alphablendvalue properties..this will allow the OS to perform the luminosity transformation for you. An alphablendvalue of 128 is = 50%.
EDIT
As mghie pointed out, there is the possibility of a user pressing alt-tab to switch to another application. One way to handle this scenario would be to hide the "overlay" window in the application.OnDeactivate event, and to show it on the application.OnActivate event. Just remember to set the zorder of the overlay window lower than your modal dialog.

Answer 5

I created a similar effect to the Jedi Concentrate with a Form sized to the Screen.WorkArea with Color := clBlack and BorderStyle := bsNone
I found setting the AlphaBlendValue was too slow to animate nicely, so I use SetLayeredWindowAttributes()
The unit's code:
unit frmConcentrate;
{$WARN SYMBOL_PLATFORM OFF}
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs;
type
TFadeThread = class(TThread)
private
fForm: TForm;
public
constructor Create(frm: TForm);
procedure Execute; override;
end;
TConcentrateFrm = class(TForm)
procedure FormDestroy(Sender: TObject);
procedure FormClick(Sender: TObject);
private
{ Private declarations }
fThread: TFadeThread;
public
{ Public declarations }
end;
procedure StartConcentrate(aForm: TForm = nil);
var
ConcentrateFrm: TConcentrateFrm;
implementation
{$R *.dfm}
procedure StartConcentrate(aForm: TForm = nil);
var
Hnd: HWND;
begin
try
if not Assigned(ConcentrateFrm) then
ConcentrateFrm := TConcentrateFrm.Create(nil)
else
Exit;
ConcentrateFrm.Top := Screen.WorkAreaTop;
ConcentrateFrm.Left := Screen.WorkAreaLeft;
ConcentrateFrm.Width := Screen.WorkAreaWidth;
ConcentrateFrm.Height := Screen.WorkAreaHeight;
Hnd := GetForegroundWindow;
SetWindowLong(ConcentrateFrm.Handle, GWL_EXSTYLE,
GetWindowLong(ConcentrateFrm.Handle, GWL_EXSTYLE) or WS_EX_LAYERED
);
SetLayeredWindowAttributes(
ConcentrateFrm.Handle,
ColorToRGB(clBlack),
0,
LWA_ALPHA
);
ConcentrateFrm.Show;
if Assigned(aForm) then
aForm.BringToFront
else
SetForegroundWindow(Hnd);
ConcentrateFrm.fThread := TFadeThread.Create(ConcentrateFrm);
Application.ProcessMessages;
ConcentrateFrm.fThread.Resume;
except
FreeAndNil(ConcentrateFrm);
end;
end;
procedure TConcentrateFrm.FormClick(Sender: TObject);
var
p: TPoint;
hnd: HWND;
begin
GetCursorPos(p);
ConcentrateFrm.Hide;
hnd := WindowFromPoint(p);
while GetParent(hnd) 0 do
hnd := GetParent(hnd);
SetForegroundWindow(hnd);
Release;
end;
procedure TConcentrateFrm.FormDestroy(Sender: TObject);
begin
ConcentrateFrm := nil;
end;
{ TFadeThread }
constructor TFadeThread.Create(frm: TForm);
begin
inherited Create(true);
FreeOnTerminate := true;
Priority := tpIdle;
fForm := frm;
end;
procedure TFadeThread.Execute;
var
i: Integer;
begin
try
// let the main form open before doing this intensive process.
Sleep(300);
i := 0;
while i < 180 do
begin
if not Win32Check(
SetLayeredWindowAttributes(
fForm.Handle,
ColorToRGB(clBlack),
i,
LWA_ALPHA
)
) then
begin
RaiseLastOSError;
end;
Sleep(10);
Inc(i, 4);
end;
except
end;
end;
end.