In most of my applications, I make all form size and position persistent: On startup (FormShow) I read the size and position back from an ini file and on close, I write the size and position back to the ini file.
But sometimes, the number of attached monitor is reduced, or I change the relative position of the monitors, or the screen resolution is lowered. This has the negative side effect that my forms are sometime positioned on an invisible part of the desktop!
The fix for this annoying issue is quite easy. #Delphi has a global variable “Screen” which holds an array of monitor descriptors. It is enough to iterate thru this array and check if the form position lies inside a visible monitor area. Actually the code below make sure at least 100 pixels are visible.
Here is the code to put in the FormShow event handler:
var
I : Integer;
Ri : TRect;
const
Margin = 100; // Number of pixels to be seen, at least
begin
I := 0;
while I < Screen.MonitorCount do begin
// Compute the intersection between screen and form
Windows.IntersectRect(Ri, BoundsRect,
Screen.Monitors[I].BoundsRect);
// Check the intersection is large enough
if (Ri.Width > Margin) and (Ri.Height > Margin) then
break;
Inc(I);
end;
if I >= Screen.MonitorCount then begin
// Form is outside of any monitor.
// Move to center of main monitor
Top := (Screen.Height - Height) div 2;
Left := (Screen.Width - Width) div 2;
end;
end;
Suggested readings:
Writing an iterator for a container
MidWare multi-tier framework
Follow me on Twitter
You can replace the loop with TScreen.MonitorFromWindow():
ReplyDeleteif Screen.MonitorFromWindow(Handle, mdNull) = null then begin
// Form is outside of any monitor. Move to center of main monitor
Top := (Screen.Height - Height) div 2;
Left := (Screen.Width - Width) div 2;
end;
And if the're two monitors - the form would launch split half between them ?
ReplyDeleteAnd if monitors have different PPI resolution or there is taskbar in the middle - that would look weird...
I believe you select soem monitor and arrange form to it's center, not to the virtual screen center
@Arioch,
ReplyDeleteI thought the same, but that code is correct. TScreen.Width/Height actually returns the width/height of the primary monitor, not all of the monitors combined.
Use Screen.DesktopWidth and Screen.DesktopHeight for the dimensions of the combined monitors.
ReplyDeleteThank you - just what I needed!
ReplyDeleteAlternative approach:
ReplyDeleteprocedure TMyForm.FormShow(Sender: TObject);
var
L, T, W, H : Integer;
begin
if LoadWindowRegPos(Name, L, T, W, H) then begin
Left:=L;
Top:=T;
Width:=W;
Height:=H;
end;
end;
procedure TMyForm.FormHide(Sender: TObject);
begin
SaveWindowRegPos(Name, Left, Top, Width, Height)
end;
GLOBAL Functions
//Adjust the left for Multiple Monitors
Function AdjustLeftForMultipleMonitors(L : Integer; Screen : TScreen) : Integer;
Var
I : Integer;
OurBoundsrect : TRect;
begin
Result:=10;
OurBoundsrect.Left:=MaxInt; OurBoundsrect.Top:=0; OurBoundsrect.Right:=-MaxInt; OurBoundsrect.Bottom:=0;
for I:= 0 to Screen.MonitorCount-1 do begin
if Screen.Monitors[I].BoundsRect.Left < OurBoundsrect.Left then OurBoundsrect.Left:= Screen.Monitors[I].BoundsRect.Left;
if Screen.Monitors[I].BoundsRect.Right > OurBoundsrect.Right then OurBoundsrect.Right:= Screen.Monitors[I].BoundsRect.Right;
end;
if L < OurBoundsrect.Left then Exit; //Left is Out of Bounds Rect
if L > (OurBoundsrect.Right{-OurBoundsrect.Left}) then Exit; //Left is larger then the desktop width
Result:=L;
end;
//Adjust the top for Multiple Monitors
Function AdjustTopForMultipleMonitors(T : Integer; Screen : TScreen) : Integer;
Var
I : Integer;
OurBoundsrect : TRect;
begin
Result:=10;
OurBoundsrect.Left:=0; OurBoundsrect.Top:=MaxInt; OurBoundsrect.Right:=0; OurBoundsrect.Bottom:=-MaxInt;
for I:= 0 to Screen.MonitorCount-1 do begin
if Screen.Monitors[I].BoundsRect.Top < OurBoundsrect.Top then OurBoundsrect.Top:= Screen.Monitors[I].BoundsRect.Top;
if Screen.Monitors[I].BoundsRect.Bottom > OurBoundsrect.Bottom then OurBoundsrect.Bottom:= Screen.Monitors[I].BoundsRect.Bottom;
end;
if T < OurBoundsrect.Top then Exit; //Top is Out of Bounds Rect
if T > (OurBoundsrect.Bottom {- OurBoundsrect.Top}) then Exit; //Top is larger then the desktop width
Result:=T;
end;
///////////////////////////////////////////////////////////////////////////////////////////
//Get Saved Window Position
///////////////////////////////////////////////////////////////////////////////////////////
Function LoadWindowRegPos(WindowName : String; var L,T,W,H : Integer) : Boolean;
Var
R : TRegistry;
RL, RT : Integer;
begin
R := TRegistry.Create(KEY_READ);
R.RootKey := HKEY_CURRENT_USER;
try
Result:=True;
if R.OpenKey(cStrPosition, False) then begin
try
if R.ValueExists(WindowName+'L') then L:=AdjustLeftForMultipleMonitors(R.ReadInteger(WindowName+'L'), Screen) else Result:=False;
if R.ValueExists(WindowName+'T') then T:=AdjustTopForMultipleMonitors(R.ReadInteger(WindowName+'T'), Screen) else Result:=False;
if R.ValueExists(WindowName+'W') then W:=R.ReadInteger(WindowName+'W') else Result:=False;
if R.ValueExists(WindowName+'H') then H:=R.ReadInteger(WindowName+'H') else Result:=False;
Except
Result:=False;
end;
end else Result:=False;
finally
R.Free;
end;
end;
///////////////////////////////////////////////////////////////////////////////////////////
//Save Window Pos to Registry
///////////////////////////////////////////////////////////////////////////////////////////
Procedure SaveWindowRegPos(WindowName : String; L,T,W,H : Integer);
Var
R : TRegistry;
begin
R := TRegistry.Create(KEY_READ or KEY_WRITE);
R.RootKey := HKEY_CURRENT_USER;
try
if R.OpenKey(cStrPosition, True) then begin
R.WriteInteger(WindowName+'L', L);
R.WriteInteger(WindowName+'T', T);
R.WriteInteger(WindowName+'W', W);
R.WriteInteger(WindowName+'H', H);
end;
finally
R.Free;
end;
end;
For anyone searching for a newer Solution:
ReplyDeleteprocedure CorrectFormPosition(fForm: TForm);
begin
fForm.Left := MIN(MAX(-7,fForm.left-Screen.DesktopLeft),Screen.DesktopWidth-fForm.Width+7)+Screen.DesktopLeft;
fForm.top := MIN(MAX(0,fForm.top),Screen.DesktopHeight-fForm.Height);
fForm.Width := MIN(fForm.Width,Screen.DesktopWidth);
fForm.Height := MIN(fForm.Height,Screen.DesktopHeight);
end;
This works for any Monitor-Setup with a higher priority on the left-right position of the given form.
2 lines of code:
ReplyDeleteif not Assigned(Screen.MonitorFromWindow(Handle, mdNull)) then
MakeFullyVisible;