Hi,
I had a similar experience with taking a screenshot programmatically.
Simply waiting or processing application messages after hiding the form
often doesn't help, and results in a form being a part of the screenshot
anyway.
I managed to work around it by forcing Windows to repaint everything on
the desktop by broadcasting WM_PAINT message, like so:
SendMessageTimeout(HWND_BROADCAST, WM_PAINT, 0, 0, SMTO_ABORTIFHUNG,
1000, MsgResult);
You might also need to disable transition effects (fade-in and fade-out)
by setting the DWMWA_TRANSITIONS_FORCEDISABLED flag on the form before
hiding it, and then unsetting it when showing the form again.
DwmSetWindowAttribute(AForm.Handle, DWMWA_TRANSITIONS_FORCEDISABLED,
@dwAttribute, SizeOf(dwAttribute));
Good luck,
Denis
On 07/02/2021 09:37, Bo Berglund via lazarus wrote:
I have worked on a tool to copy a region of the Windows desktop for use in
illustrations. The tool consists of a transparent form which is supposed to be
located on top of the area to copy.
This form has a pop-up menu where there are 3 items to select from:
- Copy image
- Copy position
- Close
When I use the "Copy image" function the resulting image contains the selected
menu item caption on top of the copied desktop bitmap...
I have tried various ways to get rid of this but everything I tried has failed.
So how can I hide the menu item caption in code before I make the image
extraction?
I even added a timer set to 50 ms interval and put the image copy in its ontimer
event hoping that the menu click should have exited and the text disappeared
before the image copy happened, but no go...
Here is the way the copy is commanded via the popup menu:
http://blog.boberglund.com/files/Lazarus_popmenu_usage.png
And here is a captured image where the popup caption is visible:
http://blog.boberglund.com/files/Lazarus_popmenu.png
As you can see the caption of the clicked menu item is still present in the
screenshot image...
Here is parts of the code:
procedure TfrmMain.miCopyImageClick(Sender : TObject);
begin
//CopyScreenRect; //Moved to timer
//miCopyImage.Visible := false; //Does not work
//self.Refresh; //Does not work
timCopyImg.Enabled := true; //make copy inside timer event?
end;
procedure TfrmMain.miCopyPosClick(Sender : TObject);
begin
SaveRectCoords; //Saving rect coordinates to clipboard (OK)
end;
procedure TfrmMain.timCopyImgTimer(Sender : TObject);
begin
timCopyImg.Enabled := false;
miCopyImage.Visible := false; //Does not work, caption still present
self.Refresh; //Does also not work to remove caption
CopyScreenRect;
miCopyImage.Visible := true; //Put it back to enable next capture
end;
procedure TfrmMain.CopyScreenRect;
var
MyCapture : TBgraBitmap;
Clip: TRect;
begin
try
Clip := Bounds(Self.Left, Self.Top, Self.Width, Self.Height);
Self.Visible := false; //Hide selection form before copy
//Self.Hide; //Not working for popup menu item...
MyCapture := TBgraBitmap.Create();
MyCapture.TakeScreenShot(Clip);
Self.Visible := true; //Show selection form after copy is done
//Self.Show; //Not working for popup menu item...
Clipboard.Assign(MyCapture.Bitmap);
except
on E: exception do
Clipboard.AsText := E.Message;
end;
end;
Even Self.Visible or Self.Hide do not remove the menuitem caption....
What can I do?
Lazarus 2.0.10 / fpc 3.2.0 on Windows 10
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