[Qt] #15882: "QT: automatic tool tip window tries to draw beyond screen boundaries and fails."

[Juha Manninen]

Zeljko,

I found something interesting about issue #15882.

The problem is not about drawing beyond screen boundaries.
In THintWindow.ActivateHintData, I commented out the offset calculation which 
moves the window up / left so it is fully visible. After that the tool tip 
windows show up nicely, only the bottom / right part is cropped off by screen 
boundary.
I can't explain why it happens. The offset code looks correct and it works 
correctly with other widgetsets.

If I understand right, the QT's builtin tooltip class (QToolTipH) is not used 
for LCL tooltip but it is created from CustomForm.
I guess all widgetsets support tooltips. LCL should be changed accordingly. 
That would surely solve this problem in QT as well.

In:
  procedure TQtWidget.SlotPaint(Sender: QObjectH; Event: QEventH); cdecl;
I noticed this:
  if LCLObject is THintWindow then
    Msg.DC := Msg.DC;

It looks useless but maybe it has some meaning. (for debugging only?)


Regards,
Juha


-------------------

procedure THintWindow.ActivateHintData(ARect: TRect; const AHint: String; 
AData: pointer);
var
  InvalidateNeeded: Boolean;
  AMonitor: TMonitor;
  ABounds: TRect;
begin
  if FActivating then exit;
  FActivating := True;
  try
    //debugln('THintWindow.ActivateHint OldHint="',DbgStr(Caption),'" 
NewHint="',DbgStr(AHint),'"');
    InvalidateNeeded := Visible and (Caption <> AHint);
    Caption := AHint;
    AMonitor := Screen.MonitorFromPoint(ARect.TopLeft);
    ABounds := AMonitor.BoundsRect;
    // limit width, height by monitor
    if (ARect.Right - ARect.Left) > (ABounds.Right - ABounds.Left) then
      ARect.Right := ARect.Left + (ABounds.Right - ABounds.Left);

    if (ARect.Bottom - ARect.Top) > (ABounds.Bottom - ABounds.Top) then
      ARect.Bottom := ARect.Top + (ABounds.Bottom - ABounds.Top);
    // offset hint to fit into monitor
{    if ARect.Bottom > ABounds.Bottom then
    begin
      ARect.Top := ABounds.Bottom - (ARect.Bottom - ARect.Top);
      ARect.Bottom := ABounds.Bottom;
    end;
    if ARect.Right > ABounds.Right then
    begin
      ARect.Left := ABounds.Right - (ARect.Right - ARect.Left);
      ARect.Right := ABounds.Right;
    end;
}
    if ARect.Left < ABounds.Left then ARect.Left := ABounds.Left;
    if ARect.Top < ABounds.Top then ARect.Top := ABounds.Top;
    SetBounds(ARect.Left, ARect.Top,
              ARect.Right - ARect.Left, ARect.Bottom - ARect.Top);
    Visible := True;
    TCustomTimer(FAutoHideTimer).Enabled := False;
    TCustomTimer(FAutoHideTimer).Enabled := FAutoHide;
    if InvalidateNeeded then Invalidate;
  finally
    FActivating := False;
  end;
end;