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{
@author(Richard B. Winston <rbwinst@usgs.gov>)
The main purpose of @name is to define GetHelpControl which is used to find
a control that has help for a control.
Contributions to this unit by Richard B. Winston are in the public domain.
As of Nov. 2, 2005, this entire unit is by Richard B. Winston.
}
unit HelpProcessor;
interface
uses
Classes, SysUtils, Controls, StdCtrls, Forms;
{ @abstract(@name returns @true if it can find a control that has help starting
its search with HelpRequestControl. The control that it finds is
returned in HasHelpControl.)
In its search, the function checks the FocusControl property of
TCustomStaticText and TCustomLabel, the Parent property of TControl,
and finally Application.MainForm.
@name works for both HelpType = htKeyword and HelpType = htContext.}
function GetHelpControl(const HelpRequestControl: TControl;
out HasHelpControl: TControl): boolean;
implementation
type
TCustomLabelCracker = class(TCustomLabel);
function GetHelpControl(const HelpRequestControl: TControl;
out HasHelpControl: TControl): boolean;
var
AControl: TControl;
AlreadyTried: TList;
begin
AControl := HelpRequestControl;
HasHelpControl := nil;
Result := FALSE;
AlreadyTried := TList.Create;
try
while AControl <> nil do begin
// Test if AControl has help. If it does, set HasHelpControl
// and exit;
case AControl.HelpType of
htKeyword:
begin
if AControl.HelpKeyword <> '' then
begin
HasHelpControl := AControl;
Exit;
end;
end;
htContext:
begin
if AControl.HelpContext <> 0 then
begin
HasHelpControl := AControl;
Exit;
end;
end;
else
Assert(False);
end;
// AControl does not have help, find the next one to test.
{
if (AControl is TCustomStaticText)
and (TCustomStaticText(AControl).FocusControl <> nil) then
begin
AControl := TCustomStaticText(AControl).FocusControl;
end
else }
if (AControl is TCustomLabel)
and (TCustomLabelCracker(AControl).FocusControl <> nil) then
begin
AControl := TCustomLabelCracker(AControl).FocusControl;
end
else if AControl.Parent <> nil then
begin
AControl := AControl.Parent;
end
else if (Application <> nil)
and (AControl <> Application.MainForm)
and (Application.MainForm <> nil) then
begin
AControl := Application.MainForm;
end
else
begin
// nothing left to test so quit.
Exit;
end;
// If the FocusControl of a TCustomStaticText or TCustomLabel
// refers back to itself either directly or indirectly the
// while loop might never exit. The following prevents that
// from happening.
if AlreadyTried.IndexOf(AControl) >= 0 then
begin
Exit;
end
else
begin
AlreadyTried.Add(AControl);
end;
end;
finally
AlreadyTried.Free;
result := HasHelpControl <> nil;
end;
end;
end.
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