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{
 * This Source Code Form is subject to the terms of the Mozilla Public License,
 * v. 2.0. If a copy of the MPL was not distributed with this file, You can
 * obtain one at http://mozilla.org/MPL/2.0/
 *
 * Copyright (C) 2007-2012, Peter Johnson (www.delphidabbler.com).
 *
 * $Rev$
 * $Date$
 *
 * Implements a class that manages the Page Setup dialog box.
}


unit UPageSetupDlgMgr;


interface


uses
  // Delphi
  Classes,
  // Project
  UBaseObjects;


type

  {
  TPageSetupDlgMgr:
    Class that manages the Page Setup dialog box. The class sets the dialog's
    properties, converting between units used by application and units used by
    dialog box. It also persists information entered by user in the dialog box.
  }
  TPageSetupDlgMgr = class(TNoConstructObject)
  strict private
    class function MMToDlgUnits(const Value: Double): Integer;
      {Converts millimeters to units required by Page Setup dialog.
        @param Value [in] Millimeters to convert.
        @return Converted value in dialog box units.
      }
    class function DlgUnitsToMM(const Value: Integer): Double;
      {Converts units used by Page Setup dialog into millimeters.
        @param Dialog box units to convert.
        @return Converted value in millimeters.
      }
  public
    class function Execute(AOwner: TComponent): Boolean;
      {Configures and displays page setup dialog box and updates persistent page
      setup properties as required.
        @return True if user OKs dialog and False if user cancels.
      }
  end;


implementation


uses
  // Delphi
  SysUtils, Dialogs,
  // Project
  UExceptions, UMeasurement, UPageSetupDialogEx, UPreferences, UPrintInfo;


{ TPageSetupDlgMgr }

class function TPageSetupDlgMgr.DlgUnitsToMM(const Value: Integer): Double;
  {Converts units used by Page Setup dialog into millimeters.
    @param Dialog box units to convert.
    @return Converted value in millimeters.
  }
const
  // Bug error message
  cBadValueBug = '.DlgUnitsToMM: Unexpected TMeasurementUnits value';
begin
  // See comments in MMToDlgUnits for details of how dialog stores values
  case Preferences.MeasurementUnits of
    muInches: Result := InchesToMM(Value / 1000.0);
    muMillimeters: Result := Value / 100.0;
    else raise EBug.Create(ClassName + cBadValueBug);
  end;
end;

class function TPageSetupDlgMgr.Execute(AOwner: TComponent): Boolean;
  {Configures and displays page setup dialog box and updates persistent page
  setup properties as required.
    @return True if user OKs dialog and False if user cancels.
  }

var
  Dlg: TPageSetupDialogEx;  // object that encapsulates page setup dialog

  // ---------------------------------------------------------------------------
  procedure SetDlgMargins;
    {Sets dialog's margins properties from persistent page margins.
    }
  begin
    Dlg.MarginLeft := MMToDlgUnits(PrintInfo.PageMargins.Left);
    Dlg.MarginTop := MMToDlgUnits(PrintInfo.PageMargins.Top);
    Dlg.MarginRight := MMToDlgUnits(PrintInfo.PageMargins.Right);
    Dlg.MarginBottom := MMToDlgUnits(PrintInfo.PageMargins.Bottom);
  end;

  procedure UpdatePageMargins;
    {Update persistent page margins per values entered in dialog box.
    }
  begin
    PrintInfo.PageMargins := TPageMargins.Create(
      DlgUnitsToMM(Dlg.MarginLeft),
      DlgUnitsToMM(Dlg.MarginTop),
      DlgUnitsToMM(Dlg.MarginRight),
      DlgUnitsToMM(Dlg.MarginBottom)
    );
  end;
  // ---------------------------------------------------------------------------

begin
  Dlg := TPageSetupDialogEx.Create(AOwner);
  try
    // Set dialog box's margin properties.
    // We don't pass other values, like page size, to dialog box since it
    // automatically gets these from printer's document properties.
    SetDlgMargins;
    // Store required units of measurement
    case Preferences.MeasurementUnits of
      muInches: Dlg.Units := pmInches;
      muMillimeters: Dlg.Units := pmMillimeters;
    end;
    // Show Help button to access specified topic and disable Printers button
    Dlg.Options := [psoShowHelp, psoDisablePrinter, psoMargins];
    Dlg.HelpKeyword := 'PageSetupDlg';
    // Display dialog box
    Result := Dlg.Execute;
    if Result then
      // Update page margins. We convert back to mm since we always use mm when
      // persisting margins.
      // We don't need to record other values since dialog box automatically
      // updates current printer's document properties to reflect changes.
      UpdatePageMargins;
  finally
    FreeAndNil(Dlg);
  end;
end;

class function TPageSetupDlgMgr.MMToDlgUnits(const Value: Double): Integer;
  {Converts millimeters to units required by Page Setup dialog.
    @param Value [in] Millimeters to convert.
    @return Converted value in dialog box units.
  }
const
  // Bug error message
  cBadValueBug = '.MMToDlgUnits: Unexpected TMeasurementUnits value';
begin
  // Page Setup dialog stores different values depending on units of
  // measurement being used. If millimeters are being used, dialog box stores
  // values in 100ths of a millimeter. If inches are being used values are
  // stored in 1000th of an inch.
  case Preferences.MeasurementUnits of
    muInches: Result := Round(1000.0 * MMToInches(Value));
    muMillimeters: Result := Round(100 * Value);
    else raise EBug.Create(ClassName + cBadValueBug);
  end;
end;

end.