打印的单位转换问题？

Screen.PixelsPerInch这个可以取得每英寸的象素数,然后一英寸等于25.4毫米.

dpi表示的是每英寸多少个像素点，据此可以换算

//取得水平方向每英寸Canvas的点数
function HPointsPerInch(Canvas: TCanvas): Integer; overload;
begin
  Result := GetDeviceCaps(Canvas.Handle, LOGPIXELSX);
end;//取得纵向方向每英寸Canvas的点数
function VPointsPerInch(Canvas: TCanvas): Integer; overload;
begin
  Result := GetDeviceCaps(Canvas.Handle, LOGPIXELSY)
end;//取得纵向方向每英寸打印机的光栅数
function VPointsPerInch: Integer; overload;
begin
  Result := GetDeviceCaps(Printer.Handle, LOGPIXELSY)
end;//取得水平方向每英寸打印机的点数
function HPointsPerInch: Integer; overload;
begin
  Result := GetDeviceCaps(Printer.Handle, LOGPIXELSX);
end;//横向点单位转换为毫米单位
function XPointToMm(Pos: Integer): Extended;
begin
  Result := Pos*25.4/HPointsPerInch;
end;//纵向点单位转换为毫米单位
function YPointToMm(Pos: Integer): Extended;
begin
  Result := Pos*25.4/VPointsPerInch;
end;

unit PPanel;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls, Printers, StdCtrls, DBCtrls, Mask, ComCtrls, Grids, DBGrids,
  Chart;type
  TPPanel = class(TPanel)
  private
    { Private declarations }
    SX,SY:Real;
    FShowBorder:Boolean;    FXOffset:Integer;
    FYOffset:Integer;    PreviewForm:TForm;
  protected
    { Protected declarations }
  public
    { Public declarations }
    Constructor Create(AOwner:TComponent); Override;
    Procedure PrintToCanvas(ACanvas:TCanvas);    Procedure WhenKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
    Procedure WhenFormPaint(Sender: TObject);
    Procedure WhenFormClose(Sender: TObject; var Action: TCloseAction);
  published
    { Published declarations }
    Function  Print(Preview:Boolean):Boolean;
    Procedure About;    Property ShowBorder:Boolean Read FShowBorder Write FShowBorder;
    Property XOffset:Integer Read FXOffset Write FXOffset;
    Property YOffset:Integer Read FYOffset Write FYOffset;
  end;procedure Register;implementation//注册组件
procedure Register;
begin
  RegisterComponents('Standard', [TPPanel]);
end;Constructor TPPanel.Create(AOwner:TComponent);
Begin
     Inherited;     FXOffset:=0;
     FYOffset:=0;
End;//关于组件
Procedure TPPanel.About;
Begin
     Application.MessageBox('PPanel 作者：彭富章 2000.03','关于 PPanel',MB_OK+MB_ICONINFORMATION);
End;//打印预览窗口键盘按下
Procedure TPPanel.WhenKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
Begin
     If Key=VK_Return Then
     Begin
          Self.Print(False);
          If Sender Is TForm Then
             TForm(Sender).ModalResult:=mrOK;
     End
     Else If Key=VK_ESCAPE Then
          PreViewForm.Close;
End;//窗口刷新
Procedure TPPanel.WhenFormPaint(Sender: TObject);
Begin
     PrintToCanvas(PreviewForm.Canvas);
End;//窗口关闭
Procedure TPPanel.WhenFormClose(Sender: TObject; var Action: TCloseAction);
Begin
     Action:=caFree;
End;//打印
Function TPPanel.Print(Preview:Boolean):Boolean;
Begin
     Result:=False;
     If Preview Then
     Begin
          SX:=1.0;
          SY:=1.0;          PreViewForm:=TForm.Create(Application);
          PreViewForm.Caption:='打印预览按[Enter]打印按[Esc] 关闭';
          PreViewForm.BorderStyle:=bsDialog;
          PreViewForm.ClientWidth:=self.Width;
          PreViewForm.ClientHeight:=self.Height;
          PreViewForm.Color:=clWhite;
          PreviewForm.Position:=poScreenCenter;          PreviewForm.OnKeyDown:=WhenKeyDown;
          PreviewForm.OnPaint:=WhenFormPaint;
          PreviewForm.OnClose:=WhenFormClose;          If PreViewForm.ShowModal=mrOK Then
             Result:=True;
     End
     Else
     Begin
          SX:=GetDeviceCaps(Printer.Handle,logPixelsX)/Screen.PixelsPerInch;
          SY:=GetDeviceCaps(Printer.Handle,logPixelsY)/Screen.PixelsPerInch;          Printer.BeginDoc;
          Printer.Title:='Doc printed by PrintPanel '+FormatDateTime('YYYY-MM-DD HH:MM:SS',Now);
          PrintToCanvas(Printer.Canvas);
          Printer.EndDoc;          Result:=True;
     End;
End;//绘制到指定画布
Procedure TPPanel.PrintToCanvas(ACanvas:TCanvas);
Var NowPage:Integer;
    I,N:Integer;
    AObj:TControl;
    ARect:TRect;
    PX,PY:Integer;
    Stemp:String;    WidthArray:Array[1..24] of Integer;
    ValueArray:Array[1..24] Of String;
    ColumnCount,X,Y,NowX,NowY:Integer;    NowRow:Integer;
Begin
     NowPage:=1;     Try
     ACanvas.Lock;     With ACanvas Do
     For I:=0 To ControlCount-1 Do
     If Controls[I].Visible Then
     Begin
          AObj:=Controls[I];
          ARect:=AObj.BoundsRect;          ARect.Left:=ARect.Left+FXOffset;
          ARect.Top:=ARect.Top+FYOffset;
          ARect.Right:=ARect.Right+FXOffset;
          ARect.Bottom:=ARect.Bottom+FYOffset;          PX:=Round((ARect.Left+4)*SX);
          PY:=Round((ARect.Top+2)*SY);          ARect.Left:=Round(ARect.Left*SX);
          ARect.Top:=Round(ARect.Top*SY);
          ARect.Right:=Round(ARect.Right*SX);
          ARect.Bottom:=Round(ARect.Bottom*SY);          Font:=self.Font;          If (FShowBorder ) Then //OR (AObj Is TStringGrid)
          If ((AObj Is TEdit) OR (AObj Is TDBEdit) OR (AObj Is TMaskEdit) OR (AObj Is TDateTimePicker) OR (AObj Is TComboBox)
          OR (AObj Is TDbComboBox) OR (AObj Is TMemo) OR (AObj Is TDBmemo) OR (AObj Is TDBGrid) OR (AObj Is TStringGrid)) Then
          Begin
               Pen.Width:=1;
               MoveTo(ARect.Left,ARect.Top);
               LineTo(ARect.Right,ARect.Top);
               LineTo(ARect.Right,ARect.Bottom);
               LineTo(ARect.Left,ARect.Bottom);
               LineTo(ARect.Left,ARect.Top);
          End;.

var
  ScaleX,ScaleY:Integer;
  MapRect:TRect;
begin
//设置像素点放大系数
   ScaleX:=GetDeviceCaps(Printer.Handle,LogPixelsX) div PixelsPerInch;
   ScaleY:=GetDeviceCaps(Printer.Handle,LogPixelsY) div PixelsPerInch;   MapRect:=Rect(0, 0, Image1.Picture.Width * ScaleX , Image1.Picture.Height * ScaleY);   // * ScaleX   * ScaleY
   //设置位图在打印机上的输出区域
   Printer.BeginDoc;          //开始打印作业
   Printer.Canvas.StretchDraw(MapRect,Image1.Picture.Graphic);//输出位图
   Printer.EndDoc;            //结束打印作业

调试易

打印的单位转换问题？

解决方案 »