delphi - 如何使用 AggPas 绘制埃 (Å)？

Question

总结:

没有找到如何使用 AggPas 库输出埃符号。

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AggPas 库中的文本绘制函数采用 PAnsiChar 参数。我想知道如何使用 PAnsiChar 指向包含埃 (Å) 的文本？

  SetThreadLocale($0409);                                       // No difference.

  ShowMessage(Chr(0197));                                       // Correct
  ShowMessage(AnsiString(Chr(0197)));                           // Wrong - question mark
  ShowMessage(PAnsiChar(Chr(0197)));                            // AV
  ShowMessage(UTF8String(Chr(0197)));                           // Correct
  ShowMessage(UTF8Encode(Chr(0197)));                           // Correct
  ShowMessage(RawByteString(Chr(0197)));                        // Wrong - question mark

  ShowMessage(AnsiString(UTF8String(Chr(0197))));               // Wrong - question mark
  ShowMessage(AnsiString(UTF8Encode(Chr(0197))));               // Correct

  ShowMessage(RawByteString(UTF8String(Chr(0197))));            // Wrong - question mark
  ShowMessage(RawByteString(UTF8Encode(Chr(0197))));            // Correct

  ShowMessage(PAnsiChar(AnsiString(UTF8Encode(Chr(0197)))));    // Wrong - strange character
  ShowMessage(PAnsiChar(RawByteString(UTF8Encode(Chr(0197))))); // Wrong - strange character

为方便起见，以下代码中的 DrawTextCenterAligned 过程无法输出埃字母。

    unit u2DRenderEngine_aggpas;

    interface

    uses
      u2DRenderEngine, uMathVector3D,
      agg_2D,
      Graphics, IniFiles, Types;

    type
      T2DRenderEngine_aggpas = class;

      T2DRenderEngine_aggpas = class(T2DRenderEngine)

      private
        fFontBMP: TBitmap;
        fVG: Agg2D;

      protected

        function GetActualStringBoundingBox(aText: string; aFont: TFont)
          : TRect; override;

      public

        constructor Create;
        destructor Destroy; override;

        procedure AttachBMP(aBMP: TBitmap; flip_y: Boolean);

        procedure Flush; override;

        procedure DrawLine(aP, bP: TPoint3D; aPen: TPen); override;
        procedure DrawCircle(Center: TPoint3D; Radius: Extended;
          R, G, B: Integer); override;
        procedure FillCircle(Center: TPoint3D; Radius: Extended;
          R, G, B: Integer); override;
        procedure DrawPolygon(aPts: TAPoint3D; R, G, B: Integer); override;
        procedure FillPolygon(aPts: TAPoint3D; R, G, B: Integer); override;

        procedure DrawTextLeftAligned(aLeft: TPoint3D; aText: string; aFont: TFont;
          clearBackground: Boolean); override;
        procedure DrawTextCenterAligned(aCenter: TPoint3D; aText: string;
          aFont: TFont; clearBackground: Boolean); override;

      end;

    implementation

    uses
      u2DUtils_Vcl, SysUtils, Math;

    { TRenderEngine_2D_aggpas }

    constructor T2DRenderEngine_aggpas.Create;
    begin
      inherited;

      fFontBMP := TBitmap.Create;
      fFontBMP.Width := 2;
      fFontBMP.Height := 2;

      fVG.Construct;
    end;

    destructor T2DRenderEngine_aggpas.Destroy;
    begin

      inherited;
    end;

    procedure T2DRenderEngine_aggpas.AttachBMP(aBMP: TBitmap; flip_y: Boolean);
    var
      tmpBuffer: pointer;
      tmpStride: Integer;
    begin
      if aBMP.Empty then
        raise Exception.Create('AttachBMP: aBMP is Empty!');

      if aBMP.PixelFormat <> pf32bit then
        raise Exception.Create('AttachBMP: aBMP should be 32bit!');

      tmpStride := Integer(aBMP.ScanLine[1]) - Integer(aBMP.ScanLine[0]);

      if tmpStride < 0 then
        tmpBuffer := aBMP.ScanLine[aBMP.Height - 1]
      else
        tmpBuffer := aBMP.ScanLine[0];

      if flip_y then
        tmpStride := tmpStride * -1;

      fVG.attach(tmpBuffer, aBMP.Width, aBMP.Height, tmpStride);
    end;

    procedure T2DRenderEngine_aggpas.Flush;
    begin
    end;

    procedure T2DRenderEngine_aggpas.DrawLine(aP, bP: TPoint3D; aPen: TPen);
    begin
      fVG.line(aP.X, aP.Y, bP.X, bP.Y);
    end;

    procedure T2DRenderEngine_aggpas.DrawCircle(Center: TPoint3D; Radius: Extended;
      R, G, B: Integer);
    begin
      fVG.lineColor(R, G, B);
      fVG.noFill;
      fVG.ellipse(Center.X, Center.Y, Radius, Radius);
    end;

    procedure T2DRenderEngine_aggpas.FillCircle(Center: TPoint3D; Radius: Extended;
      R, G, B: Integer);
    begin
      fVG.fillColor(R, G, B);
      fVG.noLine;
      fVG.ellipse(Center.X, Center.Y, Radius, Radius);
    end;

    procedure T2DRenderEngine_aggpas.DrawPolygon(aPts: TAPoint3D; R, G, B: Integer);
    var
      Len, I: Integer;
      poly: array of double;
    begin
      Len := Length(aPts);

      SetLength(poly, Len * 2);
      for I := 0 to Len - 1 do
      begin
        poly[2 * I] := aPts[I].X;
        poly[2 * I + 1] := aPts[I].Y;
      end;

      fVG.lineColor(R, G, B);
      fVG.noFill;
      fVG.polygon(@poly[0], 4);
    end;

    procedure T2DRenderEngine_aggpas.FillPolygon(aPts: TAPoint3D; R, G, B: Integer);
    var
      Len, I: Integer;
      poly: array of double;
    begin
      Len := Length(aPts);

      SetLength(poly, Len * 2);
      for I := 0 to Len - 1 do
      begin
        poly[2 * I] := aPts[I].X;
        poly[2 * I + 1] := aPts[I].Y;
      end;

      fVG.fillColor(R, G, B);
      fVG.noLine;
      fVG.polygon(@poly[0], 4);
    end;

    procedure T2DRenderEngine_aggpas.DrawTextLeftAligned(aLeft: TPoint3D;
      aText: string; aFont: TFont; clearBackground: Boolean);
    var
      tmpRect: TRect;
      tmpRectWidth, tmpRectHeight: Integer;
      tmpPt: TPoint3D;
    begin
      tmpRect := GetActualStringBoundingBox(aText, aFont);
      tmpRectWidth := tmpRect.Right - tmpRect.Left;
      tmpRectHeight := tmpRect.Bottom - tmpRect.Top;
      tmpPt.X := aLeft.X;
      tmpPt.Y := aLeft.Y - tmpRectHeight;

      if clearBackground then
      begin
        fVG.fillColor(255, 255, 255);
        fVG.noLine;
        fVG.Rectangle(tmpPt.X, tmpPt.Y, tmpPt.X + tmpRectWidth,
          tmpPt.Y + tmpRectHeight);
      end;

      // Font & Colors
      fVG.fillColor(0, 0, 0);
      fVG.noLine;
      fVG.TextHints(True);
      if Agg2DUsesFreeType then
        fVG.Font(PAnsiChar(AnsiString(UTF8Encode(LowerCase(aFont.Name) + '.ttf'))),
          Abs(aFont.Height))
      else
        fVG.Font('Arial', 40.0);
      // Text
      fVG.Text(tmpPt.X, tmpPt.Y + tmpRectHeight, PAnsiChar(AnsiString(aText)));
    end;

    procedure T2DRenderEngine_aggpas.DrawTextCenterAligned(aCenter: TPoint3D;
      aText: string; aFont: TFont; clearBackground: Boolean);
    var
      tmpRect: TRect;
      tmpRectWidth, tmpRectHeight: Integer;
      tmpPt: TPoint3D;
    begin
      tmpRect := GetActualStringBoundingBox(aText, aFont);
      tmpRectWidth := tmpRect.Right - tmpRect.Left;
      tmpRectHeight := tmpRect.Bottom - tmpRect.Top;
      tmpPt.X := aCenter.X - tmpRectWidth / 2.0;
      tmpPt.Y := aCenter.Y - tmpRectHeight / 2.0;

      if clearBackground then
      begin
        fVG.fillColor(255, 255, 255);
        fVG.noLine;
        fVG.Rectangle(tmpPt.X, tmpPt.Y, tmpPt.X + tmpRectWidth,
          tmpPt.Y + tmpRectHeight);
      end;

      // Font & Colors
      fVG.fillColor(0, 0, 0);
      fVG.noLine;
      fVG.TextHints(True);
      if Agg2DUsesFreeType then
        fVG.Font(PAnsiChar(AnsiString(UTF8Encode(LowerCase(aFont.Name) + '.ttf'))),
          Abs(aFont.Height))
      else
        fVG.Font('Arial', 40.0);
      // Text
      fVG.Text(tmpPt.X, tmpPt.Y + tmpRectHeight, PAnsiChar(AnsiString(aText)));
    end;

    function T2DRenderEngine_aggpas.GetActualStringBoundingBox(aText: string;
      aFont: TFont): TRect;
    var
      tmpRectWidth, tmpRectHeight: Integer;
    begin
      Self.fFontBMP.Canvas.Font.Assign(aFont);
      tmpRectWidth := Self.fFontBMP.Canvas.TextWidth(aText);
      tmpRectHeight := Self.fFontBMP.Canvas.TextHeight(aText);

      // 2011-03-07 hard-coded
      tmpRectWidth := Ceil(tmpRectWidth * 1.05);
      // 2011-03-07 hard-coded
      tmpRectHeight := Ceil(tmpRectHeight * 0.70);

      FillChar(Result, SizeOf(Result), 0);
      Result.Right := tmpRectWidth;
      Result.Bottom := tmpRectHeight;
    end;

    end.

Answer 1

如果设备将其输入视为 PAnsiChar，那么您就完蛋了。除非系统上的默认代码页可以对 Å 字符进行编码，否则根本无法将该信息放入 ANSI CHAR 中。如果这样的编码可用，那么现在显示问号的所有例程都将显示正确的字符。

<小时/>

稍长的信息:

Unicode正在编码大量的字符，包括所有书面语言的所有字符、特殊符号、音符，空间如此之大，竟然有克林贡字符的编码! Ansi 字符使用表查找进行编码，该表查找将可以在一个字节中编码的值映射到一组 Unicode 字符。

使用 AnsiString 时，一次只能使用少于 256 个 Unicode 字符。当您尝试将一个 Unicode 字符编码为一个 AnsiString 时，您实际上会在代码页表中进行查找，寻找指向原始 Unicode 字符的代码。如果没有这样的编码可用，您会得到著名的问号!

<小时/>

这是一个将字符串转换为 UTF8 字符串并将其作为 AnsiString 返回的例程(所有 UTF8 实际上都是有效的 - 但毫无意义 - AnsiString):

function Utf8AsAnsiString(s:string):AnsiString;
var utf8s:UTF8String;
begin
  utf8s := UTF8String(s);
  SetLength(Result, Length(utf8s));
  if Length(utf8s) > 0 then
    Move(utf8s[1], Result[1], Length(utf8s));
end;

您可以传递该函数的结果并希望该单元可以处理UTF8。祝你好运。