光滑字体

先将文字放大一倍字号画到临时内存中, 再用AntiAlias算法缩小, 绝对光滑.
而且速度很快.我这有个AntiAlias算法的例子, 很简单但很说明问题:
其中核心代码如下:
procedure TAntiAliasForm.SeparateColor(color : TColor;
    var r, g, b : Integer);
begin
    r := color Mod 256;
    g := (color Div 256) Mod 256;
    b := color Div 65536;
end;

procedure TAntiAliasForm.CmdGoClick(Sender: TObject);
var
    txt                       : String;
    wid, hgt, x, y, i, j      : Integer;
    r, g, b, totr, totg, totb : Integer;
begin
    txt := InputText.Text;

    // Use the correct colors.
    big_bm.Canvas.Font.Color := InputText.Font.Color;
    big_bm.Canvas.Brush.Color := InputText.Color;

    // Set the new font.
    big_bm.Canvas.Font := InputText.Font;
    big_bm.Canvas.Font.Size := 2 * InputText.Font.Size;
    big_bm.Canvas.Refresh; // Make the font take effect.

    // Make big_bm and BigBox big enough.
    wid := big_bm.Canvas.TextWidth(txt);
    hgt := Round(big_bm.Canvas.TextHeight(txt) * 1.1);
    big_bm.Width := wid;
    big_bm.Height := hgt;
    big_bm.Canvas.Refresh;
    BigBox.Width := wid;
    BigBox.Height := hgt;
    BigBox.Refresh;

// Draw the text in big_bm.
big_bm.Canvas.TextOut(0, 0, txt);

// Display it in BigBox.
BigBox.Invalidate;

    // ********************************
    // Anti-alias the text into out_bm.
    // ********************************
    // Create a new out_bm.
    // out_bm.Free;                    - Removed by RLV on 12/29/97
    // out_bm := TBitmap.Create;       - Removed by RLV on 12/29/97
    out_bm.Width := wid Div 2;
    out_bm.Height := hgt Div 2;
    out_bm.Canvas.Refresh;

    // The "- 3" keeps us from falling off the edge
    // of BigBox. Over the edge Point would
    // return -1 and mess up the colors.
    for y := 0 to (big_bm.Height - 3) Div 2 do
    begin
        for x := 0 to (big_bm.Width - 3) Div 2 do
        begin
            // Compute the value of output pixel (x, y).
            totr := 0;
            totg := 0;
            totb := 0;
            for j := 0 to 1 do
            begin
                for i := 0 to 1 do
                begin
                    SeparateColor(big_bm.Canvas.Pixels
                        [2 * x + i, 2 * y + j], r, g, b);
                    totr := totr + r;
                    totg := totg + g;
                    totb := totb + b;
                end;
            end;
            out_bm.Canvas.Pixels[x, y] :=
                RGB(totr Div 4, totg Div 4, totb Div 4);
        end;
    end;
    OutBox.Invalidate;

// Remove the hourglass cursor.
Screen.Cursor := crDefault;
end;

当然, 它的代码还可以进一步优化, 比如用scanline代替pixels, 速度可以进一步
提高.