Delphi XE5开发Android程序使用自定义字体文件.

最近在做一个电子书阅读器的Android小程序来验证Delphi XE5的移动开发功能.
万事大吉,只欠根据字体文件(.ttf文件)切换阅读字体,通常Android系统只带三种以下字体.一般用Java/Eclipse开发的话比较简单,typeface的createFromAsset,createFromFile之类的很容易使用.
但是由于FireMonkey是跨平台的类库,必然不能和平台帮得太紧,所以提供了抽象的封装.
但是也许Delphi XE5是Android平台的第一个版本,有些地方难免有疏漏,FireMonkey的封装没有提供更换字体的功能.

但是我要实现的电子书阅读器换字体几乎是必须要实现的功能,所以只能给FireMonkey动动小手术了.

FireMonkey的字体加载是由抽象类TFontGlyphManager来实现的,在各个具体平台又有不同的实现,TWinFontGlyphManager,TIOSFontGlyphManager,TMacFontGlyphManager,TAndroidFontGlyphManager.

我们这里只针对Android不能加载字体文件换字体进行手术.

把TAndroidFontGlyphManager的实现单元FMX.FontGlyphs.Android拷贝到我们自己要使用更换字的的工程的目录中.修改TAndroidFontGlyphManager.LoadResource方法,当应用某字体的时候先判断我们指定的目录中是否存在同名的.ttf文件.有的话优先使用我们的字体文件.

做了两处改动.一处是uses添加了System.IOUtils单元.一处是TAndroidFontGlyphManager.LoadResource.
在这里做这样的小手术好处是我们的程序不收任何影响.例如:
Text1.Font.Family:=’微软雅黑’;
Text2.Font.Family:=’楷体’;
那么只要在我们指定的目录中存在”楷体.ttf”和”微软雅黑.ttf”那么这两个控件的字体就会分别应用对应的字体文件.

希望XE6版本中Android能投提供一种让我们动态加载字体的办法.不过也许我这个不是一个大众需求,毕竟大多数Android软件不需要太多的字体文件,在系统两三款字体下也活得好好的.

下面贴出来我修改过的文件.

{ ******************************************************* }
{ }
{ Delphi FireMonkey Platform }
{ Copyright(c) 2013 Embarcadero Technologies, Inc. }
{ }
{ ******************************************************* }

unit FMX.FontGlyphs.Android;

interface

uses
  System.Types, System.Classes, System.SysUtils, System.UITypes,
  System.UIConsts, System.Generics.Collections,
  FMX.Types, FMX.Surfaces, FMX.FontGlyphs, FMX.PixelFormats,
  Androidapi.JNI.JavaTypes, Androidapi.JNI.GraphicsContentViewText,
  Androidapi.JNIBridge;

{$SCOPEDENUMS ON}

type

  TAndroidFontGlyphManager = class(TFontGlyphManager)
  private
    FPaint: JPaint;
    // Current metrics
    FSpacing: Single;
    FTop: Single;
    FTopInt: Integer;
    FAscent: Single;
    FDescent: Single;
    FBottom: Single;
    FBottomInt: Integer;
    FLeading: Single;
    FLeadingInt: Integer;
  protected
    procedure LoadResource; override;
    procedure FreeResource; override;
    function DoGetGlyph(const Char: UCS4Char;
      const Settings: TFontGlyphSettings): TFontGlyph; override;
  public
    constructor Create;
    destructor Destroy; override;
  end;

implementation

uses
  System.Math, System.Character,
  Androidapi.Bitmap,
  //引入System.IOUtils是为了能够获取Android的各种系统目录
  System.IOUtils,
  //
  FMX.Graphics;

{ TAndroidFontGlyphManager }

constructor TAndroidFontGlyphManager.Create;
begin
  inherited Create;
  FPaint := TJPaint.Create;
end;

destructor TAndroidFontGlyphManager.Destroy;
begin
  FPaint := nil;
  inherited;
end;

procedure TAndroidFontGlyphManager.LoadResource;
const
  BoldAndItalic = [TFontStyle.fsBold, TFontStyle.fsItalic];
var
  TypefaceFlag: Integer;
  Typeface: JTypeface;
  FamilyName: JString;
  Metrics: JPaint_FontMetrics;
  MetricsInt: JPaint_FontMetricsInt;
  FontFile: string;
begin
  FPaint.setAntiAlias(True);
  FPaint.setTextSize(CurrentSettings.Size * CurrentSettings.Scale);
  FPaint.setARGB(255, 255, 255, 255);
  FPaint.setUnderlineText(TFontStyle.fsUnderline in CurrentSettings.Style);
  FPaint.setStrikeThruText(TFontStyle.fsStrikeOut in CurrentSettings.Style);
  if TOSVersion.Check(4, 0) then
    FPaint.setHinting(TJPaint.JavaClass.HINTING_ON);
  // Font
  try
    FamilyName := StringToJString(CurrentSettings.Family);
    if (BoldAndItalic * CurrentSettings.Style) = BoldAndItalic then
      TypefaceFlag := TJTypeface.JavaClass.BOLD_ITALIC
    else if TFontStyle.fsBold in CurrentSettings.Style then
      TypefaceFlag := TJTypeface.JavaClass.BOLD
    else if TFontStyle.fsItalic in CurrentSettings.Style then
      TypefaceFlag := TJTypeface.JavaClass.ITALIC
    else
      TypefaceFlag := TJTypeface.JavaClass.NORMAL;

    { Fix Begin 修改开始.如果在下载目录中存在跟字体同名的.ttf文件,那么优先使用ttf文件.
      我是放在SD卡的下载目录中.大家可以按需要任意改这个位置.
      甚至也可以放在Asset目录中,这样可以打包在APK中.
    }
    FontFile := TPath.GetSharedDownloadsPath + PathDelim +
      CurrentSettings.Family + '.ttf';
    if FileExists(FontFile) then
      Typeface := TJTypeface.JavaClass.createFromFile(StringToJString(FontFile))
    else
      Typeface := TJTypeface.JavaClass.Create(FamilyName, TypefaceFlag);
    { Fix End 修改结束 }
    FPaint.setTypeface(Typeface);
    try
      Metrics := FPaint.getFontMetrics;
      MetricsInt := FPaint.getFontMetricsInt;
      //
      FSpacing := FPaint.getFontMetrics(Metrics);
      FTop := Metrics.top;
      FTopInt := MetricsInt.top;
      FAscent := Metrics.ascent;
      FDescent := Metrics.descent;
      FBottom := Metrics.bottom;
      FBottomInt := MetricsInt.bottom;
      FLeading := Metrics.leading;
      FLeadingInt := MetricsInt.leading;

      // SysDebug(FloatToStr(CurrentSettings.Size) + ':' + FloatToStr(CurrentSettings.Scale));
      // Log.d(Format('Top=(%d %f) Bottom=(%d %f) Leading=(%d %f) FAscent=(%d %f)', [FTopInt, FTop, FBottomInt, FBottom, FLeadingInt, FLeading, MetricsInt.ascent, FAscent]));
    finally
      Metrics := nil;
      MetricsInt := nil;
    end;
  finally
    FamilyName := nil;
    Typeface := nil;
  end;
end;

procedure TAndroidFontGlyphManager.FreeResource;
begin
  if Assigned(FPaint) then
    FPaint.reset;
end;

function TAndroidFontGlyphManager.DoGetGlyph(const Char: UCS4Char;
  const Settings: TFontGlyphSettings): TFontGlyph;
var
  Text: JString;
  Bitmap: JBitmap;
  Canvas: JCanvas;
  GlyphRect: TRect;
  C, I, J, Width, Height: Integer;
  Advance: Single;
  Bounds: JRect;
  GlyphStyle: TFontGlyphStyles;
  PixelBuffer: Pointer;
  Data: PIntegerArray;
  Path: JPath;
  PathMeasure: JPathMeasure;
  PathLength: Single;
  Coords: TJavaArray<Single>;
  StartPoint, LastPoint, Point: TPointF;
  NewContour, HasStartPoint: Boolean;
begin
  try
    Text := StringToJString(System.Char.ConvertFromUtf32(Char));
    Advance := FPaint.measureText(Text);
    // SysDebug(Format('%s %f', [System.Char.ConvertFromUtf32(Char), Advance]));
    Height := Abs(FTopInt) + Abs(FBottomInt) + 2;
    Width := Ceil(Abs(Advance)) + 2;
    try
      Bitmap := TJBitmap.JavaClass.createBitmap(Width, Height,
        TJBitmap_Config.JavaClass.ARGB_8888);
      try
        Bounds := TJRect.Create;
        FPaint.getTextBounds(Text, 0, Text.length, Bounds);
        // Log.d(Format('Bounds=(%d %d %d %d) %d %d ', [Bounds.left, Bounds.top, Bounds.right, Bounds.bottom, Bounds.width, Bounds.height]));
        try
          Canvas := TJCanvas.JavaClass.init(Bitmap);
          Canvas.drawText(Text, 0, -Trunc(FAscent), FPaint);
        finally
          Canvas := nil;
        end;

        GlyphStyle := [];
        if ((FAscent = 0) and (FDescent = 0)) or not HasGlyph(Char) then
          GlyphStyle := [TFontGlyphStyle.NoGlyph];
        if TFontGlyphSetting.gsPath in Settings then
          GlyphStyle := GlyphStyle + [TFontGlyphStyle.HasPath];

        Result := TFontGlyph.Create(TPoint.Create(Bounds.left,
          Abs(FTopInt - Bounds.top)), Advance, Abs(FTopInt) + Abs(FBottomInt) +
          Abs(FLeadingInt), GlyphStyle);

        if (TFontGlyphSetting.gsBitmap in Settings) and
          (HasGlyph(Char) or ((FAscent <> 0) or (FDescent <> 0))) and
          (AndroidBitmap_lockPixels(TJNIResolver.GetJNIEnv,
          (Bitmap as ILocalObject).GetObjectID, @PixelBuffer) = 0) then
        begin
          Data := PIntegerArray(PixelBuffer);
          GlyphRect.left := Bounds.left;
          GlyphRect.Right := Bounds.Right;
          GlyphRect.top := Abs(Trunc(FAscent) - Bounds.top);
          GlyphRect.bottom := Abs(Trunc(FAscent) - Bounds.bottom);
          // Log.d(Format('GlyphRect=(%d %d %d %d) %d %d', [GlyphRect.Left, GlyphRect.Top, GlyphRect.Right, GlyphRect.Bottom, GlyphRect.Width, GlyphRect.Height]));

          if (GlyphRect.Width > 0) or (GlyphRect.Height > 0) then
          begin
            Result.Bitmap.SetSize(GlyphRect.Width + 1, GlyphRect.Height + 1,
              TPixelFormat.pfA8R8G8B8);
            if TFontGlyphSetting.gsPremultipliedAlpha in Settings then
            begin
              for I := GlyphRect.top to GlyphRect.bottom do
                Move(Data[I * Width + Max(GlyphRect.left, 0)],
                  Result.Bitmap.GetPixelAddr(0, I - GlyphRect.top)^,
                  Result.Bitmap.Pitch);
            end
            else
              for I := GlyphRect.top to GlyphRect.bottom - 1 do
                for J := GlyphRect.left to GlyphRect.Right - 1 do
                begin
                  C := Data[I * Width + J];
                  if C <> 0 then
                  begin
                    C := ((C shr 16) and $FF + (C shr 8) and
                      $FF + (C and $FF)) div 3;
                    Result.Bitmap.Pixels[J - GlyphRect.left, I - GlyphRect.top]
                      := MakeColor($FF, $FF, $FF, C);
                  end
                end;
          end;
          AndroidBitmap_unlockPixels(TJNIResolver.GetJNIEnv,
            (Bitmap as ILocalObject).GetObjectID);
        end;
        // Path
        if TFontGlyphSetting.gsPath in Settings then
          try
            Path := TJPath.Create;
            FPaint.getTextPath(Text, 0, Text.length, Result.Origin.X,
              Result.Origin.Y, Path);
            PathMeasure := TJPathMeasure.Create;
            PathMeasure.setPath(Path, False);
            Coords := TJavaArray<Single>.Create(2);
            if PathMeasure.getLength > 0 then
              repeat
                PathLength := PathMeasure.getLength;
                NewContour := True;
                HasStartPoint := False;
                I := 0;
                while I < PathLength do
                begin
                  if PathMeasure.getPosTan(I, Coords, nil) then
                  begin
                    Point := PointF(Coords[0], Coords[1]);
                    if NewContour then
                    begin
                      Result.Path.MoveTo(Point);
                      NewContour := False;
                      HasStartPoint := False;
                    end
                    else if Point <> LastPoint then
                    begin
                      if HasStartPoint and (LastPoint <> StartPoint) then
                        if not SameValue
                          (((Point.Y - StartPoint.Y) / (Point.X - StartPoint.X)
                          ), ((Point.Y - LastPoint.Y) / (Point.X - LastPoint.X)
                          ), Epsilon) then
                        begin
                          Result.Path.LineTo(Point);
                          HasStartPoint := False;
                        end
                        else
                      else
                        Result.Path.LineTo(Point);
                    end;
                    LastPoint := Point;
                    if not HasStartPoint then
                    begin
                      StartPoint := Point;
                      HasStartPoint := True;
                    end;
                  end;
                  Inc(I);
                end;
                if Result.Path.Count > 0 then
                  Result.Path.ClosePath;
              until not PathMeasure.nextContour;
            Point := Result.Path.GetBounds.TopLeft;
            Result.Path.Translate(-Point.X + Result.Origin.X,
              -Point.Y + Result.Origin.Y);
          finally
            FreeAndNil(Coords);
            Path := nil;
            PathMeasure := nil;
          end;
      finally
        Bounds := nil;
      end;
    finally
      Bitmap.recycle;
      Bitmap := nil;
    end;
  finally
    Text := nil;
  end;
end;

end.