Delphi XE5开发Android程序使用自定义字体文件.

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 .