IDWriteGdiInterop 接口的主要用途是它提供 IDWriteBitmapRenderTarget 留出了 HDC 接口，以与 GDI、GDI+ 交互；
另提供了 LOGFONT 结构与 IDWriteFont、IDWriteFontFace 的相互转换的方法。
IDWriteGdiInterop = interface(IUnknown)
function CreateFontFromLOGFONT( { LOGFONT -> IDWriteFont }
var logFont: LOGFONTW; //
out font: IDWriteFont //
): HResult; stdcall;
function ConvertFontToLOGFONT( { IDWriteFont -> LOGFONT }
font: IDWriteFont; //
var logFont: LOGFONTW; //
var isSystemFont: BOOL //如果指定的字体对象是系统字体集合的一部分则返回 True
): HResult; stdcall;
function ConvertFontFaceToLOGFONT( { IDWriteFontFace -> LOGFONT }
var font: IDWriteFontFace; //
var logFont: LOGFONTW //
): HResult; stdcall;
function CreateFontFaceFromHdc( { HDC -> IDWriteFontFace }
hdc: HDC; //
out fontFace: IDWriteFontFace //
): HResult; stdcall;
function CreateBitmapRenderTarget( { Create IDWriteBitmapRenderTarget }
hdc: HDC; //
width: Cardinal; //
height: Cardinal; //
out renderTarget: IDWriteBitmapRenderTarget //
): HResult; stdcall;
end;
{ 封装可用于呈现字形的位图和内存 DC }
IDWriteBitmapRenderTarget = interface(IUnknown)
function DrawGlyphRun( { 将字形串绘制到位图中的指定黑框矩形中 }
baselineOriginX: Single; //水平位置(DIP)
baselineOriginY: Single; //垂直位置(DIP)
measuringMode: TDWriteMeasuringMode; //用于字形串中各字形的度量方法
var glyphRun: TDwriteGlyphRun; //包含字形串属性的结构
renderingParams: IDWriteRenderingParams; //控制呈现行为的对象
textColor: COLORREF; //文本的前景色
blackBoxRect: PRect //黑框矩形(单位像素), 可选
): HResult; stdcall;
function GetMemoryDC: HDC; stdcall; { 获取内存设备上下文的句柄 }
function GetPixelsPerDip: Single; stdcall; { 设置每个 DIP 的位图像素数；1 DIP(与设备无关的像素) = 1/96 英寸 }
function SetPixelsPerDip(pixelsPerDip: Single): HResult; stdcall; { 获取每个 DIP 的位图像素数 }
function GetCurrentTransform(var transform: TDwriteMatrix): HResult; stdcall; { 获取将抽象坐标映射为 DIP 的转换, 和世界转换无关 }
function SetCurrentTransform(var transform: TDwriteMatrix): HResult; stdcall; { 设置将抽象坐标映射为 DIP 的转换, 和世界转换无关 }
function GetSize(var size: TSize): HResult; stdcall; { 获取位图尺寸 }
function Resize(width: Cardinal; height: Cardinal): HResult; stdcall; { 调整位图大小 }
end;
{LOGFONTW 结构}
tagLOGFONTW = record
lfHeight: Longint; //指定字体的字符单元或字符的高度
lfWidth: Longint; //指定字体中的字符的平均宽度
lfEscapement: Longint; //指定设备的行距向量和 x 轴之间的角度, 单位 1/10 度
lfOrientation: Longint; //指定设备的每个字符的基线和 x 轴之间的角度, 单位 1/10 度
lfWeight: Longint; //粗细
lfItalic: Byte; //斜体
lfUnderline: Byte; //下划线
lfStrikeOut: Byte; //删除线
lfCharSet: Byte; //字符集
lfOutPrecision: Byte; //输出精度
lfClipPrecision: Byte; //剪辑精度
lfQuality: Byte; //输出质量
lfPitchAndFamily: Byte; //字体系列
lfFaceName: array[0..LF_FACESIZE - 1] of WideChar; //字体名称
end;
练习从 GDI 结构获取 IDWriteFont 和 IDWriteFontFace
uses Direct2D, D2D1;
{ IDWriteGdiInterop.CreateFontFromLOGFONT() 方法测试 }
procedure TForm1.Button1Click(Sender: TObject);
var
iGdiInterop: IDWriteGdiInterop;
iFontFace: IDWriteFontFace;
begin
Self.Font.Name := '宋体';
DWriteFactory.GetGdiInterop(iGdiInterop); //获取 IDWriteGdiInterop 接口
iGdiInterop.CreateFontFaceFromHdc(Canvas.Handle, iFontFace); //TLogFont -> IDWriteFont
{获取当前字体的字形总数}
ShowMessage(IntToStr(iFontFace.GetGlyphCount)); //22141
end;
{ IDWriteGdiInterop.CreateFontFromLOGFONT() 方法测试 }
procedure TForm1.Button2Click(Sender: TObject);
var
logFont: TLogFont;
iGdiInterop: IDWriteGdiInterop;
iFont: IDWriteFont;
iFontFace: IDWriteFontFace;
iFontFamily: IDWriteFontFamily;
iLocalizedStrings: IDWriteLocalizedStrings;
buf: array[0..LF_FACESIZE] of Char;
begin
Self.Font.Name := '宋体';
GetObject(Self.Font.Handle, SizeOf(TLogFont), @logFont); //获取当前窗口使用的 TLogFont 结构
DWriteFactory.GetGdiInterop(iGdiInterop); //获取 IDWriteGdiInterop 接口
iGdiInterop.CreateFontFromLOGFONT(logFont, iFont); //TLogFont -> IDWriteFont
{从 IDWriteFont 获取字体名称}
iFont.GetFontFamily(iFontFamily);
iFontFamily.GetFamilyNames(iLocalizedStrings);
iLocalizedStrings.GetString(iLocalizedStrings.GetCount-1, buf, Length(buf));
ShowMessage(buf); //宋体
iFont.CreateFontFace(iFontFace); //IDWriteFont -> IDWriteFontFace
{获取当前字体的字形总数}
ShowMessage(IntToStr(iFontFace.GetGlyphCount)); //22141
end;
使用 IDWriteBitmapRenderTarget
uses Direct2D, D2D1;
procedure TForm1.FormPaint(Sender: TObject);
var
str1,str2: string;
logFont: TLogFont;
iGdiInterop: IDWriteGdiInterop;
iFont: IDWriteFont;
iTextFormat: IDWriteTextFormat;
iTextLayout: IDWriteTextLayout;
rTextRange: TDwriteTextRange;
iBitmapRenderTarget: IDWriteBitmapRenderTarget;
cvs: TDirect2DCanvas;
iBrush: ID2D1SolidColorBrush;
rRect: TRect;
gdiCVS: TCanvas;
begin
str1 := 'Sample text using GDI TextOut.';
str2 := 'Sample text using DirectWrite.';
Canvas.Font.Name := '微软雅黑';
Canvas.Font.Size := 32;
rRect := Bounds(0, 0, ClientWidth, ClientHeight div 2);
{从 IDWriteGdiInterop.IDWriteBitmapRenderTarget 获取 DC, 并以 GDI 的方式输出文本}
DWriteFactory.GetGdiInterop(iGdiInterop);
iGdiInterop.CreateBitmapRenderTarget(Canvas.Handle, ClientWidth, ClientHeight div 2, iBitmapRenderTarget);
gdiCVS := TCanvas.Create;
gdiCVS.Handle := iBitmapRenderTarget.GetMemoryDC;
gdiCVS.Font := Canvas.Font;
gdiCVS.Rectangle(rRect);
gdiCVS.TextRect(rRect, str1, [tfSingleLine, tfCenter, tfVerticalCenter]);
gdiCVS.Free;
{把 IDWriteBitmapRenderTarget 中的绘制结果复制到当前窗口}
BitBlt(
Canvas.Handle,
0, 0,
ClientWidth, ClientHeight div 2,
iBitmapRenderTarget.GetMemoryDC,
0, 0,
SRCCOPY
);
{根据当前窗口的 Font 建立 IDWriteFont}
GetObject(Canvas.Font.Handle, SizeOf(TLogFont), @logFont);
iGdiInterop.CreateFontFromLOGFONT(logFont, iFont);
{以 DirectWrite 方式输出文本}
DWriteFactory.CreateTextFormat(
PWideChar(Canvas.Font.Name),
nil,
iFont.GetWeight,
iFont.GetStyle,
iFont.GetStretch,
-MulDiv(logFont.lfHeight, 96, GetDeviceCaps(Canvas.Handle, LOGPIXELSX)), //FontSize
'',
iTextFormat
);
iTextFormat.SetTextAlignment(DWRITE_TEXT_ALIGNMENT_CENTER);
iTextFormat.SetParagraphAlignment(DWRITE_PARAGRAPH_ALIGNMENT_CENTER);
DWriteFactory.CreateTextLayout(
PWideChar(str2),
Length(str2),
iTextFormat,
ClientWidth,
ClientHeight div 2,
iTextLayout
);
rTextRange.startPosition := 0;
rTextRange.length := Length(str1);
// iTextLayout.SetUnderline(True, rTextRange);
iTextLayout.SetStrikethrough(True, rTextRange);
OffsetRect(rRect, 0, ClientHeight div 2);
cvs := TDirect2DCanvas.Create(Canvas, rRect);
cvs.RenderTarget.CreateSolidColorBrush(D2D1ColorF(clRed), nil, iBrush);
cvs.RenderTarget.BeginDraw;
cvs.RenderTarget.DrawTextLayout(D2D1PointF(0, 0), iTextLayout, iBrush);
cvs.RenderTarget.EndDraw;
cvs.Free;
end;
procedure TForm1.FormResize(Sender: TObject);
begin
Repaint;
end;
效果图：
