procedure TTextLayoutNG.DoDrawLayout(const ACanvas: TCanvas);
varCharDic: TCharDic;Rec: PCharRec;Pos: TPointF;R, SrcR, ClipBounds: TRectF;LLine: TGPULine;LRun: TGPURun;I, J, K: Integer;VerticalAligned, HorizontalAligned, ColoredGlyph: Boolean;Styles: TFontStyles;Thickness: Single;
beginif Text.IsEmpty thenExit;{在渲染函数 DoRenderLayout 中记录了原来的颜色，如果当前颜色与渲染时颜色不一致，则重新设置}if FOldColor <> Color thenbeginFOldColor := Color;for I := 0 to FFrame.Count - 1 dobeginLLine := FFrame[I];for J := 0 to LLine.Count - 1 dobeginLRun := LLine[J];LRun.SetColor(Color, True);end;end;end;{检查画布 Canvas 的缩放比例与当前比例是否一致，如果不一致则重新渲染}if not SameValue(FScale, ACanvas.Scale, Epsilon) thenbeginFScale := ACanvas.Scale;FScaleFactor := 1 / FScale;DoRenderLayout;end;{检查左上顶点是否为0，以此判断是否按照 横向和纵向 进行排列布局}HorizontalAligned := SameValue(Frac(TopLeft.X), 0.0, TEpsilon.Position) and SameValue(Frac(ACanvas.Matrix.m31), 0.0, TEpsilon.Position);VerticalAligned := SameValue(Frac(TopLeft.Y), 0.0, TEpsilon.Position) and SameValue(Frac(ACanvas.Matrix.m32), 0.0, TEpsilon.Position);{对输出的帧进行处理，帧（Frame）、行（Line）、渲染单元（Run） 的关系如下--------GPUFrame-------------|(GPURun)(GPURun)...(GPURun)| <- GPULine (several GPURun's with different font and/or color)|(GPURun)                   | <- GPULine (no additional styling, so only a single GPURun)|(GPURun)                   | <- GPULine|                           | ...|                           ||                           |-----------------------------帧有若干行，对每一行进行处理}for I := 0 to FFrame.Count - 1 dobeginLLine := FFrame[I];{定位每一行的左上顶点位置}Pos := LLine.TopLeft + TopLeft;{每行有若干渲染单元，对每个渲染单元进行处理}for J := 0 to LLine.Count - 1 dobeginLRun := LLine[J];{得到渲染单元的字体类型TFontStyle = (fsBold, fsItalic, fsUnderline, fsStrikeOut);TFontStyles = set of TFontStyle;}if LRun.Font <> nil thenStyles := LRun.Font.StyleelseStyles := Self.Font.Style;{每个渲染单元是按照 字体 + 颜色 进行区分的，即若干相同字体和颜色的字符，纳入到一个渲染单元中对每个渲染单元，按照其对应的字体获取 字符渲染处理对象（TCharDic）每个字符渲染处理对象记录了在当前字体下，该字符对应的 字形、大小，并预先绘制好图片。其核心思想应该是：预先将每个字符在不同的字体下，绘制到一个图片中保存，当需要绘制时，将这些图片直接绘制到画布上，以加快渲染速度PCharRec = ^TCharRec;TCharRec = recordGlyph: TFontGlyph;SrcRect: TRectF;Bitmap: TBitmap;end;TCharDic = class(TDictionary<UCS4Char, PCharRec>)还有一种做法是，将绘制过程放入TPathData中存储，在绘制时直接调用Path进行快速绘制}CharDic := GetCharDictionary(LRun.Font);{画布的调制色彩？}TCustomCanvasGpu(ACanvas).ModulateColor := LRun.Color;{对渲染单元的每一个字符进行处理}for K := 0 to LRun.Chars.Count - 1 dobegin{得到该渲染单元对应的预先绘制好的字符图片记录，如果没有预先绘制，则立即处理...UpdateCharRec(...)}Rec := AddOrGetChar(ACanvas, LRun.Chars[K], CharDic, LRun.Font);{如果图片存在，则处理其绘制的位置}if Assigned(Rec.Bitmap) thenbegin{计算水平位置}if HorizontalAligned thenR.Left := ACanvas.AlignToPixelHorizontally(Pos.X) + Rec.Glyph.Origin.X * FScaleFactorelseR.Left := Pos.X + Rec.Glyph.Origin.X * FScaleFactor;{计算垂直位置}if VerticalAligned thenR.Top := ACanvas.AlignToPixelVertically(Pos.Y) + Rec.Glyph.Origin.Y * FScaleFactorelseR.Top := Pos.Y + Rec.Glyph.Origin.Y * FScaleFactor;{计算宽度Rec.SrcRect代表原始宽度，再乘以比例}R.Right := R.Left + (Rec.SrcRect.Width * FScaleFactor);R.Bottom := R.Top + (Rec.SrcRect.Height * FScaleFactor);SrcR := Rec.SrcRect;{根据是否裁剪进行处理 ，如果裁剪则设置裁剪的范围}if LRun.IsClipped thenbeginClipBounds := LRun.ClipBounds[K];SrcR.Top := SrcR.Top + ClipBounds.Top * FScale;R.Top := R.Top + ClipBounds.Top;SrcR.Bottom := SrcR.Bottom - ClipBounds.Bottom * FScale;R.Bottom := R.Bottom - ClipBounds.Bottom;SrcR.Left := SrcR.Left + ClipBounds.Left * FScale;R.Left := R.Left + ClipBounds.Left;SrcR.Right := SrcR.Right - ClipBounds.Right * FScale;R.Right := R.Right - ClipBounds.Right;endelse{不裁剪则进行平滑处理}beginR.Inflate(FSmoothRenderMarginInPixels, FSmoothRenderMarginInPixels);SrcR.Inflate(SmoothRenderMargin, SmoothRenderMargin);end;{判断是否彩色，并变更画布的调制色彩？}ColoredGlyph := TFontGlyphStyle.ColorGlyph in Rec.Glyph.Style;if ColoredGlyph thenTCustomCanvasGpu(ACanvas).ModulateColor := $FFFFFFFF;{将预先绘制好的内容绘制到画布上}ACanvas.DrawBitmap(Rec.Bitmap, SrcR, R, Opacity);{还原画布的调制色彩}if ColoredGlyph thenTCustomCanvasGpu(ACanvas).ModulateColor := LRun.Color;end;{移动横坐标到本字符的后面，以便进行下一个字符绘制}Pos.X := Pos.X + (Rec.Glyph.Advance * FScaleFactor);end;{}if LRun.IsTrimmed thenbeginRec := AddOrGetChar(ACanvas, FEllipsisChar, GetCharDictionary(Self.Font), Self.Font);TCustomCanvasGpu(ACanvas).ModulateColor := Self.Color;if Assigned(Rec.Bitmap) thenbeginif HorizontalAligned thenR.Left := ACanvas.AlignToPixelHorizontally(Pos.X) + Rec.Glyph.Origin.X * FScaleFactorelseR.Left := Pos.X + Rec.Glyph.Origin.X * FScaleFactor;if VerticalAligned thenR.Top := ACanvas.AlignToPixelVertically(Pos.Y) + Rec.Glyph.Origin.Y * FScaleFactorelseR.Top := Pos.Y + Rec.Glyph.Origin.Y * FScaleFactor;R.Right := R.Left + (Rec.SrcRect.Width * FScaleFactor);R.Bottom := R.Top + (Rec.SrcRect.Height * FScaleFactor);// DrawR.Inflate(FSmoothRenderMarginInPixels, FSmoothRenderMarginInPixels);SrcR.Inflate(SmoothRenderMargin, SmoothRenderMargin);ACanvas.DrawBitmap(Rec.Bitmap, Rec.SrcRect, R, Opacity);end;end;{处理下划线和删除线}if ([TFontStyle.fsStrikeOut, TFontStyle.fsUnderline] * Styles) <> [] thenbegin{颜色}FStrokeBrush.Color := LRun.Color;{线条厚度}if LRun.Font <> nil thenThickness := LRun.Font.Size / 15elseThickness := Self.Font.Size / 15;FStrokeBrush.Thickness := Thickness;{删除线Pos的位置为最后一个字符的后面}if TFontStyle.fsStrikeOut in Styles thenACanvas.DrawLine(TPointF.Create(Pos.X - LRun.ImageRect.Width, Pos.Y + LRun.ImageRect.Height / 2),TPointF.Create(Pos.X, Pos.Y + LRun.ImageRect.Height / 2),Opacity,      

//

不透明FStrokeBrush);{下划线}if TFontStyle.fsUnderline in Styles thenACanvas.DrawLine(TPointF.Create(Pos.X - LRun.ImageRect.Width, Pos.Y + CharDic.Baseline * FScaleFactor + 1.5 * Thickness),TPointF.Create(Pos.X, Pos.Y + CharDic.Baseline * FScaleFactor + 1.5 * Thickness),Opacity,FStrokeBrush);end;

//

下一个渲染单元end;

//

下一行end;TCustomCanvasGpu(ACanvas).ModulateColor := $FFFFFFFF;
end;