Direct2D (14) : 畫筆

畫筆類 TDirect2DPen 的 Brush 屬性是 TDirect2DBrush，現在的單色畫筆其實是調用的實心畫刷。
因為畫刷的強大，所以讓畫筆豐富起來不是難事。

TDirect2DPen 的 StrokeStyle 屬性是 ID2D1StrokeStyle 類型，它決定著線帽、拐角樣式等；但遺憾的是該屬性是唯讀，基本無用。
但 TDirect2DPen 的 Style 屬性還是巧妙實現了 psSolid, psDash, psDot, psDashDot, psDashDotDot。

測試代碼：

uses Direct2D, D2D1;procedure TForm1.FormPaint(Sender: TObject);var  cvs: TDirect2DCanvas;  R: TRect;begin  cvs := TDirect2DCanvas.Create(Canvas, ClientRect);  R := ClientRect;  InflateRect(R, -ClientWidth div 6, -ClientHeight div 6);  cvs.Pen.Color := clRed;  cvs.Pen.Style := psDash;  cvs.BeginDraw;  cvs.Ellipse(R);  cvs.EndDraw;  cvs.Free;end;procedure TForm1.FormResize(Sender: TObject);begin  Repaint;end;

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下面是較原始的實現方法(效果同上):

uses Direct2D, D2D1;procedure TForm1.FormPaint(Sender: TObject);var  cvs: TDirect2DCanvas;  iBrush: ID2D1SolidColorBrush;  iStrokeStyle: ID2D1StrokeStyle;  rStrokeStyleProperties: TD2D1StrokeStyleProperties;  R: TRect;  rEllipse: TD2D1Ellipse;begin  cvs := TDirect2DCanvas.Create(Canvas, ClientRect);  R := ClientRect;  InflateRect(R, -ClientWidth div 6, -ClientHeight div 6);  rEllipse := D2D1Ellipse(D2D1PointF((R.Right-R.Left)/2+R.Left, (R.Bottom-R.Top)/2+R.Top), (R.Right-R.Left)/2, (R.Bottom-R.Top)/2);  cvs.BeginDraw;  cvs.RenderTarget.CreateSolidColorBrush(D2D1ColorF(clRed), nil, iBrush);  rStrokeStyleProperties := D2D1StrokeStyleProperties(); //擷取 StrokeStyle 屬性的預設值  rStrokeStyleProperties.dashStyle := D2D1_DASH_STYLE_DASH;  D2DFactory.CreateStrokeStyle(rStrokeStyleProperties, nil, 0, iStrokeStyle);  cvs.RenderTarget.DrawEllipse(rEllipse, iBrush, 1, iStrokeStyle);  cvs.EndDraw;  cvs.Free;end;procedure TForm1.FormResize(Sender: TObject);begin  Repaint;end;

自訂虛線：

uses Direct2D, D2D1;procedure TForm1.FormPaint(Sender: TObject);var  cvs: TDirect2DCanvas;  iBrush: ID2D1SolidColorBrush;  iStrokeStyle: ID2D1StrokeStyle;  rStrokeStyleProperties: TD2D1StrokeStyleProperties;  R: TRect;  rEllipse: TD2D1Ellipse;  arrSingle: array[0..3] of Single;begin  cvs := TDirect2DCanvas.Create(Canvas, ClientRect);  R := ClientRect;  InflateRect(R, -ClientWidth div 6, -ClientHeight div 6);  rEllipse := D2D1Ellipse(D2D1PointF((R.Right-R.Left)/2+R.Left, (R.Bottom-R.Top)/2+R.Top), (R.Right-R.Left)/2, (R.Bottom-R.Top)/2);  cvs.BeginDraw;  cvs.RenderTarget.CreateSolidColorBrush(D2D1ColorF(clRed), nil, iBrush);  rStrokeStyleProperties := D2D1StrokeStyleProperties();  rStrokeStyleProperties.dashStyle := D2D1_DASH_STYLE_CUSTOM;  arrSingle[0] := 10;  arrSingle[1] := 5;  arrSingle[2] := 1;  arrSingle[3] := 5;  D2DFactory.CreateStrokeStyle(rStrokeStyleProperties, @arrSingle[0], Length(arrSingle), iStrokeStyle);  cvs.RenderTarget.DrawEllipse(rEllipse, iBrush, 2, iStrokeStyle);  cvs.EndDraw;  cvs.Free;end;procedure TForm1.FormResize(Sender: TObject);begin  Repaint;end;

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自訂拐角樣式：

uses Direct2D, D2D1;procedure TForm1.FormPaint(Sender: TObject);var  cvs: TDirect2DCanvas;  iBrush: ID2D1SolidColorBrush;  iStrokeStyle: ID2D1StrokeStyle;  rStrokeStyleProperties: TD2D1StrokeStyleProperties;  R: TRect;begin  cvs := TDirect2DCanvas.Create(Canvas, ClientRect);  R := ClientRect;  InflateRect(R, -ClientWidth div 5, -ClientHeight div 5);  cvs.BeginDraw;  cvs.RenderTarget.CreateSolidColorBrush(D2D1ColorF(clGray), nil, iBrush);  rStrokeStyleProperties := D2D1StrokeStyleProperties();  rStrokeStyleProperties.lineJoin := D2D1_LINE_JOIN_BEVEL;  D2DFactory.CreateStrokeStyle(rStrokeStyleProperties, nil, 0, iStrokeStyle);  cvs.RenderTarget.DrawRectangle(R, iBrush, 25, iStrokeStyle);  cvs.EndDraw;  cvs.Free;end;procedure TForm1.FormResize(Sender: TObject);begin  Repaint;end;

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