FireMonkey 繪圖(1)

FMX 的 Canvas 在不同的系統上會分別使用:
WinVista、Win7: D2D (FMX.Canvas.D2D.pas)
WinXP: GDI+ (FMX.Canvas.GDIP.pas)
Mac 系列: Core Graphics (FMX.Canvas.Mac.pas)

和 HTML5 中的 Canvas 非常類似, 現在的 Canvas 模糊了 Pen 的概念:
之前的 Canvas.Pen 對應: Canvas.Stroke;
之前的 Canvas.Brush 對應: Canvas.Fill.

在 FMX 中, Canvas 無處不在, 其 Canvas.Stroke、Canvas.Fill 的狀態也各不相同, 一般要先初始化它們.

測試: 表單上放 Button1、Panel1, 啟用 Panel1 的 OnPaint 事件:

procedure TForm1.FormCreate(Sender: TObject);begin  Self.OnPaint := Panel1.OnPaint;  Button1.OnPaint := Panel1.OnPaint;  Panel1.Opacity := 0.75;end;procedure TForm1.Panel1Paint(Sender: TObject; Canvas: TCanvas; const ARect: TRectF);begin  {畫直線}  Canvas.Stroke.Kind := TBrushKind.bkSolid;//  Canvas.Stroke.Color := claBlack;  Canvas.DrawLine(ARect.Location, ARect.BottomRight, 1);  {填充橢圓}//  Canvas.Fill.Kind := TBrushKind.bkSolid;  Canvas.Fill.Color := claGreen;  Canvas.FillEllipse(RectF(ARect.Width/5, ARect.Height/5, ARect.Width/5*4, ARect.Height/5*4), 1);end;

:

繪圖命令:

Canvas.DrawLine();      //Canvas.DrawRect();      //畫矩形; 集合 TCorners: 四個角是否使用指定的樣式類型; 枚舉 TCornerType: 角樣式類型Canvas.DrawRectSides(); //畫矩形邊; 集合 TSides 指定要畫的邊Canvas.DrawEllipse();   //Canvas.DrawArc();       //Canvas.DrawPath();      //Canvas.DrawBitmap();    //Canvas.DrawThumbnail(); //畫略縮圖Canvas.DrawPolygon();   //Canvas.FillRect();      //Canvas.FillEllipse();   //Canvas.FillArc();       //Canvas.FillPath();      //Canvas.FillPolygon();   //Canvas.FillText();      //{測試文本輸出}procedure TForm1.Panel1Paint(Sender: TObject; Canvas: TCanvas; const ARect: TRectF);begin  Canvas.Fill.Color := claRed;  Canvas.Font.Size := 30;  Canvas.FillText(ARect, '萬一的 Delphi 部落格', True, 1, [], TTextAlign.taLeading, TTextAlign.taCenter);end;