再學GDI+[50]: 路徑 - GetPathPoints、GetPathTypes、TPathData

本例效果圖:

代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls, Grids;
type
　TForm1 = class(TForm)
　　StringGrid1: TStringGrid;
　　procedure FormCreate(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure StringGrid1SelectCell(Sender: TObject; ACol, ARow: Integer;
　　　var CanSelect: Boolean);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　StringGrid1.Align := alRight;
　StringGrid1.FixedCols := 0;
　StringGrid1.ColCount := 3;
　StringGrid1.ColWidths[0] := 25;
　StringGrid1.ColWidths[1] := 25;
　StringGrid1.ColWidths[2] := 80;
　StringGrid1.DefaultRowHeight := 20;
　StringGrid1.Cells[0,0] := 'X';
　StringGrid1.Cells[1,0] := 'Y';
　StringGrid1.Cells[2,0] := '點類型';
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　p: TGPPen;
　path: TGPGraphicsPath;
　points: array of TGPPoint;
　types: PByte;
　typestr: string;
　i: Integer;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(aclRed);
　path := TGPGraphicsPath.Create;
　path.StartFigure;
　path.AddRectangle(MakeRect(30,20,90,40));
　path.AddEllipse(MakeRect(30,80,90,180));
　path.CloseFigure;
　g.DrawPath(p, path);
　SetLength(points, path.GetPointCount);
　GetMem(types, path.GetPointCount);
　path.GetPathPoints(PGPPoint(points), Length(points));
　path.GetPathTypes(types, Length(points));
　StringGrid1.RowCount := Length(points) + 1;
　for i := 0 to Length(points) - 1 do
　begin
　　case types^ of
　　　$00 : typestr := '路徑起始點';
　　　$01 : typestr := '直線點';
　　　$03 : typestr := '貝塞爾線點';
　　　$07 : typestr := '遮蓋點';
　　　$10 : typestr := '虛線點';
　　　$20 : typestr := '路徑標記';
　　　$80 : typestr := '子路徑結束點';
　　end;
　　StringGrid1.Cells[0, i+1] := IntToStr(points[i].X);
　　StringGrid1.Cells[1, i+1] := IntToStr(points[i].Y);
　　StringGrid1.Cells[2, i+1] := typestr;
　　Inc(types);
　end;
　Dec(types, Length(points));
　FreeMem(types);
　types := nil;
　path.Free;
　p.Free;
　g.Free;
end;
procedure TForm1.StringGrid1SelectCell(Sender: TObject; ACol, ARow: Integer;
　var CanSelect: Boolean);
var
　x,y: Integer;
begin
　x := StrToIntDef(StringGrid1.Cells[0,ARow], 0);
　y := StrToIntDef(StringGrid1.Cells[1,ARow], 0);
　Repaint;
　Canvas.Brush.Color := clBlue;
　Canvas.FillRect(Bounds(x-3,y-3,6,6));
　Text := Format('%d,%d',[x,y]);
end;
end.

這個例子有點麻煩, 如果使用 TPathData 類會簡單許多, 下面是用 TPathData 實現的代碼, 運行效果相同; 不過這樣獲取的點數組必須是小數數組. 代碼如下:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls, Grids;
type
　TForm1 = class(TForm)
　　StringGrid1: TStringGrid;
　　procedure FormCreate(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure StringGrid1SelectCell(Sender: TObject; ACol, ARow: Integer;
　　　var CanSelect: Boolean);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
procedure TForm1.FormCreate(Sender: TObject);
begin
　StringGrid1.Align := alRight;
　StringGrid1.FixedCols := 0;
　StringGrid1.ColCount := 3;
　StringGrid1.ColWidths[0] := 25;
　StringGrid1.ColWidths[1] := 25;
　StringGrid1.ColWidths[2] := 80;
　StringGrid1.DefaultRowHeight := 20;
　StringGrid1.Cells[0,0] := 'X';
　StringGrid1.Cells[1,0] := 'Y';
　StringGrid1.Cells[2,0] := '點類型';
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
　p: TGPPen;
　path: TGPGraphicsPath;
　PathData: TPathData;
　Points: PGPPointF;
　Types: PByte;
　TypeStr: string;
　i: Integer;
begin
　g := TGPGraphics.Create(Canvas.Handle);
　p := TGPPen.Create(aclRed);
　path := TGPGraphicsPath.Create;
　path.StartFigure;
　path.AddRectangle(MakeRect(30,20,90,40));
　path.AddEllipse(MakeRect(30,80,90,180));
　path.CloseFigure;
　g.DrawPath(p, path);
　PathData := TPathData.Create;
　path.GetPathData(PathData);
　Points := PathData.Points;
　Types := PathData.Types;
　StringGrid1.RowCount := PathData.Count + 1;
　for i := 0 to PathData.Count - 1 do
　begin
　　case Types^ of
　　　$00 : TypeStr := '路徑起始點';
　　　$01 : TypeStr := '直線點';
　　　$03 : TypeStr := '貝塞爾線點';
　　　$07 : TypeStr := '遮蓋點';
　　　$10 : TypeStr := '虛線點';
　　　$20 : TypeStr := '路徑標記';
　　　$80 : TypeStr := '子路徑結束點';
　　end;
　　StringGrid1.Cells[0, i+1] := IntToStr(Trunc(Points.X));
　　StringGrid1.Cells[1, i+1] := IntToStr(Trunc(Points.Y));
　　StringGrid1.Cells[2, i+1] := TypeStr;
　　Inc(Points);
　　Inc(Types);
　end;
　PathData.Free;
　path.Free;
　p.Free;
　g.Free;
end;
procedure TForm1.StringGrid1SelectCell(Sender: TObject; ACol, ARow: Integer;
　var CanSelect: Boolean);
var
　x,y: Integer;
begin
　x := StrToIntDef(StringGrid1.Cells[0,ARow], 0);
　y := StrToIntDef(StringGrid1.Cells[1,ARow], 0);
　Repaint;
　Canvas.Brush.Color := clBlue;
　Canvas.FillRect(Bounds(x-3,y-3,6,6));
　Text := Format('%d,%d',[x,y]);
end;
end.

窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClientHeight = 276
　ClientWidth = 303
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poDesktopCenter
　OnCreate = FormCreate
　OnPaint = FormPaint
　PixelsPerInch = 96
　TextHeight = 13
　object StringGrid1: TStringGrid
　　Left = 88
　　Top = 40
　　Width = 154
　　Height = 120
　　TabOrder = 0
　　OnSelectCell = StringGrid1SelectCell
　end
end

路徑中的點類型枚舉:PathPointType = (
　PathPointTypeStart　　　　= $00, {路徑起始點}
　PathPointTypeLine　　　　 = $01, {直線點}
　PathPointTypeBezier　　　 = $03, {默認貝塞爾線點}
　PathPointTypePathTypeMask = $07, {遮蓋點}
　PathPointTypeDashMode　　 = $10, {虛線點}
　PathPointTypePathMarker　 = $20, {路徑標記}
　PathPointTypeCloseSubpath = $80, {子路徑結束點}
　PathPointTypeBezier3　　　= $03　{立體貝塞爾線點}
);
TPathPointType = PathPointType;