GdiPlus[39]: IGPGraphicsPath (六) - 路径的辅助工具 IGPGraphicsPathIterator

IGPGraphicsPathIterator 能遍历路径中的子路径和路径标记.

---

IGPGraphicsPathIterator.Count;          { 点总数 }
IGPGraphicsPathIterator.SubpathCount;   { 子路径数 }
IGPGraphicsPathIterator.HasCurve;       { 是否包含曲线 }

IGPGraphicsPathIterator.Rewind;         { 重新开始, 用于遍历前 }
IGPGraphicsPathIterator.NextSubPath();  { 下一个子路径 }
IGPGraphicsPathIterator.NextPathType(); { 当前子路径起始点的类型; 必须和 NextSubPath 同时使用 }
IGPGraphicsPathIterator.Enumerate;      { 获取路径数据的函数, 应在 NextMarker 过程中使用 }
IGPGraphicsPathIterator.CopyData();     { 复制指定范围的路径数据 }
IGPGraphicsPathIterator.NextMarker();   { 下一个路径标记 }

Count、SubpathCount、HasCurve 测试:

---

uses GdiPlus;

procedure TForm1.FormCreate(Sender: TObject);
var
  Path: IGPGraphicsPath;
  PathIterator: IGPGraphicsPathIterator;
  Rect: TGPRect;
  str: string;
begin
  Rect.Initialize(20, 20, 150, 100);
  Path := TGPGraphicsPath.Create;
  Path.AddRectangle(Rect);
  Path.AddEllipse(Rect);

  PathIterator := TGPGraphicsPathIterator.Create(Path);

  with TStringBuilder.Create do
  begin
    Append('点总数: ');
    Append(PathIterator.Count);
    AppendLine;

    Append('子路径数: ');
    Append(PathIterator.SubpathCount);
    AppendLine;

    Append('是否包含曲线: ');
    Append(PathIterator.HasCurve);

    str := ToString;
    Free;
  end;
  ShowMessage(str);
end;

NextSubPath、Rewind 测试:

---

uses GdiPlus, GdiPlusHelpers;

var
  Path: IGPGraphicsPath;
  PathIterator: IGPGraphicsPathIterator;

{ 初始化数据 }
procedure TForm1.FormCreate(Sender: TObject);
var
  Pt1,Pt2: TGPPoint;
  Rect: TGPRect;
begin
  Pt1.Initialize(20, 20);
  Pt2.Initialize(150, 150);
  Rect.InitializeFromLTRB(Pt1.X, Pt1.Y, Pt2.X , Pt2.Y);
  Path := TGPGraphicsPath.Create;

  Path.AddRectangle(Rect);
  Path.AddEllipse(Rect);
  Path.AddLine(Pt1.X, Pt1.Y, Pt2.X, Pt2.Y);

  PathIterator := TGPGraphicsPathIterator.Create(Path);
end;

{ 绘制路径 }
procedure TForm1.FormPaint(Sender: TObject);
var
  Pen: IGPPen;
begin
  Pen := TGPPen.Create($FFC0C0C0);
  Canvas.ToGPGraphics.DrawPath(Pen, Path);
end;

{ 遍历路径 }
procedure TForm1.Button1Click(Sender: TObject);
var
  Pen: IGPPen;
  PathSection: IGPGraphicsPath;
  B: Boolean; //这 out 参数需要的
begin
  Pen := TGPPen.Create($FFFF0000, 2);
  PathSection := TGPGraphicsPath.Create; //这也需要先建立
  PathIterator.NextSubPath(PathSection, B);

  Repaint;
  Canvas.ToGPGraphics.DrawPath(Pen, PathSection);
  Tag := Tag + 1; //借 Self.Tag 一用

  if Tag = PathIterator.SubpathCount then
  begin
    Tag := 0;
    PathIterator.Rewind;
  end;
end;

NextPathType 测试:

---

uses GdiPlus;

procedure TForm1.FormCreate(Sender: TObject);
var
  Path: IGPGraphicsPath;
  PathIterator: IGPGraphicsPathIterator;
  Rect: TGPRect;
  bool: Boolean;
  m1,m2,n,n1,n2: Integer;
  b: Byte;
begin
  Rect.Initialize(20, 20, 150, 100);
  Path := TGPGraphicsPath.Create;
  Path.AddRectangle(Rect);
  Path.AddEllipse(Rect);

  PathIterator := TGPGraphicsPathIterator.Create(Path);

  while PathIterator.NextSubPath(m1, m2, bool) <> 0 do
  begin
    n := PathIterator.NextPathType(b, n1, n2);
    ShowMessageFmt('%d-%d; %d: %d-%d', [m1,m2,n,n1,n2]);
  end;
//0-3;  4:  0-3
//4-16; 13: 4-16
end;

NextMarker、CopyData、Enumerate 测试:

---

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses GdiPlus, GdiPlusHelpers;

var
  Path: IGPGraphicsPath;
  PathIterator: IGPGraphicsPathIterator;

{ 初始化 Path 与 PathIterator }
procedure TForm1.FormCreate(Sender: TObject);
var
  Rect: TGPRect;
begin
  Path := TGPGraphicsPath.Create;

  { 用路径 Marker 把路径分成了三部分 }
  Path.AddLine(TGPPoint.Create(20, 20), TGPPoint.Create(200, 20));
  Path.AddLine(TGPPoint.Create(20, 50), TGPPoint.Create(200, 50));
  Path.SetMarker;

  Path.AddLine(TGPPoint.Create(20, 80), TGPPoint.Create(200, 80));
  Path.AddLine(TGPPoint.Create(20, 110), TGPPoint.Create(200, 110));
  Path.SetMarker;

  Path.AddLine(TGPPoint.Create(20, 140), TGPPoint.Create(200, 140));
  Path.AddLine(TGPPoint.Create(20, 170), TGPPoint.Create(200, 170));

  PathIterator := TGPGraphicsPathIterator.Create(Path);
end;

{ 绘制 Path }
procedure TForm1.FormPaint(Sender: TObject);
var
  Pen: IGPPen;
begin
  Pen := TGPPen.Create($FFC0C0C0, 2);
  Canvas.ToGPGraphics.DrawPath(Pen, Path);
end;

{ 测试 CopyData 函数 }
procedure TForm1.Button1Click(Sender: TObject);
var
  Pen: IGPPen;
  Brush: IGPSolidBrush;
  PathTmp: IGPGraphicsPath;
  n1,n2: Integer;
  Data: IGPPathData;
  Rect: TGPRectF;
  i: Integer;
  ps: array of TGPPointF;
  ts: array of Byte;
begin
  Repaint;
  Pen := TGPPen.Create($80FF0000, 2);
  Brush := TGPSolidBrush.Create($FF0000FF);

  if PathIterator.NextMarker(n1, n2) = 0 then
  begin
    PathIterator.Rewind;
    Exit;
  end;

  Data := PathIterator.CopyData(n1, n2);

  for i := 0 to Data.Count - 1 do
  begin
    Rect.Initialize(Data.Points[i].X -3, Data.Points[i].Y-3, 6, 6);
    Canvas.ToGPGraphics.FillRectangle(Brush, Rect);
  end;

  SetLength(ps, Data.Count);
  SetLength(ts, Data.Count);
  CopyMemory(ps, Data.PointPtr, Data.Count * SizeOf(TGPPointF));
  CopyMemory(ts, Data.TypePtr, Data.Count);
  PathTmp := TGPGraphicsPath.Create(ps, ts);
  Canvas.ToGPGraphics.DrawPath(Pen, PathTmp);
end;

{ 测试 Enumerate 函数 }
procedure TForm1.Button2Click(Sender: TObject);
var
  Pen: IGPPen;
  Brush: IGPSolidBrush;
  PathTmp: IGPGraphicsPath;
  n1,n2: Integer;
  Data: IGPPathData;
  Rect: TGPRectF;
  i: Integer;
  ps: array of TGPPointF;
  ts: array of Byte;
begin
  Repaint;
  Pen := TGPPen.Create($80FF0000, 2);
  Brush := TGPSolidBrush.Create($FF0000FF);

  if PathIterator.NextMarker(n1, n2) = 0 then
  begin
    PathIterator.Rewind;
    Exit;
  end;

  Data := PathIterator.Enumerate; { 和 Button1Click 就这一句不一样 }

  for i := 0 to Data.Count - 1 do
  begin
    Rect.Initialize(Data.Points[i].X -3, Data.Points[i].Y-3, 6, 6);
    Canvas.ToGPGraphics.FillRectangle(Brush, Rect);
  end;

  SetLength(ps, Data.Count);
  SetLength(ts, Data.Count);
  CopyMemory(ps, Data.PointPtr, Data.Count * SizeOf(TGPPointF));
  CopyMemory(ts, Data.TypePtr, Data.Count);
  PathTmp := TGPGraphicsPath.Create(ps, ts);
  Canvas.ToGPGraphics.DrawPath(Pen, PathTmp);
end;

end.