鹰眼的实现方法（Delphi & TatukGIS）

// 定义常量
const
  MINIMAP_R_NAME = 'minimap_rect';
  MINIMAP_O_NAME = 'minimap_rect_outline';
  MINIMAP_S_NAME = 'minimap_line';

//定义私有变量
  minishp: TGIS_Shape; // 鹰眼框
  minishpo: TGIS_Shape; // 外围线
  miniLine: TGIS_Shape; // 鹰眼中的十字丝
  fminiMove: Boolean; 

// 声明 过程
procedure miniMapRefresh(Sender: TObject);

procedure TfrmMain.miniMapRefresh(Sender: TObject);
var
  ptg1: TGIS_Point;
  ptg2: TGIS_Point;
  ptg3: TGIS_Point;
  ptg4: TGIS_Point;
  ptg5, ptg6, ptg7, ptg8: TGIS_Point;
  ex: TGIS_Extent;
begin
  if GIS.IsEmpty then
    exit;

  ex := GISm.CS.ExtentFromCS(GIS.CS, GIS.VisibleExtent);
  ex := GIS.UnrotatedExtent(ex);

  if (ex.XMin < -360) and (ex.XMax > 360) and (ex.YMin < -180) and
    (ex.YMax > 180) then
    exit;

  ptg1 := GisPoint(ex.XMin, ex.YMin);
  ptg2 := GisPoint(ex.XMax, ex.YMin);
  ptg3 := GisPoint(ex.XMax, ex.YMax);
  ptg4 := GisPoint(ex.XMin, ex.YMax);

  minishp.Reset;
  minishp.Lock(gisLockExtent);
  minishp.AddPart;
  minishp.AddPoint(ptg1);
  minishp.AddPoint(ptg2);
  minishp.AddPoint(ptg3);
  minishp.AddPoint(ptg4);
  minishp.Unlock;

  minishpo.Reset;
  minishpo.Lock(gisLockExtent);
  minishpo.AddPart;
  minishpo.AddPoint(ptg1);
  minishpo.AddPoint(ptg2);
  minishpo.AddPoint(ptg3);
  minishpo.AddPoint(ptg4);
  minishpo.AddPoint(ptg1);
  minishpo.Unlock;

  // 用于显示十字丝
  ptg5.X := GISm.Left;
  ptg5.Y := (ptg1.Y + ptg4.Y) / 2;
  ptg6.X := GISm.Left + GISm.Width;
  ptg6.Y := (ptg2.Y + ptg3.Y) / 2;
  ptg7.X := (ptg1.X + ptg2.X) / 2;
  ptg7.Y := 0;
  ptg8.X := ptg7.X;
  ptg8.Y := GISm.Height;

  miniLine.Reset;
  miniLine.Lock(gisLockExtent);
  miniLine.AddPart;
  miniLine.AddPoint(ptg5);
  miniLine.AddPoint(ptg6);
  miniLine.AddPart;
  miniLine.AddPoint(ptg7);
  miniLine.AddPoint(ptg8);
  miniLine.Unlock;

  GISm.Update;
end;

  // FormLoad事件中：
  llm := TGIS_LayerVector(GisCreateLayer('区县级行政区划', sPathEagle)); // 此处的“sPathEagle”指向与该地图对应的一个shp格式的区域图
  llm.UseConfig := false;
  llm.Params.Area.Color := clWhite;
  llm.Params.Area.OutlineColor := clSilver;
  GISm.Add(llm); // add to minimap

  lv := TGIS_LayerVector.Create; // minimap transparent rectangle
  lv.Transparency := 30;
  lv.Params.Area.Color := clRed;
  lv.Params.Area.OutlineWidth := -2;
  lv.Name := MINIMAP_R_NAME;
  lv.CS := llm.CS;
  GISm.Add(lv);
  minishp := TGIS_LayerVector(GISm.Get(MINIMAP_R_NAME)).CreateShape
    (gisShapeTypePolygon);
  lw := TGIS_LayerVector.Create;
  lw.Params.Line.Color := clMaroon;
  lw.Params.Line.Width := -2;
  lw.Name := MINIMAP_O_NAME;
  lw.CS := llm.CS;
  GISm.Add(lw);
  minishpo := TGIS_LayerVector(GISm.Get(MINIMAP_O_NAME)).CreateShape
    (gisShapeTypeArc);

  lx := TGIS_LayerVector.Create;
  lx.Params.Line.Color := clMaroon;
  lx.Params.Line.Width := -2;
  lx.Name := MINIMAP_S_NAME;
  lx.CS := llm.CS;
  GISm.Add(lx);
  miniLine := TGIS_LayerVector(GISm.Get(MINIMAP_S_NAME)).CreateShape
    (gisShapeTypeArc);

  GISm.FullExtent;
  GIS.FullExtent;

  GISm.RestrictedExtent := GISm.Extent;
  minishp.layer.Extent := GISm.Extent;
  GISm.Cursor := crArrow;
  fminiMove := false;

// GISAfterPaint事件：
var
  ex: TGIS_Extent;
begin
  ex := GIS.VisibleExtent;
  miniMapRefresh(self);
end;

// GISZoomChange事件：
  miniMapRefresh(self);

 

/* 以上代码只能通过主地图控制鹰眼视图，还不能实现两者之间的互动*/