这个是怎么显示矢量图的源码。做gis的基础

//--------------------------------------------------------------------------- #include <vcl.h> #pragma hdrstop #include "Vector.h" //--------------------------------------------------------------------------- #pragma package(smart_init) //--------------------------------------------------------------------------- //构造函数 TGisVectorLayer::TGisVectorLayer() { m_lpPolygonList=NULL; m_nSelectID = -1; } //--------------------------------------------------------------------------- //析构函数 TGisVectorLayer::~TGisVectorLayer() { if(m_lpPolygonList) { //释放资源 for(int i=0;i<m_lpPolygonList->Count;i++) { delete m_lpPolygonList->Items[i]; } delete m_lpPolygonList; } } //--------------------------------------------------------------------------- //读入Idris格式的矢量文件 BOOL TGisVectorLayer::OpenIdrisFile(AnsiString FileName) { //首先读入文件头 AnsiString DocFileName= ChangeFileExt(FileName,".dvc"); TStringList *StringList1=new TStringList(); StringList1->LoadFromFile(DocFileName); AnsiString type=StringList1->Strings[3].SubString(15,StringList1->Strings[4].Length()-13); if(type=="polygon") m_gisFileHeader.giType=GIS_POLYGON; else if(type=="point") m_gisFileHeader.giType=GIS_POINT; else m_gisFileHeader.giType=GIS_LINE; m_gisFileHeader.giMinX = StringList1->Strings[7].SubString(15,StringList1->Strings[7].Length()-13).ToDouble(); m_gisFileHeader.giMaxX = StringList1->Strings[8].SubString(15,StringList1->Strings[8].Length()-13).ToDouble(); m_gisFileHeader.giMinY = StringList1->Strings[9].SubString(15,StringList1->Strings[9].Length()-13).ToDouble(); m_gisFileHeader.giMaxY = StringList1->Strings[10].SubString(15,StringList1->Strings[10].Length()-13).ToDouble(); delete StringList1; TFileStream* File=new TFileStream(FileName,fmOpenRead); if(m_gisFileHeader.giType==GIS_POLYGON || m_gisFileHeader.giType==GIS_LINE) { m_lpPolygonList=new TList; float test[2]; File->Read(test,8); do { LPGISPOLYGON polygon = new GISPOLYGON; polygon->point = new GISPOINT[test[1]]; polygon->pPen = new TPen; polygon->pBrush = new TBrush; polygon->id=test[0]; polygon->numberPoint=test[1]; File->Read((float*)polygon->point ,4*2*test[1]); //计算多边形的外包围矩形 polygon->outRect.x1=polygon->point[0].x; polygon->outRect.x2=polygon->point[0].x; polygon->outRect.y1=polygon->point[0].y; polygon->outRect.y2=polygon->point[0].y; for(int i=1;i<test[1];i++) { if(polygon->outRect.x1>polygon->point[i].x) polygon->outRect.x1=polygon->point[i].x; if(polygon->outRect.x2<polygon->point[i].x) polygon->outRect.x2=polygon->point[i].x; if(polygon->outRect.y1>polygon->point[i].y) polygon->outRect.y1=polygon->point[i].y; if(polygon->outRect.y2<polygon->point[i].y) polygon->outRect.y2=polygon->point[i].y; } m_lpPolygonList->Add (polygon); File->Read(test,8); }while(test[0]!=0 && test[1]!=0); } delete File; return TRUE; } //--------------------------------------------------------------------------- //绘制函数 void TGisVectorLayer::Draw(TCanvas* canvas,GISRECT SourceRect,TRect DestRect) { m_DrawRect=DestRect; m_gisSourceRect=SourceRect; m_canvas=canvas; m_ratioX=DestRect.Width() /(SourceRect.x2-SourceRect.x1); m_ratioY=DestRect.Height()/(SourceRect.y2-SourceRect.y1); canvas->Brush->Color=clBlack; if(m_gisFileHeader.giType==GIS_POLYGON || m_gisFileHeader.giType==GIS_LINE) { for(int i=0;i<m_lpPolygonList->Count;i++) { LPGISPOLYGON polygon=(GISPOLYGON*)m_lpPolygonList->Items[i]; DrawAPolygon(polygon,SourceRect,DestRect); if(i == m_nSelectID) { DrawSelectPolygon(SourceRect,DestRect); } } } } //--------------------------------------------------------------------------- //绘制一个多边形 void TGisVectorLayer::DrawAPolygon(LPGISPOLYGON polygon,GISRECT SourceRect,TRect DestRect) { int pointCount=polygon->numberPoint ; TPoint* points = new TPoint[pointCount]; for(int i=0; i<pointCount; i++) { points[i].x = m_ratioX*(polygon->point[i].x-SourceRect.x1); points[i].y = DestRect.Height()-m_ratioY*(polygon->point[i].y-SourceRect.y1); } m_canvas->Pen->Style = polygon->pPen->Style; m_canvas->Pen->Width = polygon->pPen->Width; m_canvas->Pen->Color = polygon->pPen->Color; m_canvas->Brush->Style = polygon->pBrush->Style; m_canvas->Brush->Color = polygon->pBrush->Color; if(polygon->pBrush->Bitmap) { m_canvas->Brush->Bitmap = polygon->pBrush->Bitmap; } m_canvas->Polygon(points, pointCount-1); m_canvas->Brush->Bitmap = NULL; delete points; } //--------------------------------------------------------------------------- //用于判断一个点是否在一个多边形中 //返回TRUE：表示点在多边形中，否则点不在多边形中 BOOL TGisVectorLayer::PointIsInPolygon(LPGISPOLYGON polygon,GISPOINT point) { //如果点在多边形的外包围矩形外，那么肯定没有交点 if( point.x < polygon->outRect.x1 || point.x > polygon->outRect.x2 || point.y < polygon->outRect.y1 || point.y > polygon->outRect.y2) return FALSE; int count=0; for(int i=0;i<polygon->numberPoint-1;i++) { GISLINE tempLine(polygon->point[i].x, polygon->point[i].y, polygon->point[i+1].x, polygon->point[i+1].y); if(point.y < tempLine.Y1 && point.y < tempLine.Y2) continue; float a; float b; if(tempLine.X2==tempLine.X1) continue; a=(tempLine.Y2-tempLine.Y1)/(tempLine.X2-tempLine.X1); b=tempLine.Y1-a*tempLine.X1; float y=a*point.x+b; if(y<point.y && y<=(tempLine.Y1>tempLine.Y2 ? tempLine.Y1 : tempLine.Y2) && y>=(tempLine.Y1<tempLine.Y2? tempLine.Y1 : tempLine.Y2) && point.x<=(tempLine.X1>tempLine.X2 ? tempLine.X1 : tempLine.X2) && point.x>=(tempLine.X1<tempLine.X2 ? tempLine.X1 : tempLine.X2)) count++; } if(count%2) return TRUE; else return FALSE; } //--------------------------------------------------------------------------- //将行列值的坐标变换成X、Y值坐标 GISPOINT TGisVectorLayer::TPointToGisPoint(TPoint SourcePoint) { GISPOINT point; point.x= SourcePoint.x/m_ratioX + m_gisFileHeader.giMinX; point.y= (m_DrawRect.Height()-SourcePoint.y)/m_ratioY + m_gisFileHeader.giMinY; return point; } //--------------------------------------------------------------------------- //选择多边形函数 void TGisVectorLayer::SelectPolygon(TPoint SourcePoint) { for(int i=0;i<m_lpPolygonList->Count;i++) { GISPOINT point=TPointToGisPoint(SourcePoint); if(PointIsInPolygon((GISPOLYGON*)(m_lpPolygonList->Items[i]),point)) { m_nSelectID = i; return; } } m_nSelectID = -1; } //--------------------------------------------------------------------------- void TGisVectorLayer::DrawSelPlyWithBitmap(GISRECT SourceRect,TRect DestRect) {/* Graphics::TBitmap *BrushBmp = new Graphics::TBitmap; try { LPGISPOLYGON polygon = (GISPOLYGON*)m_lpPolygonList->Items[m_nSelectID]; int pointCount=polygon->numberPoint ; BrushBmp->LoadFromFile(m_strBitmapFileName); m_canvas->Brush->Bitmap = BrushBmp; TPoint* points = new TPoint[pointCount]; for(int i=0; i<pointCount; i++) { points[i].x=ratioX*(polygon->point[i].x-SourceRect.x1); points[i].y=DestRect.Height()-ratioY*(polygon->point[i].y-SourceRect.y1); } m_canvas->Polygon(points, pointCount-1); delete points; m_canvas->Brush->Bitmap = NULL; } __finally { m_canvas->Brush->Bitmap = NULL; delete BrushBmp; } */ } //--------------------------------------------------------------------------- void TGisVectorLayer::DrawSelectPolyg