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C++ 如何获取瓦片数据,这里通过向谷歌地图发起http请求,获取多个地图保存到本地,部分关键源码如下所示
int CGenerateJpgAccessImpl::FetchTiles(int zoomLevel, int x, int y, int width, int height, int nMaxThreads, bool yReversed, bool bNewBuild)
{
int failedCount = 0;
CString strTilePath = _strFullPath + L"瓦片";
if (CFileToolkit::FileExist(strTilePath))
CFileToolkit::DeleteToRecycle(strTilePath);
CFileToolkit::CreateDirectory(strTilePath);
vector<StructUrl2Path> vctUrl2Path;
int nJpgI = 0;
int nJpgJ = 0;
if (yReversed)
{
// 下载图片
for (int row = y - height + 1; row <= y; row++)
{
nJpgI++;
nJpgJ = 0;
for (int col = x; col <= x + width - 1; col++)
{
CString strJpgBwUrl;
CString strWorkSpace = CPathConfig::GetWorksapce();
strJpgBwUrl.Format(_T("http://tiles.google.com.cn:8510/TileService/Tile?type=Mapbox&layerStyle=Satellite&x=%d&y=%d&z=%d"), col, row, zoomLevel);
CString strFullPath;
strFullPath.Format(L"%s\\%s#%s.jpg", strTilePath, CStringToolkit::IntToStr(nJpgI), CStringToolkit::IntToStr(nJpgJ));
StructUrl2Path sup;
sup.strPat = strFullPath;
sup.strUrl = strJpgBwUrl;
vctUrl2Path.push_back(sup);
nJpgJ++;
}
}
}
else
{
// 下载图片
for (int row = y; row >= y - height + 1; row--)
{
nJpgI++;
nJpgJ = 0;
for (int col = x; col <= x + width - 1; col++)
{
CString strJpgBwUrl;
CString strWorkSpace = CPathConfig::GetWorksapce();
strJpgBwUrl.Format(_T("http://tiles.google.com.cn:8510/TileService/Tile?type=Mapbox&layerStyle=Satellite&x=%d&y=%d&z=%d"), col, row, zoomLevel);
CString strFullPath;
strFullPath.Format(L"%s\\%s#%s.jpg", strTilePath, CStringToolkit::IntToStr(nJpgI), CStringToolkit::IntToStr(nJpgJ));
StructUrl2Path sup;
sup.strPat = strFullPath;
sup.strUrl = strJpgBwUrl;
vctUrl2Path.push_back(sup);
nJpgJ++;
}
}
}
#pragma omp parallel for num_threads(2 * omp_get_num_procs() - 1)
for (int i = 0; i < (int)vctUrl2Path.size();i++)
{
StructUrl2Path sup = vctUrl2Path[i];
DownLoadTile(sup.strUrl, sup.strPat);
}
return failedCount;
}
bool CGenerateJpgAccessImpl::DownLoadTile(CString strUrl, CString strSaveFile)
{
std::string strUrlA = CW2A(strUrl);;
CURL *curl;
curl_global_init(CURL_GLOBAL_ALL);
const std::string url = strUrlA;
curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
std::string full_path = CW2A(strSaveFile);
FILE *fp;
if ((fp = fopen(/*"C:/00zbb/test.jfif"*/full_path.c_str(), "ab")) == NULL)
{
curl_easy_cleanup(curl);
return false;
}
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
curl_easy_setopt(curl, CURLOPT_USERAGENT, "libcurl-agent/1.0");//这个要加不然文件传输不完全,字符串内容可自定义
double downloadFileLenth = 0;
if (CURLE_OK == curl_easy_perform(curl))
{
curl_easy_getinfo(curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &downloadFileLenth);
}
fclose(fp);
curl_easy_cleanup(curl);
return true;
}
下载完成后 图片如下文件夹:
对于多个瓦片数据,想要实现瓦片数据的合并,应该如何实现呢,这里假设已经下载到了瓦片数据,并且瓦片的格式如下图
int nPicWidth = 256; //瓦片宽
int nPicHeight = 256; //瓦片高
int nTotalPicSize = nPicWidth*nPicHeight;
CImage dst;
dst.Create(width, height, 24, 0);//创建一个dst对象;参数意义分别为dst宽;dst高;没有alpha通道;
HDC hDC = dst.GetDC();
// #pragma omp parallel for num_threads(2 * omp_get_num_procs() - 1)
for (int nCur = 0; nCur < (int)vctFile.size(); nCur++)
{
int nCurMapRow = nCur / nFirRowSize;
int nCurMapCol = nCur % nFirRowSize;
CString strFileName = vctFile[nCur];
CImage curImageData;
curImageData.Load(strFileName);
HDC hDestDC = curImageData.GetDC();
int xDest = 0;
int yDest = 0;
int nDestWidth = 256;
int nDestHeight = 256;
int xSrc = 0;
int ySrc = 0;
if (nCurMapCol == 0)
{
xDest = 0;
nDestWidth = nPicWidth - leftTopPixelX;
xSrc = leftTopPixelX;
}
if (nCurMapCol == 1)
{
xDest = (nPicWidth - leftTopPixelX);
}
if (nCurMapCol >1)
{
xDest = (nPicWidth - leftTopPixelX) + (nCurMapCol - 1) * nPicWidth;
}
if (nCurMapRow == 0)
{
yDest = 0;
nDestHeight = nPicHeight - leftTopPixelY;
ySrc = leftTopPixelY;
}
if (nCurMapRow == 1)
{
yDest = (nPicHeight - leftTopPixelY);
}
if (nCurMapRow > 1)
{
yDest = (nPicHeight - leftTopPixelY) + (nCurMapRow - 1) * nPicHeight;
}
if (xDest + nDestWidth > width)
{
nDestWidth = width - xDest;
}
if (yDest + nDestHeight > height)
{
nDestHeight = height - yDest;
}
BOOL bResult = ::BitBlt(hDC, xDest, yDest, nDestWidth, nDestHeight, hDestDC,
xSrc, ySrc, SRCCOPY);
curImageData.ReleaseDC();
}
dst.ReleaseDC();
CString strSaveFilePath = _strFullPath + _strProjectBaseName + L"\\";
if (!CFileToolkit::DirectoryExist(strSaveFilePath))
CFileToolkit::CreateDirectory(strSaveFilePath);
CString strSaveFileName = strSaveFilePath + _strProjectBaseName + L".jpg";
dst.Save(strSaveFileName);
只需要不到1秒的时间就能合并100多张图片:
下面是计算完整的流程:根据多个地理坐标(经纬度),计算这些地理坐标的范围内。去谷歌地图上获取范围内的所有瓦片,并完成最终的瓦片合并
// 读取json获取所有的地理坐标(根据自己的途径获取)
vector<AcGePoint3d> vcP = GetAllCoords(strFileName);
if (vcP.empty())
return;
// 计算包围框
CalcBox(strFileName, vcP);
_nZoomLevel = CalcZoomLevel();
// 计算填充 方便调整经纬度和层级
CalcPad(basePad, minSideLength);
_nZoomLevel = CalcZoomLevel();
// 下载合并所有瓦片的流程方法
Merge();
提供代码下载,代码包含完整核心步骤和算法,不能够独立运行,下载请慎重
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