The preparation

We will demonstrate creating the new tool on simple tool which compute raster file statistics.

To create your own tool you need to create the new project in your favourite IDE. The CmakeLists.txt file for such project can be looks like:

Todo:: Add link to cmakes files in repository

cmake_minimum_required (VERSION 2.8)
project (wxgisgpcompstattool)
set(LIB_NAME wxgisgpcompstattool)
set(CMAKE_CONFIGURATION_TYPES "Debug;Release" CACHE STRING "Configs" FORCE)
set(CMAKE_COLOR_MAKEFILE ON)
include_directories(${CMAKE_CURRENT_SOURCE_DIR})
include_directories(${CMAKE_CURRENT_BINARY_DIR})
include_directories(${CMAKE_CURRENT_SOURCE_DIR}/include)
# set path to additional CMake modules
set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake ${CMAKE_MODULE_PATH})
# For windows, do not allow the compiler to use default target (Vista).
if(WIN32)
  add_definitions(-D_WIN32_WINNT=0x0501)
endif(WIN32)
add_definitions(-DSTRICT)
if(MSVC)
    if(CMAKE_CL_64)
        set_target_properties(${the_target} PROPERTIES STATIC_LIBRARY_FLAGS "/machine:x64")
        add_definitions(-D_WIN64)
    endif()
endif()
if(UNIX)
     if(CMAKE_COMPILER_IS_GNUCXX OR CV_ICC)
        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIC -fno-strict-aliasing")
        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -fno-strict-aliasing")
     endif()
endif()    
set(wxWidgets_EXCLUDE_COMMON_LIBRARIES ON)
find_package(wxWidgets COMPONENTS base xml REQUIRED)
# wxWidgets include (this will do all the magic to configure everything)
if(wxWidgets_FOUND)
    include(${wxWidgets_USE_FILE})
endif(wxWidgets_FOUND)
find_package(WXGIS COMPONENTS core catalog geoprocessing REQUIRED)
if(WXGIS_FOUND)
    include_directories(${WXGIS_INCLUDE_DIR})
endif(WXGIS_FOUND)
#find needed packages
find_package(GDAL REQUIRED)
if(GDAL_FOUND)
    include_directories(${GDAL_INCLUDE_DIR})
    include_directories(${GDAL_INCLUDE_DIR}/ogr)
    include_directories(${GDAL_INCLUDE_DIR}/ogr/ogrsf_frmts)
    include_directories(${GDAL_INCLUDE_DIR}/port)
    include_directories(${GDAL_INCLUDE_DIR}/gcore)
    include_directories(${GDAL_INCLUDE_DIR}/alg)
    include_directories(${GDAL_INCLUDE_DIR}/frmts/vrt)
    include_directories(${GDAL_INCLUDE_DIR}/build/port) #assume that out of source build was in build dir
endif(GDAL_FOUND)
set(PROJECT_HHEADERS ${PROJECT_HHEADERS}
    ${LIB_HEADERS}/gpcompstattool.h
)
set(PROJECT_CSOURCES ${PROJECT_CSOURCES}
    ${LIB_SOURCES}/gpcompstattool.cpp
)
add_library(${LIB_NAME} SHARED ${PROJECT_HHEADERS} ${PROJECT_CSOURCES})
if(wxWidgets_FOUND)
   target_link_libraries(${LIB_NAME} ${wxWidgets_LIBRARIES})
endif(wxWidgets_FOUND)
if(WXGIS_FOUND)
   target_link_libraries(${LIB_NAME} ${WXGIS_LIBRARIES})
endif(WXGIS_FOUND)
if(GDAL_FOUND)
    target_link_libraries(${LIB_NAME} ${GDAL_LIBRARIES})
endif(GDAL_FOUND) 

The creation of a tool skeleton

To create your own tool you need to inherit the class from wxGISGPTool and reimplement need methods. The header file maybe look like this:

class WXDLLIMPEXP_GIS_GP wxGISGPCompStatTool : 
    public wxGISGPTool
{
   DECLARE_DYNAMIC_CLASS(wxGISGPCompStatTool)
public:
    wxGISGPCompStatTool(void);
    virtual ~wxGISGPCompStatTool(void);
    //IGPTool
    virtual const wxString GetDisplayName(void);
    virtual const wxString GetName(void);
    virtual const wxString GetCategory(void);
    virtual bool Execute(ITrackCancel* pTrackCancel);
    virtual GPParameters GetParameterInfo(void);
};

The only need to reimplement methods is present.

Implementing tool functionality

The source file maybe look like this:

IMPLEMENT_DYNAMIC_CLASS(wxGISGPCompStatTool, wxGISGPTool)
wxGISGPCompStatTool::wxGISGPCompStatTool(void) : wxGISGPTool()
{
}
wxGISGPCompStatTool::~wxGISGPCompStatTool(void)
{
}
const wxString wxGISGPCompStatTool::GetDisplayName(void)
{
    return wxString(_("Compute statistics"));
}
const wxString wxGISGPCompStatTool::GetName(void)
{
    return wxString(wxT("comp_stats"));
}
const wxString wxGISGPCompStatTool::GetCategory(void)
{
    return wxString(_("Data Management Tools/Raster"));
}
GPParameters wxGISGPCompStatTool::GetParameterInfo(void)
{
    if(m_paParam.IsEmpty())
    {
        //src path
        wxGISGPParameter* pParam1 = new wxGISGPParameter();
        pParam1->SetName(wxT("src_path"));
        pParam1->SetDisplayName(_("Source raster"));
        pParam1->SetParameterType(enumGISGPParameterTypeRequired);
        pParam1->SetDataType(enumGISGPParamDTPath);
        pParam1->SetDirection(enumGISGPParameterDirectionInput);
        wxGISGPGxObjectDomain* pDomain1 = new wxGISGPGxObjectDomain();
        pDomain1->AddFilter(new wxGxDatasetFilter(enumGISRasterDataset));
        pParam1->SetDomain(pDomain1);
        m_paParam.Add(static_cast<IGPParameter*>(pParam1));
        //build approx
        wxGISGPParameter* pParam2 = new wxGISGPParameter();
        pParam2->SetName(wxT("approx_ok"));
        pParam2->SetDisplayName(_("Compute statistics based on overviews or a subset of all tiles"));
        pParam2->SetParameterType(enumGISGPParameterTypeOptional);
        pParam2->SetDataType(enumGISGPParamDTBool);
        pParam2->SetDirection(enumGISGPParameterDirectionInput);
        pParam2->SetValue(false);
        m_paParam.Add(static_cast<IGPParameter*>(pParam2));
    }
    return m_paParam;
}
bool wxGISGPCompStatTool::Execute(ITrackCancel* pTrackCancel)
{
    if(!Validate())
    {
        //add messages to pTrackCancel
        if(pTrackCancel)
            pTrackCancel->PutMessage(_("Unexpected error occurred"), -1, enumGISMessageErr);
        return false;
    }
    IGxObjectContainer* pGxObjectContainer = dynamic_cast<IGxObjectContainer*>(m_pCatalog);
    if(!pGxObjectContainer)
    {
        if(pTrackCancel)
            pTrackCancel->PutMessage(_("Error getting catalog object"), -1, enumGISMessageErr);
        return false;
    }
    wxString sSrcPath = m_paParam[0]->GetValue();
    IGxObject* pGxObject = pGxObjectContainer->SearchChild(sSrcPath);
    if(!pGxObject)
    {
        if(pTrackCancel)
            pTrackCancel->PutMessage(_("Error getting source object"), -1, enumGISMessageErr);
        return false;
    }
    IGxDataset* pGxDataset = dynamic_cast<IGxDataset*>(pGxObject);
    if(!pGxDataset)
    {
        if(pTrackCancel)
            pTrackCancel->PutMessage(_("Source object is of incompatible type"), -1, enumGISMessageErr);
        return false;
    }
    wxGISRasterDatasetSPtr pSrcDataSet = boost::dynamic_pointer_cast<wxGISRasterDataset>(pGxDataset->GetDataset());
    if(!pSrcDataSet)
    {
        if(pTrackCancel)
            pTrackCancel->PutMessage(_("Source dataset is of incompatible type"), -1, enumGISMessageErr);
        return false;
    }
    if(!pSrcDataSet->Open(false))
        return false;
    GDALDataset* poGDALDataset = pSrcDataSet->GetRaster();
    if(!poGDALDataset)
    {
        if(pTrackCancel)
            pTrackCancel->PutMessage(_("Error getting raster"), -1, enumGISMessageErr);
        return false;
    }
    bool bApproxOK = m_paParam[1]->GetValue();
    for(int nBand = 0; nBand < poGDALDataset->GetRasterCount(); nBand++ )
    {
        double      dfMin(0), dfMax(255), dfMean(127), dfStdDev(2);
        CPLErr      eErr;
        if(pTrackCancel)
            pTrackCancel->PutMessage(wxString::Format(_("Proceed band %d"), nBand + 1), -1, enumGISMessageInfo);
        GDALRasterBand* pBand = poGDALDataset->GetRasterBand(nBand + 1);
        eErr = pBand->ComputeStatistics(bApproxOK, &dfMin, &dfMax, &dfMean, &dfStdDev, ExecToolProgress, (void*)pTrackCancel);   
        if(eErr != CE_None)
        {
            if(pTrackCancel)
            {
                const char* pszErr = CPLGetLastErrorMsg();
                pTrackCancel->PutMessage(wxString::Format(_("ComputeStatistics failed! GDAL error: %s"), wxString(pszErr, wxConvUTF8).c_str()), -1, enumGISMessageErr);
            }
            return false;
        }
        pTrackCancel->PutMessage(wxString::Format(_("Band %d: min - %.2f, max - %.2f, mean - %.2f, StdDev - %.2f"), nBand + 1, dfMin, dfMax, dfMean, dfStdDev), -1, enumGISMessageNorm);
    pSrcDataSet->SetHasStatistics(true);
    return true;
}

In function GetDisplayName we returns the tool name, which will be shown in user interface (toolbox and other controls). This name can be repeated (not recommended).

The GetName returns the internal name. This name should be unique.

The GetCategory returns the category name with subcategories. The subcategories divided by "/".

The GetParameterInfo return the array of parameters. In our case there are two parameters:

Source raster
Compute statistics based on overviews or a subset of all tiles

The first parameter is the type of choose path and second checkbox.

The Execute do all the work and returns true on success and false vice versa.

Add to the toolbox

After you successfully create and compile tool you need add it to the wxGIS toolbox.

To do it, you need:

Add library path (absolute or relative) to the <libs> section of wxGISCommon.xml config file.
Add class name and tool internal name (the same name as you set in GetName function) to the <tools> section of wxGISToolbox.xml config file.
Put internal name to the <toolboxes> section in appropriate <toolbox> subsection of wxGISToolbox.xml config file.

The special console tool which will do it automatically is planned.

Table of Contents

The preparation

The creation of a tool skeleton

Implementing tool functionality

Add to the toolbox