QGIS符号（样式）配置研究与实现

左手的ㄟ右手 2022-12-06 12:43 570阅读 0赞

最近接到任务是进行QGIS符号配置界面的开发，由于当时把QGIS集成到我们桌面三维GIS平台时用到的QGIS版本是2.18.5（比较坑的一个版本，集成之后发现不少bug,补bug补了好久，换版本再集成不是那么容易的，无奈沿用至今），所以就还选用这个版本，毕竟最后还是要集成到三维平台里。其实各个版本核心功能差别不大。  
其实符号配置这个网上都有，直接拿来用完成简单任务不成问题，但是个人觉得对深入学习QGIS并无多大助益，要想学好必须要深入源码进行研究。这里还想再说一点，QGIS不仅是学习开源GIS的最佳平台，还是学习Qt极好的选择，只不过对于非GIS专业的同学来说有点吃力，因为在研究源码里Qt相关内容时，要有意识的去掉GIS的内容。

# 符号配置研究 #

我们一般配置样式的步骤就是双击图层，弹出属性对话框，调整到样式界面，开始配置符号，如下图  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center]  
图层属性对话框对应的类是QgsVectorLayerProperties隶属于APP模块。其继承自QgsVectorLayerPropertiesBase，其实就是一个ui文件。如下图  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center 1]  
可以看到右侧是空白，其实是一个QStackWidget，根据点击左边的list的item不同，显示出不同的Widget。  
当我们点击style选项卡时，出现如下界面  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center 2]  
右面这个的组成分为两部分，第一是不能上下滑动的部分，它的类名叫QgsRendererV2PropertiesDialog，还有一部分是滑动的部分，其本质是嵌套在一个QStackWidget上的，它和上面的Comobox关联，根据符号渲染类型的不同，显示对应的widget。这些widget都继承自QgsRendererV2Widget，根据不同的符号渲染类型又派生出QgsSingleSymbolRendererV2Widget、Qgs25DRendererWidget、QgsCategorizedSymbolRendererV2Widget等。由于本次重点研究的是单一符号配置，所以关注焦点放在QgsSingleSymbolRendererV2Widget，进一步查看源码发现，并结合ui文件发现，其中的一个成员QgsSymbolV2SelectorWidget正是整个符号配置对话框的核心。那它怎么用呢？打开qgisapp.cpp尝试搜索一下这个类，发现没找到。后来偶然发现，在QgsSymbolV2SelectorWidget文件里还有一个类QgsSymbolV2SelectorDialog，这个类完全就是把QgsSymbolV2SelectorWidget包了一下，那这个类有没有呢，还在qgisapp.cpp的文件里，果然搜到了。实在是不得不佩服QGIS的作者们，这个类用法极其简单，而且与其他类耦合程度很低，完全就是一个工具类的感觉，只要构造一下，传入需要的参数，接下来你就不用管了，里面都给你做好了，你直接显示就行。另外，QgsSymbolV2SelectorWidget里面包含了QgsSymbolV2，QgsSymbolV2也很独立。特别符合GIS的相关概念，QgsSymbolV2就是GIS中符号这一概念在QGIS中的体现。下面展示了QGIS符号配置界面相关结构图  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center 3]  
对话框创建顺序图如下  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center 4]

# 代码实现 #

最后再贴出完整的代码，时间仓促，匆匆写了一个测试代码，目的是实现功能，后续肯定要优化。

#ifndef MAINWINDOW_H
    #define MAINWINDOW_H
    
    #include <QMainWindow>
    #include <QModelIndex>
    #include <qgsmapcanvas.h>
    #include <qgslayertreeview.h>
    #include <qgslayertreemapcanvasbridge.h>
    class QgsLayerTreeMapCanvasBridge;
    namespace Ui { 
    class MainWindow;
    }
    
    class MainWindow : public QMainWindow
    { 
        Q_OBJECT
    
    public:
        explicit MainWindow(QWidget *parent = 0);
        ~MainWindow();
    
        void showMap();
    public slots:
        void extentChanged();
        void openStyleDlg(QModelIndex index);
    private:
        Ui::MainWindow *ui;
        QgsMapCanvas m_Canvas;
        QgsLayerTreeView m_Tree;
        QgsLayerTreeMapCanvasBridge* m_bridge;
    };
    
    #endif // MAINWINDOW_H

#include "MainWindow.h"
    #include "ui_MainWindow.h"
    #include <qgsproviderregistry.h>
    #include <qgsapplication.h>
    #include <qgsproject.h>
    #include <qgslayertreelayer.h>
    #include <qgslayertreegroup.h>
    #include <qgsmaptoolpan.h>
    #include <qgslayertreeview.h>
    #include <qgslayertreemodel.h>
    #include <qgslayertreemodellegendnode.h>
    #include <qgssymbolv2selectordialog.h>
    #include <qgssymbolv2.h>
    #include <qgsstylev2.h>
    #include <qgsvectorlayer.h>
    #include <qgsrendererv2.h>
    #include <qgssinglesymbolrendererv2.h>
    
    #include <QSettings>
    #include <QFont>
    #include <qfileinfo.h>
    #include <QHBoxLayout>
    #include <QSplitter>
    #include <QMessageBox>
    #include <QDebug>
    MainWindow::MainWindow(QWidget *parent) :
        QMainWindow(parent),
        ui(new Ui::MainWindow)
        ,m_bridge(NULL)
    { 
        ui->setupUi(this);
        m_Canvas.setParent(this->centralWidget());//此句一定要在ui->setupUi(this);之后
        QSplitter* sp = new QSplitter(Qt::Horizontal,this->centralWidget());
        m_Tree.setParent(sp);
        m_Canvas.setParent(sp);
        sp->setStretchFactor(1,10);
        QHBoxLayout* hclay = new QHBoxLayout(this->centralWidget());
        hclay->addWidget(sp);
    
        connect(&m_Tree,SIGNAL( doubleClicked( QModelIndex )),this, SLOT(openStyleDlg(QModelIndex)));
        qDebug()<<885544;
    }
    
    MainWindow::~MainWindow()
    { 
        delete ui;
    }
    
    void MainWindow::showMap()
    { 
        //1.初始化
        //设置插件及资源目录前缀
        QDir dir(qApp->applicationDirPath());//获取应用程序所在路径
    
        QString strAppPath(dir.absolutePath());
        QgsProviderRegistry::instance( strAppPath + "/QGIS_Plugins");//注册插件
        qDebug()<<"插件目录为" + strAppPath + "/QGIS_Plugins";
    
        //设置资源目录
        QgsApplication::setPkgDataPath(strAppPath);
    
        //设置GDAL_DATA
        QString strENVValue = strAppPath + "/resources/gdal_data";
        if (!qputenv( "GDAL_DATA",  strENVValue.toStdString().c_str() ))
        { 
            std::cout << "GDAL_DATA设置失败" << std::endl;
        }
    
    
        //2读取工程
        QFileInfo pro("F:/VBF/Data/QGIS/shp/bac/VBF_CommonMapbac.qgs");
    
        QgsProject* pPro = QgsProject::instance();
        if((!pPro) || (!pPro->read(pro)))//读取工程失败
        { 
            std::cout << "读取工程失败" << std::endl;
            return ;
        }
        std::cout<<"GDAL_DATA设置失败\n";
    
        QgsLayerTreeModel* model = new QgsLayerTreeModel( QgsProject::instance()->layerTreeRoot(), this );
        model->setFlag( QgsLayerTreeModel::AllowNodeReorder );
        model->setFlag( QgsLayerTreeModel::AllowNodeRename );
        model->setFlag( QgsLayerTreeModel::AllowNodeChangeVisibility );
        model->setFlag( QgsLayerTreeModel::ShowLegendAsTree );
        model->setFlag( QgsLayerTreeModel::UseEmbeddedWidgets );
        m_Tree.setModel( model );
        m_Tree.collapseAll();
    
    
        connect(&m_Canvas,SIGNAL(extentsChanged()),this, SLOT(extentChanged()));
    
        //设置图层
        QList <QgsMapCanvasLayer> listCanvasLayer;
        QList<QgsLayerTreeLayer*> listLayer = QgsProject::instance()->layerTreeRoot()->findLayers();
        foreach (QgsLayerTreeLayer* pLayer, listLayer)
        { 
            QgsMapCanvasLayer CanvasLayer(pLayer->layer());
            listCanvasLayer.append(CanvasLayer);
        }
    
        QgsMapToolPan* pTool = new QgsMapToolPan(&m_Canvas);
        m_Canvas.setMapTool(pTool);
        m_Canvas.setLayerSet(listCanvasLayer);
        m_Canvas.zoomToFullExtent();
        m_bridge = new QgsLayerTreeMapCanvasBridge(QgsProject::instance()->layerTreeRoot(), &m_Canvas, this);
        m_Canvas.setParallelRenderingEnabled(true);
    
    
    }
    
    void MainWindow::extentChanged()
    { 
        m_Tree.layerTreeModel()->setLegendMapViewData( m_Canvas.mapUnitsPerPixel(), m_Canvas.mapSettings().outputDpi(), m_Canvas.scale());
    }
    
    void MainWindow::openStyleDlg(QModelIndex index)
    { 
    
    
        if (QgsSymbolV2LegendNode* node = dynamic_cast<QgsSymbolV2LegendNode*>( m_Tree.currentLegendNode() ))//图例节点
        { 
            //获取符号
            const QgsSymbolV2* originalSymbol = node->symbol();
            if ( !originalSymbol ) return;
            QScopedPointer< QgsSymbolV2 > symbol( originalSymbol->clone() );
            QgsVectorLayer* vlayer = qobject_cast<QgsVectorLayer*>( node->layerNode()->layer() );
            QgsSymbolV2SelectorDialog dlg( symbol.data(), QgsStyleV2::defaultStyle(), vlayer, this );
            dlg.setMapCanvas( &m_Canvas );
            if ( dlg.exec() )
            { 
                node->setSymbol( symbol.take() );
            }
            return;
        }
    
        if(QgsVectorLayer* vlayer = dynamic_cast<QgsVectorLayer*>( m_Tree.currentLayer() ))//图层节点
        { 
    
    
            if (!vlayer->rendererV2()) return;
    // try{ 
    // QgsSingleSymbolRendererV2* pRender = QgsSingleSymbolRendererV2::convertFromRenderer(vlayer->rendererV2());
    // }
    // catch(...){ 
    // qDebug()<<555;
    // }
    
            //return;
    // QgsSingleSymbolRendererV2* pRender = QgsSingleSymbolRendererV2::convertFromRenderer(vlayer->rendererV2());
            QgsSingleSymbolRendererV2* pRender = NULL;
            try { 
                pRender = dynamic_cast<QgsSingleSymbolRendererV2*>(vlayer->rendererV2());
            }
            catch(...){ 
                qDebug()<<45789;
            }
    
            if (!pRender) return;
    
            QScopedPointer< QgsSymbolV2 > symbol(  pRender->symbol()->clone() );
    
            QgsSymbolV2SelectorDialog dlg(symbol.data(), QgsStyleV2::defaultStyle(), vlayer, m_Tree.window() );
            dlg.setMapCanvas( &m_Canvas );
            if ( dlg.exec() )
            { 
                pRender->setSymbol( symbol.take() );
                vlayer->triggerRepaint();
                m_Tree.refreshLayerSymbology(vlayer->id());
    
            }
    
            if (QgsProject::instance()->write()) qDebug() <<"保存失败";
    
        }
    
    
    }

#include "MainWindow.h"
    #include <QApplication>
    #include <QTextCodec>
    #include <QDebug>
    int main(int argc, char *argv[])
    { 
    
        QApplication a(argc, argv);
    
        设置文件编码
    // QApplication::addLibraryPath("./plugins");
        //return 0;
        QTextCodec* code= QTextCodec::codecForName ( "GBK" );
        QTextCodec::setCodecForCStrings(code);
        QTextCodec::setCodecForTr(code);
        QTextCodec::setCodecForLocale(code);
        MainWindow w;
        w.showMap();
        w.showMaximized();
        return a.exec();
    }

#-------------------------------------------------
    #
    # Project created by QtCreator 2020-09-07T08:41:12
    #
    #-------------------------------------------------
    
    QT       += core gui xml
    
    greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
    CONFIG +=console
    CONFIG +=rtti
    TARGET = SymbolConfigTool
    TEMPLATE = app
    
    # The following define makes your compiler emit warnings if you use
    # any feature of Qt which as been marked as deprecated (the exact warnings
    # depend on your compiler). Please consult the documentation of the
    # deprecated API in order to know how to port your code away from it.
    DEFINES += QT_DEPRECATED_WARNINGS
    
    DEFINES += CORE_EXPORT=Q_DECL_IMPORT
    DEFINES += GUI_EXPORT=Q_DECL_IMPORT
    DEFINES += noexcept=
    DEFINES += override=
    DEFINES += nullptr=0
    DEFINES += _USE_MATH_DEFINES
    DEFINES -= HAVE_TOUCH
    #3rdparty
    INCLUDEPATH += E:\VBF_GlobalGIS\3rdParty_vs2010_x64\include
    INCLUDEPATH += E:\VBF_GlobalGIS\3rdParty_vs2010_x64\include\sqlite3
    #QGIS
    INCLUDEPATH += ../../3rdParty/include\
                   ../../3rdParty/include/core\
                   ../../3rdParty/include/core/geos\
                   ../../3rdParty/include/core/geometry\
                   ../../3rdParty/include/core/layertree\
                   ../../3rdParty/include/core/raster\
                   ../../3rdParty/include/core/symbology-ng\
                   ../../3rdParty/include/gui\
                   ../../3rdParty/include/gui/layertree\
                   ../../3rdParty/include/gui/symbology-ng\
                   ../../3rdParty/include/gui/editorwidgets\
                   ../../3rdParty/include/gui/effects\
    
    CONFIG(debug, debug|release){
        DESTDIR = $$PWD/../build/bin/Debug
        TARGET = SymbolConfigToold
        LIBS += -L$$PWD/../../3rdParty/lib -lqgis_cored -lqgis_guid #-lVBF_SliceByProd
    
    }else{
        DESTDIR = $$PWD/../build/bin/Release
        TARGET = SymbolConfigTool
        LIBS += -L$$PWD/../../3rdParty/lib -lqgis_core -lqgis_gui #-lVBF_SliceByPro
    
    }
    
    
    SOURCES += main.cpp\
        MainWindow.cpp
    HEADERS  += \
        MainWindow.h
    
    FORMS    += \
    gssymbolv2selectordialogbase.ui

最后的效果  
![在这里插入图片描述][20200924221143275.gif_pic_center]  
其它阅读  
[HCZJEarth介绍][HCZJEarth]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center]: /images/20221123/347cc3b8683d4e04974f38b06c3029d5.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20221123/7880b202aba74d95b9500d45d3b5d5d3.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center 2]: /images/20221123/373ef1a089f849578878ee65cdd2b9cb.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center 3]: /images/20221123/b9070cac0bec44798b1d3810d88fb925.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2EzNzQ2ODI5NDk_size_16_color_FFFFFF_t_70_pic_center 4]: /images/20221123/4a661c3cc0ff4088bea0da34eaf21495.png
[20200924221143275.gif_pic_center]: /images/20221123/1433ccb9f3d2445494c41bd2e30a5daf.png
[HCZJEarth]: https://blog.csdn.net/a374682949/article/details/108227653