最近真是懶得一X，直接上代碼。。。。。

最近搞Qt，需要利用QGis實現(xiàn)一些地理坐標顯示還有插值圖渲染功能。折騰了一大圈，終于實現(xiàn)了，記錄一下，分享給需要的同學們。（￣︶￣）↗

安裝QGis啥的就自己百度吧，很傻瓜，就是慢。。。

1. 引入相關(guān)頭文件

#include <qgsapplication.h>
#include <qgsproviderregistry.h>
#include <qgsmapcanvas.h>
#include <qgsvectorlayer.h>
#include <qgsproject.h>
#include <qgsrasterlayer.h>
#include <QDialog>
#include <QFileDialog>
#include <QMessageBox>
#include "ogrsf_frmts.h"


// 功能函數(shù)的頭文件
#include <qgssinglesymbolrenderer.h>
#include <qgsinterpolator.h>
#include <qgstininterpolator.h>
#include <qgsgridfilewriter.h>
#include "qgssinglebandpseudocolorrenderer.h"
#include <qgsrastershader.h>

2.修改主函數(shù)

注意此處用Release模式運行（不知道為啥，反正Debug就是錯！！╮（╯＿╰）╭）

#include <qgsapplication.h>

int main(int argc, char *argv[])
{
    //QApplication a(argc, argv);  正常qt application的初始化
    QgsApplication a(argc, argv, true);
    QgsApplication::setPrefixPath("D:\\SoftWares\\QGIS\\install\\apps\\qgis\\plugins", true); 
    // 此處用自己的安裝路徑下面的庫
    QgsApplication::initQgis();    //初始化QGIS應用
    APP w;
    w.show();
    return a.exec();
}

3. 添加圖層向量

定義變量

QgsMapCanvas* mapCanvas; // 地圖畫布
//QList<QgsMapCanvasLayer> mapCanvasLayerSet; // 地圖畫布所用的圖層集合
QList<QgsMapLayer*> layers;
QPushButton* train_button;

實現(xiàn)函數(shù)

void onClickedBtnAddVectorLayers()
{
    QString filename = QFileDialog::getOpenFileName(this, tr("open vector"), "", "*.shp");
    QStringList temp = filename.split(QDir::separator());
    QString basename = temp.at(temp.size() - 1);
    QgsVectorLayer* vecLayer = new QgsVectorLayer(filename, basename, "ogr");
    if (!vecLayer->isValid())
    {
        QMessageBox::critical(this, "error", "layer is invalid");
        return;
    }


    QgsProject::instance()->addMapLayer(vecLayer);
    //mapCanvas->setVisible(true);
    layers.append(vecLayer);
    mapCanvas->setExtent(vecLayer->extent());
    mapCanvas->setLayers(layers);
    mapCanvas->zoomToFullExtent();
    //mapCanvas->freeze(false);
    mapCanvas->refresh();
    
}

4. 添加柵格圖層

本實現(xiàn)方法將柵格屬性中的顏色表進行了自定義，實現(xiàn)了彩色漸變?？梢宰孕行薷模。?！

void onClickedBtnAddRasterLayers()
{
    QString filename = QFileDialog::getOpenFileName(this, tr("open vector"), "", "*.tif");
    QStringList temp = filename.split(QDir::separator());
    QString basename = temp.at(temp.size() - 1);
    QgsRasterLayer* rasterLayer = new QgsRasterLayer(filename, basename, "gdal");
    if (!rasterLayer->isValid())
    {
        QMessageBox::critical(this, "error", "layer is invalid");
        return;
    }
    
    // 尋找柵格圖層數(shù)據(jù)中的最大值和最小值
    double max_value = 0, min_value = 100000,op=0;
    max_value = rasterLayer->dataProvider()->bandStatistics(1).maximumValue;
    min_value = rasterLayer->dataProvider()->bandStatistics(1).minimumValue;
    op = (max_value - min_value) / 4;
    
    //ui.lineEdit->setText(QString::number(max_value));
    //ui.lineEdit_2->setText(QString::number(min_value));

    //獲取當前默認Qgis工程
    QgsProject* project = QgsProject::instance();
    project->addMapLayer(rasterLayer);

    
    //構(gòu)建一個柵格ColorRampItem列表，每個ColorRampItem表示柵格數(shù)據(jù)一個值對應一個顏色
    QList<QgsColorRampShader::ColorRampItem> crlist;
    //添加填充色
    crlist.append(QgsColorRampShader::ColorRampItem(min_value, QColor(143, 131, 86, 255), QString("Fill")));
    //添加云色
    crlist.append(QgsColorRampShader::ColorRampItem(min_value+op, QColor(171, 221, 164, 255), QString("Cloud")));
    //添加海洋水體顏色
    crlist.append(QgsColorRampShader::ColorRampItem(min_value+op*2, QColor(255, 255, 191, 255), QString("Sea")));
    //添加陸地顏色
    crlist.append(QgsColorRampShader::ColorRampItem(min_value + op * 3, QColor(253, 174, 97, 255), QString("Land")));
    //添加積雪顏色
    crlist.append(QgsColorRampShader::ColorRampItem(max_value, QColor(215, 25, 28, 255), QString("Snow")));
    //構(gòu)建新的QgsColorRampShader 著色器
    QgsColorRampShader* crshader = new QgsColorRampShader(0, 100, nullptr, QgsColorRampShader::Type::Interpolated);
    //將顏色列表添加到著色器中
    crshader->setColorRampItemList(crlist);
    //構(gòu)建柵格著色器，我也不知道為啥要包裝這么多層
    QgsRasterShader* rasterShader = new QgsRasterShader();
    //設置渲染函數(shù)為剛剛新建的QgsColorRampShader 著色器
    rasterShader->setRasterShaderFunction(crshader);
    //構(gòu)建一個偽彩色單波段渲染器，使用前面的柵格著色器作為輸入，我也不明白為什么這么麻煩
    QgsSingleBandPseudoColorRenderer* pseudRender = new QgsSingleBandPseudoColorRenderer(
        rasterLayer->dataProvider(), 1, rasterShader);
    //柵格圖層設置偽彩色單波段渲染器
    rasterLayer->setRenderer(pseudRender);

    
    layers.append(rasterLayer);
    mapCanvas->setExtent(rasterLayer->extent());
    mapCanvas->setLayers(layers);
    mapCanvas->zoomToFullExtent();
    mapCanvas->refresh();
}

5. 生成TIN插值圖

void onClickedBtnGenerateTINMap()
{
    // 路徑可修改為自己的 .shp 文件路徑
    QgsVectorLayer* exp5Layer = new QgsVectorLayer("D:/newShp.shp", "shapefile", "ogr");

    const int index = 0;
    QgsInterpolator::LayerData ld5;

    ld5.source = exp5Layer;
    ld5.interpolationAttribute = index;
    ld5.sourceType = QgsInterpolator::SourceType::SourcePoints;
    ld5.valueSource = QgsInterpolator::ValueSource::ValueAttribute;

    QList<QgsInterpolator::LayerData> lds;
    lds.append(ld5);                                                                                                                                         
     
    QgsTinInterpolator* itp = new QgsTinInterpolator(lds);

    QgsWkbTypes::Type wkbType = exp5Layer->wkbType();
    QgsFields fields = exp5Layer->fields();

    // 范圍選擇圖層范圍，參數(shù)也可按自己需求修改（不明白參數(shù)的意思，可以先用QGis的Desktop軟件試一試，功能對應）
    QgsRectangle rect = exp5Layer->extent();
    int ncol = (rect.xMaximum() - rect.xMinimum()) / 5;
    int nrow = (rect.yMaximum() - rect.yMinimum()) / 5;
    double current_y_value = rect.yMaximum() - 0.1 / 2.0;
    double current_x_value = rect.xMinimum() + 0.1 / 2.0;
    double interpolatedValue;

    QgsGridFileWriter* writer = new QgsGridFileWriter(itp, "D:/d.tif", rect, ncol, nrow);
    writer->writeFile();
    
}

效果圖如下

[參考鏈接]
https://zhuanlan.zhihu.com/p/268609488
https://docs.qgis.org/3.16/en/docs/training_manual/processing/interpolation.html?highlight=interpolation
https://blog.csdn.net/deirjie/article/details/50413117
http://caiyi.tech/post.html?postKey=qgis_dev_1_env_setup
https://www.codenong.com/cs106838694/