在上一篇中实现一个icon + label的Marker需要使用两个Tangram的Marker， 今天分析了Tangram的源码后， 发现Tangram时支持单一Marker同时显示的， 这需要使用嵌套的Style。

上一篇使用的Style是两个：

style: points, color: white, size: [32px, 32px], order: 100, collide: false

和

text:    text_source: function(){ return "label"},    priority: 100

但其实points style支持text属性， 两个合并后变成：

style: points,color: white,size: [32px, 32px],order: 100,collide: false,text:    text_source: 'function(){ return \"Title\"}',    priority: 100

代码如下

void MarkerImpl::createMarker(const std::string &iconURI, const std::string &title){    QImage img(QString(iconURI.c_str()));    int width = img.width();    int height = img.height();    auto argb = new unsigned int [width * height];    for(int h=height-1; h>-1; --h){        for(int w=0; w
     
      > 16) & 0xff;            int pr = (pix << 16) & 0x00ff0000;            int pix1 = (pix & 0xff00ff00) | pr | pb;            argb[w + h*width] = pix1;        }    }    m_map->markerSetBitmap(m_ID, width, height, argb);    delete[] argb;    static const char* MARKER_STYLE_TEMPLATE =            "{ style: 'points',"            " color: 'white',"            " size: [%1px, %2px],"            " order: 100,"            " collide: false,"            " text: {
    "                " text_source: 'function(){ return \"%3\"}',"                " priority: 100 } }";    QString iconStyle = QString(MARKER_STYLE_TEMPLATE).arg(width).arg(height).arg(title.c_str());    m_map->markerSetStyling(m_ID, iconStyle.toStdString().c_str());}
     

这里使用了单行YAML的写法， 详见