List the contents of a KML file.
Use case
KML files can contain a hierarchy of features, including network links to other KML content. A user may wish to traverse through the contents of KML nodes to know what data is contained within each node and, recursively, their children.
How to use the sample
The contents of the KML file are shown in a list of buttons. Select a node to zoom to that node and see its child nodes, if it has any. Not all nodes can be zoomed to (e.g. screen overlays).
How it works
- Add the KML file to the scene as a layer.
- Explore the root nodes of the
KmlDataset
recursively to create a view model.
- Each node is enabled for display at this step. KML files may include nodes that are turned off by default.
- When a node is selected, use the node's
Extent
to determine a viewpoint and set theSceneView
object's viewpoint to it.
Relevant API
- KmlContainer
- KmlDataset
- KmlDocument
- KmlFolder
- KmlGroundOverlay
- KmlLayer
- KmlNetworkLink
- KmlNode
- KmlPlacemark
- KmlScreenOverlay
Offline data
To set up the sample's offline data, see the Use offline data in the samples section of the Qt Samples repository overview.
Link | Local Location |
---|---|
ESRI test data | <userhome> /ArcGIS/Runtime/Data/kml/esri_test_data.kmz |
About the data
This is an example KML file meant to demonstrate how Runtime supports several common features.
Tags
Keyhole, KML, KMZ, layers, OGC
Sample Code
// [WriteFile Name=ListKmlContents, Category=Layers]
// [Legal]
// Copyright 2020 Esri.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// [Legal]
#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD
#include "ListKmlContents.h"
#include "ArcGISTiledElevationSource.h"
#include "KmlContainer.h"
#include "KmlDataset.h"
#include "KmlLayer.h"
#include "KmlNetworkLink.h"
#include "KmlNode.h"
#include "KmlNodeListModel.h"
#include "Scene.h"
#include "SceneQuickView.h"
#include <algorithm>
#include <QDir>
#ifdef Q_OS_IOS
#include <QStandardPaths>
#endif // Q_OS_IOS
using namespace Esri::ArcGISRuntime;
// helper method to get cross platform data path
namespace
{
QString defaultDataPath()
{
QString dataPath;
#ifdef Q_OS_ANDROID
dataPath = "/sdcard";
#elif defined Q_OS_IOS
dataPath = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
#else
dataPath = QDir::homePath();
#endif
return dataPath;
}
} // namespace
ListKmlContents::ListKmlContents(QObject* parent /* = nullptr */):
QObject(parent),
m_scene(new Scene(BasemapStyle::ArcGISImagery, this))
{
// create a new elevation source from Terrain3D REST service
ArcGISTiledElevationSource* elevationSource = new ArcGISTiledElevationSource(
QUrl("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"), this);
// add the elevation source to the scene to display elevation
m_scene->baseSurface()->elevationSources()->append(elevationSource);
const QString filepath = defaultDataPath() + "/ArcGIS/Runtime/Data/kml/esri_test_data.kmz";
// create new KML layer
m_kmlDataset = new KmlDataset(filepath, this);
KmlLayer* kmlLayer = new KmlLayer(m_kmlDataset, this);
m_scene->operationalLayers()->append(kmlLayer);
connect(m_kmlDataset, &KmlDataset::doneLoading, this, [this](Error loadError)
{
if (!loadError.isEmpty())
{
qDebug() << loadError.message() << loadError.additionalMessage();
return;
}
// recursively build tree to display KML contents
const auto nodes = m_kmlDataset->rootNodes();
for (KmlNode* node : nodes)
{
m_kmlNodesList << node;
buildTree(node);
}
// if at top node, then display children
if (!m_kmlNodesList.isEmpty() && m_kmlNodesList[0]->parentNode() == nullptr)
{
m_currentNode = m_kmlNodesList[0];
emit currentNodeChanged();
emit levelNodeNamesChanged();
}
});
}
QString ListKmlContents::getKmlNodeType(KmlNode *node)
{
if (node == nullptr)
return "";
QString type = "";
switch (node->kmlNodeType()) {
case KmlNodeType::KmlDocument:
type = "KmlDocument";
break;
case KmlNodeType::KmlFolder:
type = "KmlFolder";
break;
case KmlNodeType::KmlNetworkLink:
type = "KmlNetworkLink";
break;
case KmlNodeType::KmlPlacemark:
type = "KmlPlacemark";
break;
case KmlNodeType::KmlPhotoOverlay:
type = "KmlPhotoOverlay";
break;
case KmlNodeType::KmlGroundOverlay:
type = "KmlGroundOverlay";
break;
case KmlNodeType::KmlScreenOverlay:
type = "KmlScreenOverlay";
break;
case KmlNodeType::KmlTour:
type = "KmlTour";
break;
default:
return "";
}
return type;
}
// recursively build string to indicate node's ancestors
QStringList ListKmlContents::buildPathLabel(KmlNode* node) const
{
if (node != nullptr)
return buildPathLabel(node->parentNode()) << node->name();
else
return QStringList {};
}
void ListKmlContents::displayPreviousLevel()
{
KmlNode* parentNode = m_currentNode->parentNode();
if (parentNode == nullptr)
return;
KmlNode* grandparentNode = parentNode->parentNode();
if (grandparentNode != nullptr)
{
m_currentNode = grandparentNode;
emit currentNodeChanged();
emit labelTextChanged();
emit levelNodeNamesChanged();
}
// if grandparent node is nullptr, then at top of tree
else
{
m_currentNode = parentNode;
emit currentNodeChanged();
emit labelTextChanged();
emit levelNodeNamesChanged();
}
}
// display selected node on sceneview and show its children
void ListKmlContents::processSelectedNode(const QString& nodeName)
{
// extract the node's name from the string, formatted "name - nodeType"
QString extractedNodeName = nodeName;
if (nodeName.contains(" - "))
{
int ind = nodeName.lastIndexOf(" - ");
extractedNodeName = nodeName.left(ind);
}
// find node in the list
for (KmlNode* node : qAsConst(m_kmlNodesList))
{
if (extractedNodeName == node->name())
{
// update current node
m_currentNode = node;
emit currentNodeChanged();
emit labelTextChanged();
m_viewpoint = Viewpoint();
getViewpointFromKmlViewpoint(node);
if (m_needsAltitudeFixed)
{
getAltitudeAdjustedViewpoint(node);
}
else
{
if (!m_viewpoint.isEmpty() && !m_viewpoint.targetGeometry().isEmpty())
m_sceneView->setViewpoint(m_viewpoint);
}
// reset m_lastLevel before levelNodeNames() is called
emit levelNodeNamesChanged();
// if displaying end-nodes, change m_currentNode to first end-node for correct behavior of back button
if (noGrandchildren(m_currentNode))
{
m_currentNode = static_cast<KmlContainer*>(m_currentNode)->childNodesListModel()->at(0);
emit currentNodeChanged();
}
break;
}
}
}
void ListKmlContents::getViewpointFromKmlViewpoint(KmlNode* node)
{
const KmlViewpoint kmlViewpoint = node->viewpoint();
if (!kmlViewpoint.isEmpty())
{
// altitude adjustment is needed for all but Absolute altitude mode
m_needsAltitudeFixed = (kmlViewpoint.altitudeMode() != KmlAltitudeMode::Absolute);
switch (kmlViewpoint.type())
{
case KmlViewpointType::LookAt:
m_viewpoint = Viewpoint(kmlViewpoint.location(), Camera(kmlViewpoint.location(), kmlViewpoint.range(),
kmlViewpoint.heading(), kmlViewpoint.pitch(), kmlViewpoint.roll()));
return;
case KmlViewpointType::Camera:
m_viewpoint = Viewpoint(kmlViewpoint.location(), Camera(kmlViewpoint.location(),
kmlViewpoint.heading(), kmlViewpoint.pitch(), kmlViewpoint.roll()));
return;
default:
qWarning("Unexpected KmlViewpointType");
return;
}
}
// if viewpoint was empty, then use node's extent
const Envelope nodeExtent = node->extent();
if (nodeExtent.isValid() && !nodeExtent.isEmpty())
{
// when no altitude is specified, assume elevation needs to be adjusted
m_needsAltitudeFixed = true;
if (nodeExtent.width() == 0 && nodeExtent.height() == 0)
{
// default values: distance = 1000m, pitch = 45 degrees
m_viewpoint = Viewpoint(nodeExtent);
m_sceneView->setViewpointCameraAndWait(Camera(nodeExtent.center(), 1000, 0, 45, 0));
return;
}
else
{
// add padding to extent
double bufferDistance = qMax(nodeExtent.width(), nodeExtent.height()) / 20;
Envelope bufferedExtent = Envelope(nodeExtent.xMin() - bufferDistance, nodeExtent.yMin() - bufferDistance,
nodeExtent.xMax() + bufferDistance, nodeExtent.yMax() + bufferDistance,
nodeExtent.zMin() - bufferDistance, nodeExtent.zMax() + bufferDistance,
SpatialReference::wgs84());
m_viewpoint = Viewpoint(bufferedExtent);
}
}
else
{
// can't show viewpoint
m_needsAltitudeFixed = false;
m_viewpoint = Viewpoint();
}
}
void ListKmlContents::getAltitudeAdjustedViewpoint(KmlNode* node)
{
// assume altitude mode is clamp-to-ground if not specified
KmlAltitudeMode altMode = KmlAltitudeMode::ClampToGround;
KmlViewpoint kmlViewpoint = node->viewpoint();
if (!kmlViewpoint.isEmpty())
{
altMode = kmlViewpoint.altitudeMode();
}
// if altitude mode is Absolute, viewpoint doesn't need adjustment
if (altMode == KmlAltitudeMode::Absolute)
{
m_sceneView->setViewpoint(m_viewpoint);
return;
}
const Envelope lookAtExtent = geometry_cast<Envelope>(m_viewpoint.targetGeometry());
const Point lookAtPoint = geometry_cast<Point>(m_viewpoint.targetGeometry());
if (lookAtExtent.isValid())
{
m_scene->baseSurface()->locationToElevation(lookAtExtent.center());
}
else if (lookAtPoint.isValid())
{
m_scene->baseSurface()->locationToElevation(lookAtPoint);
}
}
// recursively build list of all KML nodes
void ListKmlContents::buildTree(KmlNode* parentNode)
{
auto addNode = [this](KmlNode* node)
{
// some nodes have default visibility set to false
node->setVisible(true);
m_kmlNodesList << node;
buildTree(node);
};
if (KmlContainer* container = dynamic_cast<KmlContainer*>(parentNode))
{
const KmlNodeListModel& childNodes = *container->childNodesListModel();
std::for_each(std::begin(childNodes), std::end(childNodes), addNode);
}
else if (KmlNetworkLink* networkLink = dynamic_cast<KmlNetworkLink*>(parentNode))
{
const QList<KmlNode*> childNodes = networkLink->childNodes();
std::for_each(std::begin(childNodes), std::end(childNodes), addNode);
}
}
ListKmlContents::~ListKmlContents() = default;
void ListKmlContents::init()
{
// Register classes for QML
qmlRegisterType<SceneQuickView>("Esri.Samples", 1, 0, "SceneView");
qmlRegisterType<ListKmlContents>("Esri.Samples", 1, 0, "ListKmlContentsSample");
}
SceneQuickView* ListKmlContents::sceneView() const
{
return m_sceneView;
}
// Set the view (created in QML)
void ListKmlContents::setSceneView(SceneQuickView* sceneView)
{
if (!sceneView || sceneView == m_sceneView)
return;
m_sceneView = sceneView;
m_sceneView->setArcGISScene(m_scene);
connect(m_scene->baseSurface(), &Surface::locationToElevationCompleted, this, [this](QUuid, double elevation)
{
// assume altitude mode is clamp-to-ground if not specified
KmlAltitudeMode altMode = KmlAltitudeMode::ClampToGround;
KmlViewpoint kmlViewpoint = m_currentNode->viewpoint();
if (!kmlViewpoint.isEmpty())
{
altMode = kmlViewpoint.altitudeMode();
}
// if altitude mode is Absolute, viewpoint doesn't need adjustment
if (altMode == KmlAltitudeMode::Absolute)
return;
const Envelope lookAtExtent = geometry_cast<Envelope>(m_viewpoint.targetGeometry());
const Point lookAtPoint = geometry_cast<Point>(m_viewpoint.targetGeometry());
if (lookAtExtent.isValid())
{
Envelope target;
if (altMode == KmlAltitudeMode::ClampToGround)
{
// if depth of extent is 0, add 100m to the elevation to get zMax
if (lookAtExtent.depth() == 0)
{
target = Envelope(lookAtExtent.xMin(), lookAtExtent.yMin(),
lookAtExtent.xMax(), lookAtExtent.yMax(),
elevation, elevation + 100,
lookAtExtent.spatialReference());
}
else
{
target = Envelope(lookAtExtent.xMin(), lookAtExtent.yMin(),
lookAtExtent.xMax(), lookAtExtent.yMax(),
// set the camera slightly above the placemark by adding one meter
elevation, lookAtExtent.depth() + elevation + 1,
lookAtExtent.spatialReference());
}
}
else
{
target = Envelope(lookAtExtent.xMin(), lookAtExtent.yMin(),
lookAtExtent.xMax(), lookAtExtent.yMax(),
lookAtExtent.zMin() + elevation, lookAtExtent.zMax() + elevation,
lookAtExtent.spatialReference());
}
// if node has viewpoint specified, return adjusted geometry with adjusted camera
if (!kmlViewpoint.isEmpty())
{
m_sceneView->setViewpointCameraAndWait(m_viewpoint.camera().elevate(elevation));
m_viewpoint = Viewpoint(target);
m_sceneView->setViewpoint(m_viewpoint);
return;
}
else
{
m_viewpoint = Viewpoint(target);
m_sceneView->setViewpoint(m_viewpoint);
return;
}
}
else if (lookAtPoint.isValid())
{
Point target;
if (altMode == KmlAltitudeMode::ClampToGround)
{
target = Point(lookAtPoint.x(), lookAtPoint.y(), elevation, lookAtPoint.spatialReference());
}
else
{
target = Point(lookAtPoint.x(), lookAtPoint.y(), lookAtPoint.z() + elevation, lookAtPoint.spatialReference());
}
// set the viewpoint using the adjusted target
if (!kmlViewpoint.isEmpty())
{
m_sceneView->setViewpointCameraAndWait(m_viewpoint.camera().elevate(elevation));
m_viewpoint = Viewpoint(target);
m_sceneView->setViewpoint(m_viewpoint);
return;
}
else
{
// use default values to set camera: distance = 1000m, pitch = 45 degrees
m_viewpoint = Viewpoint(target);
m_sceneView->setViewpoint(m_viewpoint);
m_sceneView->setViewpointCameraAndWait(Camera(target, 1000, 0, 45, 0));
return;
}
}
});
emit sceneViewChanged();
}
QStringList ListKmlContents::levelNodeNames()
{
if (m_currentNode == nullptr)
return {};
QStringList nodeNames = {};
// if node is not a container, m_levelNodeNames will be unchanged
if (KmlContainer* container = dynamic_cast<KmlContainer*>(m_currentNode))
{
// for current level, get names of child nodes
for (KmlNode* node: *(container->childNodesListModel()))
{
QString str = node->name() + " - " + getKmlNodeType(node);
// if node has children, add ">" to indicate further levels
if (!node->children().isEmpty())
{
str.append(" >");
}
nodeNames << str;
}
m_levelNodeNames = nodeNames;
}
return m_levelNodeNames;
}
bool ListKmlContents::noGrandchildren(KmlNode *currentNode) const
{
bool hasNoGrandchildren = false;
if (KmlContainer* container = dynamic_cast<KmlContainer*>(currentNode))
{
hasNoGrandchildren = true;
// for current level, get names of child nodes
for (KmlNode* node: *(container->childNodesListModel()))
{
// if node has children, add ">" to indicate further levels
if (!node->children().isEmpty())
{
hasNoGrandchildren = false;
}
}
}
return hasNoGrandchildren;
}
QString ListKmlContents::labelText() const
{
return buildPathLabel(m_currentNode).join(" > ");
}
bool ListKmlContents::isTopLevel() const
{
if (m_currentNode == nullptr)
return true;
else if (m_currentNode->parentNode() == nullptr)
return true;
else if (m_currentNode->name() == "")
return true;
else
return false;
}