Read symbols from a mobile style

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Combine multiple symbols from a mobile style file into a single symbol.

screenshot

Use case

You may choose to display individual elements of a dataset like a water infrastructure network (such as valves, nodes, or endpoints) with the same basic shape, but wish to modify characteristics of elements according to some technical specifications. Multilayer symbols lets you add or remove components or modify the colors to create advanced symbol styles.

How to use the sample

Select a symbol and a color from each of the category lists to create an emoji. A preview of the symbol is updated as selections are made. The size of the symbol can be set using the slider. Click the map to create a point graphic using the customized emoji symbol, and click Clear to clear all graphics from the display.

How it works

  1. Create a new SymbolStyle from a stylx file, and load it.
  2. Get a list of symbols in the style by calling SymbolStyle::searchSymbolsAsync within ReadSymbolsFromMobileStyle::searchSymbolLayer.
  3. Display the resulting SymbolStyleSearchResultListModel inside a series of ComboBoxes.
  4. When symbol selections change, create a new multilayer symbol by passing the keys for the selected symbols into SymbolStyle::fetchSymbolAsync.
  5. Iterate through the symbol layers and color lock all symbol layers except the base layer and update the current symbol preview image by calling Symbol::createSwatchAsync.
  6. Create graphics symbolized with the current symbol when the user taps the map view.

Relevant API

  • MultilayerPointSymbol
  • Symbol::createSwatch
  • SymbolLayer
  • SymbolStyle
  • SymbolStyle::fetchSymbolAsync
  • SymbolStyle::searchSymbolsAsync
  • SymbolStyleSearchParameters
  • SymbolStyleSearchResult
  • SymbolStyleSearchResultListModel

Offline Data

A mobile style file (created using ArcGIS Pro) provides the symbols used by the sample.

Link Local Location
Emoji mobile style <userhome>/ArcGIS/Runtime/Data/style/emoji-mobile.stylx

About the data

The mobile style file used in this sample was created using ArcGIS Pro, and is hosted on ArcGIS Online. It contains symbol layers that can be combined to create emojis.

Additional information

While each of these symbols can be created from scratch, a more convenient workflow is to author them using ArcGIS Pro and store them in a mobile style file (.stylx). The ArcGIS Maps SDK for Qt can read symbols from a mobile style, and you can modify and combine them as needed in your app.

Tags

advanced symbology, mobile style, multilayer, stylx

Sample Code

ReadSymbolsFromMobileStyle.cppReadSymbolsFromMobileStyle.cppReadSymbolsFromMobileStyle.hSymbolComboBox.qmlSymbolImageProvider.cppSymbolImageProvider.hReadSymbolsFromMobileStyle.qml
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// [WriteFile Name=ReadSymbolsFromMobileStyle, Category=DisplayInformation]
// [Legal]
// Copyright 2019 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 "ReadSymbolsFromMobileStyle.h"

#include "Map.h"
#include "MapQuickView.h"
#include "GraphicsOverlay.h"
#include "Graphic.h"
#include "SymbolStyle.h"
#include "MultilayerSymbol.h"
#include "Point.h"
#include "MultilayerPointSymbol.h"
#include "SymbolImageProvider.h"
#include "SymbolStyleSearchResultListModel.h"
#include "MapTypes.h"
#include "Error.h"
#include "SymbolStyleSearchParameters.h"
#include "SymbolLayerListModel.h"
#include "SymbolLayer.h"
#include "GraphicsOverlayListModel.h"
#include "GraphicListModel.h"
#include "SymbolStyleSearchResult.h"

#include <QFuture>
#include <QObject>
#include <QQmlContext>
#include <QTemporaryDir>
#include <QtCore/qglobal.h>
#include <QStandardPaths>

using namespace Esri::ArcGISRuntime;

constexpr int hatIndex = 0;
constexpr int mouthIndex = 1;
constexpr int eyeIndex = 2;
constexpr int faceIndex = 3;

// helper method to get cross platform data path
namespace
{
QString defaultDataPath()
{
  QString dataPath;

#ifdef Q_OS_IOS
  dataPath = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
#else
  dataPath = QStandardPaths::writableLocation(QStandardPaths::HomeLocation);
#endif

  return dataPath;
}
} // namespace

ReadSymbolsFromMobileStyle::ReadSymbolsFromMobileStyle(QObject* parent /* = nullptr */) :
  QObject(parent),
  m_map(new Map(BasemapStyle::ArcGISTopographic, this)),
  m_graphicParent(new QObject())
{
  m_symbolStyle = new SymbolStyle(defaultDataPath() + "/ArcGIS/Runtime/Data/styles/emoji-mobile.stylx", this);

  // Load the style
  connect(m_symbolStyle, &SymbolStyle::doneLoading, this, [this](const Error& e)
  {
    if (!e.isEmpty())
      return;
    searchSymbolLayer("Hat", hatIndex);
    searchSymbolLayer("Mouth", mouthIndex);
    searchSymbolLayer("Eyes", eyeIndex);
    searchSymbolLayer("Face", faceIndex);
  });

  m_symbolStyle->load();
}

ReadSymbolsFromMobileStyle::~ReadSymbolsFromMobileStyle() = default;

void ReadSymbolsFromMobileStyle::init()
{
  // Register the map view for QML
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<ReadSymbolsFromMobileStyle>("Esri.Samples", 1, 0, "ReadSymbolsFromMobileStyleSample");
  qmlRegisterUncreatableType<SymbolStyleSearchResultListModel>("Esri.Samples", 1, 0, "SymbolStyleSearchResultListModel", "SymbolStyleSearchResultListModel is uncreateable");
}

MapQuickView* ReadSymbolsFromMobileStyle::mapView() const
{
  return m_mapView;
}

// Set the view (created in QML)
void ReadSymbolsFromMobileStyle::setMapView(MapQuickView* mapView)
{
  if (!mapView || mapView == m_mapView)
    return;

  m_mapView = mapView;
  m_mapView->setMap(m_map);

  // Get the image provider from the QML Engine
  QQmlEngine* engine = QQmlEngine::contextForObject(this)->engine();
  engine->addImageProvider(SymbolImageProvider::imageProviderId(), new SymbolImageProvider);
  m_symbolImageProvider = static_cast<SymbolImageProvider*>(engine->imageProvider(SymbolImageProvider::imageProviderId()));

  // add a graphics overlay
  GraphicsOverlay* overlay = new GraphicsOverlay(this);
  m_mapView->graphicsOverlays()->append(overlay);

  // connect to mouse clicked signal
  connect(m_mapView, &MapQuickView::mouseClicked, this, [this, overlay](QMouseEvent& mouseEvent)
  {
    if (!m_currentSymbol)
      return;

    const Point clickedPoint = m_mapView->screenToLocation(mouseEvent.position().x(), mouseEvent.position().y());
    Graphic* graphic = new Graphic(clickedPoint, m_currentSymbol, m_graphicParent.get());
    overlay->graphics()->append(graphic);
  });

  emit mapViewChanged();
}

// Clear the graphics from the overlay and delete each object
void ReadSymbolsFromMobileStyle::clearGraphics()
{
  if (!m_mapView)
    return;

  GraphicsOverlay* overlay = m_mapView->graphicsOverlays()->first();
  if (!overlay)
    return;

  // clear the list model
  overlay->graphics()->clear();

  // reset m_graphicsParent to delete all children
  m_graphicParent.reset(new QObject());
}

void ReadSymbolsFromMobileStyle::updateSymbol(int requestHatIndex, int requestMouthIndex, int requestEyeIndex, QColor color, int size)
{
  if (!m_symbolStyle || !hatResults() || !mouthResults() || !eyeResults() || !faceResults())
    return;

  // set the color and size members
  m_currentColor = color;
  m_symbolSize = size;

  // fetch the new symbol based on keys
  QStringList keys;
  keys.append(faceResults()->searchResults().at(0).key());
  keys.append(eyeResults()->searchResults().at(requestEyeIndex).key());
  keys.append(mouthResults()->searchResults().at(requestMouthIndex).key());
  keys.append(hatResults()->searchResults().at(requestHatIndex).key());
  m_symbolStyle->fetchSymbolAsync(keys).then(this,
  [this](Symbol* symbol)
  {
    if (m_currentSymbol)
      delete m_currentSymbol;

    // store the resulting symbol
    m_currentSymbol = static_cast<MultilayerPointSymbol*>(symbol);

    // ensure cast was successful
    if (!m_currentSymbol)
      return;

    // set the size
    m_currentSymbol->setSize(m_symbolSize);

    // set the color preferences per layer
    for (SymbolLayer* lyr : *(m_currentSymbol->symbolLayers()))
      lyr->setColorLocked(true);

    m_currentSymbol->symbolLayers()->at(0)->setColorLocked(false);

    // set the color
    m_currentSymbol->setColor(m_currentColor);

    // request symbol swatch
    m_currentSymbol->createSwatchAsync().then(this,
    [this](const QImage& img)
    {
      if (!m_symbolImageProvider)
        return;

      // convert the QUuid into a QString
      const QString imageId = QUuid().createUuid().toString(QUuid::StringFormat::WithoutBraces);

      // add the image to the provider
      m_symbolImageProvider->addImage(imageId, img);

      // update the URL with the unique id
      m_symbolImageUrl = QString("image://%1/%2").arg(SymbolImageProvider::imageProviderId(), imageId);

      // emit the signal to trigger the QML Image to update
      emit symbolImageUrlChanged();
    });

  });
}

SymbolStyleSearchResultListModel* ReadSymbolsFromMobileStyle::hatResults() const
{
  return m_models[hatIndex];
}

SymbolStyleSearchResultListModel* ReadSymbolsFromMobileStyle::mouthResults() const
{
  return m_models[mouthIndex];
}

SymbolStyleSearchResultListModel* ReadSymbolsFromMobileStyle::eyeResults() const
{
  return m_models[eyeIndex];
}

SymbolStyleSearchResultListModel* ReadSymbolsFromMobileStyle::faceResults() const
{
  return m_models[faceIndex];
}

void ReadSymbolsFromMobileStyle::searchSymbolLayer(const QString& category, int index)
{
  SymbolStyleSearchParameters params;
  params.setCategories({category});
  m_symbolStyle->searchSymbolsAsync(params).then(this,
  [this, index](SymbolStyleSearchResultListModel* results)
  {
    m_models[index] = results;
    emit symbolResultsChanged();
  });
}

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