Show magnifier

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C++

QML

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Sample viewer app

Tap and hold on a map to show a magnifier.

screenshot

Use case

Due to the limited screen size of some mobile devices, it may be difficult to identify individual features on a map where there is a high density of information, or the scale is very small. This can be the case when a mobile device is used for navigation, and the user wishes to magnify a particular area to better identify a road intersection.

How to use the sample

Tap and hold on the map to show a magnifier, then drag across the map to move the magnifier. You can also pan the map while holding the magnifier, by dragging the magnifier to the edge of the map.

How it works

Create a new MapView, and add a Map to it: mapView::setMap(map).
Enable the magnifier using mapView::setMagnifierEnabled(true). This will set the magnifier to be shown on the map when the user performs a long press gesture. Note: The default value is false.
MapView::setMagnifierMapPanningEnabled() is set to true by default to allow you to pan the map when the magnifier get's near the edge of the map.

Relevant API

Map
MapView
MapView::setMagnifierMapPanningEnabled()
MapView::setMagnifierEnabled()

Additional information

This sample only works on a device with a touch screen. The magnifier will not appear via a mouse click.

Sample Code

ShowMagnifier.cpp

ShowMagnifier.h

ShowMagnifier.qml

Use dark colors for code blocksCopy
// [WriteFile Name=ShowMagnifier, Category=Maps]
// [Legal]
// Copyright 2016 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 "ShowMagnifier.h"

#include "Map.h"
#include "MapQuickView.h"
#include "Basemap.h"
#include "Viewpoint.h"

using namespace Esri::ArcGISRuntime;

ShowMagnifier::ShowMagnifier(QQuickItem* parent) :
  QQuickItem(parent)
{
}

ShowMagnifier::~ShowMagnifier() = default;

void ShowMagnifier::init()
{
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<ShowMagnifier>("Esri.Samples", 1, 0, "ShowMagnifierSample");
}

void ShowMagnifier::componentComplete()
{
  QQuickItem::componentComplete();

  // find QML MapView component
  m_mapView = findChild<MapQuickView*>("mapView");

  // create a new basemap instance
  Basemap* basemap = new Basemap(BasemapStyle::ArcGISImageryStandard, this);

  // create a new map instance
  m_map = new Map(basemap, this);
  m_map->setInitialViewpoint(Viewpoint(Point(-110.8258, 32.1545089, SpatialReference::wgs84()), 2e4));

  // set map on the map view
  m_mapView->setMap(m_map);

  // enable magnifier
  m_mapView->setMagnifierEnabled(true);
}