Take a screenshot of the map.
Use case
GIS users may want to export a screenshot of a map to enable sharing as an image or printing.
How to use the sample
Pan and zoom to find an interesting location. Press Take screenshot, and a screenshot image will display over the map. Note that there may be a small delay if the map is still rendering when you push the button.
How it works
- The
exportImagefunction is executed on theMapView. - Once the asynchronous task completes, a
QImageis returned. - QML cannot directly render a
QImage. Instead, a QML Image Provider must be created for generating an in-memory URL to the returnedQImage. This is done with the following steps:
- Subclass
QQuickImageProvider. - Reimplement the
requestImagefunction. - Add an image provider to the
QQmlEngineinstance usingQQmlEngine::addImageProvider. - Create a
Q_PROPERTYthat returns the image URL from the Image Provider. - Bind the QML Image to the image URL property. When this property changes, it will automatically trigger the
requestImagefunction and return the URL to the image.
Relevant API
- GeoView::exportImage
Tags
capture, export, image, print, screen capture, screenshot, share, shot
Sample Code
// [WriteFile Name=TakeScreenshot, Category=Maps]
// [Legal]
// Copyright 2018 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 "TakeScreenshot.h"
#include "Map.h"
#include "MapQuickView.h"
#include "MapImageProvider.h"
#include "MapTypes.h"
#include <QFuture>
#include <QQmlContext>
#include <QUuid>
using namespace Esri::ArcGISRuntime;
TakeScreenshot::TakeScreenshot(QQuickItem* parent /* = nullptr */):
QQuickItem(parent)
{
}
void TakeScreenshot::init()
{
// Register the map view for QML
qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
qmlRegisterType<TakeScreenshot>("Esri.Samples", 1, 0, "TakeScreenshotSample");
}
void TakeScreenshot::componentComplete()
{
QQuickItem::componentComplete();
// find QML MapView component
m_mapView = findChild<MapQuickView*>("mapView");
// Create a map using the imagery basemap
m_map = new Map(BasemapStyle::ArcGISImageryStandard, this);
// Set map to map view
m_mapView->setMap(m_map);
// Get the image provider from the QML Engine
QQmlEngine* engine = QQmlEngine::contextForObject(this)->engine();
m_imageProvider = dynamic_cast<MapImageProvider*>(engine->imageProvider(MapImageProvider::imageProviderId()));
}
// Q_INVOKABLE function to kick off the export image asynchronous task
void TakeScreenshot::captureScreenshot()
{
m_mapView->exportImageAsync().then(this, [this](QImage img)
{
// convert the QUuid into a QString
const QString imageId = QUuid().createUuid().toString(QUuid::WithoutBraces);
// add the image to the provider
m_imageProvider->addImage(imageId, img);
// update the URL with the unique id
m_mapImageUrl = QString("image://%1/%2").arg(MapImageProvider::imageProviderId(), imageId);
// emit the signal to trigger the QML Image to update
emit mapImageUrlChanged();
});
}
QUrl TakeScreenshot::mapImageUrl() const
{
return m_mapImageUrl;
}