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 exportImage function is executed on the MapView.
Once the asynchronous task completes, a QImage is returned.
QML cannot directly render a QImage. Instead, a QML Image Provider must be created for generating an in-memory URL to the returned QImage. This is done with the following steps:
Subclass QQuickImageProvider.
Reimplement the requestImage function.
Add an image provider to the QQmlEngine instance using QQmlEngine::addImageProvider.
Create a Q_PROPERTY that 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 requestImage function and return the URL to the image.
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// [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"TaskWatcher.h"#include<QQmlContext>#include<QUuid>usingnamespace Esri::ArcGISRuntime;
TakeScreenshot::TakeScreenshot(QQuickItem* parent /* = nullptr */):
QQuickItem(parent)
{
}
voidTakeScreenshot::init(){
// Register the map view for QML qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
qmlRegisterType<TakeScreenshot>("Esri.Samples", 1, 0, "TakeScreenshotSample");
}
voidTakeScreenshot::componentComplete(){
QQuickItem::componentComplete();
// find QML MapView component m_mapView = findChild<MapQuickView*>("mapView");
// Create a map using the imagery basemap m_map = newMap(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()));
// Connect to the exportImageCompleted signalconnect(m_mapView, &MapQuickView::exportImageCompleted, this, [this](const QUuid& id, const QImage& img)
{
// convert the QUuid into a QStringconst QString imageId = id.toString().remove("{").remove("}");
// 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();
});
}
// Q_INVOKABLE function to kick off the export image asynchronous taskvoidTakeScreenshot::captureScreenshot(){
m_mapView->exportImage();
}
QUrl TakeScreenshot::mapImageUrl()const{
return m_mapImageUrl;
}
