Set the map's reference scale and which feature layers should honor the reference scale.
Use case
Setting a reference scale on a Map fixes the size of symbols and text to the desired height and width at that scale. As you zoom in and out, symbols and text will increase or decrease in size accordingly. When no reference scale is set, symbol and text sizes remain the same size relative to the MapView.
Map annotations are typically only relevant at certain scales. For instance, annotations to a map showing a construction site are only relevant at that construction site's scale. So, when the map is zoomed out that information shouldn't scale with the MapView, but should instead remain scaled with the Map.
How to use the sample
- Use the drop box at the top to set the map's reference scale (1:500,000 1:250,000 1:100,000 1:50,000).
- Click the button to set the map scale to the reference scale.
- Use the menu checkboxes in the layer menu to set which feature layers should honor the reference scale.
How it works
- Get and set the reference scale property on the
Mapobject. - Get and set the scale symbols property on each individual
FeatureLayerobject.
Relevant API
- Map
- FeatureLayer
Additional Information
The map reference scale should normally be set by the map's author and not exposed to the end user like it is in this sample.
Tags
map, reference scale, scene
Sample Code
MapReferenceScale.qml
// [WriteFile Name=MapReferenceScale, Category=Maps]
// [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]
import QtQuick
import Esri.ArcGISRuntime
import QtQuick.Controls
import QtQuick.Layouts
Rectangle {
id: rootRectangle
clip: true
width: 800
height: 600
readonly property var referenceScales: [500000, 250000, 100000, 50000]
readonly property string webMapId: "3953413f3bd34e53a42bf70f2937a408"
property LayerListModel featureLayerModel
MapView {
id: mapView
anchors.fill: parent
Component.onCompleted: {
// Set the focus on MapView to initially enable keyboard navigation
forceActiveFocus();
}
// Create a Map from a Portal Item
Map {
id: map
PortalItem {
id: mapPortalItem
portal: portal
itemId: webMapId
onErrorChanged: {
console.log("Error in portal item: %1(%2)".arg(error.message).arg(error.additionalMessage));
}
onLoadStatusChanged: {
if (loadStatus === Enums.LoadStatusLoaded) {
//load operational layers into listmodel
featureLayerModel = map.operationalLayers;
}
}
}
}
}
Rectangle {
anchors {
margins: 5
left: parent.left
top: parent.top
}
width: childrenRect.width
height: childrenRect.height
color: "#000000"
opacity: .75
radius: 5
ColumnLayout {
Text {
color: "#ffffff"
text: "Current Map Scale 1:%1".arg(Math.round(mapView.mapScale))
Layout.fillWidth: true
Layout.margins: 3
font {
weight: Font.DemiBold
pointSize: 10
}
}
Text {
color: "#ffffff"
text: qsTr("Select a new reference scale")
Layout.fillWidth: true
Layout.margins: 3
font {
weight: Font.DemiBold
pointSize: 10
}
}
ComboBox {
id: scales
font {
weight: Font.DemiBold
pointSize: 10
}
Layout.margins: 3
Layout.fillWidth: true
model: ["1:500000","1:250000","1:100000","1:50000"]
Component.onCompleted: applyReferenceScaleToMap();
onActivated: applyReferenceScaleToMap();
// Add a background to the ComboBox
Rectangle {
anchors.fill: parent
radius: 10
// Make the rectangle visible if a dropdown indicator exists
// An indicator only exists if a theme is set
visible: parent.indicator
border.width: 1
}
}
Button {
text: qsTr("Set Map Scale to Reference Scale")
font {
weight: Font.DemiBold
pointSize: 10
}
Layout.margins: 3
Layout.fillWidth: true
onClicked: mapView.setViewpointScale(referenceScales[scales.currentIndex]);
}
}
}
Rectangle {
anchors {
margins: 5
right: parent.right
top: parent.top
}
width: childrenRect.width
height: childrenRect.height
color: "#000000"
opacity: .75
radius: 5
ColumnLayout {
Text {
text: qsTr("Apply Reference Scale")
horizontalAlignment: Text.AlignHCenter
Layout.fillWidth: true
Layout.margins: 2
font {
weight: Font.DemiBold
pointSize: 10
}
color: "#ffffff"
}
Repeater {
id: featureLayerRepeater
// Assign the model to the list model of operational layers
model: featureLayerModel
width: childrenRect.width
height: childrenRect.height
// Assign the delegate to display text next to checkbox as a row
delegate: Row {
CheckBox {
id: featureLayerBox
checked: true
onCheckStateChanged: featureLayerScaleSymbols(name,featureLayerBox.checked);
}
Text {
id: featureLayerText
text: name
height: featureLayerBox.height
verticalAlignment: Text.AlignVCenter
font.pointSize: 10
color: "#ffffff"
}
}
}
}
}
function applyReferenceScaleToMap() {
map.referenceScale = referenceScales[scales.currentIndex];
}
//pass in layers name and checked status to update featurelayer.ScaleSymbols property accordingly
function featureLayerScaleSymbols(layerName, checkedStatus) {
featureLayerModel.forEach(lyr => {
if(layerName === lyr.name){
lyr.scaleSymbols = checkedStatus;
}
})
}
}