Feature Description
A snapshot layer is a special type of layer group where all layers within the snapshot layer group are considered snapshot layers. The rendering method of snapshot layers is unique: they only draw during the initial display. When browsing the map subsequently, snapshot layers will not redraw if the map's visible bounds remain unchanged, meaning they don't refresh with regular map refresh operations. If the map's visible bounds change, the snapshot layers will automatically trigger a refresh. Snapshot layers serve as one of the methods to enhance map display performance.
As snapshot layers are special layer groups, they can contain group layer objects (LayerGroup). However, snapshot layers cannot contain other snapshot layers, and group layer objects (LayerGroup objects) cannot contain snapshot layers either.
Application Scenario: During the mapping process, some layers with large data volumes may affect map refresh efficiency. In such cases, layers with low refresh frequency, large data volumes, and mandatory display requirements can be added to snapshot layers. When the map's visible bounds remain unchanged, layers in the snapshot layer group won't refresh, thereby improving map display performance.
Steps
- Right-click on a blank area in the layer manager and select the New Snapshot Group option to create a snapshot layer group.
- Select one or multiple layers and move them into the snapshot layer group. These layers will then function as snapshot layers, maintaining their state without refreshing when the map extent remains unchanged.