TdxCustomMapControl.Layers Property

Provides access to the map layer collection.

Declaration

delphi

property Layers: TdxMapLayers read; write;

Property Value

Type	Description
TdxMapLayers

A collection of map layers.

Remarks

Map Control content is arranged into layers that can display different information, such as terrain, roads, routes, waypoints, etc.

Available API Functionality

Call Layers.Add, Layers.Clear, and Layers.Remove methods to manage layers in the Map Control. The Layers.Items property provides indexed access to all layers in the collection.

Refer to the TdxMapLayers class description for detailed information on all available options.

Map Layer Z-Order

Map layer indexes in the Layers collection also determine the Z-order (draw order) of corresponding layers. A map layer with the highest index is displayed on top of all other layers.

Tip

The more transparent elements a map layer has, the higher collection index (Z-order) it should have. Otherwise, an opaque layer overlaps all transparent layers beneath it.

For example, we recommend that you display a map item layer with shapes and other markers on top of all other layers.

Design-Time Layer Management

You can use the Collection Editor dialog to manage map layers at design time. To open the dialog, do any of the following:

Select the Map Control, and click the ellipsis button to the right of the Layers property in the Object Inspector.
Double-click the Map Control.
Click Layers Editor… in the control’s context menu.

Collection Editor

Click Add New , Delete Selected , Move Selected Up , and Move Selected Down buttons to manage map layers.

The Add New button creates a tile map layer. To create other supported map layers, open the button’s drop-down menu:

Type-Specific Layer Creation Functions

You can call the following functions to create corresponding map layers (as an alternative to the Layers.Add function):

AddImageTileLayerCreates a new image tile layer and adds it to the map layer collection.AddItemFileLayerCreates a new item file layer and adds it to the map layer collection.AddItemLayerCreates a new item layer.

Code Example: Add a Tile Map Layer and Load Azure Maps Data

The following code example implements a procedure that accepts an Azure Maps account key, creates and configures a map tile layer, and loads data:

Delphi
C++

delphi

uses
  dxAzureMapImageryDataProvider; // Declares TdxMapControlAzureMapImageryDataProvider
// ...

procedure TMyForm.AddAzureMapLayer(const AAzureKey: string);
var
  ATileLayer: TdxMapImageTileLayer;
  AProvider: TdxMapControlAzureMapImageryDataProvider;
begin
  ATileLayer := dxMapControl1.Layers.Add(TdxMapImageTileLayer) as TdxMapImageTileLayer;
  ATileLayer.ProviderClass := TdxMapControlAzureMapImageryDataProvider;
  AProvider := ATileLayer.Provider as TdxMapControlAzureMapImageryDataProvider;
  AProvider.BeginUpdate; // Initiates the following batch change
  try
    AProvider.AzureKey := AAzureKey; // Assigns the Azure account key
    AProvider.Tileset := TdxAzureMapTileset.Satellite; // Changes the default tileset
    AProvider.MaxParallelConnectionCount := 8; // Explicitly defines the number of parallel connections
  finally
    AProvider.EndUpdate; // Calls EndUpdate regardless of the batch operation's success
  end;
end;

cpp

#include "dxAzureMapImageryDataProvider.hpp" // Declares TdxMapControlAzureMapImageryDataProvider
// ...

void __fastcall TMyForm::AddAzureMapLayer(const UnicodeString &AAzureKey)
{
  TdxMapLayer *ALayer;
  TdxMapImageTileLayer *ATileLayer;
  TdxMapControlAzureMapImageryDataProvider *AProvider;

  ALayer = dxMapControl1->Layers->Add(__classid(TdxMapImageTileLayer));
  ATileLayer = dynamic_cast<TdxMapImageTileLayer*>(ALayer);
  ATileLayer->ProviderClass = __classid(TdxMapControlAzureMapImageryDataProvider);
  AProvider = dynamic_cast<TdxMapControlAzureMapImageryDataProvider*>(ATileLayer->Provider);
  AProvider->BeginUpdate(); // Initiates the following batch change
  try
  {
    AProvider->AzureKey = AAzureKey; // Assigns the Azure account key
    AProvider->Tileset = TdxAzureMapTileset::Satellite; // Changes the default tileset
    AProvider->MaxParallelConnectionCount = 8; // Explicitly defines the number of parallel connections
  }
  __finally
  {
    AProvider->EndUpdate(); // Calls EndUpdate regardless of the batch operation's success
  }
}