GeoImageLayer¶
Namespace: ThinkGeo.Core
Represents a layer that draws a single GeoImage at a specific map location.
public class GeoImageLayer : Layer
Inheritance object → LayerBase → Layer → GeoImageLayer
Remarks:
The image is loaded from GeoImageLayer.ImagePathFilename when the layer opens and is rendered at GeoImageLayer.CenterPoint using the configured GeoImageLayer.Scale. Use GeoImageLayer.UpperScale and GeoImageLayer.LowerScale to control visibility per scale.
Properties¶
ImagePathFilename¶
Gets or sets the path of the image file that the layer should display.
public string ImagePathFilename { get; set; }
Property Value¶
Remarks:
Update this property before calling so the layer can load the specified file.
CenterPoint¶
Gets or sets the center point of the image in world coordinates.
public PointShape CenterPoint { get; set; }
Property Value¶
Scale¶
Gets or sets the map scale at which the image size is considered native.
public double Scale { get; set; }
Property Value¶
UpperThreshold¶
Gets or sets the upper threshold in the scale at which to display the image.
public double UpperThreshold { get; set; }
Property Value¶
double
This property gets the upper threshold in the scale at which to display the image.
Remarks:
Above this threshold the image will not be displayed. Use GeoImageLayer.UpperScale instead to achieve the same behavior.
LowerThreshold¶
Gets or sets the lower threshold in the scale at which to display the image.
public double LowerThreshold { get; set; }
Property Value¶
double
This property gets the lower threshold in the scale at which to display the image.
Remarks:
Below the lower threshold in scale, the image will not be displayed. Used together with GeoImageLayer.UpperThreshold (or GeoImageLayer.UpperScale), it allows you to create a visibility band for the image source. By default the image is visible at all scales.
UpperScale¶
Gets or sets the maximum map scale (least detailed) at which the image is drawn.
public double UpperScale { get; set; }
Property Value¶
double
The maximum map scale where the layer remains visible. Defaults to .
Remarks:
Pair this property with GeoImageLayer.LowerScale to limit when the image appears. Values greater than this threshold hide the image.
LowerScale¶
Gets or sets the minimum map scale (most detailed) at which the image is drawn.
public double LowerScale { get; set; }
Property Value¶
double
The minimum map scale where the layer remains visible. Defaults to zero.
Remarks:
Pair this property with GeoImageLayer.UpperScale to define the visibility range. Values below this threshold hide the image.
RequestDrawingInterval¶
Gets or sets the interval between automatic draw requests. Obsolete.
public TimeSpan RequestDrawingInterval { get; set; }
Property Value¶
Name¶
Gets or sets the display name for the layer.
public string Name { get; set; }
Property Value¶
string
The name used to identify the layer within UI components such as legends.
Remarks:
The name is user defined. Assign a descriptive value so tooling such as legends and layer lists can surface a meaningful label to end users.
IsOpen¶
Gets a value indicating whether the layer is currently open.
public bool IsOpen { get; }
Property Value¶
bool
true if the layer has completed its open routine; otherwise, false.
Remarks:
This method is the concrete wrapper for the abstract method IsOpenCore. Various methods on the Layer require that it be in an open state. If one of those methods is called when the state is not open, then the method will throw an exception. To enter the open state, you must call the Layer Open method. The method will raise an exception if the current Layer is already open.
As this is a concrete public method that wraps a Core method, we reserve the right to add events and other logic to pre- or post-process data returned by the Core version of the method. In this way, we leave our framework open on our end, but also allow you the developer to extend our logic to suit your needs. If you have questions about this, please contact our support team as we would be happy to work with you on extending our framework.
IsVisible¶
Gets or sets a value indicating whether the layer is visible.
public bool IsVisible { get; set; }
Property Value¶
bool
true to draw the layer; otherwise, false.
Remarks:
If this property is set to false, the layer will not draw. We ensure this in the Draw method. This is useful for legends and other controls that control the visibility of layers.
DrawingTime¶
Gets the last recorded drawing time for the layer.
public TimeSpan DrawingTime { get; protected set; }
Property Value¶
TimeSpan
The duration of the most recent draw operation.
Remarks:
We track the drawing time for the layer and report it back in this method. This is useful for determining the speed of various layers.
Projection¶
Gets the projection of the layer.
public Projection Projection { get; set; }
Property Value¶
DrawingExceptionMode¶
Gets or sets how drawing exceptions are handled when the layer renders.
public DrawingExceptionMode DrawingExceptionMode { get; set; }
Property Value¶
Background¶
Gets or sets the background color used when rendering the layer.
public GeoColor Background { get; set; }
Property Value¶
GeoColor
The fill applied to areas not covered by layer content.
Transparency¶
Gets or sets the amount of transparency applied to the rendered image.
public float Transparency { get; set; }
Property Value¶
float
A value between 0 (fully transparent) and 255 (fully opaque).
BlueTranslation¶
Gets or sets the intensity adjustment applied to the blue channel.
public float BlueTranslation { get; set; }
Property Value¶
float
A value between -255 and 255 representing the blue channel translation.
RedTranslation¶
Gets or sets the intensity adjustment applied to the red channel.
public float RedTranslation { get; set; }
Property Value¶
float
A value between -255 and 255 representing the red channel translation.
GreenTranslation¶
Gets or sets the intensity adjustment applied to the green channel.
public float GreenTranslation { get; set; }
Property Value¶
float
A value between -255 and 255 representing the green channel translation.
KeyColors¶
Gets the collection of key colors that should be rendered as transparent.
public Collection<GeoColor> KeyColors { get; }
Property Value¶
Remarks:
Attempting to access this collection when the associated GeoCanvas does not support key colors (see GeoCanvas.SupportKeyColor) results in an exception. Add colors to this collection to ensure they render as transparent.
IsNegative¶
Gets or sets a value indicating whether the image should be rendered with inverted colors.
public bool IsNegative { get; set; }
Property Value¶
bool
true to invert the color channels; otherwise, false.
IsGrayscale¶
Gets or sets a value indicating whether the image should be converted to grayscale prior to rendering.
public bool IsGrayscale { get; set; }
Property Value¶
bool
true to apply a grayscale filter; otherwise, false.
HasBoundingBox¶
Gets a value indicating whether the layer supports retrieving its bounding box.
public bool HasBoundingBox { get; }
Property Value¶
Remarks:
When this property is false, calls to or GetFullExtent throw an exception. The default implementation returns false.
ThreadSafe¶
Gets or sets the threading guarantees provided by the layer implementation.
public ThreadSafetyLevel ThreadSafe { get; set; }
Property Value¶
ThreadSafetyLevel
The level of thread safety that callers can expect when interacting with the layer.
ColorMappings¶
Gets the color translation map that will be applied when rendering the layer.
public Dictionary<GeoColor, GeoColor> ColorMappings { get; }
Property Value¶
Dictionary<GeoColor, GeoColor>
WrappingMode¶
Gets or sets how the layer wraps when the map extent crosses world boundaries.
public WrappingMode WrappingMode { get; set; }
Property Value¶
WrappingExtent¶
Gets or sets the geographic extent to use when wrapping is enabled.
public RectangleShape WrappingExtent { get; set; }
Property Value¶
Constructors¶
GeoImageLayer()¶
Initializes a new instance of the GeoImageLayer class.
public GeoImageLayer()
Remarks:
The instance is created with LayerBase.Transparency set to fully opaque. Set additional properties before calling .
GeoImageLayer(string)¶
Initializes a new instance of the GeoImageLayer class for the specified image path.
public GeoImageLayer(string imagePathFilename)
Parameters¶
imagePathFilename string
The path of the image file to render.
Methods¶
GetBoundingBoxCore()¶
Gets the bounding box of the layer. This implementation is not supported.
protected RectangleShape GetBoundingBoxCore()
Returns¶
RectangleShape
Nothing is returned because the method always throws.
Exceptions¶
NotImplementedException
Thrown because the bounding box cannot be determined without additional context.
OpenCore()¶
Loads the internal GeoImage using the configured GeoImageLayer.ImagePathFilename.
protected void OpenCore()
Returns¶
CloseCore()¶
Releases the internal GeoImage resources.
protected void CloseCore()
Returns¶
DrawCore(GeoCanvas, Collection<SimpleCandidate>)¶
Draws the loaded GeoImage on the supplied GeoCanvas when the scale is within the allowed range.
protected void DrawCore(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers)
Parameters¶
canvas GeoCanvas
The that receives the drawing commands.
labelsInAllLayers Collection<SimpleCandidate>
A collection of labeling candidates shared across layers.
Returns¶
IsDrawingNeededCore(double)¶
Determines whether drawing should occur at the provided scale.
protected bool IsDrawingNeededCore(double currentScale)
Parameters¶
currentScale double
The current map scale.
Returns¶
bool
true if the layer should draw; otherwise, false.
Events¶
DrawingProgressChanged¶
Occurs as the layer reports drawing progress (useful for async or tiled rendering scenarios).
public event EventHandler<DrawingProgressChangedEventArgs> DrawingProgressChanged;
RequestedDrawing¶
Raised after the drawing buffer elapses so consumers can handle a legacy drawing cycle. Obsolete.
public event EventHandler<RequestedDrawingLayerEventArgs> RequestedDrawing;
RequestingDrawing¶
Raised before the drawing buffer elapses so consumers can cancel a legacy drawing operation. Obsolete.
public event EventHandler<RequestingDrawingLayerEventArgs> RequestingDrawing;
DrawingException¶
Occurs when the DrawingException event is raised.
public event EventHandler<DrawingExceptionLayerEventArgs> DrawingException;
DrawnException¶
Occurs when the DrawnException event is raised.
public event EventHandler<DrawnExceptionLayerEventArgs> DrawnException;