RasterLayer¶
Namespace: ThinkGeo.Core
This abstract class is the basis for all image-based layers in the system.
public abstract class RasterLayer : Layer
Inheritance object → LayerBase → Layer → RasterLayer
Remarks:
This abstract class is the basis for all image-based layers in the system. Its methods and properties deal with image manipulation. Currently, some classes that inherit from this are EcwRasterLayer, MrSidRasterLayer, GridRasterLayer and so on.
When creating your own RasterLayer, you need only to set a RasterSource and create a useful constructor; the class will take care of the rest. There are no required abstract members. It may be helpful for you to add additional properties specific to your Image.
Properties¶
ImageSource¶
This property gets and sets the Image used by the RasterLayer.
public RasterSource ImageSource { get; protected set; }
Property Value¶
RasterSource
This property gets the Image used by the RasterLayer.
Remarks:
The set for this property is protected and only intended to be used by developers who are creating their own ImageSources. This is the main property to set for developers who are creating their own RasterLayer derivatives.
UpperThreshold¶
This property gets and 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 the upper threshold in scale, the image will not be displayed. This, in conjunction with the LowerThreshold property, allows you to create a band in which it is suitable to display the image source. By default, the upper threshold is double.max and lower threshold is 0. This means the image should always display.
LowerThreshold¶
This property gets and 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. This, in conjunction with the UpperThreshold property, allows you to create a band in which it is suitable to display the image source. By default, the upper threshold is double.max and lower threshold is 0. This means the image should always display.
UpperScale¶
This property gets and sets the upper threshold in the scale at which to display the image.
public double UpperScale { get; set; }
Property Value¶
double
This property gets the upper threshold in the scale at which to display the image.
Remarks:
Above the upper threshold in scale, the image will not be displayed. This, in conjunction with the LowerThreshold property, allows you to create a band in which it is suitable to display the image source. By default, the upper threshold is double.max and lower threshold is double.min. This means the image should always display.
LowerScale¶
This property gets and sets the lower threshold in the scale at which to display the image.
public double LowerScale { 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. This, in conjunction with the UpperThreshold property, allows you to create a band in which it is suitable to display the image source. By default, the upper threshold is double.max and lower threshold is double.min. This means the image should always display.
ScaleFactor¶
The scale factor when drawing the primitive image. For example I am looking for an image with 100100px, If the ScaleFactor is set to 2, it means the component will get the image with 200200px. We want to keep it as 1 (by default) for most cases.
public double ScaleFactor { get; set; }
Property Value¶
Projection¶
Gets the projection used by the underlying RasterLayer.ImageSource.
public Projection Projection { get; }
Property Value¶
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.
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¶
Methods¶
GetRasterContentTypeCore()¶
Returns the content type from the underlying RasterLayer.ImageSource.
protected RasterContentType GetRasterContentTypeCore()
Returns¶
GetHorizontalResolution()¶
This method returns the horizontal resolution of the image.
public float GetHorizontalResolution()
Returns¶
float
This method returns the horizontal resolution of the image.
Exceptions¶
InvalidOperationException
In the event you attempt to call this method on a image layer which has not been opened, it will throw an InvalidOperationException.
Remarks:
This method returns the horizontal resolution of the image.
GetVerticalResolution()¶
This method returns the vertical resolution of the image.
public float GetVerticalResolution()
Returns¶
float
This method returns the vertical resolution of the image.
Exceptions¶
InvalidOperationException
In the event you attempt to call this method on a image layer which has not been opened, it will throw an InvalidOperationException.
Remarks:
This method returns the vertical resolution of the image.
GetBoundingBoxCore()¶
This method returns the bounding box of the RasterLayer.
protected RectangleShape GetBoundingBoxCore()
Returns¶
RectangleShape
This method returns the bounding box of the RasterLayer.
Exceptions¶
InvalidOperationException
In the event you attempt to call this method on a image layer which has not been opened, it will throw an InvalidOperationException.
Remarks:
This method returns the bounding box of the RasterLayer.
OpenCore()¶
This method opens the RasterLayer so that it is initialized and ready to use.
protected void OpenCore()
Returns¶
void
None
Exceptions¶
InvalidOperationException
In the event you attempt to call this method on a image source which has already been opened, it will throw an InvalidOperationException.
Remarks:
The open method plays an important role, as it is responsible for initializing the RasterLayer. Most methods on the RasterLayer will throw an exception if the state of the RasterLayer is not opened. When the map draws each layer, it will open the RasterLayer as one of its first steps; then, after it is finished drawing with that layer, it will close it. In this way, we are sure to release all resources used by the RasterLayer.
CloseCore()¶
This method closes the RasterLayer and releases any resources it was using.
protected void CloseCore()
Returns¶
void
None
Remarks:
The close method plays an important role in the life cycle of the RasterLayer. It may be called after drawing to release any memory and other resources that were allocated since the Open method was called.
If you override this method, it is recommended that you take the following things into account: This method may be called multiple times, so we suggest you write the method so that that a call to a closed RasterLayer is ignored and does not generate an error. We also suggest that in the Close you free all resources that have been opened. Remember that the object will not be destroyed, but will be re-opened possibly in the near future.
IsDrawingNeededCore(double)¶
Determines whether the raster should draw at the specified scale based on RasterLayer.UpperScale and RasterLayer.LowerScale.
protected bool IsDrawingNeededCore(double currentScale)
Parameters¶
currentScale double
The map scale currently being rendered.
Returns¶
bool
true if the scale is within the configured range; otherwise, false.
DrawCore(GeoCanvas, Collection<SimpleCandidate>)¶
This method will draw the image from the NativeImage source based on the parameters provided.
protected void DrawCore(GeoCanvas canvas, Collection<SimpleCandidate> labelsInAllLayers)
Parameters¶
canvas GeoCanvas
This parameter is the GeoCanvas used to Draw the RasterLayer.
labelsInAllLayers Collection<SimpleCandidate>
This parameter is not used for ImageLayers.
Returns¶
void
None
Remarks:
The DrawCore method will be called when the layer is being drawn. It will determine if the image is within the extent and the threshold defined. If these parameters are met, it will query the RasterSource for an image and then apply the other various properties (such as transparency, etc.) on the image. Lastly, it will draw the image on the NativeImage or native image passed into the method.
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;