ArcObjects Library Reference (Display)

IDisplayTransformation Interface

Provides access to members that control Display Transformation.

Product Availability

Available with ArcGIS Engine, ArcGIS Desktop, and ArcGIS Server.

When To Use

Use IDisplayTransformation for converting coordinates between real-world and device space and back. To prepare a transform for use, follow these steps:

Set the full map extent with the Bounds property
Set the visible map extent (zoom rectangle) with the VisibleBounds property
Set the output area of the device using the DeviceFrame property
Set the resolution of the output device using the Resolution property

The transform is based on the ratio between the VisibleBounds and the DeviceFrame. Normally the DeviceFrame is simply the full extent of the device with the origin equal to 0,0.

The transform object calculates the FittedBounds automatically and this is the visible map extent adjusted to fit the device.

Members

		Description
	Bounds	Full extent in world coordinates.
	ConstrainedBounds	Intersection of Bounds and VisibleBounds.
	DeviceFrame	Visible extent in device coordinates.
	FittedBounds	Device frame in world coordinates.
	FromMapPoint	Calculates device coordinates corresponding to the map point.
	FromPoints	Calculates a map distance corresponding to a point (1/72) distance.
	ReferenceScale	Reference scale for computing scaled symbol sizes.
	Resolution	Resolution of the device in dots (pixels) per inch.
	Rotation	Rotation angle in degrees.
	ScaleRatio	Scale between FittedBounds and DeviceFrame.
	SpatialReference	Current spatial reference.
	SuppressEvents	Indicates if transformation object suppresses events.
	ToMapPoint	Calculates a point in map coordinates corresponding to the device point.
	ToPoints	Calculates a distance in points (1/72 inch) corresponding to the map distance.
	TransformCoords	Transforms a set of points or measurements from device to world space or vice versa. Use the flags specified by esriDisplayTransformEnum.
	TransformMeasuresFF	Transforms floating point measures to floating point measures (or do the inverse).
	TransformMeasuresFI	Transforms floating point measures to integer measures (or do the inverse).
	TransformMeasuresIF	Transforms integer measures to floating point measures (or do the inverse).
	TransformMeasuresII	Transforms integer measures to integer measures (or do the inverse).
	TransformPointsFF	Transforms floating point points to floating point points (or do the inverse).
	TransformPointsFI	Transforms floating point points to integer points (or do the inverse).
	TransformPointsIF	Transforms integer points to floating point points (or do the inverse).
	TransformPointsII	Transforms integer points to integer points (or do the inverse).
	TransformRect	Transforms a rectangle from device to world space or vice versa. Use the flags specified by esriDisplayTransformEnum.
	Units	Units used by world coordinates.
	VisibleBounds	Visible extent in world coordinates.
	ZoomResolution	Indicates if resolution is tied to visible bounds. If true, zooming in magnifies contents (i.e., zoom in on page).

Inherited Interfaces

Interfaces	Description
ITransformation	Provides access to members that apply a function (or its inverse) to a set of points or measures. The suffix of each method indicates the type of parameters operated on.

CoClasses that implement IDisplayTransformation

CoClasses and Classes	Description
DisplayTransformation	Display transformation class for converting from world to device units.

Remarks

Obtain an IDisplayTransformation reference to the DisplayTransformation object from IDisplay::DisplayTransformation. Because IScreenDisplay inherits from IDisplay, you can also use IScreenDisplay::DisplayTransformation.

Each DisplayTransformation manages a coordinate system object such as a GeographicCoordinateSystem or ProjectedCoordinateSystem. Obtain a reference to the display's coordinate system object using IDisplayTransformation::SpatialReference.

The DisplayTransformation of a PageLayout object does not have a spatial reference and translates between device units and page units.

.NET Snippets

Draw Point | Get Map Coordinates from Screen Coordinates | Get Screen Coordinates from Map Coordinates | Convert Display Pixels to Map Units

.NET Samples

Dynamic display layer (Code Files: MyDynamicLayerClass) | Custom map selection commands (Code Files: SelectFeatures) | Implementing a schematic digitizing tool (Code Files: DigitTool) | Dynamic display�tracking dynamic object (Code Files: TrackObject) | Copy the PageLayoutControl focus map and overwrite the MapControl map (Code Files: CopyFocusMap) | Building a MapViewer application using the ArcGIS Engine controls (Code Files: MapViewer) | RSS weather layer (Code Files: AddWeatherItemTool RSSWeatherLayerClass) | Triangle graphic element (Code Files: TriangleElementClass) | Time Series Graph tool add-in (Code Files: TimeSeriesGraph)

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