Actions are processes that can be applied to the images attached to cells within the image viewer. LEADTOOLS supports several standard or "built-in" actions and custom or "user-defined" actions. LEADTOOLS supports the following built-in actions:

• Window-Leveling: Maps grayscale intensities using a user-defined color map (LUT).
• Alpha: A window-leveling factor used when the window-leveling lookup table is not linear.
• Scale: Increases or decreases the size of the image in the cell.
• Offset: Changes the offset of the image within the cell.
• Magnifying Glass: Magnifies the image in the cell.
• Stack: Scrolls the images within the cell.
• Annotation ruler: adds a ruler object to the cell.
• Annotation rectangle: Adds a rectangle object to the cell.
• Annotation angle: Adds an angle object to the cell.
• Annotation hilite: Adds a highlight object to the cell.
• Annotation arrow: Adds an arrow object to the cell.
• Annotation text: Adds a text object to the cell.
• Rectangle region: Adds a rectangular region to the cell.
• Square region: Adds a square region to the cell.
• Elliptical region: Adds an elliptical region to the cell.
• Circular region: Adds a circular region to the cell.
• Free hand region: Adds a free hand region to the cell.
• Polygon region: Adds a polygonal region to the cell.
• "Magic Wand" region: Sets a region based on the color at a selected point, growing outward in all directions from that point. Dragging increases the variation allowed from the selected color.
• "Color Range" region: Adds a color range region to the cell.

Custom actions are completely controlled by the user, including any mouse movement and keystroke association. Custom actions are handled through the following events:

• UserActionMouseDown
• UserActionMouseUp
• UserActionMouseMove
• UserActionMouseWheel
• UserActionKeyDown
• UserActionKeyUp

Regardless of whether the action is built-in or custom, any action must be added to the medical viewer before it can be used. To add an action to the medical viewer, call the AddAction method. When adding a custom action to the medical viewer, pass your action ID by casting it to the (MedicalViewerActionType) enumeration. For example, AddAction((MedicalViewerAction)YourActionID). Since the Image Viewer supports custom actions, there is no limit on how many actions the medical viewer can have. However, an action cannot be added to the medical viewer twice. To determine how many actions are currently in a particular viewer, call the ActionCount method.

To determine whether a specific action is added, call the IsActionAdded method. You can assign the added action to a mouse button using the SetAction method. An action can only be assigned to one mouse button. To check whether the button or the flag is valid to be assigned to the specific action, call the IsValidForAction method. The SetAction method also lets the user decide whether the applied action will affect one cell, selected cells, or all cells in the medical viewer, and whether the action is applied during mouse movement or after mouse button release. Retrieve the assigned mouse button and flags for the specified action by calling the GetActionButton and the GetActionFlags methods.

In addition to assigning an action to a mouse button, an action can also be assigned to a keystroke combination. To set the keystroke combination for an action, call the SetActionKeys method. To get the current keystroke combination associated with a specific action, call the GetActionKeys method.

Keep track of which action has been applied by triggering the MedicalViewer.UIChanged event.

Each action has properties that can be set or retrieved by calling the SetActionProperties and GetActionProperties methods. Each action has a corresponding class that is used to set or retrive its properties, as follows:

How To Use Actions

First, add the action that is to be used. This is done by calling AddAction, passing the appropriate action ID. Custom actions use action IDs with values above 100. Next, assign a mouse button using SetAction, passing the action ID and the mouse button that is to be associated with it. Assign a keyboard shortcut using the SetActionKeys method.

As an example, suppose you add the "Window level" action and assign it to the left mouse button. To use the action, the user clicks and holds the left mouse button, and drags it toward any direction. The brightness and contrast of the gray image changes according to the direction to which the user is dragging the mouse. The keyboard shortcuts imitate mouse movements to any of the four sides: for example, the Shift + Left Arrow will perform the same action as if the mouse were dragged to the left.

The mouse controls the different actions as follows:

Window Level

Alpha

Scale

Magnify glass

Stack

Offset

Rectangle Region

Ellipse Region

Square Region

Circle Region

Polygon Region

Freehand Region

Magic Wand Region

Color Range Region

Rectangle Annotation

Ellipse Annotation

Arrow Annotation

Text Annotation

Angle Annotation

Ruler Annotation

Highlight Annotation

Built-in Actions

The following built-in actions are supported:

• "Nudge Tool" region: Expands the region border using the mouse. It also serves as a region painter.
• "Shrink Tool" region: Shrinks the region border using the mouse.

Each action has a corresponding class that is used to set or retrive its properties, as follows:

Action	Class used to set/retrieve
Nudge Tool	Leadtools.MedicalViewer.MedicalViewerNudgeTool
Shrink Tool	Leadtools.MedicalViewer.MedicalViewerNudgeTool

The mouse controls the different actions as follows:

Nudge Tool

Shrink Tool

	Click and hold the mouse to start the effect. When the assigned mouse button is released the action ends.
	Dragging the mouse up shrinks the image.

Window Level Actions

Support for Window Level Actions is provided with the MedicalViewer.MedicalViewerWindowLevelValues class. Set default window level values by using the MedicalViewerCell.SetDefaultWindowLevelValues method. If the low memory usage feature has been enabled, window level values can be calculated internally by calling the MedicalViewerCell.SetRequestedImage method. For more information about the low memory usage feature, refer to the MedicalViewerCell.EnableLowMemoryUsage method. To reset the window level values to the default values call the MedicalViewerCell.ResetWindowLevelValues method. To get the default window level values, call the MedicalViewerCell.GetDefaultWindowLevelValues method. To get or change the current window level values call the MedicalViewer.GetActionProperties method or the MedicalViewer.SetActionProperties method, respectively.