com.openinventor.inventor.drawers

Class SoPolyLineScreenDrawer

java.lang.Object

com.openinventor.inventor.Inventor

com.openinventor.inventor.misc.SoBase

com.openinventor.inventor.fields.SoFieldContainer

com.openinventor.inventor.nodes.SoNode

com.openinventor.inventor.drawers.SoScreenDrawer

com.openinventor.inventor.drawers.SoPolyLineScreenDrawer

All Implemented Interfaces:

SafeDisposable

Direct Known Subclasses:

SoEllipseScreenDrawer, SoLassoScreenDrawer, SoPolygonScreenDrawer, SoRectangleScreenDrawer

public class SoPolyLineScreenDrawer
extends SoScreenDrawer

Interactively draw a polyline in normalized screen space. This class is a base class used to allow the user to dynamically draw line-based shapes (lasso, circle, rectangle, ...) on screen. The geometry is defined in normalized screen space ([-1, 1]x[-1, 1]).

Applications will typically use one of the derived classes, for example, SoEllipseScreenDrawer, SoRectangleScreenDrawer, SoPolygonScreenDrawer or SoLassoScreenDrawer.

The line color is specified by the color field (default is red).

SoPolyLineScreenDrawer classes can automatically reduce the number of points in the shape drawn by the user. This is especially useful with SoLassoScreenDrawer. See the simplificationThreshold field.

Sub-classes can implement the onMouseDown, onMouseMove, etc... methods, to add and edit points.

Notes:

• Viewer:
  
  • Screen drawers, like draggers, depend on SoHandleEventAction to get events. Therefore when using one of the Open Inventor viewer classes, screen drawers will only work when the viewer is in "selection" mode (arrow cursor). (In "viewing" mode, mouse events are handled by the viewer to control the camera.)
    
    
  • The escape key (ESC) can be used to cancel creation of the polyline. However, currently it also changes the viewer mode (this is a known problem).
• Event handling:
  The drawer will automatically begin a new polyline when it sees a mouse button 1 down event. However the drawer does not call setHandled(), so other nodes in the scene graph, e.g. SoEventCallback or a dragger, may also handle this event.
• Finish notification:
  
  • An event is raised to notify the application when the line is finished. (see onFinish ). This event is called at the end of line finalization (after simplification etc). See SbEventHandler for methods to set a callback to be notified when this event is raised.
    
    
  • In this callback the application can retrieve coordinates from the point field. These points are in Open Inventor normalized device coordinates (-1 to 1), not pixel coordinates.
    
    
  • The drawer does not call the SoHandleEventAction's setHandled() method for the event that finished the polyline. The application can call setHandled() in this callback.
    
    
  • With some drawers it is possible to get a call with zero points if the user pressed ESC to cancel the interaction. Applications should check for this case.
    
    
  • With some drawers it is also possible to get a call with a non-zero number of points, but all points are the same coordinate. E.g. SoRectangleScreenDrawer stores four points even if the mouse down/up events are at the same location.
    
    
  • Typically the application will want to remove the polyline from the screen in this callback. See the next note.
• Part of the scene graph:
  
  • Note that the polyline remains on the screen (because it is part of the scene graph) until clear() is called or the user starts a new interaction.
    
    
  • Changing the color field or the isClosed field will immediately change the appearance of a polyline currently on the screen.
• Simplification:
  Simplification is done (if > 0) when the user releases the mouse button and also if the simplificationThreshold is changed. But note that the old points are thrown away, so you can't re-simplify with a different value.
• isClosed field:
  If true (default), the polyline will be closed while being drawn (not just when the user releases the mouse button). The default in this class is false, but most sub-classes set it to true.
• Coordinates:
  This node and its subclasses use screen coordinates ranging from -1 to 1. (Because this is the default view volume for an SoOrthographicCamera node.) Be careful because other classes in Open Inventor use normalized screen coordinates ranging from 0 to 1. In particular the SbViewportRegion normalize() methods and the SbViewVolume methods that project from 3D to 2D and vice-versa.
• There should only be one SoScreenDrawer derived node in the sceneGraph (to avoid conflicts in mouse events).

EXAMPLE

Create a screen drawer, set the callback and add it to the scene graph:

 SoRectangleScreenDrawer drawer = new SoRectangleScreenDrawer();
 drawer.onFinish.addEventListener(new LineDrawerListener());
 root.addChild( drawer );

A finish callback that gets the number of points created by the screen drawer:

 class LineDrawerListener implements SbEventListener<EventArg>
 {
   @Override
   public void onEvent(EventArg eventArg)
   {
     SoPolyLineScreenDrawer drawer = eventArg.getSource();
     SoHandleEventAction action = eventArg.getAction();
 
     int numPoints = drawer.point.getNum();
     if ( numPoints > 0 )
     {
       // Use points
       SbVec2f point0 = drawer.point.getValueAt(0);
     }
     drawer.clear(); // Remove polyline from screen
     action.setHandled();
   }
 }

See also:

SoEllipseScreenDrawer, SoLassoScreenDrawer, SoPolygonScreenDrawer, SoRectangleScreenDrawer, SoScreenDrawer

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SoPolyLineScreenDrawer.EventArg Structure given to callback when an event is raised.

Nested classes/interfaces inherited from class com.openinventor.inventor.nodes.SoNode

SoNode.RenderModes

Nested classes/interfaces inherited from class com.openinventor.inventor.Inventor

Inventor.ConstructorCommand

Field Summary

Fields

Modifier and Type	Field and Description
SoSFColor	color Color of line.
SoSFBool	doCCW Make the line counter-clockwise when it is finalized.
SoSFBool	isClosed Close the line during display (connect last point to first point).
SoSFUShort	linePattern Stipple pattern.
SoSFInt32	linePatternScaleFactor Stipple pattern scale factor.
SoSFFloat	lineWidth Width of lines.
SbEventHandler<SoPolyLineScreenDrawer.EventArg>	onFinish Event raised when the line is finished.
SbEventHandler<SoPolyLineScreenDrawer.EventArg>	onMove Event raised during polyline drawing.
SbEventHandler<SoPolyLineScreenDrawer.EventArg>	onStart Event raised when starting to draw a polyline.
SoMFVec2f	point Points of line.
SoSFUInt32	simplificationThreshold Threshold (in pixels) used to simplify line when it is finished.

Fields inherited from class com.openinventor.inventor.drawers.SoScreenDrawer

sceneGraph

Fields inherited from class com.openinventor.inventor.Inventor

VERBOSE_LEVEL, ZeroHandle

Constructor Summary

Constructors

Constructor and Description
SoPolyLineScreenDrawer() Constructor.

Method Summary

Modifier and Type	Method and Description
void	clear() Convenience method to clear the points in the line.

Methods inherited from class com.openinventor.inventor.nodes.SoNode

affectsState, callback, copy, copy, distribute, doAction, getAlternateRep, getBoundingBox, getByName, getMatrix, getPrimitiveCount, getRenderEngineMode, getRenderUnitID, GLRender, GLRenderBelowPath, GLRenderInPath, GLRenderOffPath, grabEventsCleanup, grabEventsSetup, handleEvent, isBoundingBoxIgnoring, isOverride, pick, rayPick, search, setOverride, touch, write

Methods inherited from class com.openinventor.inventor.fields.SoFieldContainer

copyFieldValues, copyFieldValues, enableNotify, fieldsAreEqual, get, getAllFields, getEventIn, getEventOut, getField, getFieldName, hasDefaultValues, isNotifyEnabled, set, setToDefaults

Methods inherited from class com.openinventor.inventor.misc.SoBase

dispose, getName, isDisposable, isSynchronizable, setName, setSynchronizable

Methods inherited from class com.openinventor.inventor.Inventor

getNativeResourceHandle

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

simplificationThreshold

public final SoSFUInt32 simplificationThreshold

Threshold (in pixels) used to simplify line when it is finished. A value of 0 means no simplification. Default value is 5 pixels.

doCCW

public final SoSFBool doCCW

Make the line counter-clockwise when it is finalized. This can change order of points. Default is true.

Note Some shapes (like "8") do not have a defined clockwiseness. In these cases, the result is undefined.

Since:

Open Inventor 9.0

color

public final SoSFColor color

Color of line. Default value is red.

point

public final SoMFVec2f point

Points of line. Default is empty.

isClosed

public final SoSFBool isClosed

Close the line during display (connect last point to first point). Default is false (but most sub-classes automatically set it to true).

Warning This only affects the display.

linePattern

public final SoSFUShort linePattern

Stipple pattern. This specifies how dashed or dotted lines will be drawn. The pattern is a 16-bit series of 0s and 1s and is repeated as necessary to stipple a given line. A 1 indicates that drawing occurs, and a 0 that it does not, on a pixel-by-pixel basis, starting with the low-order bits of the pattern. Values can range from 0 (invisible) to 0xffff (solid). Default is 0xffff.

The line pattern can be stretched using the linePatternScaleFactor field.

linePatternScaleFactor

public final SoSFInt32 linePatternScaleFactor

Stipple pattern scale factor. It stretches the line pattern (see linePattern) by multiplying each subseries of consecutive 1s and 0s. Scale factors are clamped to lie between 1 and 255. Default is 1.

lineWidth

public final SoSFFloat lineWidth

Width of lines. The default line width is 0, meaning to use the default OpenGL value (1). Line widths greater than zero are considered to be specified in printer's points, where 1 inch = 72 printer's points. However the default pixels-per-inch value (managed by SbViewportRegion) is also 72. So effectively line width is specified in pixels unless the application sets a different pixels-per-inch value.

onStart

public final SbEventHandler<SoPolyLineScreenDrawer.EventArg> onStart

Event raised when starting to draw a polyline. See SbEventHandler for methods to set a callback to be notified when this event is raised. The callback will be called with an EventArg from which it can query the current action and drawer objects.
Note that the callback parameter must be declared const .

onMove

public final SbEventHandler<SoPolyLineScreenDrawer.EventArg> onMove

Event raised during polyline drawing. See SbEventHandler for methods to set a callback to be notified when this event is raised. The callback will be called with an EventArg from which it can query the current action and drawer objects. Note that the callback parameter must be declared const .

onFinish

public final SbEventHandler<SoPolyLineScreenDrawer.EventArg> onFinish

Event raised when the line is finished. See SbEventHandler for methods to set a callback to be notified when this event is raised. The callback will be called with a line drawer specific EventArg from which you can query the current action and drawer objects. Note that the callback parameter in this case is not const.

Constructor Detail

SoPolyLineScreenDrawer

public SoPolyLineScreenDrawer()

Constructor.

Method Detail

clear

public void clear()

Convenience method to clear the points in the line.