# Edit Tools

The follow tools allow manipulation of vectors, as well as some special view management operations. Only one mode may be active at a time (with the exception of Link Views), and most operate on a single vector layer (with the exception of Zoom, Draw ROI, and Link Views) which must be the active layer in the Layer Management Dialog. The various vector editing tools will attempt to make a vector layer active if there is no active layer, or if the active layer is not a vector layer. It is a common frustration to be unable to select or modify vectors because they are not in the active layer.

Most of the editing modes have particular button combinations to do actions, but in all editing modes the standard View Area Button/Key Sequences remain valid. Note that while not explicitly disabled in 3D mode the various editing interactions will generally not work properly in 3D mode.

Also, note that essentially all editing operations can be undone by hitting Control-Z or selecting Edit->Undo in the menu.

## Select

Select mode allows selection of vector features, and limited manipulation of those features. Selected features are highlighted with small diamonds around the nodes. Selection may be accomplished in several ways:

- LeftButton-Click: Select the feature at the click location. Note that points and lines have only a modest tolerance for selection. Clicking inside a filled area will select the area. If more than one features overlaps the click location, only one will be selected (based on internal stacking order).
- LeftButton-Drag: Drags out a box and on release selects all features intersecting the box. Note that the box drag has to start at a location where there is no feature, otherwise it will be interpreted as a single selection, and the selected feature will be dragged instead of a box being drawn.

- Shift-LeftButton-Click: Operates like LeftButton-Click, but adds or removes the selected feature from the current selection instead of clearing the existing selection. In most editing systems this would be Control-LeftButton-Click, but that is already bound to continuous zoom.

While in selection mode it is also possible to drag the selected features around by left clicking on a selected feature, and dragging. If multiple features are already selected, they are all dragged as a group.

The Delete or Backspace key may be used to delete the currently selected feature(s).

## Zoom

Zoom mode is not for editing of vector features, but instead adds some simplified view operations. The following are always available via the generic Control chorded alternatives described in View Area Button/Key Sequences but in zoom mode these simplier alternatives are made available.

- LeftButton-DoubleClick: Zoom in by one increment (normally a factor of two), and recenter on target location.

- LeftButton-Drag: Drag out a zoom rectangle, and zoom on release.

- LeftButton-PressAndHold: Continuous zoom in.

- RightButton-DoubleClick: Zoom out by one increment (normally a factor of two), and recenter on target location.

- RightButton-PressAndHold: Continuous zoom out.

- MiddleButton-Drag: Drag the image to pan.

## Point Edit

Point edit mode is for creation of point features.

Each LeftButton-Clock in the view will result in a new point feature being created, and after creation it will be the selected feature. The Delete key can be used to delete the currently selected point if there is one. It is not possible to move, or otherwise manipulate points in this mode. Switch to Select mode to do that.

## Point Query

Point Query mode operates the same as Point Edit mode, but it operates on a point query layer, instead of a normal vector layer.

On entering Point Query mode, a new point query layer will be created if one is not already available on the current view. Otherwise the point query layer will be made the active layer if it is not already active.

Point query layers can show location and raster pixel value information for the selected points. The Point Query Properties panel has options for controlling what is shown for each query point.

## Draw Line

Line edit mode is for digitizing new line features. Note that Select mode is used to modify existing lines, and Node edit mode is used to modify individual nodes within an existing line.

The LeftButton-Click action is used to initiate digitizing of a new polyline. Subsequent left clicks will add new nodes to the polyline. The RightButton-Click or Escape key can be used to terminate line mode. While digitizing a line, the Delete key can be used to delete the last node added.

Note that while digitizing a line undo support is temporarily disabled.

## Rotate/Resize

Rotate/resize mode allows lines, areas and point symbols to be rotated and resized. At this time textual labels and plain points (not using symbols) cannot be rotated or resized.

The LeftButton-Click action can be used to select a shape to operate on. Once selected the shape will be drawn with the normal selection styling but a resize/rotate control will also be drawn in red, centered on the shape to be modified. It will look something like this:

The LeftButton-Drag action on the red two-directional arrowhead will rotate the shape in question. A LeftButton-Drag action on the red one directional arrow head will allow scaling the shape larger or smaller. A RightButton-Drag action on either arrowhead will result in a rotation and scaling effect.

Rotation and scaling are around a center point for the shape (the crossing point of the two arrows). Rotation and scaling applied to a point symbol result in the angle and scaling parameters being modified. Rotation and scaling applied to a line or area shape result in the actual vertex locations being modified.

Note that selecting the boxes around vertex of lines or areas has no effect in rotation and scaling mode. The Escape key may be used to terminate a rotation or scaling drag.

## Draw Rectangle

Rectangle drawing mode is for digitizing and modifying rectangular area features. While the rectangles created are just stored internally as normal area polygons, like those produced by Draw Area, rectangle mode offers special editing capabilities that maintains the rectangular constraint.

In rectangle mode LeftButton-Drag can be used to draw a new rectangle feature. If you click on the corner of an existing rectangle, that corner can be dragged, resizing the existing rectangle. If you click on the edge of an existing rectangle, that edge can be dragged resizing the existing rectangle.

The Escape key can be used to abort creation of a new rectangle, but while dragging an edge or corner of an existing rectangle it will just stop the dragged, equivelent to releasing the button.

## Draw Area

Area drawing mode is for digitizing area (polygon) features, which can contain holes. Moving existing areas is done with Select mode, and adding, removing or moving nodes in an existing polygon is done with Node Edit mode.

Digitizing a new polygon is accomplished by LeftButton-Clicking at each vertex location. When complete a RightButton-Clock terminates the process, and the polygon is closed.

Adding an internal ring (a hole) to an existing polygon is done by digitizing a new polygon entirely within the old polygon. The nesting is recognised, and the new polygon is treated as an internal ring to the main polygon. Note that this implies it is impossible to digitize a separate polygon that is inside another polygon ... to accomplish this, digitize it elsewhere, and then drag it into the area. If you digitize an a new polygon that starts inside another polygon, but goes outside the parent, it will be discarded on termination as a corrupt hole.

## Edit Node

Edit node mode is used to add, move, and remove individual nodes making up point, line and area features. To create new features use the point, line and area drawing modes.

In order to manipulate the nodes of a feature it is necessary to feature select the feature. Node editing mode only supports selection of a single feature at a time, by LeftButton-Clicking on it. Area selects are not supported. Selecting a feature will highlight all it's nodes at which point one of them can be selected, by left clicking on it.

A new node may be introduced into the selected feature by LeftButton-Pressing on an edge, but not too close to a node. The new node may then be positioned by dragging it before releasing.

An existing node is selected by clicking on it (or very close to it), at which point the node will be highlighted and filled in. The node may then be dragged to a new location. A node may be deleted by hitting the Delete key.

## Draw Labels

Label mode is used to draw labels on a shapes layer.

## Draw ROI

The ROI tool allows a rectangular region of interest (ROI) to be drawn. The value of a raster rectangle selected with the ROI tool can also be used with the get_roi() function to create a subregion array for use with Numeric Python.

The ROI tool does not operate on a feature layer. It draws a free standing rectangle by LeftButton-Draging it out. Edges, and corners can also be grabbed and dragged.

## Choose POI

The POI tool allows a point of interest (POI) to be drawn. The location of the selected pixel can be found using the get_poi() function. The POI tool does not operate on a feature layer. It can be used to draw a free standing point by LeftButton-Clicking.

## Link Views

Selecting Link Views will cause the view of each all windows to be linked. Pressing the button again will unlink the views. Any change of view in a linked window will result in all other windows also being updated similarly.

View characteristics includes the view position, zoom level, and rotation in 2D. In 3D this includes the view position, view direction, and vertical exaggeration. View characters does not include details about layers displayed, layer colors or anything of that sort.

Link windows will only operate correctly if all views are in the same coordinate system. For instance, if one view is georeferenced in UTM, and another is in lat/long degrees, the linked views will not operate in a useful manner.