GSoC2009 Node Tool Rewrite
This page tracks the progress of the node tool rewrite project which is a part of the Google Summer of Code 2009. This project is being implemented by Krzysztof Kosiński, and the mentor is Bulia Byak. This page will be kept updated with the current status of the student's code (it may not reflect the code in the trunk).
(Work in progress)
Control points (Knots) will be represented by a new class called ControlPoint, based on SPKnot, but with a slightly different set of signals. A set of control points will be managed in a Manipulator. Manipulators will be sets of control points that have queriable selection status. Manipulators will be managed in a top level ItemEditor object, which will be the main object used by the new node context (this object cannot be called ShapeEditor for now, because they have to exist side by side).
- signal_dragged - emitted when the point is dragged to a new position
- signal_grabbed - start of drag. Emitted when there was a click and a move larger than drag tolerance.
- signal_ungrabbed - end of drag
- signal_moved - knot was moved to new position. Emitted in response to the move() method or finished drag.
Order of emission:
Examples of implementation
- Moving selection: the manipulator connects to signal_dragged and signal_ungrabbed. It updates the position of its other selected control points in response to signal_dragged, which it keeps in a list (selectable control points have signal_selected and signal_deselected which are connected to from the manipulator to update the list of selected control points accordingly) and updates the XML in response to signal_ungrabbed.
- Dragging out handles: the manipulator connects to signal_clicked, and intercepts it if Shift is held. It then creates a new ControlPoint for the dragged out handle and connects to signal_moved, which is only emitted when the drag is finished. in response to signal_moved, the distance between the node and the handle is checked against the drag tolerance; if it's smaller, the handle is deleted and the path is not updated. If it's larger, repr is updated.
- Constrained dragging: the manipulator connects to signal_dragged. In response to it, it calculates the constrained position, calls setPosition (which doesn't emit any signals) and returns true, which prevents the position from being updated. The events still flow only to the control point due to a pointer grab.
- Handle dragging: A control point representing a node will be subclassed, and will know about its handles. Handles will also be subclassed and know about their nodes. There will be an additional handler for signal_dragged, which will update the position of the other handle appropriately.
|Feature||Description||Old tool||New tool|
|Object selection||Selecting objects to node-edit (incl. Shift-click, Alt-click); ignores groups||Yes|
|Selecting single nodes||Whether selecting single nodes with left-click works correctly.||Yes|
|Select segment||Click on a path segment to select adjacent nodes||Yes|
|Selecting multiple nodes||Shift-click to toggle selection of a node||Yes|
|Select all||Ctrl+A selects all nodes in subpaths that have something selected, Ctrl+Alt+A selects all nodes||Yes|
|Deselect||Esc or click outside of selected paths to deselect||Yes|
|Multi-path selection||Selecting nodes in two or more different paths||No|
|Prev/Next node||Tab to select next node, Shift+Tab to select previous||Yes|
|Invert Selection||! key inverts node selection in selected subpaths, Alt+! in the whole path||Yes|
|Nodeset selection cue||Whether a selection cue with transform handles can be toggled for sets of nodes (needs sensible behavior when one node is selected)||No|
|Move||Moving selections of nodes||Yes|
|Move with keyboard||arrows, Shift+arrows, Alt+arrows, Shift+Alt+arrows||Yes|
|Scale with mouse||Scaling node sets with the mouse (needs selection cue)||No|
|Scale with keyboard||Both Ctrl and Alt keys + >, <||Yes|
|Rotate with mouse||Rotating node sets with the mouse||No|
|Rotate with keyboard||Both Ctrl and Alt keys and [, ]||Yes|
|Skew with mouse||Skewing node sets with the mouse||No|
|Skew with keyboard||No|
|Flip nodes||v for vertical flip, h for horizontal||Yes|
|Movement restriction||Ctrl to restrict movement to axes||Yes|
|Sculpting||Alt to move selected nodes depending on their distance from the cursor||Yes|
|Affect handles||Ability to specify whether handles should be transformed (toggle button)||No|
|Add nodes||Double-click on path segment to add node||Yes|
|Delete nodes||Del to remove nodes while trying to preserve shape||Yes|
|Join nodes||Fuse two nodes into one||Yes|
|Multi-path node join||Joining nodes in different paths works sensibly||No|
|Join segment||Joining two nodes with a segment works correctly||Yes|
|Multi-path segment join||Join between subpaths in different paths works||No|
|Delete segment||Removing a path segment between two nodes||Yes|
|Align nodes||Alignment actions in Align and Distribute dialog||Yes|
|Snap nodes||Nodes snap according to snap settings when transformed||Yes|
|Unselected path outline||Outline promptly flashes when hovering over a unselected path||Yes|
|Selected path outline||Outline of the selected path is drawn||Yes|
|Handle display||Handles are displayed on the selected nodes and their neighbors||Yes|
|Flip handles||v for vertical flip, h for horizontal||Yes|
|Lock handle length||Alt to move handles while preserving length||Yes|
|Move along handles||Ctrl+Alt to restrict node movement to the handle lines||Yes|
|Drag out handles||Shift + mouse drag to drag out a handle that coincides with a node||Yes|
|Restrict movement||Ctrl to restrict handle movements to ~15 degree angle increments from axis-aligned and the original angle||Yes|
|Snap handles||Handles can be snapped to other snap targets||No|
|Copy / paste handles||Ability to copy and paste handles between nodes||No|
|Copy / paste subpaths||Ability to add a subpath by pasting it into the selected path||No|
|Drag tolerance||Drags shorter than a configurable distance are regarded as clicks||Yes|
|Clip / mask editing||Buttons to edit the clipping and masking paths in place||Yes|
|Path effect param editing||Button to to edit the next path parameter of the selected live path effect||Yes|
|Prefs page||Node tool preferences page with various settings||Yes|
Inkscape key guide for the node tool - more detailed description of the old node tool's features