ugurdogrusoz
commented
8 years ago What we need can be summarized as follows:
- When "snap to grid" is enabled, all nodes should be resized (minimally) to have dimensions multiple of the unit grid size, and relocated so that their centers, left, right, top and bottom coordinates align with the grid. In order for this to hold for compound nodes, after simple node sizes have been adjusted, compound node margins might need to be adjusted as well. For instance, if I have a node centered at (2,8) with dimensions 24x36, and snap to grid (grid is always assumed to have a point at the origin) is enabled with grid size 10, the node should be centered at (0,10) with adjusted dimensions (20,40).
- When the grid size is changed while snap to grid is enabled, we need to re-adjust position and dimensions as above as well.
- When a node is dragged, it should move in "discrete" grid steps; thus, when the mouse is released, the node should be snapped to the grid (all 5 coordinates: center, left, right, top, and bottom). For instance, the node above centered at (0,10) when the node is being dragged and currently centered at (22,39), the node should be repositioned automatically to be at (20,40).
In addition, during drag operation, we should scan for neighboring nodes (all five coordinates of such nodes) and in order check:
- if the current node coordinate (1 of the 3 coordinates) is horizontally aligned with center, top, or bottom of a nearby "visible" (this might be difficult to check and we might settle for a nearby neighbor!) neighbor node, we should draw a visual cue (helper horizontal line segment) from the node coordinate to neighbor node's aligning coordinate (1 of the 3 coordinates). Checks for the current node coordinate and neighboring node coordinate should be done in the following order: center, top, bottom.
- if the current node coordinate (1 of the 3 coordinates) is vertically aligned with center, left or right of a nearby "visible" neighbor node, we should draw a visual cue (helper vertical line segment) similarly.
- When a node is resized, we should round the new dimension(s) w.r.t. the grid as well. For instance, if the user choose the new dimensions of the node above as (32,48), it should get adjusted to (30,50).
selimfirat
We would like to implement a grid and functionality to snap to grid along with drawing vertical and/or horizontal lines as alignment cues. We need to discuss and design this first.