ch0ic3/cutter
1
0
Fork 0
mirror of https://github.com/rizinorg/cutter.git synced 2025-01-18 18:38:51 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

Update GraphGridLayout documentation (#3000)

Browse Source 
* Updated GraphGridLayout documentation

* Don't use potentially misleading  name "segment tree" .

Not exactly segment tree (although sometimes called that), and for the purpose of high level understanding how graph layout works doesn't matter what it is. Any data structure which provides required queries could be used.

Co-authored-by: Kārlis Seņko <karlis3p70l1ij@gmail.com>
This commit is contained in:
Jeremy Rifkin 2022-08-10 09:05:01 -04:00 committed by GitHub
parent a4a4b9d2ec
commit 278b4e19b9
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 12 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
src/widgets/GraphGridLayout.cpp
View File

@ -103,14 +103,24 @@ Edge routing can be split into: main column selection, rough routing, segment of
Transition from source to target row is done using single vertical segment. This is called main
column.
A sweep line is used for computing main columns: Blocks and edges are processed as events top to
bottom based off their row (max(start row, end row) for edges). Blocked columns are tracked in a
tree structure which allows searching nearest column with at least last N rows empty. The column
of the starting block is favored for the main column, otherwise the target block's column is chosen
if it is not blocked. If both the source and target columns are blocked, nearest unblocked column
is chosen. An empty column can always be found, in the worst case there are empty columns at the
sides of drawing. If two columns are equally close, the tie is broken based on whether the edge is a
true or false branch. In case of upward edges it is allowed to choose a column on the outside which
is slightly further than nearest empty to reduce the chance of producing tilted figure 8 shaped
crossing between two blocks.
Rough routing creates the path of edge using up to 5 segments using grid coordinates.
Due to nodes being placed in a grid. Horizontal segments of edges can't intersect with any nodes.
The path for edges is chosen so that it consists of at most 5 segments, typically resulting in
sideways U shape or square Z shape.
- short vertical segment from node to horizontal line
- move to empty column
- vertical segment between starting row and end row, an empty column can always be found, in the
worst case there are empty columns at the sides of drawing
- vertical segment between starting row and end row
- horizontal segment to target node column
- short vertical segment connecting to target node
@ -118,9 +128,6 @@ There are 3 special cases:
- source and target nodes are in the same column with no nodes between - single vertical segment
- column bellow stating node is empty - segments 1-3 are merged
- column above target node is empty - segments 3-5 are merged
Vertical segment intersection with nodes is prevented using a 2d array marking which vertical
segments are blocked and naively iterating through all rows between start and end at the desired
column.
After rough routing segment offsets are calculated relative to their corresponding edge column. This
ensures that two segments don't overlap. Segment offsets within each column are assigned greedily