Add support for backdrops in the Graph

[cbentejac]

Description

This PR is a replacement for #2574.

It introduces a new "Backdrop" node type to Meshroom's core and UI, allowing users to visually group nodes in the graph editor.

Backdrops are a specific type of node that can be instantiated as any other node type, but have no input or output attributes. They only possess internal attributes, including their size (width and height) as they can be resized. Backdrops can be given custom names, colors, and display any comment that was added by the user (with an adjustable font size).

Visually, backdrops are always placed behind any non-backdrop node they may be overlapping with. Whenever a node is fully contained within a backdrop node, it is automatically "attached" to it: moving the backdrop will move the node as well. Conversely, moving a node that is contained within a backdrop will not move the backdrop. As selecting a backdrop adds the nodes that are contained in it to the selection, two new controls are added when clicking on a backdrop:

• Ctrl + Clic: only select the nodes contained in the backdrop
• Alt + Clic: only select the backdrop and not the nodes that are contained in it. This is especially useful to "detach" the backdrop from the nodes it contains and move it on its own or remove it from the graph altogether without removing the other nodes.

Features list

• Add a new core BackdropNode type of node which is non-computable and only has internal attributes.
• Add a new Backdrop node description to make backdrops instantiable.
• Add a new Backdrop QML component.

Implementation remarks

Backdrop Node Support:

• Added a new BackdropNode class in both desc.node and core.node, representing a non-computable node for grouping other nodes visually. The Backdrop node has its own internal attributes and serialization logic. (F2d2396aL336R336, [1] [2]
• Updated the node factory logic and graph logic to support creating and deserializing Backdrop nodes, including a new getNodeConstructor utility. [1] [2] [3] [4] [5] [6]
• Extended the MrNodeType enum and related type-handling logic to recognize the new BACKDROP node type. [1] [2] [3] [4] [5] [6]

Node Internal Attributes & Display Properties:

• Refactored internal node attributes into an InternalAttributesFactory, with attribute sets for basic, invalidation, and resizable (font size, width, height) properties. [1] [2]
• Added new getter methods and Qt properties to Node for fontSize, nodeWidth, and nodeHeight, enabling UI customization for nodes, especially Backdrop nodes. [1] [2]
• Updated node type checks and properties to distinguish Backdrop nodes from computable and input nodes, including new isBackdropNode property. [1] [2] [3]

[codecov]

Codecov Report

❌ Patch coverage is 95.33679% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.37%. Comparing base (306e2f7) to head (d1f0f83).
⚠️ Report is 50 commits behind head on develop.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
meshroom/core/desc/node.py	92.10%	3 Missing ⚠️
meshroom/core/node.py	92.85%	3 Missing ⚠️
tests/test_nodes.py	96.80%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2979      +/-   ##
===========================================
+ Coverage    81.09%   81.37%   +0.28%     
===========================================
  Files           66       67       +1     
  Lines         8858     9022     +164     
===========================================
+ Hits          7183     7342     +159     
- Misses        1675     1680       +5     

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[Copilot]

Pull request overview

This PR adds support for backdrop nodes in the graph editor, enabling users to visually group and organize nodes with resizable backdrop containers. It replaces PR #2574.

Changes:

• Introduces a new BackdropNode type at both the core (Python) and UI (QML) levels
• Adds resizing functionality for backdrop nodes with drag handles for all four sides
• Implements automatic child node selection when backdrop nodes are selected or dragged

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 17 comments.

Show a summary per file

File	Description
meshroom/ui/qml/GraphEditor/qmldir	Registers the new Backdrop.qml component
meshroom/ui/qml/GraphEditor/Backdrop.qml	New component implementing the visual representation and interaction logic for backdrop nodes
meshroom/ui/qml/GraphEditor/GraphEditor.qml	Updates node instantiation to use Loader pattern supporting both Node and Backdrop components; removes semicolons for consistency
meshroom/ui/qml/GraphEditor/NodeEditor.qml	Adds conditional UI handling for backdrop nodes (hides attributes tab, shows only notes/documentation)
meshroom/ui/qml/GraphEditor/Node.qml	Adds isBackdropNode property for type checking
meshroom/ui/qml/Controls/DelegateSelectionBox.qml	Adds logic to automatically select backdrop children when backdrop is selected
meshroom/ui/graph.py	Implements resizeNode and resizeAndMoveNode methods for backdrop manipulation; adds BackdropNode import
meshroom/ui/components/geom2D.py	Adds rectRectFullIntersect method for checking if one rectangle fully contains another
meshroom/nodes/general/Backdrop.py	Defines the Backdrop node plugin
meshroom/core/nodeFactory.py	Adds getNodeConstructor function to select appropriate node class (BackdropNode vs Node)
meshroom/core/node.py	Implements BackdropNode class with resizing properties (nodeWidth, nodeHeight, fontSize)
meshroom/core/graph.py	Updates node creation to use getNodeConstructor
meshroom/core/desc/node.py	Adds BACKDROP MrNodeType, BackdropNode descriptor, and InternalAttributesFactory for managing node internal attributes
meshroom/core/desc/init.py	Exports new BackdropNode and InternalAttributesFactory classes

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[Copilot]

Pull request overview

Copilot reviewed 14 out of 14 changed files in this pull request and generated 10 comments.

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[Alxiice]

Great work! Honestly on the UI side I didn't have any issue, it's really great to have this too !
I have though some small remarks and bugs to report :

• The NodeActions disappeared :(((
• I would love to be able to make a horizontal+vertical resize (like the diagonal control)
• To select nodes with the ctrl+click (so only nodes without backdrop) we need to click twice
• If the text is too long it goes outside of the backdrop, maybe this is okay or we want to clip the text ouside of the backdrop
• I think we should put the backdrop on top of the menu and not on the Utils submenu
• The compute/submit doesn't work well it should remove the Backdrop node from the list of nodes to create, now it raises an issue because of the chunk creation process
• Same issues with cut/copy : there are either issues in the QML or directly bugs in the python side (see comments for the code review that will come next)
• It would be cool to have some additional features (to do in a future PRs though) :
  • a "fit nodes" button so that the bckdrop is resized to fir the nodes inside
  • if we have selected nodes when we create the backdrop the backdrop could be created in a way so it fits the nodes
  • We could use ctrl+click+drag to draw the backdrop : if no node is selected, we press ctrl and click on the graph editor then drag and it draws the rectangle for the backdrop

[nicolas-lambert-tc]

Could be useful to add a text color parameter (or handle the color based on luminance), to handle cases where user choose a dark background color ?

[cbentejac]

Could be useful to add a text color parameter (or handle the color based on luminance), to handle cases where user choose a dark background color ?

This is done! A "Font Color" internal attribute has been added so the user can set the font color at the same time they set the font size (it is also easier to handle than checking the luminance and adapting the color to it).

Great work! Honestly on the UI side I didn't have any issue, it's really great to have this too ! I have though some small remarks and bugs to report :

• The NodeActions disappeared :(((

• I would love to be able to make a horizontal+vertical resize (like the diagonal control)

• To select nodes with the ctrl+click (so only nodes without backdrop) we need to click twice

• If the text is too long it goes outside of the backdrop, maybe this is okay or we want to clip the text ouside of the backdrop

• I think we should put the backdrop on top of the menu and not on the Utils submenu

• The compute/submit doesn't work well it should remove the Backdrop node from the list of nodes to create, now it raises an issue because of the chunk creation process

• Same issues with cut/copy : there are either issues in the QML or directly bugs in the python side (see comments for the code review that will come next)

• It would be cool to have some additional features (to do in a future PRs though) :

  • a "fit nodes" button so that the bckdrop is resized to fir the nodes inside
  • if we have selected nodes when we create the backdrop the backdrop could be created in a way so it fits the nodes
  • We could use ctrl+click+drag to draw the backdrop : if no node is selected, we press ctrl and click on the graph editor then drag and it draws the rectangle for the backdrop

All the remarks have been addressed except for the one suggesting to move the Backdrop node outside of the "Utils" category, as it is currently impossible in Meshroom to have a node that doesn't belong in any category. The suggestions for improvements will be made in an ulterior pull request, once this one will have been integrated.

[Alxiice]

Small bug :

ERROR:root:Error while undoing command 'Disconnect 'SleepNode_9.output' -> 'SleepNode_8.inputs[0]'': 
Traceback (most recent call last):
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/ui/commands.py", line 36, in undo
    self.undoImpl()
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/ui/commands.py", line 486, in undoImpl
    edge[0].connectTo(edge[1])
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/core/attribute.py", line 551, in connectTo
    connectedEdge, deletedEdge = graph.addEdge(self, dstAttribute)
                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/core/graph.py", line 157, in decorator
    result = func(self, *args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/core/graph.py", line 937, in addEdge
    if not srcAttr.node.graph == dstAttr.node.graph == self:
                                 ^^^^^^^^^^^^^^^^^^
AttributeError: 'PySide6.QtCore.Property' object has no attribute 'graph'

[cbentejac]

Small bug :

ERROR:root:Error while undoing command 'Disconnect 'SleepNode_9.output' -> 'SleepNode_8.inputs[0]'': 
Traceback (most recent call last):
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/ui/commands.py", line 36, in undo
    self.undoImpl()
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/ui/commands.py", line 486, in undoImpl
    edge[0].connectTo(edge[1])
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/core/attribute.py", line 551, in connectTo
    connectedEdge, deletedEdge = graph.addEdge(self, dstAttribute)
                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/core/graph.py", line 157, in decorator
    result = func(self, *args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/s/apps/users/sonoleta/packages/meshroom/asdev2/repo/meshroom/core/graph.py", line 937, in addEdge
    if not srcAttr.node.graph == dstAttr.node.graph == self:
                                 ^^^^^^^^^^^^^^^^^^
AttributeError: 'PySide6.QtCore.Property' object has no attribute 'graph'

So I have both good and bad news about this: the good one is that it is not related to this specific PR 😀 The bad one is that it is an issue that's already on the "develop" branch (and should thus preferably be fixed with its own PR).