Handle conditional visibility of data defined size legend nodes

[uclaros]

Description

This PR Fixes #50301

The solution is a little hacky.

Would it make more sense to have QgsDataDefinedSizeLegendNode class also handle the rendering of the data defined size label and also individual classes, instead of having separate QgsSymbolLegendNodes for them?

Solution is no longer hacky, #57461 (comment) was implemented

[github-actions]

🪟 Windows builds ready!

Windows builds of this PR are available for testing here. Debug symbols for this build are available here.

(Built from commit a31dfb5)

[github-actions]

Tests failed for Qt 6

One or more tests failed using the build from commit 108aa23

legend_data_defined_size_separated (testDataDefinedSizeSeparated)

legend_data_defined_size_separated

Test failed at _verifyImage at tests/src/core/testqgslegendrenderer.cpp:225

Rendered image did not match tests/testdata/control_images/legend/expected_legend_data_defined_size_separated/expected_legend_data_defined_size_separated.png (found 3540 pixels different)

legend_data_defined_size_filter_by_map (testDataDefinedSizeCollapsedFilterByMap)

legend_data_defined_size_filter_by_map

Test failed at _verifyImage at tests/src/core/testqgslegendrenderer.cpp:225

Rendered image did not match tests/testdata/control_images/legend/expected_legend_data_defined_size_filter_by_map/expected_legend_data_defined_size_filter_by_map.png (found 347 pixels different)

legend_data_defined_size_filter_by_map (testDataDefinedSizeSeparatedFilterByMap)

legend_data_defined_size_filter_by_map

Test failed at _verifyImage at tests/src/core/testqgslegendrenderer.cpp:225

Rendered image did not match tests/testdata/control_images/legend/expected_legend_data_defined_size_filter_by_map/expected_legend_data_defined_size_filter_by_map.png (found 347 pixels different)

The full test report (included comparison of rendered vs expected images) can be found here.

Further documentation on the QGIS test infrastructure can be found in the Developer's Guide.

[nyalldawson]

instead of the abuse, how about we add a QMap< int, QVariant > userData to QgsLegendSymbolItem, and adapt QgsSymbolLegendNode::data to return those values for unknown roles.

[uclaros]

We could have a new role in QgsLayerTreeModelLegendNode::CustomRole for that, instead of handling all unknown roles.
But, why a QMap< int, QVariant >? What would you store there (in this case and/or in future uses of it)?

[nyalldawson]

We could have a new role in QgsLayerTreeModelLegendNode::CustomRole for that, instead of handling all unknown roles.

That also works. I was just thinking ahead if allowing custom roles in QgsLegendSymbolItem would also be useful in future.

But, why a QMap< int, QVariant >? What would you store there (in this case and/or in future uses of it)?

The int keys would correspond to a role from QgsLayerTreeModelLegendNode (either public or private). I'd find a QMap approach slightly preferable to having separate members for every property we decide to add in future.

[github-actions]

Tests failed for Qt 5

One or more tests failed using the build from commit a31dfb5

layout_export_markerline_masked_geometry

layout_export_markerline_masked_geometry

Test failed at test_markerline_masked at tests/src/python/test_selective_masking.py:1376

Rendered image did not match tests/testdata/control_images/selective_masking/layout_export_markerline_masked/layout_export_markerline_masked.png (found 124 pixels different)

The full test report (included comparison of rendered vs expected images) can be found here.

Further documentation on the QGIS test infrastructure can be found in the Developer's Guide.

[qgis-bot]

The backport to release-3_38 failed:

The process '/usr/bin/git' failed with exit code 128

stderr

error: commit ac292ac6fdebb5f852dc99ba75a440f0d621dde2 is a merge but no -m option was given.
fatal: cherry-pick failed

stdout

Auto-merging src/core/layertree/qgslayertreemodel.cpp
[backport-57461-to-release-3_38 36c22aa426c] handle conditional visibility of data defined size legend nodes
 Author: uclaros <[email protected]>
 Date: Thu May 16 13:40:22 2024 +0300
 2 files changed, 15 insertions(+), 4 deletions(-)
Auto-merging tests/src/core/testqgslegendrenderer.cpp
[backport-57461-to-release-3_38 070e8126eb9] tests added
 Author: uclaros <[email protected]>
 Date: Tue May 21 09:42:00 2024 +0300
 3 files changed, 206 insertions(+)
 create mode 100644 tests/testdata/control_images/legend/expected_legend_data_defined_size_filter_by_map/expected_legend_data_defined_size_filter_by_map.png
 create mode 100644 tests/testdata/control_images/legend/expected_legend_data_defined_size_separated/expected_legend_data_defined_size_separated.png
[backport-57461-to-release-3_38 20c451ea421] update test masks
 Author: uclaros <[email protected]>
 Date: Tue May 21 16:13:07 2024 +0300
 2 files changed, 0 insertions(+), 0 deletions(-)
 create mode 100644 tests/testdata/control_images/legend/expected_legend_data_defined_size_filter_by_map/expected_legend_data_defined_size_filter_by_map_mask.png
 create mode 100644 tests/testdata/control_images/legend/expected_legend_data_defined_size_separated/expected_legend_data_defined_size_separated_mask.png

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-release-3_38 release-3_38
# Navigate to the new working tree
cd .worktrees/backport-release-3_38
# Create a new branch
git switch --create backport-57461-to-release-3_38
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick 016cfe60a0411761bbc0f0971b7cd22d88820689,108aa23f67b9f43a77fffaf3ce46e6806c9c9d87,cb491ea9baa466a260943edfb0135ad932f180c0,ac292ac6fdebb5f852dc99ba75a440f0d621dde2,3bb06c107118f62812404bce1390da43877de10d,b44b51cc109cd9954dc92d8f8b5fa3f65d695ba2,2bc7bc57547215da53a7e4dab7884057e060bb40,a31dfb5c2be8af26cf173286fd183c746fd557f4
# Push it to GitHub
git push --set-upstream origin backport-57461-to-release-3_38
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release-3_38

Then, create a pull request where the base branch is release-3_38 and the compare/head branch is backport-57461-to-release-3_38.