[FEATURE] New line symbol type: Hash line

This line symbol type is designed to replicate the ArcGIS Hash Line symbol layer type. It allows for a repeating line segment to be drawn over the length of a feature, with a line-sub symbol used to render each individual segment. To reduce code duplication, this is heavily based off the current line marker symbol layer, since the functionality is almost identical (draw some sub symbol at some interval along a line). Accordingly, I've split off QgsMarkerLineSymbolLayer to move as much of the common functionality as possible to a new abstract base class, so that only the actual marker/line segment rendering occurs in the marker line/hash line subclasses. This also gives the hash line all the existing placement options permissible for marker lines -- e.g. first/last vertex, mid points, regular intervals, etc. The hash line length and angle can have data defined overrides, which are evaluated per-line segment, allowing for the hash line to change size and angle over the length of a single rendered feature.
qgis · Apr 2, 2019 · 48d2a37 · 48d2a37
1 parent 59ed078
commit 48d2a37
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diff --git a/python/core/__init__.py.in b/python/core/__init__.py.in
@@ -28,6 +28,7 @@ from qgis._core import *
 
 from .additions.edit import edit, QgsEditError
 from .additions.fromfunction import fromFunction
+from .additions.markerlinesymbollayer import *
 from .additions.metaenum import metaEnumFromType, metaEnumFromValue
 from .additions.processing import processing_output_layer_repr, processing_source_repr
 from .additions.projectdirtyblocker import ProjectDirtyBlocker

diff --git a/python/core/additions/markerlinesymbollayer.py b/python/core/additions/markerlinesymbollayer.py
@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+
+"""
+***************************************************************************
+    markerlinesymbollayer.py
+    ---------------------
+    Date                 : March 2019
+    Copyright            : (C) 2019 by Nyall Dawson
+    Email                : nyall dot dawson at gmail dot com
+***************************************************************************
+*                                                                         *
+*   This program is free software; you can redistribute it and/or modify  *
+*   it under the terms of the GNU General Public License as published by  *
+*   the Free Software Foundation; either version 2 of the License, or     *
+*   (at your option) any later version.                                   *
+*                                                                         *
+***************************************************************************
+"""
+from qgis._core import (
+    QgsMarkerLineSymbolLayer,
+    QgsTemplatedLineSymbolLayerBase)
+
+
+# monkey patch deprecated enum values to maintain API
+# TODO - remove for QGIS 4.0
+QgsMarkerLineSymbolLayer.Interval = QgsTemplatedLineSymbolLayerBase.Interval
+QgsMarkerLineSymbolLayer.Vertex = QgsTemplatedLineSymbolLayerBase.Vertex
+QgsMarkerLineSymbolLayer.LastVertex = QgsTemplatedLineSymbolLayerBase.LastVertex
+QgsMarkerLineSymbolLayer.FirstVertex = QgsTemplatedLineSymbolLayerBase.FirstVertex
+QgsMarkerLineSymbolLayer.CentralPoint = QgsTemplatedLineSymbolLayerBase.CentralPoint
+QgsMarkerLineSymbolLayer.CurvePoint = QgsTemplatedLineSymbolLayerBase.CurvePoint