fix: correct display of StrokePattern.solid at high zoom levels (fl…

…eaflet#1871)

fix: 1864 - correct display of solid style in high zoom levels

Impacted files:
* `polygon_layer/painter.dart`: now using the new `SolidPixelHiker` for solid style display
* `polyline_layer/painter.dart`: now using the new `SolidPixelHiker` for solid style display
* `pixel_hiker.dart`: new `SolidPixelHiker` class

lib/src/layer/misc/line_patterns/pixel_hiker.dart

@@ -237,6 +237,45 @@ class DashedPixelHiker extends _PixelHiker {
  }
 }
 
+/// Pixel hiker that lists the visible solid segments to display on the way.
+@internal
+class SolidPixelHiker extends _PixelHiker {
+ /// Standard Solid Pixel Hiker constructor.
+ SolidPixelHiker({
+ required super.offsets,
+ required super.closePath,
+ required super.canvasSize,
+ }) : super(
+ segmentValues: [],
+ patternFit: PatternFit.none,
+ );
+
+ /// Returns all visible segments.
+ List<VisibleSegment> getAllVisibleSegments() {
+ final List<VisibleSegment> result = [];
+
+ if (offsets.length < 2) {
+ return result;
+ }
+
+ for (int i = 0; i < offsets.length - 1 + (closePath ? 1 : 0); i++) {
+ final VisibleSegment? visibleSegment = VisibleSegment.getVisibleSegment(
+ offsets[i],
+ offsets[(i + 1) % offsets.length],
+ canvasSize,
+ );
+ if (visibleSegment != null) {
+ result.add(visibleSegment);
+ }
+ }
+
+ return result;
+ }
+
+ @override
+ double getFactor() => 1;
+}
+
 /// Pixel hiker that lists the visible items on the way.
 sealed class _PixelHiker {
  _PixelHiker({
@@ -253,6 +292,13 @@ sealed class _PixelHiker {
 
  final List<Offset> offsets;
  final bool closePath;
+
+ /// List of segments' lengths.
+ ///
+ /// Expected number of items:
+ /// * empty for "solid"
+ /// * > 0 and even for "dashed": (dash size _ space size) * n
+ /// * only 1 item for "dotted": the size of the space
  final List<double> segmentValues;
  final Size canvasSize;
  final PatternFit patternFit;
@@ -290,6 +336,9 @@ sealed class _PixelHiker {
 
  @protected
  void nextSegment() {
+ if (segmentValues.isEmpty) {
+ return;
+ }
  _segmentIndex = (_segmentIndex + 1) % segmentValues.length;
  _remaining = segmentValues[_segmentIndex];
  }
@@ -305,7 +354,7 @@ sealed class _PixelHiker {
  @protected
  Offset getIntermediateOffset(final Offset offsetA, final Offset offsetB) {
  final segmentDistance = getDistance(offsetA, offsetB);
- if (_remaining >= segmentDistance) {
+ if (segmentValues.isEmpty || _remaining >= segmentDistance) {
  _used = segmentDistance;
  return offsetB;
  }

lib/src/layer/polygon_layer/painter.dart

@@ -315,9 +315,20 @@ class _PolygonPainter<R extends Object> extends CustomPainter {
  Canvas canvas,
  Paint paint,
  ) {
+ final isSolid = polygon.pattern == const StrokePattern.solid();
  final isDashed = polygon.pattern.segments != null;
  final isDotted = polygon.pattern.spacingFactor != null;
- if (isDotted) {
+ if (isSolid) {
+ final SolidPixelHiker hiker = SolidPixelHiker(
+ offsets: offsets,
+ closePath: true,
+ canvasSize: canvasSize,
+ );
+ for (final visibleSegment in hiker.getAllVisibleSegments()) {
+ path.moveTo(visibleSegment.begin.dx, visibleSegment.begin.dy);
+ path.lineTo(visibleSegment.end.dx, visibleSegment.end.dy);
+ }
+ } else if (isDotted) {
  final DottedPixelHiker hiker = DottedPixelHiker(
  offsets: offsets,
  stepLength: polygon.borderStrokeWidth * polygon.pattern.spacingFactor!,
@@ -341,8 +352,6 @@ class _PolygonPainter<R extends Object> extends CustomPainter {
  path.moveTo(visibleSegment.begin.dx, visibleSegment.begin.dy);
  path.lineTo(visibleSegment.end.dx, visibleSegment.end.dy);
  }
- } else {
- _addLineToPath(path, offsets);
  }
  }
 
@@ -366,10 +375,6 @@ class _PolygonPainter<R extends Object> extends CustomPainter {
  }
  }
 
- void _addLineToPath(Path path, List<Offset> offsets) {
- path.addPolygon(offsets, true);
- }
-
  ({Offset min, Offset max}) _getBounds(Offset origin, Polygon polygon) {
  final bBox = polygon.boundingBox;
  return (

lib/src/layer/polyline_layer/painter.dart

@@ -159,6 +159,7 @@ class _PolylinePainter<R extends Object> extends CustomPainter {
  strokeWidth = polyline.strokeWidth;
  }
 
+ final isSolid = polyline.pattern == const StrokePattern.solid();
  final isDashed = polyline.pattern.segments != null;
  final isDotted = polyline.pattern.spacingFactor != null;
 
@@ -207,7 +208,19 @@ class _PolylinePainter<R extends Object> extends CustomPainter {
  paths.add(filterPath);
  }
  paths.add(path);
- if (isDotted) {
+ if (isSolid) {
+ final SolidPixelHiker hiker = SolidPixelHiker(
+ offsets: offsets,
+ closePath: false,
+ canvasSize: size,
+ );
+ for (final visibleSegment in hiker.getAllVisibleSegments()) {
+ for (final path in paths) {
+ path.moveTo(visibleSegment.begin.dx, visibleSegment.begin.dy);
+ path.lineTo(visibleSegment.end.dx, visibleSegment.end.dy);
+ }
+ }
+ } else if (isDotted) {
  final DottedPixelHiker hiker = DottedPixelHiker(
  offsets: offsets,
  stepLength: strokeWidth * polyline.pattern.spacingFactor!,
@@ -244,12 +257,6 @@ class _PolylinePainter<R extends Object> extends CustomPainter {
  path.lineTo(visibleSegment.end.dx, visibleSegment.end.dy);
  }
  }
- } else {
- if (offsets.isNotEmpty) {
- for (final path in paths) {
- path.addPolygon(offsets, false);
- }
- }
  }
  }