Merge pull request matplotlib#7421 from QuLogic/hatch-dpi-density

Several hatching improvements

Author: NelleV

doc/users/dflt_style_changes.rst

@@ -625,6 +625,11 @@ The behavior of the PS and Agg backends was DPI dependent, thus::
 
 There is no API level control of the hatch color or linewidth.
 
+Hatching patterns are now rendered at a consistent density, regardless of DPI.
+Formerly, high DPI figures would be more dense than the default, and low DPI
+figures would be less dense.  This old behavior cannot be directly restored,
+but the density may be increased by repeating the hatch specifier.
+
 
 .. _default_changes_font:
 

lib/matplotlib/backends/backend_pdf.py

@@ -1141,12 +1141,12 @@ def alphaState(self, alpha):
     def hatchPattern(self, hatch_style):
         # The colors may come in as numpy arrays, which aren't hashable
         if hatch_style is not None:
-            face, edge, hatch = hatch_style
-            if face is not None:
-                face = tuple(face)
+            edge, face, hatch = hatch_style
             if edge is not None:
                 edge = tuple(edge)
-            hatch_style = (face, edge, hatch)
+            if face is not None:
+                face = tuple(face)
+            hatch_style = (edge, face, hatch)
 
         pattern = self.hatchPatterns.get(hatch_style, None)
         if pattern is not None:
@@ -1171,7 +1171,9 @@ def writeHatches(self):
                  'PatternType': 1, 'PaintType': 1, 'TilingType': 1,
                  'BBox': [0, 0, sidelen, sidelen],
                  'XStep': sidelen, 'YStep': sidelen,
-                 'Resources': res})
+                 'Resources': res,
+                 # Change origin to match Agg at top-left.
+                 'Matrix': [1, 0, 0, 1, 0, self.height * 72]})
 
             stroke_rgb, fill_rgb, path = hatch_style
             self.output(stroke_rgb[0], stroke_rgb[1], stroke_rgb[2],
@@ -1184,13 +1186,11 @@ def writeHatches(self):
 
             self.output(rcParams['hatch.linewidth'], Op.setlinewidth)
 
-            # TODO: We could make this dpi-dependent, but that would be
-            # an API change
             self.output(*self.pathOperations(
                 Path.hatch(path),
                 Affine2D().scale(sidelen),
                 simplify=False))
-            self.output(Op.stroke)
+            self.output(Op.fill_stroke)
 
             self.endStream()
         self.writeObject(self.hatchObject, hatchDict)

lib/matplotlib/backends/backend_ps.py

@@ -305,6 +305,7 @@ def create_hatch(self, hatch):
             return self._hatches[hatch]
         name = 'H%d' % len(self._hatches)
         linewidth = rcParams['hatch.linewidth']
+        pageheight = self.height * 72
         self._pswriter.write("""\
   << /PatternType 1
      /PaintType 2
@@ -318,13 +319,15 @@ def create_hatch(self, hatch):
         %(linewidth)f setlinewidth
 """ % locals())
         self._pswriter.write(
-            self._convert_path(Path.hatch(hatch), Affine2D().scale(72.0),
+            self._convert_path(Path.hatch(hatch), Affine2D().scale(sidelen),
                                simplify=False))
         self._pswriter.write("""\
-          stroke
+        fill
+        stroke
      } bind
    >>
    matrix
+   0.0 %(pageheight)f translate
    makepattern
    /%(name)s exch def
 """ % locals())
@@ -861,6 +864,7 @@ def _draw_ps(self, ps, gc, rgbFace, fill=True, stroke=True, command=None):
         stroke = stroke and mightstroke
         fill = (fill and rgbFace is not None and
                 (len(rgbFace) <= 3 or rgbFace[3] != 0.0))
+        hatch = gc.get_hatch()
 
         if mightstroke:
             self.set_linewidth(gc.get_linewidth())
@@ -886,19 +890,18 @@ def _draw_ps(self, ps, gc, rgbFace, fill=True, stroke=True, command=None):
         write("\n")
 
         if fill:
-            if stroke:
+            if stroke or hatch:
                 write("gsave\n")
             self.set_color(store=0, *rgbFace[:3])
             write("fill\n")
-            if stroke:
+            if stroke or hatch:
                 write("grestore\n")
 
-        hatch = gc.get_hatch()
         if hatch:
             hatch_name = self.create_hatch(hatch)
             write("gsave\n")
-            write("[/Pattern [/DeviceRGB]] setcolorspace %f %f %f " % gc.get_hatch_color()[:3])
-            write("%s setcolor fill grestore\n" % hatch_name)
+            write("%f %f %f " % gc.get_hatch_color()[:3])
+            write("%s setpattern fill grestore\n" % hatch_name)
 
         if stroke:
             write("stroke\n")

lib/matplotlib/tests/baseline_images/test_artist/clip_path_clipping.png

@@ -58,11 +58,14 @@ RendererAgg::RendererAgg(unsigned int width, unsigned int height, double dpi)
     rendererBase.clear(_fill_color);
     rendererAA.attach(rendererBase);
     rendererBin.attach(rendererBase);
-    hatchRenderingBuffer.attach(hatchBuffer, HATCH_SIZE, HATCH_SIZE, HATCH_SIZE * 4);
+    hatch_size = int(dpi);
+    hatchBuffer = new agg::int8u[hatch_size * hatch_size * 4];
+    hatchRenderingBuffer.attach(hatchBuffer, hatch_size, hatch_size, hatch_size * 4);
 }
 
 RendererAgg::~RendererAgg()
 {
+    delete[] hatchBuffer;
     delete[] alphaBuffer;
     delete[] pixBuffer;
 }

lib/matplotlib/tests/baseline_images/test_artist/hatching.pdf

@@ -239,8 +239,8 @@ class RendererAgg
     void *lastclippath;
     agg::trans_affine lastclippath_transform;
 
-    static const size_t HATCH_SIZE = 72;
-    agg::int8u hatchBuffer[HATCH_SIZE * HATCH_SIZE * 4];
+    size_t hatch_size;
+    agg::int8u *hatchBuffer;
     agg::rendering_buffer hatchRenderingBuffer;
 
     agg::rgba _fill_color;
@@ -359,7 +359,7 @@ RendererAgg::_draw_path(path_t &path, bool has_clippath, const facepair_t &face,
         agg::trans_affine hatch_trans;
         hatch_trans *= agg::trans_affine_scaling(1.0, -1.0);
         hatch_trans *= agg::trans_affine_translation(0.0, 1.0);
-        hatch_trans *= agg::trans_affine_scaling(HATCH_SIZE, HATCH_SIZE);
+        hatch_trans *= agg::trans_affine_scaling(hatch_size, hatch_size);
         hatch_path_trans_t hatch_path_trans(hatch_path, hatch_trans);
         hatch_path_curve_t hatch_path_curve(hatch_path_trans);
         hatch_path_stroke_t hatch_path_stroke(hatch_path_curve);