Add clip path support on images. Add a new example and update the dolphin fest.

mdboom · mdboom · commit 8540e921e7ff · 2008-10-22T20:03:12.000Z
svn path=/trunk/matplotlib/; revision=6302
diff --git a/examples/pylab_examples/dolphin.py b/examples/pylab_examples/dolphin.py
@@ -1,20 +1,28 @@
+import matplotlib.cm as cm
 import matplotlib.pyplot as plt
 from matplotlib.patches import Circle, PathPatch
 from matplotlib.path import Path
 from matplotlib.transforms import Affine2D
 import numpy as np
 
+
 r = np.random.rand(50)
 t = np.random.rand(50) * np.pi * 2.0
 x = r * np.cos(t)
 y = r * np.sin(t)
 
 fig = plt.figure(figsize=(6,6))
 ax = plt.subplot(111)
-circle = Circle((0, 0), 1, facecolor=(0,0,0.8),
+circle = Circle((0, 0), 1, facecolor='none',
                 edgecolor=(0,0.8,0.8), linewidth=3, alpha=0.5)
 ax.add_patch(circle)
 
+im = plt.imshow(np.random.random((100, 100)),
+                origin='lower', cmap=cm.winter,
+                interpolation='spline36',
+                extent=([-1, 1, -1, 1]), zorder=1000)
+im.set_clip_path(circle)
+
 plt.plot(x, y, 'o', color=(0.9, 0.9, 1.0), alpha=0.8)
 
 # Dolphin from OpenClipart library by Andy Fitzsimon
diff --git a/examples/pylab_examples/image_clip_path.py b/examples/pylab_examples/image_clip_path.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python
+import numpy as np
+import matplotlib.cm as cm
+import matplotlib.mlab as mlab
+import matplotlib.pyplot as plt
+from matplotlib.path import Path
+from matplotlib.patches import PathPatch
+
+delta = 0.025
+x = y = np.arange(-3.0, 3.0, delta)
+X, Y = np.meshgrid(x, y)
+Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
+Z2 = mlab.bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
+Z = Z2-Z1  # difference of Gaussians
+
+path = Path([[0, 1], [1, 0], [0, -1], [-1, 0], [0, 1]])
+patch = PathPatch(path, facecolor='none')
+plt.gca().add_patch(patch)
+
+im = plt.imshow(Z, interpolation='bilinear', cmap=cm.gray,
+                origin='lower', extent=[-3,3,-3,3],
+                clip_path=patch, clip_on=True)
+im.set_clip_path(patch)
+
+plt.show()
+
diff --git a/src/_backend_agg.cpp b/src/_backend_agg.cpp
@@ -788,20 +788,58 @@ RendererAgg::draw_image(const Py::Tuple& args) {
   Py::Object box_obj = args[3];
   Py::Object clippath;
   agg::trans_affine clippath_trans;
+  bool has_clippath = false;
+
+  theRasterizer->reset_clipping();
+  rendererBase->reset_clipping(true);
   if (args.size() == 6) {
     clippath = args[4];
     clippath_trans = py_to_agg_transformation_matrix(args[5], false);
+    has_clippath = render_clippath(clippath, clippath_trans);
   }
 
-  theRasterizer->reset_clipping();
-  rendererBase->reset_clipping(true);
-  set_clipbox(box_obj, rendererBase);
-
   Py::Tuple empty;
-  pixfmt pixf(*(image->rbufOut));
   image->flipud_out(empty);
+  pixfmt pixf(*(image->rbufOut));
 
-  rendererBase->blend_from(pixf, 0, (int)x, (int)(height-(y+image->rowsOut)));
+  if (has_clippath) {
+    agg::trans_affine mtx;
+    mtx *= agg::trans_affine_translation((int)x, (int)(height-(y+image->rowsOut)));
+
+    agg::path_storage rect;
+    rect.move_to(0, 0);
+    rect.line_to(image->colsOut, 0);
+    rect.line_to(image->colsOut, image->rowsOut);
+    rect.line_to(0, image->rowsOut);
+    rect.line_to(0, 0);
+    agg::conv_transform<agg::path_storage> rect2(rect, mtx);
+
+    agg::trans_affine inv_mtx(mtx);
+    inv_mtx.invert();
+
+    typedef agg::span_allocator<agg::rgba8> color_span_alloc_type;
+    typedef agg::pixfmt_amask_adaptor<pixfmt, alpha_mask_type> pixfmt_amask_type;
+    typedef agg::renderer_base<pixfmt_amask_type> amask_ren_type;
+    typedef agg::image_accessor_clip<agg::pixfmt_rgba32> image_accessor_type;
+    typedef agg::span_interpolator_linear<> interpolator_type;
+    typedef agg::span_image_filter_rgba_nn<image_accessor_type, interpolator_type> image_span_gen_type;
+    typedef agg::renderer_scanline_aa_solid<amask_ren_type>    amask_aa_renderer_type;
+    typedef agg::renderer_scanline_aa<amask_ren_type, color_span_alloc_type, image_span_gen_type> renderer_type;
+
+    color_span_alloc_type sa;
+    image_accessor_type ia(pixf, agg::rgba8(0, 0, 0, 0));
+    interpolator_type interpolator(inv_mtx);
+    image_span_gen_type image_span_generator(ia, interpolator);
+    pixfmt_amask_type pfa(*pixFmt, *alphaMask);
+    amask_ren_type r(pfa);
+    renderer_type ri(r, sa, image_span_generator);
+
+    theRasterizer->add_path(rect2);
+    agg::render_scanlines(*theRasterizer, *slineP8, ri);
+  } else {
+    set_clipbox(box_obj, rendererBase);
+    rendererBase->blend_from(pixf, 0, (int)x, (int)(height-(y+image->rowsOut)));
+  }
 
   image->flipud_out(empty);
 
