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Faster path drawing for the cairo backend (cairocffi only) #8787

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Merged
merged 9 commits into from
May 6, 2018
Merged

Faster path drawing for the cairo backend (cairocffi only) #8787

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3edc982
cairo: Don't copy the ravelled image.
anntzer Jun 22, 2017
b549d12
cairo: save a pair of ctx.save/ctx.restore.
anntzer Jun 22, 2017
8a07eef
Faster path drawing with cairocffi.
anntzer Jun 21, 2017
52ed746
Implement draw_path_collection for cairo.
anntzer Jun 21, 2017
5312461
Document a bit the cairo fast path.
anntzer Jun 22, 2017
1a2848d
Actually support quadratic Beziers.
anntzer Jun 23, 2017
aca804f
Address review comments.
anntzer Feb 3, 2018
7a727a1
Avoid triggering a DeprecationWarning.
anntzer Feb 6, 2018
abbcb3e
Rebase for mpl3.
anntzer May 6, 2018
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Address review comments.
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@anntzer
anntzer committed May 6, 2018
commit aca804f865fb08df66df0c8d97787d113013d75f
13 changes: 9 additions & 4 deletions doc/api/backend_cairo_api.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,12 @@
:mod:`matplotlib.backends.backend_cairo`
========================================

.. automodule:: matplotlib.backends.backend_cairo
:members:
:undoc-members:
:show-inheritance:
.. Building the docs requires either adding pycairo/cairocffi as docs build
dependency, or bumping the minimal numpy version to one that supports
MagicMocks (which does define `__index__`) as indices (recent numpys do, but
1.7.1 doesn't).

.. .. automodule:: matplotlib.backends.backend_cairo
.. :members:
.. :undoc-members:
.. :show-inheritance:
31 changes: 14 additions & 17 deletions lib/matplotlib/backends/backend_cairo.py
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Expand Up @@ -94,15 +94,6 @@ def buffer_info(self):
_CAIRO_PATH_TYPE_SIZES[cairo.PATH_CLOSE_PATH] = 1


def _convert_path(ctx, path, transform, clip=None):
return _convert_paths(ctx, [path], [transform], clip)


def _convert_paths(ctx, paths, transforms, clip=None):
return (_convert_paths_fast if HAS_CAIRO_CFFI else _convert_paths_slow)(
ctx, paths, transforms, clip)


def _convert_paths_slow(ctx, paths, transforms, clip=None):
for path, transform in zip(paths, transforms):
for points, code in path.iter_segments(transform, clip=clip):
Expand All @@ -123,7 +114,7 @@ def _convert_paths_slow(ctx, paths, transforms, clip=None):

def _convert_paths_fast(ctx, paths, transforms, clip=None):
# We directly convert to the internal representation used by cairo, for
# which ABI compatibility is guaranteed. The layout is for each item is
# which ABI compatibility is guaranteed. The layout for each item is
# --CODE(4)-- -LENGTH(4)- ---------PAD(8)---------
# ----------X(8)---------- ----------Y(8)----------
# with the size in bytes in parentheses, and (X, Y) repeated as many times
Expand Down Expand Up @@ -154,10 +145,10 @@ def _convert_paths_fast(ctx, paths, transforms, clip=None):
# Fill the buffer.
buf = np.empty(cairo_num_data * 16, np.uint8)
as_int = np.frombuffer(buf.data, np.int32)
as_float = np.frombuffer(buf.data, np.float64)
mask = np.ones_like(as_float, bool)
as_int[::4][cairo_type_positions] = codes
as_int[1::4][cairo_type_positions] = cairo_type_sizes
as_float = np.frombuffer(buf.data, np.float64)
mask = np.ones_like(as_float, bool)
mask[::2][cairo_type_positions] = mask[1::2][cairo_type_positions] = False
as_float[mask] = vertices.ravel()
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Could be re-arranged slightly to keep the int and float bits together.

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Not sure what you meant?

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Well, you start with a buffer, make an int version, then a float version, then a mask (which is for float). But then go back to filling the int version, modifying the mask (which is float stuff again), then fill the float version. So I mean more like:

    buf = np.empty(cairo_num_data * 16, np.uint8)
    as_int = np.frombuffer(buf.data, np.int32)
    as_int[::4][cairo_type_positions] = codes
    as_int[1::4][cairo_type_positions] = cairo_type_sizes
    as_float = np.frombuffer(buf.data, np.float64)
    mask = np.ones_like(as_float, bool)
    mask[::2][cairo_type_positions] = mask[1::2][cairo_type_positions] = False
    as_float[mask] = vertices.ravel()


Expand All @@ -169,6 +160,13 @@ def _convert_paths_fast(ctx, paths, transforms, clip=None):
cairo.cairo.cairo_append_path(ctx._pointer, ptr)


_convert_paths = _convert_paths_fast if HAS_CAIRO_CFFI else _convert_paths_slow


def _convert_path(ctx, path, transform, clip=None):
return _convert_paths(ctx, [path], [transform], clip)


class RendererCairo(RendererBase):
fontweights = {
100 : cairo.FONT_WEIGHT_NORMAL,
Expand Down Expand Up @@ -247,8 +245,7 @@ def draw_markers(self, gc, marker_path, marker_trans, path, transform,

ctx.new_path()
# Create the path for the marker; it needs to be flipped here already!
_convert_path(
ctx, marker_path, marker_trans + Affine2D().scale(1, -1))
_convert_path(ctx, marker_path, marker_trans + Affine2D().scale(1, -1))
marker_path = ctx.copy_path_flat()

# Figure out whether the path has a fill
Expand Down Expand Up @@ -312,7 +309,7 @@ def _draw_paths():
for k, v in gc_vars.items():
try:
getattr(gc, "set" + k)(v)
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No underscore is needed?

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@anntzer anntzer Feb 3, 2018 •
edited
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Actually no, I'm just copying the __dict__ of the original gc, and (kind of an implementation detail...) GraphicsContextBase stores "property" foo (accessed by get/set_foo) in ._foo). Not very elegant I admit.

except (AttributeError, TypeError):
except (AttributeError, TypeError) as e:
pass
gc.ctx.new_path()
paths, transforms = zip(*grouped_draw)
Expand All @@ -326,8 +323,8 @@ def _draw_paths():
offsetTrans, facecolors, edgecolors, linewidths, linestyles,
antialiaseds, urls, offset_position):
path, transform = path_id
transform = (Affine2D(transform.get_matrix()).translate(xo, yo)
+ Affine2D().scale(1, -1).translate(0, self.height))
transform = (Affine2D(transform.get_matrix())
.translate(xo, yo - self.height).scale(1, -1))
# rgb_fc could be a ndarray, for which equality is elementwise.
new_key = vars(gc0), tuple(rgb_fc) if rgb_fc is not None else None
if new_key == reuse_key:
Expand Down