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Broken alpha handling in images #545

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Merged
merged 2 commits into from
Oct 28, 2011
Merged

Broken alpha handling in images #545

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e406c05
Make "set_alpha()" work on images. Now, alpha blending is handled in…
mdboom Oct 24, 2011
1dac36d
Tell Agg that we're giving it pre-multiplied image data
mdboom Oct 21, 2011
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4 changes: 4 additions & 0 deletions lib/matplotlib/backends/backend_svg.py
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Original file line number Diff line number Diff line change
Expand Up @@ -757,6 +757,10 @@ def draw_image(self, gc, x, y, im, dx=None, dy=None, transform=None):
im.flipud_out()
attrib['xlink:href'] = filename

alpha = gc.get_alpha()
if alpha != 1.0:
attrib['opacity'] = str(alpha)

if transform is None:
self.writer.element(
'image',
Expand Down
14 changes: 9 additions & 5 deletions lib/matplotlib/image.py
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Original file line number Diff line number Diff line change
Expand Up @@ -199,7 +199,7 @@ def _get_unsampled_image(self, A, image_extents, viewlim):
im.is_grayscale = False
else:
if self._rgbacache is None:
x = self.to_rgba(self._A, self._alpha, bytes=True)
x = self.to_rgba(self._A, bytes=True)
self._rgbacache = x
else:
x = self._rgbacache
Expand Down Expand Up @@ -345,6 +345,7 @@ def draw(self, renderer, *args, **kwargs):
gc = renderer.new_gc()
gc.set_clip_rectangle(self.axes.bbox.frozen())
gc.set_clip_path(self.get_clip_path())
gc.set_alpha(self.get_alpha())

if self._check_unsampled_image(renderer):
self._draw_unsampled_image(renderer, gc)
Expand Down Expand Up @@ -722,7 +723,7 @@ def set_data(self, x, y, A):
A.shape = A.shape[0:2]
if len(A.shape) == 2:
if A.dtype != np.uint8:
A = self.to_rgba(A, alpha=self._alpha, bytes=True)
A = self.to_rgba(A, bytes=True)
self.is_grayscale = self.cmap.is_gray()
else:
A = np.repeat(A[:,:,np.newaxis], 4, 2)
Expand Down Expand Up @@ -824,7 +825,7 @@ def make_image(self, magnification=1.0):
width = width * magnification
height = height * magnification
if self._rgbacache is None:
A = self.to_rgba(self._A, alpha=self._alpha, bytes=True)
A = self.to_rgba(self._A, bytes=True)
self._rgbacache = A
if self._A.ndim == 2:
self.is_grayscale = self.cmap.is_gray()
Expand All @@ -851,6 +852,7 @@ def draw(self, renderer, *args, **kwargs):
gc = renderer.new_gc()
gc.set_clip_rectangle(self.axes.bbox.frozen())
gc.set_clip_path(self.get_clip_path())
gc.set_alpha(self.get_alpha())
renderer.draw_image(gc,
round(self.axes.bbox.xmin),
round(self.axes.bbox.ymin),
Expand Down Expand Up @@ -974,7 +976,7 @@ def make_image(self, magnification=1.0):
if self._A is None:
raise RuntimeError('You must first set the image array')

x = self.to_rgba(self._A, self._alpha, bytes=True)
x = self.to_rgba(self._A, bytes=True)
self.magnification = magnification
# if magnification is not one, we need to resize
ismag = magnification!=1
Expand Down Expand Up @@ -1008,6 +1010,7 @@ def draw(self, renderer, *args, **kwargs):
gc = renderer.new_gc()
gc.set_clip_rectangle(self.figure.bbox)
gc.set_clip_path(self.get_clip_path())
gc.set_alpha(self.get_alpha())
renderer.draw_image(gc, round(self.ox), round(self.oy), im)
gc.restore()

Expand Down Expand Up @@ -1096,7 +1099,7 @@ def make_image(self, renderer, magnification=1.0):
im.is_grayscale = False
else:
if self._rgbacache is None:
x = self.to_rgba(self._A, self._alpha, bytes=True)
x = self.to_rgba(self._A, bytes=True)
self._rgbacache = x
else:
x = self._rgbacache
Expand Down Expand Up @@ -1148,6 +1151,7 @@ def draw(self, renderer, *args, **kwargs):
l, b, r, t = self.get_window_extent(renderer).extents
gc = renderer.new_gc()
self._set_gc_clip(gc)
gc.set_alpha(self.get_alpha())
#gc.set_clip_path(self.get_clip_path())
renderer.draw_image(gc, round(l), round(b), im)
gc.restore()
Expand Down
6 changes: 5 additions & 1 deletion src/_backend_agg.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -988,6 +988,7 @@ RendererAgg::draw_image(const Py::Tuple& args)
agg::trans_affine affine_trans;
bool has_affine = false;
double x, y, w, h;
double alpha;

if (args.size() == 7)
{
Expand All @@ -1006,6 +1007,8 @@ RendererAgg::draw_image(const Py::Tuple& args)
warnings from the compiler */
}

alpha = gc.alpha;

theRasterizer.reset_clipping();
rendererBase.reset_clipping(true);
set_clipbox(gc.cliprect, theRasterizer);
Expand Down Expand Up @@ -1097,7 +1100,8 @@ RendererAgg::draw_image(const Py::Tuple& args)
else
{
set_clipbox(gc.cliprect, rendererBase);
rendererBase.blend_from(pixf, 0, (int)x, (int)(height - (y + image->rowsOut)));
rendererBase.blend_from(
pixf, 0, (int)x, (int)(height - (y + image->rowsOut)), alpha * 255);
}

rendererBase.reset_clipping(true);
Expand Down
2 changes: 1 addition & 1 deletion src/_image.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,7 @@
#include "mplutils.h"


typedef agg::pixfmt_rgba32 pixfmt;
typedef agg::pixfmt_rgba32_pre pixfmt;
typedef agg::renderer_base<pixfmt> renderer_base;
typedef agg::span_interpolator_linear<> interpolator_type;
typedef agg::rasterizer_scanline_aa<agg::rasterizer_sl_clip_dbl> rasterizer;
Expand Down