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Fix white gap between image and border #219

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Merged
cfarrow merged 3 commits into from
Oct 2, 2014
Merged

Fix white gap between image and border #219

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5354a30
FIX: remove white hemi-border from image plots.
Sep 30, 2014
0557606
Updating CHANGES.txt
Sep 30, 2014
5d2bd65
Correcting unnecessary size increase.
Oct 1, 2014
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1 change: 1 addition & 0 deletions CHANGES.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ Fixes
* Resume running test for empty container that has been skipped (PR#190).
* Improved handling of missing or empty data in scatterplot (PR#210)
* Avoid a numpy crash when using a data source of a unicode array (PR#213).
* Fix white gap between image border and image (PR#219).

Release 4.4.1
-------------
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13 changes: 9 additions & 4 deletions chaco/image_plot.py
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Expand Up @@ -36,7 +36,7 @@ class ImagePlot(Base2DPlot):

# The interpolation method to use when rendering an image onto the GC.
interpolation = Enum("nearest", "bilinear", "bicubic")

#------------------------------------------------------------------------
# Private traits
#------------------------------------------------------------------------
Expand Down Expand Up @@ -129,7 +129,7 @@ def _compute_cached_image(self, data=None, mapper=None):

The parameter *data* is for subclasses that might not store an RGB(A)
image as the value, but need to compute one to display (colormaps, etc.).

The parameter *mapper* is also for subclasses that might not store an
RGB(A) image as their value, and gives an opportunity to produce the
values only for the visible region, rather than for the whole plot,
Expand All @@ -149,6 +149,11 @@ def _compute_cached_image(self, data=None, mapper=None):
virtual_width = ur_x - ll_x
virtual_height = ur_y - ll_y

# Convert to the coordinates of the graphics context, which expects
# origin to be at the center of a pixel.
ll_x += 0.5
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@itziakos itziakos Oct 1, 2014

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Is this true for all GraphicsContexts?

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@cfarrow cfarrow Oct 1, 2014

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Empirically, it is true for the GraphicsContextArray. I rooted around the kiva source code to find a definitive answer, but gave up.

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@rkern rkern Oct 1, 2014

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You will need to try other GCs to be sure that this is the right place to do this adjustment. The different backends can behave differently, albeit unintentionally. We have been fighting these off-by-(one/half) issues for a long time.

ll_y += 0.5

args = self.position \
+ self.bounds \
+ [ll_x, ll_y, virtual_width, virtual_height]
Expand All @@ -172,7 +177,7 @@ def _compute_cached_image(self, data=None, mapper=None):

# Since data is row-major, j1 and j2 go first
data = data[j1:j2, i1:i2]

if mapper is not None:
data = mapper(data)

Expand Down Expand Up @@ -327,4 +332,4 @@ def _index_mapper_changed_fired(self):
def _value_data_changed_fired(self):
self._image_cache_valid = False
self.request_redraw()