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Attemp to fix wrong behaviour of VoronoiPolygon when buffer is specif…
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…ied (issue #18219(?), #8002(?), #13092)

(cherry-picked from 30f5983)
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@havatv @nyalldawson
havatv authored and nyalldawson committed Jul 31, 2018
1 parent 7349b1c commit 064eac0
Showing 1 changed file with 55 additions and 57 deletions.
112 changes: 55 additions & 57 deletions python/plugins/processing/algs/qgis/VoronoiPolygons.py
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Expand Up @@ -104,7 +104,12 @@ def processAlgorithm(self, parameters, context, feedback):
outFeat = QgsFeature()
extent = source.sourceExtent()
extraX = extent.width() * (buf / 100.0)
# Adjust the extent
extent.setXMinimum(extent.xMinimum() - extraX)
extent.setXMaximum(extent.xMaximum() + extraX)
extraY = extent.height() * (buf / 100.0)
extent.setYMinimum(extent.yMinimum() - extraY)
extent.setYMaximum(extent.yMaximum() + extraY)
height = extent.height()
width = extent.width()
c = voronoi.Context()
Expand Down Expand Up @@ -151,8 +156,7 @@ def processAlgorithm(self, parameters, context, feedback):

request = QgsFeatureRequest().setFilterFid(ptDict[ids[site]])
inFeat = next(source.getFeatures(request))
lines = self.clip_voronoi(
edges, c, width, height, extent, extraX, extraY)
lines = self.clip_voronoi(edges, c, width, height, extent)

geom = QgsGeometry.fromMultiPointXY(lines)
geom = QgsGeometry(geom.convexHull())
Expand All @@ -165,46 +169,46 @@ def processAlgorithm(self, parameters, context, feedback):

return {self.OUTPUT: dest_id}

def clip_voronoi(self, edges, c, width, height, extent, exX, exY):
def clip_voronoi(self, edges, c, width, height, extent):
"""Clip voronoi function based on code written for Inkscape.
Copyright (C) 2010 Alvin Penner, penner@vaxxine.com
"""

def clip_line(x1, y1, x2, y2, w, h, x, y):
if x1 < 0 - x and x2 < 0 - x:
def clip_line(x1, y1, x2, y2, w, h):
if x1 < 0 and x2 < 0:
return [0, 0, 0, 0]
if x1 > w + x and x2 > w + x:
if x1 > w and x2 > w:
return [0, 0, 0, 0]
if x1 < 0 - x:
if x1 < 0:
y1 = (y1 * x2 - y2 * x1) / (x2 - x1)
x1 = 0 - x
if x2 < 0 - x:
x1 = 0
if x2 < 0:
y2 = (y1 * x2 - y2 * x1) / (x2 - x1)
x2 = 0 - x
if x1 > w + x:
y1 = y1 + (w + x - x1) * (y2 - y1) / (x2 - x1)
x1 = w + x
if x2 > w + x:
y2 = y1 + (w + x - x1) * (y2 - y1) / (x2 - x1)
x2 = w + x
if y1 < 0 - y and y2 < 0 - y:
x2 = 0
if x1 > w:
y1 = y1 + (w - x1) * (y2 - y1) / (x2 - x1)
x1 = w
if x2 > w:
y2 = y1 + (w - x1) * (y2 - y1) / (x2 - x1)
x2 = w
if y1 < 0 and y2 < 0:
return [0, 0, 0, 0]
if y1 > h + y and y2 > h + y:
if y1 > h and y2 > h:
return [0, 0, 0, 0]
if x1 == x2 and y1 == y2:
return [0, 0, 0, 0]
if y1 < 0 - y:
if y1 < 0:
x1 = (x1 * y2 - x2 * y1) / (y2 - y1)
y1 = 0 - y
if y2 < 0 - y:
y1 = 0
if y2 < 0:
x2 = (x1 * y2 - x2 * y1) / (y2 - y1)
y2 = 0 - y
if y1 > h + y:
x1 = x1 + (h + y - y1) * (x2 - x1) / (y2 - y1)
y1 = h + y
if y2 > h + y:
x2 = x1 + (h + y - y1) * (x2 - x1) / (y2 - y1)
y2 = h + y
y2 = 0
if y1 > h:
x1 = x1 + (h - y1) * (x2 - x1) / (y2 - y1)
y1 = h
if y2 > h:
x2 = x1 + (h - y1) * (x2 - x1) / (y2 - y1)
y2 = h
return [x1, y1, x2, y2]

lines = []
Expand All @@ -221,44 +225,40 @@ def clip_line(x1, y1, x2, y2, w, h, x, y):
c.vertices[edge[2]][0],
c.vertices[edge[2]][1],
width,
height,
exX,
exY,
height
)
elif edge[1] >= 0:
# Only one vertex
if c.lines[edge[0]][1] == 0:
# Vertical line
xtemp = c.lines[edge[0]][2] / c.lines[edge[0]][0]
if c.vertices[edge[1]][1] > (height + exY) / 2:
ytemp = height + exY
if c.vertices[edge[1]][1] > height / 2:
ytemp = height
else:
ytemp = 0 - exX
ytemp = 0
else:
xtemp = width + exX
ytemp = (c.lines[edge[0]][2] - (width + exX) *
xtemp = width
ytemp = (c.lines[edge[0]][2] - width *
c.lines[edge[0]][0]) / c.lines[edge[0]][1]
[x1, y1, x2, y2] = clip_line(
c.vertices[edge[1]][0],
c.vertices[edge[1]][1],
xtemp,
ytemp,
width,
height,
exX,
exY,
height
)
elif edge[2] >= 0:
# Only one vertex
if c.lines[edge[0]][1] == 0:
# Vertical line
xtemp = c.lines[edge[0]][2] / c.lines[edge[0]][0]
if c.vertices[edge[2]][1] > (height + exY) / 2:
ytemp = height + exY
if c.vertices[edge[2]][1] > height / 2:
ytemp = height
else:
ytemp = 0.0 - exY
ytemp = 0.0
else:
xtemp = 0.0 - exX
xtemp = 0.0
ytemp = c.lines[edge[0]][2] / c.lines[edge[0]][1]
[x1, y1, x2, y2] = clip_line(
xtemp,
Expand All @@ -267,34 +267,32 @@ def clip_line(x1, y1, x2, y2, w, h, x, y):
c.vertices[edge[2]][1],
width,
height,
exX,
exY,
)
if x1 or x2 or y1 or y2:
lines.append(QgsPointXY(x1 + extent.xMinimum(),
y1 + extent.yMinimum()))
lines.append(QgsPointXY(x2 + extent.xMinimum(),
y2 + extent.yMinimum()))
if 0 - exX in (x1, x2):
if 0 in (x1, x2):
hasXMin = True
if 0 - exY in (y1, y2):
if 0 in (y1, y2):
hasYMin = True
if height + exY in (y1, y2):
if height in (y1, y2):
hasYMax = True
if width + exX in (x1, x2):
if width in (x1, x2):
hasXMax = True
if hasXMin:
if hasYMax:
lines.append(QgsPointXY(extent.xMinimum() - exX,
height + extent.yMinimum() + exY))
lines.append(QgsPointXY(extent.xMinimum(),
height + extent.yMinimum()))
if hasYMin:
lines.append(QgsPointXY(extent.xMinimum() - exX,
extent.yMinimum() - exY))
lines.append(QgsPointXY(extent.xMinimum(),
extent.yMinimum()))
if hasXMax:
if hasYMax:
lines.append(QgsPointXY(width + extent.xMinimum() + exX,
height + extent.yMinimum() + exY))
lines.append(QgsPointXY(width + extent.xMinimum(),
height + extent.yMinimum()))
if hasYMin:
lines.append(QgsPointXY(width + extent.xMinimum() + exX,
extent.yMinimum() - exY))
lines.append(QgsPointXY(width + extent.xMinimum(),
extent.yMinimum()))
return lines

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