def calc_scale(bbox, map_renderer):
coord_transform = QgsCoordinateTransform(
QgsCoordinateReferenceSystem(4326),
QgsCoordinateReferenceSystem(27700)
)
# As we are using the QgsScaleCalculator to determine the scale we need to
# create a standard bounding box to calculate the scale for the width and a
# bounding box on it's side to calculate the scale to fit the height
width_bbox = coord_transform.transform(QgsRectangle(bbox[0], bbox[1], bbox[2], bbox[3]))
height_bbox = coord_transform.transform(QgsRectangle(bbox[1], bbox[0], bbox[3], bbox[2]))
scale_calc = QgsScaleCalculator(map_renderer.outputDpi())
scale = max(
scale_calc.calculate(width_bbox, map_renderer.width()),
scale_calc.calculate(height_bbox, map_renderer.height())
)
return scale * 1.1
def testCalculateImageSize(self):
calculator = QgsScaleCalculator()
calculator.setDpi(96)
calculator.setMapUnits(QgsUnitTypes.DistanceMeters)
extent = QgsRectangle(336609, 1162304, 354942, 1168151)
image_size = calculator.calculateImageSize(extent, 65000)
self.assertAlmostEqual(image_size.width(), 1066.001, 3)
self.assertAlmostEqual(image_size.height(), 339.983, 3)
def identify(self, params):
self.check_required_params(params)
feature_collections = []
with change_directory(self.project_root):
crs = QgsCoordinateReferenceSystem()
crs.createFromSrid(params.get('srs'))
search_box = self._calcSearchBox(
params.get('bbox'), params.get('image_size')[0],
params.get('image_size')[1],
params.get('click_point')[0], params.get('click_point')[1]
)
# initialize mapRenderer and a rendering context in order to be
# to check if a feature will actually be rendered
# we don't want to return features that are not visible
img = QImage(QSize(
settings.SUNLUMO_GFI_BUFFER*2, settings.SUNLUMO_GFI_BUFFER*2),
QImage.Format_ARGB32_Premultiplied
)
dpm = 1 / 0.00028
img.setDotsPerMeterX(dpm)
img.setDotsPerMeterY(dpm)
mapRenderer = QgsMapRenderer()
mapRenderer.clearLayerCoordinateTransforms()
mapRenderer.setOutputSize(QSize(
settings.SUNLUMO_GFI_BUFFER*2, settings.SUNLUMO_GFI_BUFFER*2),
img.logicalDpiX()
)
mapRenderer.setDestinationCrs(crs)
mapRenderer.setProjectionsEnabled(True)
mapUnits = crs.mapUnits()
mapRenderer.setMapUnits(mapUnits)
mapExtent = QgsRectangle(*search_box)
mapRenderer.setExtent(mapExtent)
renderContext = QgsRenderContext()
renderContext.setExtent(mapRenderer.extent())
renderContext.setRasterScaleFactor(1.0)
renderContext.setMapToPixel(mapRenderer.coordinateTransform())
renderContext.setRendererScale(mapRenderer.scale())
renderContext.setScaleFactor(mapRenderer.outputDpi() / 25.4)
renderContext.setPainter(None)
qfr = QgsFeatureRequest()
search_rectangle = QgsRectangle(*search_box)
qfr.setFilterRect(search_rectangle)
for q_layer in params.get('query_layers'):
layer = self.layerRegistry.mapLayer(q_layer)
if layer.type() == QgsMapLayer.RasterLayer:
# skip raster layer processing
continue
# update layer fields (expressions, calculated, joined)
layer.updateFields()
scaleCalc = QgsScaleCalculator(
(img.logicalDpiX() + img.logicalDpiY()) / 2,
mapRenderer.destinationCrs().mapUnits()
)
scaleDenom = scaleCalc.calculate(mapExtent, img.width())
# skip the layer if it's not visible at the current map scale
if layer.hasScaleBasedVisibility():
if not(layer.minimumScale()
< scaleDenom < layer.maximumScale()):
continue
# check if features actually intersect search rectangle
intersected_features = self._intersectedFeatures(
layer.getFeatures(qfr), search_rectangle
)
# visible features generator
visible_features = self._visibleFeatures(
layer, renderContext, intersected_features
)
layer_features = [featureToGeoJSON(
feature.id(), feature.geometry(),
self._collectAttributes(layer, feature)
) for feature in visible_features
]
feature_collections.append(layer_features)
return writeGeoJSON(chain(*feature_collections))
