Equilateral Triangle ROI (#1581)

* feature TriangleROI

Added equilateral  TriangleROI.
getArrayRegion is not working yet

* show off (and implicitly test) our new TriangleROI

* the PolyLineROI.getArrayRegion can be used by TriangleROI

refactor the actual logic to live on ROI

* refactors for readability

* variable names
* lint
* docstring type and purpose

Co-authored-by: Fekete Imre <feketeimre87@gmail.com>

examples/ROIExamples.py

@@ -58,6 +58,7 @@ rois = []
 rois.append(pg.RectROI([20, 20], [20, 20], pen=(0,9)))
 rois[-1].addRotateHandle([1,0], [0.5, 0.5])
 rois.append(pg.LineROI([0, 60], [20, 80], width=5, pen=(1,9)))
+rois.append(pg.TriangleROI([80, 75], 20, pen=(5, 9)))
 rois.append(pg.MultiRectROI([[20, 90], [50, 60], [60, 90]], width=5, pen=(2,9)))
 rois.append(pg.EllipseROI([60, 10], [30, 20], pen=(3,9)))
 rois.append(pg.CircleROI([80, 50], [20, 20], pen=(4,9)))

pyqtgraph/graphicsItems/ROI.py

@@ -30,7 +30,7 @@ __all__ = [
     'ROI', 
     'TestROI', 'RectROI', 'EllipseROI', 'CircleROI', 'PolygonROI', 
     'LineROI', 'MultiLineROI', 'MultiRectROI', 'LineSegmentROI', 'PolyLineROI', 
-    'CrosshairROI',
+    'CrosshairROI','TriangleROI'
 ]
 
 
@@ -1182,6 +1182,35 @@ class ROI(GraphicsObject):
             mapped = fn.transformCoordinates(img.transform(), coords)
             return result, mapped
 
+    def _getArrayRegionForArbitraryShape(self, data, img, axes=(0,1), **kwds):
+        """
+        Return the result of :meth:`~pyqtgraph.ROI.getArrayRegion`, masked by
+        the shape of the ROI. Values outside the ROI shape are set to 0.
+
+        See :meth:`~pyqtgraph.ROI.getArrayRegion` for a description of the
+        arguments.
+
+        Note: ``returnMappedCoords`` is not yet supported for this ROI type.
+        """
+        br = self.boundingRect()
+        if br.width() > 1000:
+            raise Exception()
+        sliced = ROI.getArrayRegion(self, data, img, axes=axes, fromBoundingRect=True, **kwds)
+
+        if img.axisOrder == "col-major":
+            mask = self.renderShapeMask(sliced.shape[axes[0]], sliced.shape[axes[1]])
+        else:
+            mask = self.renderShapeMask(sliced.shape[axes[1]], sliced.shape[axes[0]])
+            mask = mask.T
+
+        # reshape mask to ensure it is applied to the correct data axes
+        shape = [1] * data.ndim
+        shape[axes[0]] = sliced.shape[axes[0]]
+        shape[axes[1]] = sliced.shape[axes[1]]
+        mask = mask.reshape(shape)
+
+        return sliced * mask
+
     def getAffineSliceParams(self, data, img, axes=(0,1), fromBoundingRect=False):
         """
         Returns the parameters needed to use :func:`affineSlice <pyqtgraph.affineSlice>`
@@ -2102,34 +2131,8 @@ class PolyLineROI(ROI):
         p.lineTo(self.handles[0]['item'].pos())
         return p
 
-    def getArrayRegion(self, data, img, axes=(0,1), **kwds):
-        """
-        Return the result of :meth:`~pyqtgraph.ROI.getArrayRegion`, masked by
-        the shape of the ROI. Values outside the ROI shape are set to 0.
-
-        See :meth:`~pyqtgraph.ROI.getArrayRegion` for a description of the
-        arguments.
-
-        Note: ``returnMappedCoords`` is not yet supported for this ROI type.
-        """
-        br = self.boundingRect()
-        if br.width() > 1000:
-            raise Exception()
-        sliced = ROI.getArrayRegion(self, data, img, axes=axes, fromBoundingRect=True, **kwds)
-        
-        if img.axisOrder == 'col-major':
-            mask = self.renderShapeMask(sliced.shape[axes[0]], sliced.shape[axes[1]])
-        else:
-            mask = self.renderShapeMask(sliced.shape[axes[1]], sliced.shape[axes[0]])
-            mask = mask.T
-            
-        # reshape mask to ensure it is applied to the correct data axes
-        shape = [1] * data.ndim
-        shape[axes[0]] = sliced.shape[axes[0]]
-        shape[axes[1]] = sliced.shape[axes[1]]
-        mask = mask.reshape(shape)
-
-        return sliced * mask
+    def getArrayRegion(self, *args, **kwds):
+        return self._getArrayRegionForArbitraryShape(*args, **kwds)
 
     def setPen(self, *args, **kwds):
         ROI.setPen(self, *args, **kwds)
@@ -2344,3 +2347,44 @@ class RulerROI(LineSegmentROI):
             return r
         pxw = 50 * pxl
         return r.adjusted(-50, -50, 50, 50)
+
+
+class TriangleROI(ROI):
+    """
+    Equilateral triangle ROI subclass with one scale handle and one rotation handle.
+    Arguments
+    pos            (length-2 sequence) The position of the ROI's origin.
+    size           (float) The length of an edge of the triangle.
+    \**args        All extra keyword arguments are passed to ROI()
+    ============== =============================================================
+    """
+
+    def __init__(self, pos, size, **args):
+        ROI.__init__(self, pos, [size, size], **args)
+        self.aspectLocked = True
+        angles = np.linspace(0, np.pi * 4 / 3, 3)
+        verticies = (np.array((np.sin(angles), np.cos(angles))).T + 1.0) / 2.0
+        self.poly = QtGui.QPolygonF()
+        for pt in verticies:
+            self.poly.append(QtCore.QPointF(*pt))
+        self.addRotateHandle(verticies[0], [0.5, 0.5])
+        self.addScaleHandle(verticies[1], [0.5, 0.5])
+
+    def paint(self, p, *args):
+        r = self.boundingRect()
+        p.setRenderHint(QtGui.QPainter.Antialiasing)
+        p.scale(r.width(), r.height())
+        p.setPen(self.currentPen)
+        p.drawPolygon(self.poly)
+
+    def shape(self):
+        self.path = QtGui.QPainterPath()
+        r = self.boundingRect()
+        # scale the path to match whats on the screen
+        t = QtGui.QTransform()
+        t.scale(r.width(), r.height())
+        self.path.addPolygon(self.poly)
+        return t.map(self.path)
+
+    def getArrayRegion(self, *args, **kwds):
+        return self._getArrayRegionForArbitraryShape(*args, **kwds)