Merge pull request #543 from acq4/target

Add targetitem class

pyqtgraph/graphicsItems/TargetItem.py

@@ -0,0 +1,125 @@
+from ..Qt import QtGui, QtCore
+import numpy as np
+from ..Point import Point
+from .. import functions as fn
+from .GraphicsObject import GraphicsObject
+from .TextItem import TextItem
+
+
+class TargetItem(GraphicsObject):
+    """Draws a draggable target symbol (circle plus crosshair).
+
+    The size of TargetItem will remain fixed on screen even as the view is zoomed.
+    Includes an optional text label.
+    """
+    sigDragged = QtCore.Signal(object)
+
+    def __init__(self, movable=True, radii=(5, 10, 10), pen=(255, 255, 0), brush=(0, 0, 255, 100)):
+        GraphicsObject.__init__(self)
+        self._bounds = None
+        self._radii = radii
+        self._picture = None
+        self.movable = movable
+        self.moving = False
+        self.label = None
+        self.labelAngle = 0
+        self.pen = fn.mkPen(pen)
+        self.brush = fn.mkBrush(brush)
+
+    def setLabel(self, label):
+        if label is None:
+            if self.label is not None:
+                self.label.scene().removeItem(self.label)
+                self.label = None
+        else:
+            if self.label is None:
+                self.label = TextItem()
+                self.label.setParentItem(self)
+            self.label.setText(label)
+            self._updateLabel()
+
+    def setLabelAngle(self, angle):
+        self.labelAngle = angle
+        self._updateLabel()
+
+    def boundingRect(self):
+        if self._picture is None:
+            self._drawPicture()
+        return self._bounds
+    
+    def dataBounds(self, axis, frac=1.0, orthoRange=None):
+        return [0, 0]
+
+    def viewTransformChanged(self):
+        self._picture = None
+        self.prepareGeometryChange()
+        self._updateLabel()
+
+    def _updateLabel(self):
+        if self.label is None:
+            return
+
+        # find an optimal location for text at the given angle
+        angle = self.labelAngle * np.pi / 180.
+        lbr = self.label.boundingRect()
+        center = lbr.center()
+        a = abs(np.sin(angle) * lbr.height()*0.5)
+        b = abs(np.cos(angle) * lbr.width()*0.5)
+        r = max(self._radii) + 2 + max(a, b)
+        pos = self.mapFromScene(self.mapToScene(QtCore.QPointF(0, 0)) + r * QtCore.QPointF(np.cos(angle), -np.sin(angle)) - center)
+        self.label.setPos(pos)
+
+    def paint(self, p, *args):
+        if self._picture is None:
+            self._drawPicture()
+        self._picture.play(p)
+
+    def _drawPicture(self):
+        self._picture = QtGui.QPicture()
+        p = QtGui.QPainter(self._picture)
+        p.setRenderHint(p.Antialiasing)
+        
+        # Note: could do this with self.pixelLength, but this is faster.
+        o = self.mapToScene(QtCore.QPointF(0, 0))
+        px = abs(1.0 / (self.mapToScene(QtCore.QPointF(1, 0)) - o).x())
+        py = abs(1.0 / (self.mapToScene(QtCore.QPointF(0, 1)) - o).y())
+        
+        r, w, h = self._radii
+        w = w * px
+        h = h * py
+        rx = r * px
+        ry = r * py
+        rect = QtCore.QRectF(-rx, -ry, rx*2, ry*2)
+        p.setPen(self.pen)
+        p.setBrush(self.brush)
+        p.drawEllipse(rect)
+        p.drawLine(Point(-w, 0), Point(w, 0))
+        p.drawLine(Point(0, -h), Point(0, h))
+        p.end()
+        
+        bx = max(w, rx)
+        by = max(h, ry)
+        self._bounds = QtCore.QRectF(-bx, -by, bx*2, by*2)
+
+    def mouseDragEvent(self, ev):
+        if not self.movable:
+            return
+        if ev.button() == QtCore.Qt.LeftButton:
+            if ev.isStart():
+                self.moving = True
+                self.cursorOffset = self.pos() - self.mapToParent(ev.buttonDownPos())
+                self.startPosition = self.pos()
+            ev.accept()
+            
+            if not self.moving:
+                return
+                
+            self.setPos(self.cursorOffset + self.mapToParent(ev.pos()))
+            if ev.isFinish():
+                self.moving = False
+                self.sigDragged.emit(self)
+
+    def hoverEvent(self, ev):
+        if self.movable:
+            ev.acceptDrags(QtCore.Qt.LeftButton)
+