Nicer legend (#958)

* More customizable and nicer legend.

- Give kwargs for legend frame and background colors instead of hard-coded values.
- Reduce spacing for more compact legend
- Give separate kwarg `labelTextColor`.
- New method to clear all legend items.
- New methods to get and change `offset` relative to the legend's parent.
- Horizontal instead of tilted lines for legend pictures.

pyqtgraph/graphicsItems/LegendItem.py

@@ -8,6 +8,7 @@ from .PlotDataItem import PlotDataItem
 from .GraphicsWidgetAnchor import GraphicsWidgetAnchor
 __all__ = ['LegendItem']
 
+
 class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
     """
     Displays a legend used for describing the contents of a plot.
@@ -19,18 +20,28 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
         legend.setParentItem(plotItem)
 
     """
-    def __init__(self, size=None, offset=None):
+    def __init__(self, size=None, offset=None, horSpacing=25, verSpacing=0, pen=None,
+                 brush=None, labelTextColor=None, **kwargs):
         """
         ==============  ===============================================================
         **Arguments:**
         size            Specifies the fixed size (width, height) of the legend. If
-                        this argument is omitted, the legend will autimatically resize
+                        this argument is omitted, the legend will automatically resize
                         to fit its contents.
         offset          Specifies the offset position relative to the legend's parent.
                         Positive values offset from the left or top; negative values
                         offset from the right or bottom. If offset is None, the
                         legend must be anchored manually by calling anchor() or
                         positioned by calling setPos().
+        horSpacing      Specifies the spacing between the line symbol and the label.
+        verSpacing      Specifies the spacing between individual entries of the legend
+                        vertically. (Can also be negative to have them really close)
+        pen             Pen to use when drawing legend border. Any single argument
+                        accepted by :func:`mkPen <pyqtgraph.mkPen>` is allowed.
+        brush           QBrush to use as legend background filling. Any single argument
+                        accepted by :func:`mkBrush <pyqtgraph.mkBrush>` is allowed.
+        labelTextColor  Pen to use when drawing legend text. Any single argument
+                        accepted by :func:`mkPen <pyqtgraph.mkPen>` is allowed.
         ==============  ===============================================================
 
         """
@@ -40,17 +51,80 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
         GraphicsWidgetAnchor.__init__(self)
         self.setFlag(self.ItemIgnoresTransformations)
         self.layout = QtGui.QGraphicsGridLayout()
+        self.layout.setVerticalSpacing(verSpacing)
+        self.layout.setHorizontalSpacing(horSpacing)
+
         self.setLayout(self.layout)
         self.items = []
         self.size = size
-        self.offset = offset
         if size is not None:
             self.setGeometry(QtCore.QRectF(0, 0, self.size[0], self.size[1]))
 
+        self.opts = {
+            'pen': fn.mkPen(pen),
+            'brush': fn.mkBrush(brush),
+            'labelTextColor': labelTextColor,
+            'offset': offset,
+        }
+
+        self.opts.update(kwargs)
+
+    def offset(self):
+        return self.opts['offset']
+
+    def setOffset(self, offset):
+        self.opts['offset'] = offset
+
+        offset = Point(self.opts['offset'])
+        anchorx = 1 if offset[0] <= 0 else 0
+        anchory = 1 if offset[1] <= 0 else 0
+        anchor = (anchorx, anchory)
+        self.anchor(itemPos=anchor, parentPos=anchor, offset=offset)
+
+    def pen(self):
+        return self.opts['pen']
+
+    def setPen(self, *args, **kargs):
+        """
+        Sets the pen used to draw lines between points.
+        *pen* can be a QPen or any argument accepted by
+        :func:`pyqtgraph.mkPen() <pyqtgraph.mkPen>`
+        """
+        pen = fn.mkPen(*args, **kargs)
+        self.opts['pen'] = pen
+
+        self.paint()
+
+    def brush(self):
+        return self.opts['brush']
+
+    def setBrush(self, *args, **kargs):
+        brush = fn.mkBrush(*args, **kargs)
+        if self.opts['brush'] == brush:
+            return
+        self.opts['brush'] = brush
+
+        self.paint()
+
+    def labelTextColor(self):
+        return self.opts['labelTextColor']
+
+    def setLabelTextColor(self, *args, **kargs):
+        """
+        Sets the color of the label text.
+        *pen* can be a QPen or any argument accepted by
+        :func:`pyqtgraph.mkColor() <pyqtgraph.mkPen>`
+        """
+        self.opts['labelTextColor'] = fn.mkColor(*args, **kargs)
+        for sample, label in self.items:
+            label.setAttr('color', self.opts['labelTextColor'])
+
+        self.paint()
+
     def setParentItem(self, p):
         ret = GraphicsWidget.setParentItem(self, p)
         if self.offset is not None:
-            offset = Point(self.offset)
+            offset = Point(self.opts['offset'])
             anchorx = 1 if offset[0] <= 0 else 0
             anchory = 1 if offset[1] <= 0 else 0
             anchor = (anchorx, anchory)
@@ -70,11 +144,12 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
         title           The title to display for this item. Simple HTML allowed.
         ==============  ========================================================
         """
-        label = LabelItem(name)
+        label = LabelItem(name, color=self.opts['labelTextColor'], justify='left')
         if isinstance(item, ItemSample):
             sample = item
         else:
             sample = ItemSample(item)
+
         row = self.layout.rowCount()
         self.items.append((sample, label))
         self.layout.addItem(sample, row, 0)
@@ -90,16 +165,24 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
         item            The item to remove or its name.
         ==============  ========================================================
         """
-        # Thanks, Ulrich!
-        # cycle for a match
         for sample, label in self.items:
             if sample.item is item or label.text == item:
-                self.items.remove( (sample, label) )    # remove from itemlist
+                self.items.remove((sample, label))      # remove from itemlist
                 self.layout.removeItem(sample)          # remove from layout
                 sample.close()                          # remove from drawing
                 self.layout.removeItem(label)
                 label.close()
                 self.updateSize()                       # redraq box
+                return                                  # return after first match
+
+    def clear(self):
+        """Removes all items from legend."""
+        for sample, label in self.items:
+            self.layout.removeItem(sample)
+            self.layout.removeItem(label)
+
+        self.items = []
+        self.updateSize()
 
     def clear(self):
         """
@@ -114,23 +197,14 @@ class LegendItem(GraphicsWidget, GraphicsWidgetAnchor):
         if self.size is not None:
             return
 
-        height = 0
+        self.setGeometry(0, 0, 0, 0)
-        width = 0
-        #print("-------")
-        for sample, label in self.items:
-            height += max(sample.height(), label.height()) + 3
-            width = max(width, (sample.sizeHint(QtCore.Qt.MinimumSize, sample.size()).width() +
-                                label.sizeHint(QtCore.Qt.MinimumSize, label.size()).width()))
-            #print(width, height)
-        #print width, height
-        self.setGeometry(0, 0, width+25, height)
 
     def boundingRect(self):
         return QtCore.QRectF(0, 0, self.width(), self.height())
 
     def paint(self, p, *args):
-        p.setPen(fn.mkPen(255,255,255,100))
+        p.setPen(self.opts['pen'])
-        p.setBrush(fn.mkBrush(100,100,100,50))
+        p.setBrush(self.opts['brush'])
         p.drawRect(self.boundingRect())
 
     def hoverEvent(self, ev):
@@ -157,17 +231,14 @@ class ItemSample(GraphicsWidget):
         return QtCore.QRectF(0, 0, 20, 20)
 
     def paint(self, p, *args):
-        #p.setRenderHint(p.Antialiasing)  # only if the data is antialiased.
         opts = self.item.opts
 
-        if opts.get('fillLevel',None) is not None and opts.get('fillBrush',None) is not None:
+        if opts['antialias']:
-            p.setBrush(fn.mkBrush(opts['fillBrush']))
+            p.setRenderHint(p.Antialiasing)
-            p.setPen(fn.mkPen(None))
-            p.drawPolygon(QtGui.QPolygonF([QtCore.QPointF(2,18), QtCore.QPointF(18,2), QtCore.QPointF(18,18)]))
 
         if not isinstance(self.item, ScatterPlotItem):
             p.setPen(fn.mkPen(opts['pen']))
-            p.drawLine(2, 18, 18, 2)
+            p.drawLine(0, 11, 20, 11)
 
         symbol = opts.get('symbol', None)
         if symbol is not None:
@@ -178,7 +249,7 @@ class ItemSample(GraphicsWidget):
             brush = fn.mkBrush(opts['brush'])
             size = opts['size']
 
-            p.translate(10,10)
+            p.translate(10, 10)
             path = drawSymbol(p, symbol, size, pen, brush)