Merge branch 'scanwidget' (closes #128)

* scanwidget:
  gui: fix scanwidget usage
  scanwidget: apply changes as of 10439cb
  scanwidget: apply changes as of 98f0a56
  missing parts of 59ac567
  scanwidget: disable unmodified wheel on axis and slider
  scanwidget: wire up signals better, set values late, take scanwidget from 7aa6397
  gui: use scanwidget
  scanwidget: add from current git

artiq/gui/entries.py

@@ -4,6 +4,8 @@ from collections import OrderedDict
 from PyQt5 import QtCore, QtGui, QtWidgets
 
 from artiq.gui.tools import LayoutWidget, disable_scroll_wheel
+from artiq.gui.scanwidget import ScanWidget
+from artiq.gui.scientific_spinbox import ScientificSpinBox
 
 
 logger = logging.getLogger(__name__)
@@ -136,6 +138,7 @@ class _RangeScan(LayoutWidget):
         LayoutWidget.__init__(self)
 
         scale = procdesc["scale"]
+
         def apply_properties(spinbox):
             spinbox.setDecimals(procdesc["ndecimals"])
             if procdesc["global_min"] is not None:
@@ -151,37 +154,56 @@ class _RangeScan(LayoutWidget):
             if procdesc["unit"]:
                 spinbox.setSuffix(" " + procdesc["unit"])
 
-        self.addWidget(QtWidgets.QLabel("Min:"), 0, 0)
+        self.scanner = scanner = ScanWidget()
-        self.min = QtWidgets.QDoubleSpinBox()
+        scanner.setMinimumSize(150, 0)
+        scanner.setSizePolicy(QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Preferred, QtWidgets.QSizePolicy.Fixed))
+        disable_scroll_wheel(scanner.axis)
+        disable_scroll_wheel(scanner.slider)
+        self.addWidget(scanner, 0, 0, -1, 1)
+
+        self.min = ScientificSpinBox()
+        self.min.setStyleSheet("QDoubleSpinBox {color:blue}")
+        self.min.setMinimumSize(110, 0)
+        self.min.setSizePolicy(QtWidgets.QSizePolicy(
+            QtWidgets.QSizePolicy.Fixed, QtWidgets.QSizePolicy.Fixed))
         disable_scroll_wheel(self.min)
-        apply_properties(self.min)
         self.addWidget(self.min, 0, 1)
 
-        self.addWidget(QtWidgets.QLabel("Max:"), 1, 0)
-        self.max = QtWidgets.QDoubleSpinBox()
-        disable_scroll_wheel(self.max)
-        apply_properties(self.max)
-        self.addWidget(self.max, 1, 1)
-
-        self.addWidget(QtWidgets.QLabel("#Points:"), 2, 0)
         self.npoints = QtWidgets.QSpinBox()
+        self.npoints.setMinimum(1)
         disable_scroll_wheel(self.npoints)
-        self.npoints.setMinimum(2)
+        self.addWidget(self.npoints, 1, 1)
-        self.npoints.setValue(10)
+
-        self.addWidget(self.npoints, 2, 1)
+        self.max = ScientificSpinBox()
+        self.max.setStyleSheet("QDoubleSpinBox {color:red}")
+        self.max.setMinimumSize(110, 0)
+        disable_scroll_wheel(self.max)
+        self.addWidget(self.max, 2, 1)
 
-        self.min.setValue(state["min"]/scale)
-        self.max.setValue(state["max"]/scale)
-        self.npoints.setValue(state["npoints"])
         def update_min(value):
             state["min"] = value*scale
+            scanner.setStart(value)
+
         def update_max(value):
-            state["min"] = value*scale
+            state["max"] = value*scale
+            scanner.setStop(value)
+
         def update_npoints(value):
             state["npoints"] = value
+            scanner.setNumPoints(value)
+
+        scanner.sigStartMoved.connect(self.min.setValue)
+        scanner.sigNumChanged.connect(self.npoints.setValue)
+        scanner.sigStopMoved.connect(self.max.setValue)
         self.min.valueChanged.connect(update_min)
-        self.max.valueChanged.connect(update_max)
         self.npoints.valueChanged.connect(update_npoints)
+        self.max.valueChanged.connect(update_max)
+        self.min.setValue(state["min"]/scale)
+        self.npoints.setValue(state["npoints"])
+        self.max.setValue(state["max"]/scale)
+        apply_properties(self.min)
+        apply_properties(self.max)
 
 
 class _ExplicitScan(LayoutWidget):

artiq/gui/scanwidget.py

@@ -0,0 +1,557 @@
+import logging
+
+from PyQt5 import QtGui, QtCore, QtWidgets
+from numpy import linspace
+
+from .ticker import Ticker
+
+
+logger = logging.getLogger(__name__)
+
+
+class ScanAxis(QtWidgets.QWidget):
+    sigZoom = QtCore.pyqtSignal(float, int)
+    sigPoints = QtCore.pyqtSignal(int)
+
+    def __init__(self, zoomFactor):
+        QtWidgets.QWidget.__init__(self)
+        self.proxy = None
+        self.sizePolicy().setControlType(QtWidgets.QSizePolicy.ButtonBox)
+        self.ticker = Ticker()
+        self.zoomFactor = zoomFactor
+
+    def paintEvent(self, ev):
+        painter = QtGui.QPainter(self)
+        font = painter.font()
+        avgCharWidth = QtGui.QFontMetrics(font).averageCharWidth()
+        painter.setRenderHint(QtGui.QPainter.Antialiasing)
+        # The center of the slider handles should reflect what's displayed
+        # on the spinboxes.
+        painter.translate(self.proxy.slider.handleWidth()/2, self.height() - 5)
+        painter.drawLine(0, 0, self.width(), 0)
+        realLeft = self.proxy.pixelToReal(0)
+        realRight = self.proxy.pixelToReal(self.width())
+        ticks, prefix, labels = self.ticker(realLeft, realRight)
+        painter.drawText(0, -25, prefix)
+
+        pen = QtGui.QPen()
+        pen.setWidth(2)
+        painter.setPen(pen)
+
+        for t, l in zip(ticks, labels):
+            t = self.proxy.realToPixel(t)
+            painter.drawLine(t, 0, t, -5)
+            painter.drawText(t - len(l)/2*avgCharWidth, -10, l)
+
+        sliderStartPixel = self.proxy.realToPixel(self.proxy.realStart)
+        sliderStopPixel = self.proxy.realToPixel(self.proxy.realStop)
+        pixels = linspace(sliderStartPixel, sliderStopPixel,
+                          self.proxy.numPoints)
+        for p in pixels:
+            p_int = int(p)
+            painter.drawLine(p_int, 0, p_int, 5)
+        ev.accept()
+
+    def wheelEvent(self, ev):
+        y = ev.angleDelta().y()
+        if y:
+            if ev.modifiers() & QtCore.Qt.ShiftModifier:
+                # If shift+scroll, modify number of points.
+                # TODO: This is not perfect. For high-resolution touchpads you
+                # get many small events with y < 120 which should accumulate.
+                # That would also match the wheel behavior of an integer
+                # spinbox.
+                z = int(y / 120.)
+                self.sigPoints.emit(z)
+            else:
+                z = self.zoomFactor**(y / 120.)
+                # Remove the slider-handle shift correction, b/c none of the
+                # other widgets know about it. If we have the mouse directly
+                # over a tick during a zoom, it should appear as if we are
+                # doing zoom relative to the ticks which live in axis
+                # pixel-space, not slider pixel-space.
+                self.sigZoom.emit(
+                    z, ev.x() - self.proxy.slider.handleWidth()/2)
+            self.update()
+        ev.accept()
+
+    def eventFilter(self, obj, ev):
+        if obj is not self.proxy.slider:
+            return False
+        if ev.type() != QtCore.QEvent.Wheel:
+            return False
+        self.wheelEvent(ev)
+        return True
+
+
+# Basic ideas from https://gist.github.com/Riateche/27e36977f7d5ea72cf4f
+class ScanSlider(QtWidgets.QSlider):
+    sigStartMoved = QtCore.pyqtSignal(int)
+    sigStopMoved = QtCore.pyqtSignal(int)
+
+    def __init__(self):
+        QtWidgets.QSlider.__init__(self, QtCore.Qt.Horizontal)
+        self.startPos = 0  # Pos and Val can differ in event handling.
+        # perhaps prevPos and currPos is more accurate.
+        self.stopPos = 99
+        self.startVal = 0  # lower
+        self.stopVal = 99  # upper
+        self.offset = 0
+        self.position = 0
+        self.upperPressed = QtWidgets.QStyle.SC_None
+        self.lowerPressed = QtWidgets.QStyle.SC_None
+        self.firstMovement = False  # State var for handling slider overlap.
+        self.blockTracking = False
+
+        # We need fake sliders to keep around so that we can dynamically
+        # set the stylesheets for drawing each slider later. See paintEvent.
+        self.dummyStartSlider = QtWidgets.QSlider()
+        self.dummyStopSlider = QtWidgets.QSlider()
+        self.dummyStartSlider.setStyleSheet(
+            "QSlider::handle {background:blue}")
+        self.dummyStopSlider.setStyleSheet(
+            "QSlider::handle {background:red}")
+
+    # We basically superimpose two QSliders on top of each other, discarding
+    # the state that remains constant between the two when drawing.
+    # Everything except the handles remain constant.
+    def initHandleStyleOption(self, opt, handle):
+        self.initStyleOption(opt)
+        if handle == "start":
+            opt.sliderPosition = self.startPos
+            opt.sliderValue = self.startVal
+        elif handle == "stop":
+            opt.sliderPosition = self.stopPos
+            opt.sliderValue = self.stopVal
+
+    # We get the range of each slider separately.
+    def pixelPosToRangeValue(self, pos):
+        opt = QtWidgets.QStyleOptionSlider()
+        self.initStyleOption(opt)
+        gr = self.style().subControlRect(QtWidgets.QStyle.CC_Slider, opt,
+                                         QtWidgets.QStyle.SC_SliderGroove,
+                                         self)
+        rangeVal = QtWidgets.QStyle.sliderValueFromPosition(
+            self.minimum(), self.maximum(), pos - gr.x(),
+            self.effectiveWidth(), opt.upsideDown)
+        return rangeVal
+
+    def rangeValueToPixelPos(self, val):
+        opt = QtWidgets.QStyleOptionSlider()
+        self.initStyleOption(opt)
+        pixel = QtWidgets.QStyle.sliderPositionFromValue(
+            self.minimum(), self.maximum(), val, self.effectiveWidth(),
+            opt.upsideDown)
+        return pixel
+
+    # When calculating conversions to/from pixel space, not all of the slider's
+    # width is actually usable, because the slider handle has a nonzero width.
+    # We use this function as a helper when the axis needs slider information.
+    def handleWidth(self):
+        opt = QtWidgets.QStyleOptionSlider()
+        self.initStyleOption(opt)
+        sr = self.style().subControlRect(QtWidgets.QStyle.CC_Slider, opt,
+                                         QtWidgets.QStyle.SC_SliderHandle,
+                                         self)
+        return sr.width()
+
+    def effectiveWidth(self):
+        opt = QtWidgets.QStyleOptionSlider()
+        self.initStyleOption(opt)
+        gr = self.style().subControlRect(QtWidgets.QStyle.CC_Slider, opt,
+                                         QtWidgets.QStyle.SC_SliderGroove,
+                                         self)
+        return gr.width() - self.handleWidth()
+
+    def handleMousePress(self, pos, control, val, handle):
+        opt = QtWidgets.QStyleOptionSlider()
+        self.initHandleStyleOption(opt, handle)
+        startAtEdges = (handle == "start" and
+                        (self.startVal == self.minimum() or
+                         self.startVal == self.maximum()))
+        stopAtEdges = (handle == "stop" and
+                       (self.stopVal == self.minimum() or
+                        self.stopVal == self.maximum()))
+
+        # If chosen slider at edge, treat it as non-interactive.
+        if startAtEdges or stopAtEdges:
+            return QtWidgets.QStyle.SC_None
+
+        oldControl = control
+        control = self.style().hitTestComplexControl(
+            QtWidgets.QStyle.CC_Slider, opt, pos, self)
+        sr = self.style().subControlRect(QtWidgets.QStyle.CC_Slider, opt,
+                                         QtWidgets.QStyle.SC_SliderHandle,
+                                         self)
+        if control == QtWidgets.QStyle.SC_SliderHandle:
+            # no pick()- slider orientation static
+            self.offset = pos.x() - sr.topLeft().x()
+            self.setSliderDown(True)
+            # emit
+
+        # Needed?
+        if control != oldControl:
+            self.update(sr)
+        return control
+
+    def drawHandle(self, painter, handle):
+        opt = QtWidgets.QStyleOptionSlider()
+        self.initStyleOption(opt)
+        self.initHandleStyleOption(opt, handle)
+        opt.subControls = QtWidgets.QStyle.SC_SliderHandle
+        painter.drawComplexControl(QtWidgets.QStyle.CC_Slider, opt)
+
+    # def triggerAction(self, action, slider):
+    #     if action == QtWidgets.QAbstractSlider.SliderSingleStepAdd:
+    #         if
+
+    def setSpan(self, low, high):
+        # TODO: Is this necessary? QStyle::sliderPositionFromValue appears
+        # to clamp already.
+        low = min(max(self.minimum(), low), self.maximum())
+        high = min(max(self.minimum(), high), self.maximum())
+
+        if low != self.startVal or high != self.stopVal:
+            if low != self.startVal:
+                self.startVal = low
+                self.startPos = low
+            if high != self.stopVal:
+                self.stopVal = high
+                self.stopPos = high
+            self.update()
+
+    def setStartPosition(self, val):
+        if val != self.startPos:
+            self.startPos = val
+            if not self.hasTracking():
+                self.update()
+            if self.isSliderDown():
+                self.sigStartMoved.emit(self.startPos)
+            if self.hasTracking() and not self.blockTracking:
+                self.setSpan(self.startPos, self.stopVal)
+
+    def setStopPosition(self, val):
+        if val != self.stopPos:
+            self.stopPos = val
+            if not self.hasTracking():
+                self.update()
+            if self.isSliderDown():
+                self.sigStopMoved.emit(self.stopPos)
+            if self.hasTracking() and not self.blockTracking:
+                self.setSpan(self.startVal, self.stopPos)
+
+    def mousePressEvent(self, ev):
+        if self.minimum() == self.maximum() or (ev.buttons() ^ ev.button()):
+            ev.ignore()
+            return
+
+        # Prefer stopVal in the default case.
+        self.upperPressed = self.handleMousePress(
+            ev.pos(), self.upperPressed, self.stopVal, "stop")
+        if self.upperPressed != QtWidgets.QStyle.SC_SliderHandle:
+            self.lowerPressed = self.handleMousePress(
+                ev.pos(), self.upperPressed, self.startVal, "start")
+
+        # State that is needed to handle the case where two sliders are equal.
+        self.firstMovement = True
+        ev.accept()
+
+    def mouseMoveEvent(self, ev):
+        if (self.lowerPressed != QtWidgets.QStyle.SC_SliderHandle and
+                self.upperPressed != QtWidgets.QStyle.SC_SliderHandle):
+            ev.ignore()
+            return
+
+        opt = QtWidgets.QStyleOptionSlider()
+        self.initStyleOption(opt)
+
+        # This code seems to be needed so that returning the slider to the
+        # previous position is honored if a drag distance is exceeded.
+        m = self.style().pixelMetric(QtWidgets.QStyle.PM_MaximumDragDistance,
+                                     opt, self)
+        newPos = self.pixelPosToRangeValue(ev.pos().x() - self.offset)
+
+        if m >= 0:
+            r = self.rect().adjusted(-m, -m, m, m)
+            if not r.contains(ev.pos()):
+                newPos = self.position
+
+        if self.firstMovement:
+            if self.startPos == self.stopPos:
+                # StopSlider is preferred, except in the case where
+                # start == max possible value the slider can take.
+                if self.startPos == self.maximum():
+                    self.lowerPressed = QtWidgets.QStyle.SC_SliderHandle
+                    self.upperPressed = QtWidgets.QStyle.SC_None
+                self.firstMovement = False
+
+        if self.lowerPressed == QtWidgets.QStyle.SC_SliderHandle:
+            self.setStartPosition(newPos)
+
+        if self.upperPressed == QtWidgets.QStyle.SC_SliderHandle:
+            self.setStopPosition(newPos)
+
+        ev.accept()
+
+    def mouseReleaseEvent(self, ev):
+        QtWidgets.QSlider.mouseReleaseEvent(self, ev)
+        self.setSliderDown(False)  # AbstractSlider needs this
+        self.lowerPressed = QtWidgets.QStyle.SC_None
+        self.upperPressed = QtWidgets.QStyle.SC_None
+
+    def paintEvent(self, ev):
+        # Use QStylePainters to make redrawing as painless as possible.
+        # Paint on the custom widget, using the attributes of the fake
+        # slider references we keep around. setStyleSheet within paintEvent
+        # leads to heavy performance penalties (and recursion?).
+        # QPalettes would be nicer to use, since palette entries can be set
+        # individually for each slider handle, but Windows 7 does not
+        # use them. This seems to be the only way to override the colors
+        # regardless of platform.
+        startPainter = QtWidgets.QStylePainter(self, self.dummyStartSlider)
+        stopPainter = QtWidgets.QStylePainter(self, self.dummyStopSlider)
+
+        # Handles
+        # Qt will snap sliders to 0 or maximum() if given a desired pixel
+        # location outside the mapped range. So we manually just don't draw
+        # the handles if they are at 0 or max.
+        if self.startVal > 0 and self.startVal < self.maximum():
+            self.drawHandle(startPainter, "start")
+        if self.stopVal > 0 and self.stopVal < self.maximum():
+            self.drawHandle(stopPainter, "stop")
+
+
+# real (Sliders) => pixel (one pixel movement of sliders would increment by X)
+# => range (minimum granularity that sliders understand).
+class ScanProxy(QtCore.QObject):
+    sigStartMoved = QtCore.pyqtSignal(float)
+    sigStopMoved = QtCore.pyqtSignal(float)
+    sigNumPoints = QtCore.pyqtSignal(int)
+
+    def __init__(self, slider, axis, zoomMargin, dynamicRange):
+        QtCore.QObject.__init__(self)
+        self.axis = axis
+        self.slider = slider
+        self.realStart = 0
+        self.realStop = 0
+        self.numPoints = 10
+        self.zoomMargin = zoomMargin
+        self.dynamicRange = dynamicRange
+
+        # Transform that maps the spinboxes to a pixel position on the
+        # axis. 0 to axis.width() exclusive indicate positions which will be
+        # displayed on the axis.
+        # Because the axis's width will change when placed within a layout,
+        # the realToPixelTransform will initially be invalid. It will be set
+        # properly during the first resizeEvent, with the below transform.
+        self.realToPixelTransform = -self.axis.width()/2, 1.
+        self.invalidOldSizeExpected = True
+
+    # pixel vals for sliders: 0 to slider_width - 1
+    def realToPixel(self, val):
+        a, b = self.realToPixelTransform
+        rawVal = b*(val - a)
+        # Clamp pixel values to 32 bits, b/c Qt will otherwise wrap values.
+        rawVal = min(max(-(1 << 31), rawVal), (1 << 31) - 1)
+        return rawVal
+
+    # Get a point from pixel units to what the sliders display.
+    def pixelToReal(self, val):
+        a, b = self.realToPixelTransform
+        return val/b + a
+
+    def rangeToReal(self, val):
+        pixelVal = self.slider.rangeValueToPixelPos(val)
+        return self.pixelToReal(pixelVal)
+
+    def realToRange(self, val):
+        pixelVal = self.realToPixel(val)
+        return self.slider.pixelPosToRangeValue(pixelVal)
+
+    def moveStop(self, val):
+        sliderX = self.realToRange(val)
+        self.slider.setStopPosition(sliderX)
+        self.realStop = val
+        self.axis.update()  # Number of points ticks changed positions.
+
+    def moveStart(self, val):
+        sliderX = self.realToRange(val)
+        self.slider.setStartPosition(sliderX)
+        self.realStart = val
+        self.axis.update()
+
+    def handleStopMoved(self, rangeVal):
+        self.sigStopMoved.emit(self.rangeToReal(rangeVal))
+
+    def handleStartMoved(self, rangeVal):
+        self.sigStartMoved.emit(self.rangeToReal(rangeVal))
+
+    def handleNumPoints(self, inc):
+        self.sigNumPoints.emit(self.numPoints + inc)
+
+    def setNumPoints(self, val):
+        self.numPoints = val
+        self.axis.update()
+
+    def handleZoom(self, zoomFactor, mouseXPos):
+        newScale = self.realToPixelTransform[1] * zoomFactor
+        refReal = self.pixelToReal(mouseXPos)
+        newLeft = refReal - mouseXPos/newScale
+        newZero = newLeft*newScale + self.slider.effectiveWidth()/2
+        if zoomFactor > 1 and abs(newZero) > self.dynamicRange:
+            return
+        self.realToPixelTransform = newLeft, newScale
+        self.moveStop(self.realStop)
+        self.moveStart(self.realStart)
+
+    def viewRange(self):
+        newScale = self.slider.effectiveWidth()/abs(
+            self.realStop - self.realStart)
+        newScale *= 1 - 2*self.zoomMargin
+        newCenter = (self.realStop + self.realStart)/2
+        if newCenter:
+            newScale = min(newScale, self.dynamicRange/abs(newCenter))
+        newLeft = newCenter - self.slider.effectiveWidth()/2/newScale
+        self.realToPixelTransform = newLeft, newScale
+        self.moveStop(self.realStop)
+        self.moveStart(self.realStart)
+        self.axis.update()  # Axis normally takes care to update itself during
+        # zoom. In this code path however, the zoom didn't arrive via the axis
+        # widget, so we need to notify manually.
+
+    # This function is called if the axis width, slider width, and slider
+    # positions are in an inconsistent state, to initialize the widget.
+    # This function handles handles the slider positions. Slider and axis
+    # handle its own width changes; proxy watches for axis width resizeEvent to
+    # alter mapping from real to pixel space.
+    def viewRangeInit(self):
+        currRangeReal = abs(self.realStop - self.realStart)
+        if currRangeReal == 0:
+            self.moveStop(self.realStop)
+            self.moveStart(self.realStart)
+            # Ill-formed snap range- move the sliders anyway,
+            # because we arrived here during widget
+            # initialization, where the slider positions are likely invalid.
+            # This will force the sliders to have positions on the axis
+            # which reflect the start/stop values currently set.
+        else:
+            self.viewRange()
+        # Notify spinboxes manually, since slider wasn't clicked and will
+        # therefore not emit signals.
+        self.sigStopMoved.emit(self.realStop)
+        self.sigStartMoved.emit(self.realStart)
+
+    def snapRange(self):
+        lowRange = self.zoomMargin
+        highRange = 1 - self.zoomMargin
+        newStart = self.pixelToReal(lowRange * self.slider.effectiveWidth())
+        newStop = self.pixelToReal(highRange * self.slider.effectiveWidth())
+        sliderRange = self.slider.maximum() - self.slider.minimum()
+        # Signals won't fire unless slider was actually grabbed, so
+        # manually update so the spinboxes know that knew values were set.
+        # self.realStop/Start and the sliders themselves will be updated as a
+        # consequence of ValueChanged signal in spinboxes. The slider widget
+        # has guards against recursive signals in setSpan().
+        if sliderRange > 0:
+            self.sigStopMoved.emit(newStop)
+            self.sigStartMoved.emit(newStart)
+
+    def eventFilter(self, obj, ev):
+        if obj != self.axis:
+            return False
+        if ev.type() != QtCore.QEvent.Resize:
+            return False
+        if ev.oldSize().isValid():
+            oldLeft = self.pixelToReal(0)
+            refWidth = ev.oldSize().width() - self.slider.handleWidth()
+            refRight = self.pixelToReal(refWidth)
+            newWidth = ev.size().width() - self.slider.handleWidth()
+            # assert refRight > oldLeft
+            newScale = newWidth/(refRight - oldLeft)
+            self.realToPixelTransform = oldLeft, newScale
+        else:
+            # TODO: self.axis.width() is invalid during object
+            # construction. The width will change when placed in a
+            # layout WITHOUT a resizeEvent. Why?
+            oldLeft = -ev.size().width()/2
+            newScale = 1.0
+            self.realToPixelTransform = oldLeft, newScale
+            # We need to reinitialize the pixel transform b/c the old width
+            # of the axis is no longer valid. When we have a valid transform,
+            # we can then viewRange based on the desired real values.
+            # The slider handle values are invalid before this point as well;
+            # we set them to the correct value here, regardless of whether
+            # the slider has already resized itsef or not.
+            self.viewRangeInit()
+            self.invalidOldSizeExpected = False
+        # assert self.pixelToReal(0) == oldLeft, \
+        # "{}, {}".format(self.pixelToReal(0), oldLeft)
+        # Slider will update independently, making sure that the old
+        # slider positions are preserved. Because of this, we can be
+        # confident that the new slider position will still map to the
+        # same positions in the new axis-space.
+        return False
+
+
+class ScanWidget(QtWidgets.QWidget):
+    sigStartMoved = QtCore.pyqtSignal(float)
+    sigStopMoved = QtCore.pyqtSignal(float)
+    sigNumChanged = QtCore.pyqtSignal(int)
+
+    def __init__(self, zoomFactor=1.05, zoomMargin=.1, dynamicRange=1e8):
+        QtWidgets.QWidget.__init__(self)
+        self.slider = slider = ScanSlider()
+        self.axis = axis = ScanAxis(zoomFactor)
+        self.proxy = ScanProxy(slider, axis, zoomMargin, dynamicRange)
+        axis.proxy = self.proxy
+        slider.setMaximum(1023)
+
+        # Layout.
+        layout = QtWidgets.QGridLayout()
+        # Default size will cause axis to disappear otherwise.
+        layout.setRowMinimumHeight(0, 40)
+        layout.addWidget(axis, 0, 0, 1, -1)
+        layout.addWidget(slider, 1, 0, 1, -1)
+        self.setLayout(layout)
+
+        # Connect signals (minus context menu)
+        slider.sigStopMoved.connect(self.proxy.handleStopMoved)
+        slider.sigStartMoved.connect(self.proxy.handleStartMoved)
+        self.proxy.sigStopMoved.connect(self.sigStopMoved)
+        self.proxy.sigStartMoved.connect(self.sigStartMoved)
+        self.proxy.sigNumPoints.connect(self.sigNumChanged)
+        axis.sigZoom.connect(self.proxy.handleZoom)
+        axis.sigPoints.connect(self.proxy.handleNumPoints)
+
+        # Connect event observers.
+        axis.installEventFilter(self.proxy)
+        slider.installEventFilter(axis)
+
+        # Context menu entries
+        self.viewRangeAct = QtWidgets.QAction("&View Range", self)
+        self.snapRangeAct = QtWidgets.QAction("&Snap Range", self)
+        self.viewRangeAct.triggered.connect(self.viewRange)
+        self.snapRangeAct.triggered.connect(self.snapRange)
+
+    # Spinbox and button slots. Any time the spinboxes change, ScanWidget
+    # mirrors it and passes the information to the proxy.
+    def setStop(self, val):
+        self.proxy.moveStop(val)
+
+    def setStart(self, val):
+        self.proxy.moveStart(val)
+
+    def setNumPoints(self, val):
+        self.proxy.setNumPoints(val)
+
+    def viewRange(self):
+        self.proxy.viewRange()
+
+    def snapRange(self):
+        self.proxy.snapRange()
+
+    def contextMenuEvent(self, ev):
+        menu = QtWidgets.QMenu(self)
+        menu.addAction(self.viewRangeAct)
+        menu.addAction(self.snapRangeAct)
+        menu.exec(ev.globalPos())

artiq/gui/scientific_spinbox.py

@@ -0,0 +1,71 @@
+import re
+from PyQt5 import QtGui, QtWidgets
+
+# after
+# http://jdreaver.com/posts/2014-07-28-scientific-notation-spin-box-pyside.html
+
+
+_inf = float("inf")
+# Regular expression to find floats. Match groups are the whole string, the
+# whole coefficient, the decimal part of the coefficient, and the exponent
+# part.
+_float_re = re.compile(r"(([+-]?\d+(\.\d*)?|\.\d+)([eE][+-]?\d+)?)")
+
+
+def valid_float_string(string):
+    match = _float_re.search(string)
+    if match:
+        return match.groups()[0] == string
+    return False
+
+
+class FloatValidator(QtGui.QValidator):
+    def validate(self, string, position):
+        if valid_float_string(string):
+            return self.Acceptable, string, position
+        if string == "" or string[position-1] in "eE.-+":
+            return self.Intermediate, string, position
+        return self.Invalid, string, position
+
+    def fixup(self, text):
+        match = _float_re.search(text)
+        if match:
+            return match.groups()[0]
+        return ""
+
+
+class ScientificSpinBox(QtWidgets.QDoubleSpinBox):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.setMinimum(-_inf)
+        self.setMaximum(_inf)
+        self.validator = FloatValidator()
+        self.setDecimals(20)
+
+    def validate(self, text, position):
+        return self.validator.validate(text, position)
+
+    def fixup(self, text):
+        return self.validator.fixup(text)
+
+    def valueFromText(self, text):
+        return float(text)
+
+    def textFromValue(self, value):
+        return format_float(value)
+
+    def stepBy(self, steps):
+        text = self.cleanText()
+        groups = _float_re.search(text).groups()
+        decimal = float(groups[1])
+        decimal += steps
+        new_string = "{:g}".format(decimal) + (groups[3] if groups[3] else "")
+        self.lineEdit().setText(new_string)
+
+
+def format_float(value):
+    """Modified form of the 'g' format specifier."""
+    string = "{:g}".format(value)
+    string = string.replace("e+", "e")
+    string = re.sub("e(-?)0*(\d+)", r"e\1\2", string)
+    return string

artiq/gui/ticker.py

@@ -0,0 +1,136 @@
+# Robert Jordens <rj@m-labs.hk>, 2016
+
+import numpy as np
+
+
+class Ticker:
+    # TODO: if this turns out to be computationally expensive, then refactor
+    # such that the log()s and intermediate values are reused. But
+    # probably the string formatting itself is the limiting factor here.
+    def __init__(self, min_ticks=3, precision=3, steps=(5, 2, 1, .5)):
+        """
+        min_ticks: minimum number of ticks to generate
+            The maximum number of ticks is
+            max(consecutive ratios in steps)*min_ticks
+            thus 5/2*min_ticks for default steps.
+        precision: maximum number of significant digits in labels
+            Also extract common offset and magnitude from ticks
+            if dynamic range exceeds precision number of digits
+            (small range on top of large offset).
+        steps: tick increments at a given magnitude
+            The .5 catches rounding errors where the calculation
+            of step_magnitude falls into the wrong exponent bin.
+        """
+        self.min_ticks = min_ticks
+        self.precision = precision
+        self.steps = steps
+
+    def step(self, i):
+        """
+        Return recommended step value for interval size `i`.
+        """
+        if not i:
+            raise ValueError("Need a finite interval")
+        step = i/self.min_ticks  # rational step size for min_ticks
+        step_magnitude = 10**np.floor(np.log10(step))
+        # underlying magnitude for steps
+        for m in self.steps:
+            good_step = m*step_magnitude
+            if good_step <= step:
+                return good_step
+
+    def ticks(self, a, b):
+        """
+        Return recommended tick values for interval `[a, b[`.
+        """
+        step = self.step(b - a)
+        a0 = np.ceil(a/step)*step
+        ticks = np.arange(a0, b, step)
+        return ticks
+
+    def offset(self, a, step):
+        """
+        Find offset if dynamic range of the interval is large
+        (small range on large offset).
+
+        If offset is finite, show `offset + value`.
+        """
+        if a == 0.:
+            return 0.
+        la = np.floor(np.log10(abs(a)))
+        lr = np.floor(np.log10(step))
+        if la - lr < self.precision:
+            return 0.
+        magnitude = 10**(lr - 1 + self.precision)
+        offset = np.floor(a/magnitude)*magnitude
+        return offset
+
+    def magnitude(self, a, b, step):
+        """
+        Determine the scaling magnitude.
+
+        If magnitude differs from unity, show `magnitude * value`.
+        This depends on proper offsetting by `offset()`.
+        """
+        v = np.floor(np.log10(max(abs(a), abs(b))))
+        w = np.floor(np.log10(step))
+        if v < self.precision and w > -self.precision:
+            return 1.
+        return 10**v
+
+    def fix_minus(self, s):
+        return s.replace("-", "−")  # unicode minus
+
+    def format(self, step):
+        """
+        Determine format string to represent step sufficiently accurate.
+        """
+        dynamic = -int(np.floor(np.log10(step)))
+        dynamic = min(max(0, dynamic), self.precision)
+        return "{{:1.{:d}f}}".format(dynamic)
+
+    def compact_exponential(self, v):
+        """
+        Format `v` in in compact exponential, stripping redundant elements
+        (pluses, leading and trailing zeros and decimal point, trailing `e`).
+        """
+        # this is after the matplotlib ScalarFormatter
+        # without any i18n
+        significand, exponent = "{:1.10e}".format(v).split("e")
+        significand = significand.rstrip("0").rstrip(".")
+        exponent_sign = exponent[0].replace("+", "")
+        exponent = exponent[1:].lstrip("0")
+        s = "{:s}e{:s}{:s}".format(significand, exponent_sign,
+                                   exponent).rstrip("e")
+        return self.fix_minus(s)
+
+    def prefix(self, offset, magnitude):
+        """
+        Stringify `offset` and `magnitude`.
+
+        Expects the string to be shown top/left of the value it refers to.
+        """
+        prefix = ""
+        if offset != 0.:
+            prefix += self.compact_exponential(offset) + " + "
+        if magnitude != 1.:
+            prefix += self.compact_exponential(magnitude) + " × "
+        return prefix
+
+    def __call__(self, a, b):
+        """
+        Determine ticks, prefix and labels given the interval
+        `[a, b[`.
+
+        Return tick values, prefix string to be show to the left or
+        above the labels, and tick labels.
+        """
+        ticks = self.ticks(a, b)
+        offset = self.offset(a, ticks[1] - ticks[0])
+        t = ticks - offset
+        magnitude = self.magnitude(t[0], t[-1], t[1] - t[0])
+        t /= magnitude
+        prefix = self.prefix(offset, magnitude)
+        format = self.format(t[1] - t[0])
+        labels = [self.fix_minus(format.format(t)) for t in t]
+        return ticks, prefix, labels