Mid-way through overhaul. Proposed code path looks like:

    setRange -> updateViewRange -> matrix dirty
                            -> sigRangeChanged

    ... -> prepareForPaint -> updateAutoRange, updateMatrix if dirty

pyqtgraph/graphicsItems/GraphicsObject.py

@@ -12,6 +12,7 @@ class GraphicsObject(GraphicsItem, QtGui.QGraphicsObject):
     """
     _qtBaseClass = QtGui.QGraphicsObject
     def __init__(self, *args):
+        self.__inform_view_on_changes = True
         QtGui.QGraphicsObject.__init__(self, *args)
         self.setFlag(self.ItemSendsGeometryChanges)
         GraphicsItem.__init__(self)
@@ -20,7 +21,7 @@ class GraphicsObject(GraphicsItem, QtGui.QGraphicsObject):
         ret = QtGui.QGraphicsObject.itemChange(self, change, value)
         if change in [self.ItemParentHasChanged, self.ItemSceneHasChanged]:
             self.parentChanged()
-        if change in [self.ItemPositionHasChanged, self.ItemTransformHasChanged]:
+        if self.__inform_view_on_changes and change in [self.ItemPositionHasChanged, self.ItemTransformHasChanged]:
             self.informViewBoundsChanged()
             
         ## workaround for pyqt bug:

pyqtgraph/graphicsItems/ViewBox/ViewBox.py

@@ -17,6 +17,10 @@ __all__ = ['ViewBox']
 class ChildGroup(ItemGroup):
     
     sigItemsChanged = QtCore.Signal()
+    def __init__(self, parent):
+        ItemGroup.__init__(self, parent)
+        # excempt from telling view when transform changes
+        self._GraphicsObject__inform_view_on_change = False
     
     def itemChange(self, change, value):
         ret = ItemGroup.itemChange(self, change, value)
@@ -195,6 +199,21 @@ class ViewBox(GraphicsWidget):
     def implements(self, interface):
         return interface == 'ViewBox'
         
+    def itemChange(self, change, value):
+        ret = GraphicsWidget.itemChange(self, change, value)
+        if change == self.ItemSceneChange:
+            scene = self.scene()
+            if scene is not None:
+                scene.sigPrepareForPaint.disconnect(self.prepareForPaint)
+        elif change == self.ItemSceneHasChanged:
+            scene = self.scene()
+            if scene is not None:
+                scene.sigPrepareForPaint.connect(self.prepareForPaint)
+        return ret
+
+    def prepareForPaint(self):
+        #print "prepare"
+        pass
         
     def getState(self, copy=True):
         """Return the current state of the ViewBox. 
@@ -308,12 +327,14 @@ class ViewBox(GraphicsWidget):
             ch.setParentItem(None)
         
     def resizeEvent(self, ev):
-        #print self.name, "ViewBox.resizeEvent", self.size()
+        print self.name, "ViewBox.resizeEvent", self.size()
         #self.setRange(self.range, padding=0)
+        x,y = self.targetRange()
+        self.setRange(xRange=x, yRange=y, padding=0)
         self.linkedXChanged()
         self.linkedYChanged()
         self.updateAutoRange()
-        self.updateMatrix()
+        #self.updateMatrix()
         self.sigStateChanged.emit(self)
         self.background.setRect(self.rect())
         #self._itemBoundsCache.clear()
@@ -357,77 +378,97 @@ class ViewBox(GraphicsWidget):
         Set the visible range of the ViewBox.
         Must specify at least one of *rect*, *xRange*, or *yRange*. 
         
-        ============= =====================================================================
+        ================== =====================================================================
         **Arguments**
-        *rect*        (QRectF) The full range that should be visible in the view box.
-        *xRange*      (min,max) The range that should be visible along the x-axis.
-        *yRange*      (min,max) The range that should be visible along the y-axis.
-        *padding*     (float) Expand the view by a fraction of the requested range. 
-                      By default, this value is set between 0.02 and 0.1 depending on
-                      the size of the ViewBox.
-        ============= =====================================================================
+        *rect*             (QRectF) The full range that should be visible in the view box.
+        *xRange*           (min,max) The range that should be visible along the x-axis.
+        *yRange*           (min,max) The range that should be visible along the y-axis.
+        *padding*          (float) Expand the view by a fraction of the requested range. 
+                           By default, this value is set between 0.02 and 0.1 depending on
+                           the size of the ViewBox.
+        *update*           (bool) If True, update the range of the ViewBox immediately. 
+                           Otherwise, the update is deferred until before the next render.
+        *disableAutoRange* (bool) If True, auto-ranging is diabled. Otherwise, it is left
+                           unchanged.
+        ================== =====================================================================
         
         """
-        #print self.name, "ViewBox.setRange", rect, xRange, yRange, padding
+        print self.name, "ViewBox.setRange", rect, xRange, yRange, padding
         
-        changes = {}
+        changes = {}   # axes
+        setRequested = [False, False]
         
         if rect is not None:
             changes = {0: [rect.left(), rect.right()], 1: [rect.top(), rect.bottom()]}
+            setRequested = [True, True]
         if xRange is not None:
             changes[0] = xRange
+            setRequested[0] = True
         if yRange is not None:
             changes[1] = yRange
+            setRequested[1] = True
 
         if len(changes) == 0:
             print(rect)
             raise Exception("Must specify at least one of rect, xRange, or yRange. (gave rect=%s)" % str(type(rect)))
         
+        # Update axes one at a time
         changed = [False, False]
         for ax, range in changes.items():
-            if padding is None:
-                xpad = self.suggestPadding(ax)
-            else:
-                xpad = padding
             mn = min(range)
             mx = max(range)
-            if mn == mx:   ## If we requested 0 range, try to preserve previous scale. Otherwise just pick an arbitrary scale.
+            
+            # If we requested 0 range, try to preserve previous scale. 
+            # Otherwise just pick an arbitrary scale.
+            if mn == mx:   
                 dy = self.state['viewRange'][ax][1] - self.state['viewRange'][ax][0]
                 if dy == 0:
                     dy = 1
                 mn -= dy*0.5
                 mx += dy*0.5
                 xpad = 0.0
-            if any(np.isnan([mn, mx])) or any(np.isinf([mn, mx])):
-                raise Exception("Not setting range [%s, %s]" % (str(mn), str(mx)))
                 
+            # Make sure no nan/inf get through
+            if not all(np.isfinite([mn, mx])):
+                raise Exception("Cannot set range [%s, %s]" % (str(mn), str(mx)))
+            
+            # Apply padding
+            if padding is None:
+                xpad = self.suggestPadding(ax)
+            else:
+                xpad = padding
             p = (mx-mn) * xpad
             mn -= p
             mx += p
+            
+            # Set target range
             if self.state['targetRange'][ax] != [mn, mx]:
                 self.state['targetRange'][ax] = [mn, mx]
                 changed[ax] = True
                 
-                aspect = self.state['aspectLocked']  # size ratio / view ratio
-                if aspect is not False and len(changes) == 1:
-                    ## need to adjust orthogonal target range to match
-                    size = [self.width(), self.height()]
-                    tr1 = self.state['targetRange'][ax]
-                    tr2 = self.state['targetRange'][1-ax]
-                    if size[1] == 0 or aspect == 0:
-                        ratio = 1.0
-                    else:
-                        ratio = (size[0] / float(size[1])) / aspect
-                    if ax == 0:
-                        ratio = 1.0 / ratio
-                    w = (tr1[1]-tr1[0]) * ratio
-                    d = 0.5 * (w - (tr2[1]-tr2[0]))
-                    self.state['targetRange'][1-ax] = [tr2[0]-d, tr2[1]+d]
-                    
-                    
-                    
+        # Update viewRange to match targetRange as closely as possible while 
+        # accounting for aspect ratio constraint
+        lockX, lockY = setRequested
+        if lockX and lockY:
+            lockX = False
+            lockY = False
+        self.updateViewRange(lockX, lockY)
+            
+        # If ortho axes have auto-visible-only, update them now
+        # Note that aspect ratio constraints and auto-visible probably do not work together..
+        if changed[0] and self.state['autoVisibleOnly'][1]:
+            self.updateAutoRange()  ## Maybe just indicate that auto range needs to be updated?
+        elif changed[1] and self.state['autoVisibleOnly'][0]:
+            self.updateAutoRange()
             
-        if any(changed) and disableAutoRange:
+        # If nothing has changed, we are done.
+        if not any(changed):
+            #if update and self.matrixNeedsUpdate:
+                #self.updateMatrix(changed)
+            return 
+        
+        # Disable auto-range if needed
+        if disableAutoRange:
             if all(changed):
                 ax = ViewBox.XYAxes
             elif changed[0]:
@@ -436,26 +477,26 @@ class ViewBox(GraphicsWidget):
                 ax = ViewBox.YAxis
             self.enableAutoRange(ax, False)
                 
-                
         self.sigStateChanged.emit(self)
         
-        self.target.setRect(self.mapRectFromItem(self.childGroup, self.targetRect()))
-        
-        if update and (any(changed) or self.matrixNeedsUpdate):
-            self.updateMatrix(changed)
+        # Update target rect for debugging
+        if self.target.isVisible():
+            self.target.setRect(self.mapRectFromItem(self.childGroup, self.targetRect()))
         
-        if not update and any(changed):
-            self.matrixNeedsUpdate = True
+        ## Update view matrix only if requested
+        #if update:
+            #self.updateMatrix(changed)
+        ## Otherwise, indicate that the matrix needs to be updated
+        #else:
+            #self.matrixNeedsUpdate = True
             
-        for ax, range in changes.items():
-            link = self.linkedView(ax)
-            if link is not None:
-                link.linkedViewChanged(self, ax)
+        ## Inform linked views that the range has changed <<This should be moved>>
+        #for ax, range in changes.items():
+            #link = self.linkedView(ax)
+            #if link is not None:
+                #link.linkedViewChanged(self, ax)
+
 
-        if changed[0] and self.state['autoVisibleOnly'][1]:
-            self.updateAutoRange()
-        elif changed[1] and self.state['autoVisibleOnly'][0]:
-            self.updateAutoRange()
             
     def setYRange(self, min, max, padding=None, update=True):
         """
@@ -572,7 +613,7 @@ class ViewBox(GraphicsWidget):
             
         
         
-    def enableAutoRange(self, axis=None, enable=True):
+    def enableAutoRange(self, axis=None, enable=True, x=None, y=None):
         """
         Enable (or disable) auto-range for *axis*, which may be ViewBox.XAxis, ViewBox.YAxis, or ViewBox.XYAxes for both
         (if *axis* is omitted, both axes will be changed).
@@ -584,25 +625,40 @@ class ViewBox(GraphicsWidget):
         #if not enable:
             #import traceback
             #traceback.print_stack()
-            
+        
+        # support simpler interface:
+        if x is not None or y is not None:
+            if x is not None:
+                self.enableAutoRange(ViewBox.XAxis, x)
+            if y is not None:
+                self.enableAutoRange(ViewBox.YAxis, y)
+            return
+        
         if enable is True:
             enable = 1.0
         
         if axis is None:
             axis = ViewBox.XYAxes
         
+        needAutoRangeUpdate = False
+        
         if axis == ViewBox.XYAxes or axis == 'xy':
-            self.state['autoRange'][0] = enable
-            self.state['autoRange'][1] = enable
+            axes = [0, 1]
         elif axis == ViewBox.XAxis or axis == 'x':
-            self.state['autoRange'][0] = enable
+            axes = [0]
         elif axis == ViewBox.YAxis or axis == 'y':
-            self.state['autoRange'][1] = enable
+            axes = [1]
         else:
             raise Exception('axis argument must be ViewBox.XAxis, ViewBox.YAxis, or ViewBox.XYAxes.')
         
-        if enable:
+        for ax in axes:
+            if self.state['autoRange'][ax] != enable:
+                self.state['autoRange'][ax] = enable
+                needAutoRangeUpdate |= (enable is not False)
+        
+        if needAutoRangeUpdate:
             self.updateAutoRange()
+        
         self.sigStateChanged.emit(self)
 
     def disableAutoRange(self, axis=None):
@@ -728,6 +784,7 @@ class ViewBox(GraphicsWidget):
         if oldLink is not None:
             try:
                 getattr(oldLink, signal).disconnect(slot)
+                oldLink.sigResized.disconnect(slot)
             except TypeError:
                 ## This can occur if the view has been deleted already
                 pass
@@ -738,6 +795,7 @@ class ViewBox(GraphicsWidget):
         else:
             self.state['linkedViews'][axis] = weakref.ref(view)
             getattr(view, signal).connect(slot)
+            view.sigResized.connect(slot)
             if view.autoRangeEnabled()[axis] is not False:
                 self.enableAutoRange(axis, False)
                 slot()
@@ -1233,47 +1291,126 @@ class ViewBox(GraphicsWidget):
         bounds = QtCore.QRectF(range[0][0], range[1][0], range[0][1]-range[0][0], range[1][1]-range[1][0])
         return bounds
             
+    def updateViewRange(self, forceX=False, forceY=False):
+        ## Update viewRange to match targetRange as closely as possible, given 
+        ## aspect ratio constraints.
         
-
-    def updateMatrix(self, changed=None):
-        ## Make the childGroup's transform match the requested range.
+        viewRange = [self.state['targetRange'][0][:], self.state['targetRange'][1][:]]
         
-        if changed is None:
-            changed = [False, False]
-        changed = list(changed)
+        # Make correction for aspect ratio constraint
+        aspect = self.state['aspectLocked']  # size ratio / view ratio
         tr = self.targetRect()
         bounds = self.rect()
-        
-        ## set viewRect, given targetRect and possibly aspect ratio constraint
-        aspect = self.state['aspectLocked']
-        if aspect is False or bounds.height() == 0:
-            self.state['viewRange'] = [self.state['targetRange'][0][:], self.state['targetRange'][1][:]]
-        else:
+        if aspect is not False and tr.width() != 0 and bounds.width() != 0:
             ## aspect is (widget w/h) / (view range w/h)
             
+            
             ## This is the view range aspect ratio we have requested
             targetRatio = tr.width() / tr.height()
             ## This is the view range aspect ratio we need to obey aspect constraint
             viewRatio = (bounds.width() / bounds.height()) / aspect
             
-            if targetRatio > viewRatio:  
+            # Decide which range to keep unchanged
+            print self.name, "aspect:", aspect, "changed:", changed, "auto:", self.state['autoRange']
+            if all(setRequested):
+                ax = 0 if targetRatio > viewRatio else 1
+                print "ax:", ax
+            elif setRequested[0]:
+                ax = 0
+            else:
+                ax = 1
+            
+            #### these should affect viewRange, not targetRange!
+            if ax == 0:  
                 ## view range needs to be taller than target
                 dy = 0.5 * (tr.width() / viewRatio - tr.height())
                 if dy != 0:
                     changed[1] = True
-                self.state['viewRange'] = [
-                    self.state['targetRange'][0][:], 
-                    [self.state['targetRange'][1][0] - dy, self.state['targetRange'][1][1] + dy]
-                    ]
+                self.state['targetRange'][1] = [self.state['targetRange'][1][0] - dy, self.state['targetRange'][1][1] + dy]
+                changed[1] = True
             else:
                 ## view range needs to be wider than target
                 dx = 0.5 * (tr.height() * viewRatio - tr.width())
                 if dx != 0:
                     changed[0] = True
-                self.state['viewRange'] = [
-                    [self.state['targetRange'][0][0] - dx, self.state['targetRange'][0][1] + dx], 
-                    self.state['targetRange'][1][:]
-                    ]
+                self.state['targetRange'][0] = [self.state['targetRange'][0][0] - dx, self.state['targetRange'][0][1] + dx]
+                changed[0] = True
+            
+            
+            ## need to adjust orthogonal target range to match
+            #size = [self.width(), self.height()]
+            #tr1 = self.state['targetRange'][ax]
+            #tr2 = self.state['targetRange'][1-ax]
+            #if size[1] == 0 or aspect == 0:
+                #ratio = 1.0
+            #else:
+                #ratio = (size[0] / float(size[1])) / aspect
+            #if ax == 0:
+                #ratio = 1.0 / ratio
+            #w = (tr1[1]-tr1[0]) * ratio
+            #d = 0.5 * (w - (tr2[1]-tr2[0]))
+            #self.state['targetRange'][1-ax] = [tr2[0]-d, tr2[1]+d]
+            #changed[1-ax] = True
+        
+        self.state['viewRange'] = viewRange
+        
+        # emit range change signals here!
+        if changed[0]:
+            self.sigXRangeChanged.emit(self, tuple(self.state['viewRange'][0]))
+        if changed[1]:
+            self.sigYRangeChanged.emit(self, tuple(self.state['viewRange'][1]))
+        if any(changed):
+            self.sigRangeChanged.emit(self, self.state['viewRange'])
+        
+        # Inform linked views that the range has changed <<This should be moved>>
+        for ax, range in changes.items():
+            link = self.linkedView(ax)
+            if link is not None:
+                link.linkedViewChanged(self, ax)
+        
+        self._matrixNeedsUpdate = True
+
+    def updateMatrix(self, changed=None):
+        ## Make the childGroup's transform match the requested viewRange.
+        
+        #if changed is None:
+            #changed = [False, False]
+        #changed = list(changed)
+        #tr = self.targetRect()
+        #bounds = self.rect()
+        
+        ## set viewRect, given targetRect and possibly aspect ratio constraint
+        #self.state['viewRange'] = [self.state['targetRange'][0][:], self.state['targetRange'][1][:]]
+        
+        #aspect = self.state['aspectLocked']
+        #if aspect is False or bounds.height() == 0:
+            #self.state['viewRange'] = [self.state['targetRange'][0][:], self.state['targetRange'][1][:]]
+        #else:
+            ### aspect is (widget w/h) / (view range w/h)
+            
+            ### This is the view range aspect ratio we have requested
+            #targetRatio = tr.width() / tr.height()
+            ### This is the view range aspect ratio we need to obey aspect constraint
+            #viewRatio = (bounds.width() / bounds.height()) / aspect
+            
+            #if targetRatio > viewRatio:  
+                ### view range needs to be taller than target
+                #dy = 0.5 * (tr.width() / viewRatio - tr.height())
+                #if dy != 0:
+                    #changed[1] = True
+                #self.state['viewRange'] = [
+                    #self.state['targetRange'][0][:], 
+                    #[self.state['targetRange'][1][0] - dy, self.state['targetRange'][1][1] + dy]
+                    #]
+            #else:
+                ### view range needs to be wider than target
+                #dx = 0.5 * (tr.height() * viewRatio - tr.width())
+                #if dx != 0:
+                    #changed[0] = True
+                #self.state['viewRange'] = [
+                    #[self.state['targetRange'][0][0] - dx, self.state['targetRange'][0][1] + dx], 
+                    #self.state['targetRange'][1][:]
+                    #]
         
         vr = self.viewRect()
         if vr.height() == 0 or vr.width() == 0:
@@ -1294,15 +1431,16 @@ class ViewBox(GraphicsWidget):
         
         self.childGroup.setTransform(m)
         
-        if changed[0]:
-            self.sigXRangeChanged.emit(self, tuple(self.state['viewRange'][0]))
-        if changed[1]:
-            self.sigYRangeChanged.emit(self, tuple(self.state['viewRange'][1]))
-        if any(changed):
-            self.sigRangeChanged.emit(self, self.state['viewRange'])
+        # moved to viewRangeChanged
+        #if changed[0]:
+            #self.sigXRangeChanged.emit(self, tuple(self.state['viewRange'][0]))
+        #if changed[1]:
+            #self.sigYRangeChanged.emit(self, tuple(self.state['viewRange'][1]))
+        #if any(changed):
+            #self.sigRangeChanged.emit(self, self.state['viewRange'])
             
         self.sigTransformChanged.emit(self)  ## segfaults here: 1
-        self.matrixNeedsUpdate = False
+        self._matrixNeedsUpdate = False
 
     def paint(self, p, opt, widget):
         if self.border is not None:

pyqtgraph/graphicsItems/tests/ViewBox.py

@@ -15,41 +15,58 @@ ViewBox test cases:
 
 import pyqtgraph as pg
 app = pg.mkQApp()
-win = pg.GraphicsWindow()
-vb = win.addViewBox(name="image view")
-vb.setAspectLocked()
-p1 = win.addPlot(name="plot 1")
-p2 = win.addPlot(name="plot 2", row=1, col=0)
-win.ci.layout.setRowFixedHeight(1, 150)
-win.ci.layout.setColumnFixedWidth(1, 150)
 
-def viewsMatch():
-    r0 = pg.np.array(vb.viewRange())
-    r1 = pg.np.array(p1.vb.viewRange()[1])
-    r2 = pg.np.array(p2.vb.viewRange()[1])
-    match = (abs(r0[1]-r1) <= (abs(r1) * 0.001)).all() and (abs(r0[0]-r2) <= (abs(r2) * 0.001)).all()
-    return match
-
-p1.setYLink(vb)
-p2.setXLink(vb)
-print "link views match:", viewsMatch()
-win.show()
-print "show views match:", viewsMatch()
 imgData = pg.np.zeros((10, 10))
-imgData[0] = 1
-imgData[-1] = 1
-imgData[:,0] = 1
-imgData[:,-1] = 1
-img = pg.ImageItem(imgData)
-vb.addItem(img)
-p1.plot(x=imgData.sum(axis=0), y=range(10))
-p2.plot(x=range(10), y=imgData.sum(axis=1))
-print "add items views match:", viewsMatch()
-#p1.setAspectLocked()
-#grid = pg.GridItem()
-#vb.addItem(grid)
+imgData[0] = 3
+imgData[-1] = 3
+imgData[:,0] = 3
+imgData[:,-1] = 3
+
+def testLinkWithAspectLock():
+    global win, vb
+    win = pg.GraphicsWindow()
+    vb = win.addViewBox(name="image view")
+    vb.setAspectLocked()
+    vb.enableAutoRange(x=False, y=False)
+    p1 = win.addPlot(name="plot 1")
+    p2 = win.addPlot(name="plot 2", row=1, col=0)
+    win.ci.layout.setRowFixedHeight(1, 150)
+    win.ci.layout.setColumnFixedWidth(1, 150)
+
+    def viewsMatch():
+        r0 = pg.np.array(vb.viewRange())
+        r1 = pg.np.array(p1.vb.viewRange()[1])
+        r2 = pg.np.array(p2.vb.viewRange()[1])
+        match = (abs(r0[1]-r1) <= (abs(r1) * 0.001)).all() and (abs(r0[0]-r2) <= (abs(r2) * 0.001)).all()
+        return match
 
+    p1.setYLink(vb)
+    p2.setXLink(vb)
+    print "link views match:", viewsMatch()
+    win.show()
+    print "show views match:", viewsMatch()
+    img = pg.ImageItem(imgData)
+    vb.addItem(img)
+    vb.autoRange()
+    p1.plot(x=imgData.sum(axis=0), y=range(10))
+    p2.plot(x=range(10), y=imgData.sum(axis=1))
+    print "add items views match:", viewsMatch()
+    #p1.setAspectLocked()
+    #grid = pg.GridItem()
+    #vb.addItem(grid)
+    pg.QtGui.QApplication.processEvents()
+    pg.QtGui.QApplication.processEvents()
+    #win.resize(801, 600)
 
+def testAspectLock():
+    global win, vb
+    win = pg.GraphicsWindow()
+    vb = win.addViewBox(name="image view")
+    vb.setAspectLocked()
+    img = pg.ImageItem(imgData)
+    vb.addItem(img)
+    
+    
 #app.processEvents()
 #print "init views match:", viewsMatch()
 #p2.setYRange(-300, 300)
@@ -72,3 +89,7 @@ print "add items views match:", viewsMatch()
 #win.resize(600, 100)
 #app.processEvents()
 #print vb.viewRange()
+
+
+if __name__ == '__main__':
+    testLinkWithAspectLock()