added scroll event support

jdh2358 · jdh2358 · commit 2dc560e89b8f · 2007-06-27T13:53:37.000Z
svn path=/trunk/matplotlib/; revision=3417
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,3 +1,8 @@
+2007-06-27 Added a scroll event to the mpl event handling system and
+           implemented it for backends GTK* -- other backend
+           users/developers/maintainers, please add support for your
+           backend. - JDH
+
 2007-06-25 Changed default to clip=False in colors.Normalize;
            modified ColorbarBase for easier colormap display - EF
 
diff --git a/examples/image_slices_viewer.py b/examples/image_slices_viewer.py
@@ -0,0 +1,45 @@
+import numpy
+from pylab import figure, show
+
+
+
+
+class IndexTracker:
+    def __init__(self, ax, X):
+        self.ax = ax
+        ax.set_title('use scroll wheen to navigate images')
+
+        self.X = X
+        rows,cols,self.slices = X.shape
+        self.ind  = self.slices/2
+
+        self.im = ax.imshow(self.X[:,:,self.ind])
+        self.update()
+
+    def onscroll(self, event):
+
+        if event.button=='up':
+            self.ind = numpy.clip(self.ind+1, 0, self.slices-1)
+        else:
+            self.ind = numpy.clip(self.ind-1, 0, self.slices-1)
+
+
+        self.update()
+
+    def update(self):
+        self.im.set_data(self.X[:,:,self.ind])
+        ax.set_ylabel('slice %s'%self.ind)        
+        self.im.axes.figure.canvas.draw()
+
+
+fig = figure()
+ax = fig.add_subplot(111)
+
+X = numpy.random.rand(20,20,40)
+
+tracker = IndexTracker(ax, X)
+
+
+
+fig.canvas.mpl_connect('scroll_event', tracker.onscroll)
+show()
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -763,15 +763,16 @@ def __init__(self, name, canvas, x, y,guiEvent=None):
 
 class MouseEvent(LocationEvent):
     """
-    A mouse event (button_press_event, button_release_event,
+    A mouse event (button_press_event, button_release_event, scroll_event,
     motion_notify_event).
 
     The following attributes are defined and shown with their default
     values
 
     x      = None       # x position - pixels from left of canvas
     y      = None       # y position - pixels from bottom of canvas
-    button = None       # button pressed None, 1, 2, 3
+    button = None       # button pressed None, 1, 2, 3, 'up', 'down'
+                          (up and down are used for scroll events)
     key    = None       # the key pressed: None, chr(range(255), shift, win, or control
     inaxes = None       # the Axes instance if mouse us over axes
     xdata  = None       # x coord of mouse in data coords
@@ -856,6 +857,7 @@ class FigureCanvasBase:
         'key_release_event',
         'button_press_event',
         'button_release_event',
+        'scroll_event',                
         'motion_notify_event',
         'pick_event',
         )
@@ -915,6 +917,21 @@ def pick_event(self, mouseevent, artist, **kwargs):
         event = PickEvent(s, self, mouseevent, artist, **kwargs)
         self.callbacks.process(s, event)
 
+    def scroll_event(self, x, y, button, guiEvent=None):
+        """
+        Backend derived classes should call this function on any
+        scroll wheel event.  x,y are the canvas coords: 0,0 is lower,
+        left.  button and key are as defined in MouseEvent
+        """
+        self._button = button
+        s = 'scroll_event'
+        mouseevent = MouseEvent(s, self, x, y, button, self._key, guiEvent=guiEvent)
+        self.callbacks.process(s, mouseevent)
+
+
+        if not self.widgetlock.locked():
+            self.figure.pick(mouseevent)
+
     def button_press_event(self, x, y, button, guiEvent=None):
         """
         Backend derived classes should call this function on any mouse
@@ -1020,6 +1037,7 @@ def func(event)
         'key_release_event',
         'button_press_event',
         'button_release_event',
+        'scroll_event',
         'motion_notify_event',
         'pick_event',
 
diff --git a/lib/matplotlib/backends/backend_gtk.py b/lib/matplotlib/backends/backend_gtk.py
@@ -157,6 +157,7 @@ def __init__(self, figure):
         self._pixmap_height = -1
         self._lastCursor    = None
 
+        self.connect('scroll_event',   self.scroll_event)
         self.connect('button_press_event',   self.button_press_event)
         self.connect('button_release_event', self.button_release_event)
         self.connect('configure_event',      self.configure_event)
@@ -180,6 +181,18 @@ def __init__(self, figure):
         self._renderer_init()
 
 
+    def scroll_event(self, widget, event):
+        if _debug: print 'FigureCanvasGTK.%s' % fn_name()
+        x = event.x
+        # flipy so y=0 is bottom of canvas
+        y = self.allocation.height - event.y
+        if event.direction==gdk.SCROLL_UP:
+            direction = 'up'
+        else:
+            direction = 'down'
+        FigureCanvasBase.scroll_event(self, x, y, direction)
+        return False  # finish event propagation?
+
     def button_press_event(self, widget, event):
         if _debug: print 'FigureCanvasGTK.%s' % fn_name()
         x = event.x
