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# -*- coding: utf-8 -*-
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
from __future__ import division
import numpy as np
from .panzoom import PanZoomCamera
from ...visuals.transforms.nonlinear import (MagnifyTransform,
from import Timer
class MagnifyCamera(PanZoomCamera):
"""Camera implementing a MagnifyTransform combined with PanZoomCamera.
size_factor : float
The size factor to use.
radius_ratio : float
The radius ratio to use.
**kwargs : dict
Keyword arguments to pass to `PanZoomCamera` and create a transform.
This Camera uses the mouse cursor position to set the center position of
the MagnifyTransform, and uses mouse wheel events to adjust the
magnification factor.
At high magnification, very small mouse movements can result in large
changes, so we use a timer to animate transitions in the transform
The camera also adjusts the size of its "lens" area when the view is
transform_class = MagnifyTransform
def __init__(self, size_factor=0.25, radius_ratio=0.9, **kwargs):
# what fraction of the view width to use for radius
self.size_factor = size_factor
# ratio of inner to outer lens radius
self.radius_ratio = radius_ratio
# Extract kwargs for panzoom
camkwargs = {}
for key in ('parent', 'name', 'rect', 'aspect'):
if key in kwargs:
camkwargs[key] = kwargs.pop(key)
# Create the mag transform - kwrds go here
self.mag = self.transform_class(**kwargs)
# for handling smooth transitions
self.mag_target = self.mag.mag
self.mag._mag = self.mag_target
self.mouse_pos = None
self.timer = Timer(interval=0.016, connect=self.on_timer)
super(MagnifyCamera, self).__init__(**camkwargs)
# This tells the camera to insert the magnification transform at the
# beginning of the transform it applies to the scene. This is the
# correct place for the mag transform because:
# 1. We want it to apply to everything inside the scene, and not to
# the ViewBox itself or anything outside of the ViewBox.
# 2. We do _not_ want the pan/zoom transforms applied first, because
# the scale factors implemented there should not change the shape
# of the lens.
self.pre_transform = self.mag
def _viewbox_set(self, viewbox):
PanZoomCamera._viewbox_set(self, viewbox)
def _viewbox_unset(self, viewbox):
PanZoomCamera._viewbox_unset(self, viewbox)
def viewbox_mouse_event(self, event):
"""ViewBox mouse event handler
event : instance of Event
The mouse event.
# When the attached ViewBox reseives a mouse event, it is sent to the
# camera here.
self.mouse_pos = event.pos[:2]
if event.type == 'mouse_wheel':
# wheel rolled; adjust the magnification factor and hide the
# event from the superclass
m = self.mag_target
m *= 1.2 **[1]
m = m if m > 1 else 1
self.mag_target = m
# send everything _except_ wheel events to the superclass
super(MagnifyCamera, self).viewbox_mouse_event(event)
# start the timer to smoothly modify the transform properties.
if not self.timer.running:
def on_timer(self, event=None):
"""Timer event handler
event : instance of Event
The timer event.
# Smoothly update center and magnification properties of the transform
k = np.clip(100. / self.mag.mag, 10, 100)
s = 10**(-k * event.dt)
c = np.array(
c1 = c * s + self.mouse_pos * (1-s)
m = self.mag.mag * s + self.mag_target * (1-s)
# If changes are very small, then it is safe to stop the timer.
if (np.all(np.abs((c - c1) / c1) < 1e-5) and
(np.abs(np.log(m / self.mag.mag)) < 1e-3)):
self.timer.stop() = c1
self.mag.mag = m
def viewbox_resize_event(self, event):
"""ViewBox resize event handler
event : instance of Event
The viewbox resize event.
PanZoomCamera.viewbox_resize_event(self, event)
def view_changed(self):
# make sure radii are updated when a view is attached.
# when the view resizes, we change the lens radii to match.
if self._viewbox is not None:
vbs = self._viewbox.size
r = min(vbs) * self.size_factor
self.mag.radii = r * self.radius_ratio, r
class Magnify1DCamera(MagnifyCamera):
transform_class = Magnify1DTransform
__doc__ = MagnifyCamera.__doc__
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