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"""
Use mouse wheel to zoom and right-click to pan the viewport.
"""
from traits.api import Float
from enable.api import (AbstractOverlay, Canvas, Viewport, Window, ColorTrait,
Scrolled)
from enable.tools.api import ViewportPanTool
from enable.example_support import demo_main, DemoFrame
class EventTracer(AbstractOverlay):
""" Draws a marker under the mouse cursor where an event is occurring. """
x = Float
y = Float
color = ColorTrait("red")
size = Float(5)
angle = Float(0.0) # angle in degrees
def normal_mouse_move(self, event):
self.x = event.x
self.y = event.y
self.component.request_redraw()
def overlay(self, component, gc, view_bounds, mode):
with gc:
gc.translate_ctm(self.x, self.y)
if self.angle != 0:
gc.rotate_ctm(self.angle * 3.14159/180.)
gc.set_stroke_color(self.color_)
gc.set_line_width(1.0)
gc.move_to(-self.size, 0)
gc.line_to(self.size, 0)
gc.move_to(0, -self.size)
gc.line_to(0, self.size)
gc.stroke_path()
class MyFrame(DemoFrame):
def _create_window(self):
canvas = Canvas(bgcolor="lightsteelblue", draw_axes=True)
canvas.overlays.append(EventTracer(canvas, color="green", size=8,
angle=45.0))
viewport = Viewport(component=canvas, enable_zoom=True)
viewport.view_position = [0,0]
viewport.tools.append(ViewportPanTool(viewport, drag_button="right"))
viewport.overlays.append(EventTracer(viewport))
scrolled = Scrolled(canvas, inside_padding_width = 0,
mousewheel_scroll = False,
viewport_component = viewport,
always_show_sb = True,
continuous_drag_update = True)
return Window(self, -1, component=scrolled)
if __name__ == "__main__":
# Save demo so that it doesn't get garbage collected when run within
# existing event loop (i.e. from ipython).
demo = demo_main(MyFrame, title="Canvas example")
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