Note
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Image Click Events
Show an image and print the x, y image data coordinates for click events.
import imageio.v3 as iio
from wgpu.gui.auto import WgpuCanvas, run
import pygfx as gfx
import numpy as np
canvas = WgpuCanvas()
renderer = gfx.renderers.WgpuRenderer(canvas)
scene = gfx.Scene()
# add image
im = iio.imread("imageio:astronaut.png")
image = gfx.Image(
gfx.Geometry(grid=gfx.Texture(im, dim=2)),
gfx.ImageBasicMaterial(clim=(0, 255), pick_write=True),
)
scene.add(image)
camera = gfx.OrthographicCamera(512, 512)
camera.local.position = (256, 256, 0)
camera.local.scale_y = -1
xx = [182, 180, 161, 153, 191, 237, 293, 300, 272, 267, 254]
yy = [145, 131, 112, 59, 29, 14, 48, 91, 136, 137, 172]
colors = np.vstack([[0.0, 0.0, 1.0, 1.0]] * len(xx)).astype(np.float32)
points = gfx.Points(
gfx.Geometry(positions=[(x, y, 0) for x, y in zip(xx, yy)], colors=colors),
gfx.PointsMaterial(color_mode="vertex", size=10),
)
points.local.z = 1 # move points in front of the image
scene.add(points)
previous_selection = None
def event_handler(event):
print(
f"Canvas click coordinates: {event.x, event.y}\n"
f"Click position in coordinate system of image, i.e. data coordinates of click event: {event.pick_info['index']}\n"
f"Other `pick_info`: {event.pick_info}"
)
global previous_selection
if previous_selection is not None:
# reset colors to blue
blues = np.vstack([[0.0, 0.0, 1.0, 1.0]] * 3).astype(np.float32)
points.geometry.colors.data[previous_selection] = blues
for idx in previous_selection.tolist():
points.geometry.colors.update_range(idx, size=1)
# set the color of the 3 closest points to red
positions = points.geometry.positions.data
event_position = np.array([*event.pick_info["index"], 0])
closest = np.linalg.norm(positions - event_position, axis=1).argsort()
points.geometry.colors.data[closest[:3]] = np.array([1.0, 0.0, 0.0, 1.0])
for idx in closest[:3].tolist():
# only mark the changed points for synchronization to the GPU
points.geometry.colors.update_range(idx, size=1)
previous_selection = closest[:3]
renderer.request_draw()
image.add_event_handler(event_handler, "click")
if __name__ == "__main__":
canvas.request_draw(lambda: renderer.render(scene, camera))
run()
Total running time of the script: (0 minutes 0.631 seconds)