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69 lines
2.0 KiB
Python
69 lines
2.0 KiB
Python
def scroll_event_cb(e):
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cont = e.get_target()
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cont_a = lv.area_t()
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cont.get_coords(cont_a)
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cont_y_center = cont_a.y1 + cont_a.get_height() // 2
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r = cont.get_height() * 7 // 10
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child_cnt = cont.get_child_cnt()
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for i in range(child_cnt):
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child = cont.get_child(i)
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child_a = lv.area_t()
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child.get_coords(child_a)
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child_y_center = child_a.y1 + child_a.get_height() // 2
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diff_y = child_y_center - cont_y_center
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diff_y = abs(diff_y)
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# Get the x of diff_y on a circle.
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# If diff_y is out of the circle use the last point of the circle (the radius)
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if diff_y >= r:
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x = r
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else:
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# Use Pythagoras theorem to get x from radius and y
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x_sqr = r * r - diff_y * diff_y
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res = lv.sqrt_res_t()
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lv.sqrt(x_sqr, res, 0x8000) # Use lvgl's built in sqrt root function
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x = r - res.i
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# Translate the item by the calculated X coordinate
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child.set_style_translate_x(x, 0)
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# Use some opacity with larger translations
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opa = lv.map(x, 0, r, lv.OPA.TRANSP, lv.OPA.COVER)
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child.set_style_opa(lv.OPA.COVER - opa, 0)
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#
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# Translate the object as they scroll
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#
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cont = lv.obj(lv.scr_act())
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cont.set_size(200, 200)
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cont.center()
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cont.set_flex_flow(lv.FLEX_FLOW.COLUMN)
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cont.add_event_cb(scroll_event_cb, lv.EVENT.SCROLL, None)
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cont.set_style_radius(lv.RADIUS.CIRCLE, 0)
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cont.set_style_clip_corner(True, 0)
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cont.set_scroll_dir(lv.DIR.VER)
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cont.set_scroll_snap_y(lv.SCROLL_SNAP.CENTER)
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cont.set_scrollbar_mode(lv.SCROLLBAR_MODE.OFF)
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for i in range(20):
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btn = lv.btn(cont)
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btn.set_width(lv.pct(100))
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label = lv.label(btn)
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label.set_text("Button " + str(i))
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# Update the buttons position manually for first*
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lv.event_send(cont, lv.EVENT.SCROLL, None)
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# Be sure the fist button is in the middle
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#lv.obj.scroll_to_view(cont.get_child(0), lv.ANIM.OFF)
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cont.get_child(0).scroll_to_view(lv.ANIM.OFF)
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