Smooth scrolling and scroll multiplier for pyimgui

pyimgui_scrolling.py

from imgui.integrations.glfw import GlfwRenderer
import OpenGL.GL as gl
import imgui
import glfw


# Example usage
if __name__ == "__main__":
    imgui.create_context()
    window = impl_glfw_init()  # Get this here https://github.com/pyimgui/pyimgui/blob/24219a8d4338b6e197fa22af97f5f06d3b1fe9f7/doc/examples/integrations_glfw3.py
    impl = GlfwRenderer(window)

    smooth_scrolling = False
    smooth_scroll_speed = 8.0
    scroll_amount = 1.0
    scroll_energy = 0.0

    while not glfw.window_should_close(window):
        glfw.poll_events()
        impl.process_inputs()

        # The actual scroll modifiers
        # These must be applied before new_frame()!
        io = imgui.get_io()
        io.mouse_wheel *= scroll_amount  # Scroll multiplier / amount
        if smooth_scrolling:
            # Smooth scrolling
            scroll_energy += io.mouse_wheel
            if abs(scroll_energy) > 0.1:  # Scrolling threshold
                scroll_now = scroll_energy * io.delta_time * smooth_scroll_speed
                scroll_energy -= scroll_now
            else:
                scroll_now = 0.0
                scroll_energy = 0.0
            io.mouse_wheel = scroll_now

        imgui.new_frame()

        with imgui.begin("Example scrolling"):
            # Scroll modifiers settings
            imgui.begin_group()
            _, smooth_scrolling = imgui.checkbox("Enable smooth scrolling", smooth_scrolling)
            imgui.set_next_item_width(100)
            _, smooth_scroll_speed = imgui.input_float("Smooth scroll speed", smooth_scroll_speed, step=0.25)
            imgui.set_next_item_width(100)
            _, scroll_amount = imgui.input_float("Scroll amount", scroll_amount, step=0.25)
            imgui.end_group()
            imgui.same_line(spacing=20)
            # Scroll example
            with imgui.begin_child("Scroll region"):
                for i in range(200):
                    imgui.text(f"Some text {i}")
                    imgui.button(f"A button {i}")
                    imgui.text("")

        gl.glClearColor(0., 0., 0., 1)
        gl.glClear(gl.GL_COLOR_BUFFER_BIT)
        imgui.render()
        impl.render(imgui.get_draw_data())
        glfw.swap_buffers(window)

    impl.shutdown()
    glfw.terminate()