PyImGui + Aiohttp example, with main sync thread for window and second thread for asyncio

pyimgui_aiohttp_example.py

from imgui.integrations.glfw import GlfwRenderer
import OpenGL.GL as gl
import traceback
import threading
import asyncio
import aiohttp
import imgui
import glfw
import sys

url = "https://google.com/"
html = ""


async def fetch_url():
    global url, html
    html = ""
    try:
        async with aiohttp.ClientSession() as cs:
            async with cs.get(url) as req:
                html = await req.text()
    except Exception:
        html = "The request failed:\n" + "".join(traceback.format_exception(*sys.exc_info()))


def impl_glfw_init():
    # This initializes the window backend
    # No need to understand this function
    # Taken from https://github.com/pyimgui/pyimgui/blob/master/doc/examples/integrations_glfw3.py
    width, height = 560, 680
    window_name = "PyImGui Aiohttp Example"

    if not glfw.init():
        print("Could not initialize OpenGL context")
        sys.exit(1)

    # OS X supports only forward-compatible core profiles from 3.2
    glfw.window_hint(glfw.CONTEXT_VERSION_MAJOR, 3)
    glfw.window_hint(glfw.CONTEXT_VERSION_MINOR, 3)
    glfw.window_hint(glfw.OPENGL_PROFILE, glfw.OPENGL_CORE_PROFILE)

    glfw.window_hint(glfw.OPENGL_FORWARD_COMPAT, gl.GL_TRUE)

    # Create a windowed mode window and its OpenGL context
    window = glfw.create_window(int(width), int(height), window_name, None, None)
    glfw.make_context_current(window)

    if not window:
        glfw.terminate()
        print("Could not initialize Window")
        sys.exit(1)

    return window


def main():
    global url, html

    # Setup window:
    imgui.create_context()
    window = impl_glfw_init()
    impl = GlfwRenderer(window)

    while not glfw.window_should_close(window):

        # Process events and inputs, so GUI is responsive:
        glfw.poll_events()
        impl.process_inputs()
        imgui.new_frame()

        # Your actual code for the window goes here

        # Setup main fullscreen window:
        imgui.set_next_window_position(0, 0)
        imgui.set_next_window_size(*impl.io.display_size, imgui.ALWAYS)
        with imgui.begin(

            # All ImGui widgets and items need to have labels. You cannot have "". Prefix with ## to hide them:
            "##Main Window",
            flags=(
                imgui.WINDOW_NO_MOVE |
                imgui.WINDOW_NO_RESIZE |
                imgui.WINDOW_NO_COLLAPSE |
                imgui.WINDOW_NO_TITLE_BAR |
                imgui.WINDOW_NO_SAVED_SETTINGS |
                imgui.WINDOW_HORIZONTAL_SCROLLING_BAR
            )
        ):

            # Main window content

            # The render loop runs every frame. Because of this you give widgets their initial value and they
            # give back their new value. Many widgets return two things: a bool for whether the value changed
            # this frame, and the actual new value:
            url_changed, url = imgui.input_text("##URL", url, 999)

            # By default each widget is on its own line. This sets the render cursor to stay on the same line.
            # You can also do imgui.same_line(123) to set the horizontal position of the next element:
            imgui.same_line()

            # Buttons return one thing: whether they were pressed or not in this frame. This makes adding
            # callbacks to them as easy as putting them in an if check:
            if imgui.button("Fetch!"):

                # Run async coroutine in separate async thread:
                asyncio.run_coroutine_threadsafe(fetch_url(), loop)

            # Render the html as plain text:
            imgui.text(html)

        # Clear previous frame and add background color:
        gl.glClearColor(0.0, 0.0, 0.0, 1)
        gl.glClear(gl.GL_COLOR_BUFFER_BIT)

        # Render and show the new frame:
        imgui.render()
        impl.render(imgui.get_draw_data())
        glfw.swap_buffers(window)

    # Cleanup:
    impl.shutdown()
    glfw.terminate()


if __name__ == "__main__":

    # Setup async loop in separate thread:
    loop = asyncio.new_event_loop()
    threading.Thread(target=lambda: [asyncio.set_event_loop(loop), loop.run_forever()], daemon=True).start()

    # Start ImGui render loop in main sync thread:
    main()