From 8b2a724d9046d7eb9cb20c18e6c5ec433c5c3379 Mon Sep 17 00:00:00 2001
From: Pascal Thomet <pthomet@gmail.com>
Date: Wed, 19 Feb 2025 20:12:51 +0100
Subject: [PATCH] Python backends: add an example using wgpu (WebGPU for
 Python)

https://github.com/pygfx/wgpu-py provides a nice way to run imgui apps using Python + WebGPU.
---
 .../demos_cpp/demo_immapp_launcher.cpp        |  6 +-
 .../demos_python/demo_immapp_launcher.py      |  5 ++
 .../examples/example_python_backend_wgpu.py   | 89 +++++++++++++++++++
 3 files changed, 99 insertions(+), 1 deletion(-)
 create mode 100644 bindings/imgui_bundle/python_backends/examples/example_python_backend_wgpu.py

diff --git a/bindings/imgui_bundle/demos_cpp/demo_immapp_launcher.cpp b/bindings/imgui_bundle/demos_cpp/demo_immapp_launcher.cpp
index e27e049b..fb1271ac 100644
--- a/bindings/imgui_bundle/demos_cpp/demo_immapp_launcher.cpp
+++ b/bindings/imgui_bundle/demos_cpp/demo_immapp_launcher.cpp
@@ -70,7 +70,11 @@ std::function<void()> makeGui()
             "Python: how to use ImGui with pyglet using a *full python* backend",
             true
         },
-
+        DemoApp{
+            "example_python_backend_wgpu",
+            "Python: how to use ImGui with wgpu (WebGPU for Python)",
+            true,
+        },
     };
     std::string demoPythonBackendFolder = DemoPythonFolder() + + "/../python_backends/examples";
     DemoAppTable demoAppTable(
diff --git a/bindings/imgui_bundle/demos_python/demo_immapp_launcher.py b/bindings/imgui_bundle/demos_python/demo_immapp_launcher.py
index 1150ec2b..60347754 100644
--- a/bindings/imgui_bundle/demos_python/demo_immapp_launcher.py
+++ b/bindings/imgui_bundle/demos_python/demo_immapp_launcher.py
@@ -90,6 +90,11 @@ def make_gui() -> GuiFunction:
             "Python: how to use ImGui with pyglet using a *full python* backend",
             is_python_backend_demo=True,
         ),
+        DemoApp(
+            "example_python_backend_wgpu",
+            "Python: how to use ImGui with wgpu (WebGPU for Python)",
+            is_python_backend_demo=True,
+        ),
     ]
 
     this_dir = os.path.dirname(__file__)
diff --git a/bindings/imgui_bundle/python_backends/examples/example_python_backend_wgpu.py b/bindings/imgui_bundle/python_backends/examples/example_python_backend_wgpu.py
new file mode 100644
index 00000000..586f144b
--- /dev/null
+++ b/bindings/imgui_bundle/python_backends/examples/example_python_backend_wgpu.py
@@ -0,0 +1,89 @@
+# wgpu (see https://github.com/pygfx/wgpu-py and https://wgpu-py.readthedocs.io/en/stable/)
+# provides a Python implementation of WebGPU together with
+# an easy-to-use interface to Dear ImGui Bundle!
+#
+# See more examples in the wgpu-py repository here:
+#    https://github.com/pygfx/wgpu-py/tree/main/examples
+#    (look for examples whose name starts with "imgui_")
+#
+# Requirements: install wgpu with `pip install wgpu`
+
+import wgpu
+import sys
+from imgui_bundle import imgui, imgui_ctx
+from wgpu.gui.auto import WgpuCanvas, run
+from wgpu.utils.imgui import ImguiRenderer
+
+
+# Create a canvas to render to
+canvas = WgpuCanvas(title="imgui", size=(640, 480))
+
+# Create a wgpu device
+adapter = wgpu.gpu.request_adapter_sync(power_preference="high-performance")
+device = adapter.request_device_sync()
+
+app_state = {"text": "Hello, World\nLorem ipsum, etc.\netc."}
+imgui_renderer = ImguiRenderer(device, canvas)
+
+
+def update_gui():
+    imgui.new_frame()
+    if imgui.begin_main_menu_bar():
+        if imgui.begin_menu("File", True):
+            clicked_quit, _ = imgui.menu_item("Quit", "Cmd+Q", False, True)
+            if clicked_quit:
+                sys.exit(0)
+
+            imgui.end_menu()
+        imgui.end_main_menu_bar()
+
+    imgui.set_next_window_size((300, 0), imgui.Cond_.appearing)
+    imgui.set_next_window_pos((0, 20), imgui.Cond_.appearing)
+
+    imgui.begin("Custom window", None)
+    imgui.text("Example Text")
+
+    if imgui.button("Hello"):
+        print("World")
+
+    _, app_state["text"] = imgui.input_text_multiline(
+        "Edit", app_state["text"], imgui.ImVec2(200, 200)
+    )
+    io = imgui.get_io()
+    imgui.text(
+        f"""
+    Keyboard modifiers:
+        {io.key_ctrl=}
+        {io.key_alt=}
+        {io.key_shift=}
+        {io.key_super=}"""
+    )
+
+    if imgui.button("Open popup"):
+        imgui.open_popup("my popup")
+    with imgui_ctx.begin_popup_modal("my popup") as popup:
+        if popup.visible:
+            imgui.text("Hello from popup!")
+            if imgui.button("Close popup"):
+                imgui.close_current_popup()
+
+    imgui.end()
+
+    imgui.end_frame()
+    imgui.render()
+
+    return imgui.get_draw_data()
+
+
+# set the GUI update function that gets called to return the draw data
+imgui_renderer.set_gui(update_gui)
+
+
+def draw_frame():
+    imgui_renderer.render()
+    canvas.request_draw()
+
+
+if __name__ == "__main__":
+    canvas.request_draw(draw_frame)
+    run()