feat: add ResolutionSelector node for aspect ratio and megapixel-based resolution calculation

Amp-Thread-ID: https://ampcode.com/threads/T-019c179e-cd8c-768f-ae66-207c7a53c01d

comfy_extras/nodes_resolution.py

@@ -0,0 +1,82 @@
+from __future__ import annotations
+import math
+from enum import Enum
+from typing_extensions import override
+from comfy_api.latest import ComfyExtension, io
+
+
+class AspectRatio(str, Enum):
+    SQUARE = "1:1 (Square)"
+    PHOTO_H = "3:2 (Photo)"
+    STANDARD_H = "4:3 (Standard)"
+    WIDESCREEN_H = "16:9 (Widescreen)"
+    ULTRAWIDE_H = "21:9 (Ultrawide)"
+    PHOTO_V = "2:3 (Portrait Photo)"
+    STANDARD_V = "3:4 (Portrait Standard)"
+    WIDESCREEN_V = "9:16 (Portrait Widescreen)"
+
+
+ASPECT_RATIOS: dict[str, tuple[int, int]] = {
+    "1:1 (Square)": (1, 1),
+    "3:2 (Photo)": (3, 2),
+    "4:3 (Standard)": (4, 3),
+    "16:9 (Widescreen)": (16, 9),
+    "21:9 (Ultrawide)": (21, 9),
+    "2:3 (Portrait Photo)": (2, 3),
+    "3:4 (Portrait Standard)": (3, 4),
+    "9:16 (Portrait Widescreen)": (9, 16),
+}
+
+
+class ResolutionSelector(io.ComfyNode):
+    """Calculate width and height from aspect ratio and megapixel target."""
+
+    @classmethod
+    def define_schema(cls):
+        return io.Schema(
+            node_id="ResolutionSelector",
+            display_name="Resolution Selector",
+            category="utils",
+            description="Calculate width and height from aspect ratio and megapixel target. Useful for setting up Empty Latent Image dimensions.",
+            inputs=[
+                io.Combo.Input(
+                    "aspect_ratio",
+                    options=AspectRatio,
+                    default=AspectRatio.SQUARE,
+                    tooltip="The aspect ratio for the output dimensions.",
+                ),
+                io.Float.Input(
+                    "megapixels",
+                    default=1.0,
+                    min=0.1,
+                    max=16.0,
+                    step=0.1,
+                    tooltip="Target total megapixels. 1.0 MP ≈ 1024×1024 for square.",
+                ),
+            ],
+            outputs=[
+                io.Int.Output("width", tooltip="Calculated width in pixels (multiple of 8)."),
+                io.Int.Output("height", tooltip="Calculated height in pixels (multiple of 8)."),
+            ],
+        )
+
+    @classmethod
+    def execute(cls, aspect_ratio: str, megapixels: float) -> io.NodeOutput:
+        w_ratio, h_ratio = ASPECT_RATIOS[aspect_ratio]
+        total_pixels = megapixels * 1024 * 1024
+        scale = math.sqrt(total_pixels / (w_ratio * h_ratio))
+        width = round(w_ratio * scale / 8) * 8
+        height = round(h_ratio * scale / 8) * 8
+        return io.NodeOutput(width, height)
+
+
+class ResolutionExtension(ComfyExtension):
+    @override
+    async def get_node_list(self) -> list[type[io.ComfyNode]]:
+        return [
+            ResolutionSelector,
+        ]
+
+
+async def comfy_entrypoint() -> ResolutionExtension:
+    return ResolutionExtension()

nodes.py

@@ -2427,6 +2427,7 @@ async def init_builtin_extra_nodes():
         "nodes_audio_encoder.py",
         "nodes_rope.py",
         "nodes_logic.py",
+        "nodes_resolution.py",
         "nodes_nop.py",
         "nodes_kandinsky5.py",
         "nodes_wanmove.py",