Flutter — উইজেট ট্রি ও রেন্ডারিং ইঞ্জিন

# একটি Flutter-অনুপ্রাণিত উইজেট ট্রি -- সবকিছুই একটি উইজেট, এমনকি Padding/Column/Row-ও
# প্রতিটি উইজেট: {"type": ..., "props": {...}, "children": [...]}

tree = {
    "type": "Padding",
    "props": {"left": 16, "top": 20},
    "children": [
        {
            "type": "Column",
            "props": {},
            "children": [
                {"type": "Container", "props": {"width": 240, "height": 60, "color": "blue"}, "children": []},
                {"type": "Text", "props": {"content": "রাহুল আহমেদ", "width": 140}, "children": []},
                {
                    "type": "Row",
                    "props": {},
                    "children": [
                        {"type": "Text", "props": {"content": "ফলো", "width": 60}, "children": []},
                        {"type": "Text", "props": {"content": "মেসেজ", "width": 80}, "children": []},
                    ],
                },
            ],
        }
    ],
}

TEXT_HEIGHT = 24  # প্রতিটি Text/Row-এর ধরে নেওয়া লাইন-উচ্চতা (px) -- এই সরলীকৃত লেআউট মডেলে স্থির

def widget_height(widget):
    t = widget["type"]
    if t == "Container":
        return widget["props"]["height"]
    if t in ("Text", "Row"):
        return TEXT_HEIGHT
    return 0

def widget_width(widget):
    t = widget["type"]
    if t == "Container":
        return widget["props"]["width"]
    if t == "Text":
        return widget["props"]["width"]
    return 0

def render(widget, x=0, y=0):
    """ট্রি হেঁটে প্রকৃত ড্র-অপারেশনের তালিকা তৈরি করে -- Padding/Column/Row নিজে কিছু আঁকে না"""
    ops = []
    t = widget["type"]

    if t == "Padding":
        left = widget["props"].get("left", 0)
        top = widget["props"].get("top", 0)
        for child in widget["children"]:
            ops.extend(render(child, x + left, y + top))

    elif t == "Column":
        cur_y = y
        for child in widget["children"]:
            ops.extend(render(child, x, cur_y))
            cur_y += widget_height(child)

    elif t == "Row":
        cur_x = x
        for child in widget["children"]:
            ops.extend(render(child, cur_x, y))
            cur_x += widget_width(child)

    elif t == "Container":
        w = widget["props"]["width"]
        h = widget["props"]["height"]
        color = widget["props"].get("color", "black")
        ops.append(("draw_rect", x, y, w, h, color))

    elif t == "Text":
        content = widget["props"]["content"]
        ops.append(("draw_text", x, y, content))

    return ops

draw_ops = render(tree)

print(f"মোট ড্র-অপারেশন: {len(draw_ops)}\n")
for op in draw_ops:
    print(op)

def count_widgets(widget):
    return 1 + sum(count_widgets(c) for c in widget["children"])

total_widgets = count_widgets(tree)
print(f"\nমোট উইজেট (কাঠামোগত + দৃশ্যমান): {total_widgets}")
print(f"যার মধ্যে প্রকৃত ড্র-অপারেশন তৈরি করেছে: {len(draw_ops)} (বাকি {total_widgets - len(draw_ops)}টি শুধু কাঠামো/স্পেসিং)")