TravelContentCreator/poster_v2/layouts/overlay_center.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
布局B: 文字居中叠加在图片上
适用场景: 攻略、活动、大标题海报
"""

from typing import Tuple
from PIL import Image, ImageDraw

from .base import BaseLayout
from ..schemas.content import PosterContent
from ..schemas.theme import Theme
from ..renderers.text import TextRenderer


class OverlayCenterLayout(BaseLayout):
    """居中叠加布局"""
    
    # 字号配置
    TITLE_SIZE = 100
    SUBTITLE_SIZE = 36
    TAG_SIZE = 26
    
    def calculate_content_height(self, content: PosterContent, theme: Theme) -> int:
        """计算内容区域高度"""
        height = 0
        
        # 标题
        title_font = TextRenderer.get_title_font(self.TITLE_SIZE)
        _, title_h = TextRenderer.measure_text(content.title, title_font)
        height += title_h + 32  # 含装饰线
        
        # 副标题
        if content.subtitle:
            subtitle_font = TextRenderer.get_body_font(self.SUBTITLE_SIZE)
            _, sub_h = TextRenderer.measure_text(content.subtitle, subtitle_font)
            height += sub_h + 40
        
        height += 80  # padding
        
        return height
    
    def generate(self, content: PosterContent, theme: Theme, image_url: str = "") -> Image.Image:
        """生成海报"""
        self._reset_objects()
        
        # 创建渐变背景
        canvas = self.create_gradient_background(theme)
        
        # 如果有真实图片
        if content.image:
            img = content.image.copy().resize(self.size, Image.LANCZOS)
            canvas = img.convert("RGBA")
        
        # 背景图片 Fabric 对象
        self._add_object({
            "id": "background_image",
            "type": "image",
            "src": image_url,
            "left": 0, "top": 0,
            "width": self.width, "height": self.height,
            "selectable": True,
        })
        
        # 暗化叠加
        canvas = self.effect.darken_overlay(canvas, alpha=60)
        draw = ImageDraw.Draw(canvas)
        
        # 暗化遮罩 Fabric 对象
        self._add_object({
            "id": "dark_overlay",
            "type": "rect",
            "left": 0, "top": 0,
            "width": self.width, "height": self.height,
            "fill": "rgba(0,0,0,0.35)",
            "selectable": False,
        })
        
        text_white = theme.text_rgb
        accent = theme.accent_rgb
        
        # 字体
        title_font = TextRenderer.get_title_font(self.TITLE_SIZE)
        subtitle_font = TextRenderer.get_body_font(self.SUBTITLE_SIZE)
        tag_font = TextRenderer.get_body_font(self.TAG_SIZE)
        
        # 计算内容高度和位置
        content_height = self.calculate_content_height(content, theme)
        center_y = (self.height - content_height) // 2
        
        # === 装饰线 (标题上方) ===
        line_w = 80
        self.shape.draw_decorator_line(
            draw, ((self.width - line_w) // 2, center_y), line_w, (*accent, 200)
        )
        center_y += 32
        
        # === 标题 (居中，自适应大小) ===
        content_width = self.width - self.MARGIN * 2
        adaptive_font = TextRenderer.get_adaptive_title_font(
            content.title, content_width, base_size=self.TITLE_SIZE, min_size=64
        )
        title_w, title_h = TextRenderer.measure_text(content.title, adaptive_font)
        title_x = (self.width - title_w) // 2
        TextRenderer.draw_text_with_shadow(
            draw, (title_x, center_y), content.title, adaptive_font,
            theme.text, shadow_color=(0, 0, 0, 80), offset=(3, 3)
        )
        
        # 标题 Fabric 对象
        self._add_object({
            "id": "title",
            "type": "textbox",
            "text": content.title,
            "left": title_x, "top": center_y,
            "width": content_width,
            "fontSize": adaptive_font.size,
            "fontFamily": "PingFang SC, Microsoft YaHei, sans-serif",
            "fontWeight": "bold",
            "fill": theme.text,
            "textAlign": "center",
            "shadow": "rgba(0,0,0,0.5) 3px 3px 6px",
            "selectable": True,
        })
        center_y += title_h + 24
        
        # === 副标题 (居中) ===
        if content.subtitle:
            sub_w, sub_h = TextRenderer.measure_text(content.subtitle, subtitle_font)
            sub_x = (self.width - sub_w) // 2
            draw.text((sub_x, center_y), content.subtitle, 
                     font=subtitle_font, fill=(*text_white, 200))
            
            # 副标题 Fabric 对象
            self._add_object({
                "id": "subtitle",
                "type": "textbox",
                "text": content.subtitle,
                "left": sub_x, "top": center_y,
                "width": content_width,
                "fontSize": self.SUBTITLE_SIZE,
                "fontFamily": "PingFang SC, Microsoft YaHei, sans-serif",
                "fill": "rgba(255,255,255,0.85)",
                "textAlign": "center",
                "selectable": True,
            })
            center_y += sub_h + 40
        
        # === 装饰线 (副标题下方) ===
        self.shape.draw_decorator_line(
            draw, ((self.width - line_w) // 2, center_y), line_w, (*accent, 200)
        )
        
        # === 底部标签 (只在有价格时显示) ===
        if content.tags and content.price:
            tag_y = self.height - 120
            # 计算总宽度
            total_w = sum(
                TextRenderer.measure_text(f"#{t}", tag_font)[0] + 30
                for t in content.tags
            ) - 30
            tag_x = (self.width - total_w) // 2
            
            for tag in content.tags:
                tag_text = f"#{tag}"
                tag_w, _ = TextRenderer.measure_text(tag_text, tag_font)
                
                self.shape.draw_rounded_rect(draw,
                    (tag_x - 10, tag_y, tag_x + tag_w + 10, tag_y + 42),
                    radius=21, fill=(*accent, 50))
                draw.text((tag_x, tag_y + 8), tag_text, 
                         font=tag_font, fill=text_white)
                tag_x += tag_w + 30
        
        return canvas