TravelContentCreator/domain/poster/poster_renderer.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""
海报渲染器
负责海报图片的渲染和输出
"""

import logging
import base64
from io import BytesIO
from typing import Dict, Any, Optional, List, Tuple
from pathlib import Path

logger = logging.getLogger(__name__)

try:
    from PIL import Image
    PIL_AVAILABLE = True
except ImportError:
    PIL_AVAILABLE = False


class PosterRenderer:
    """
    海报渲染器
    
    职责：
    - 调用模板渲染海报图片
    - 处理图片格式转换
    - 管理输出文件
    """
    
    def __init__(self, output_dir: Optional[str] = None):
        """
        初始化渲染器
        
        Args:
            output_dir: 输出目录
        """
        self._output_dir = Path(output_dir) if output_dir else None
        self.logger = logging.getLogger(f"{__name__}.PosterRenderer")
    
    def render(
        self,
        template_handler,
        images: List['Image.Image'],
        content: Dict[str, Any],
        output_format: str = 'png'
    ) -> Dict[str, Any]:
        """
        渲染海报
        
        Args:
            template_handler: 模板处理器实例
            images: 输入图片列表
            content: 海报内容
            output_format: 输出格式 (png, json, both)
            
        Returns:
            渲染结果字典
        """
        try:
            self.logger.info(f"开始渲染海报，格式: {output_format}")
            
            # 获取第一张图片作为背景
            background = images[0] if images else None
            
            # 检查模板是否支持统一渲染
            if hasattr(template_handler, '_unified_render'):
                return self._render_unified(
                    template_handler, background, content, output_format
                )
            
            # 使用传统渲染
            return self._render_legacy(
                template_handler, images, content, output_format
            )
            
        except Exception as e:
            self.logger.error(f"渲染失败: {e}")
            return {"success": False, "error": str(e)}
    
    def _render_unified(
        self,
        template_handler,
        background: Optional['Image.Image'],
        content: Dict[str, Any],
        output_format: str
    ) -> Dict[str, Any]:
        """使用统一渲染方法"""
        try:
            result = template_handler._unified_render(
                images=background,
                content=content,
                theme_color=None,
                glass_intensity=1.5,
                output_format=output_format
            )
            
            if "error" in result:
                return {"success": False, "error": result["error"]}
            
            return {
                "success": True,
                "image": result.get("image"),
                "fabric_json": result.get("fabric_json"),
                "layout_params": result.get("layout_params"),
            }
            
        except Exception as e:
            self.logger.error(f"统一渲染失败: {e}")
            return {"success": False, "error": str(e)}
    
    def _render_legacy(
        self,
        template_handler,
        images: List['Image.Image'],
        content: Dict[str, Any],
        output_format: str
    ) -> Dict[str, Any]:
        """使用传统渲染方法"""
        try:
            # 调用模板的 generate 方法
            if hasattr(template_handler, 'generate'):
                result = template_handler.generate(images, content)
                
                if isinstance(result, Image.Image):
                    return {
                        "success": True,
                        "image": result,
                    }
                elif isinstance(result, dict):
                    return {
                        "success": True,
                        **result
                    }
            
            return {"success": False, "error": "模板不支持渲染"}
            
        except Exception as e:
            self.logger.error(f"传统渲染失败: {e}")
            return {"success": False, "error": str(e)}
    
    def image_to_base64(self, image: 'Image.Image', format: str = 'PNG') -> str:
        """
        将图片转换为 base64
        
        Args:
            image: PIL Image
            format: 图片格式
            
        Returns:
            base64 字符串
        """
        buffer = BytesIO()
        image.save(buffer, format=format)
        return base64.b64encode(buffer.getvalue()).decode('utf-8')
    
    def base64_to_image(self, base64_str: str) -> Optional['Image.Image']:
        """
        将 base64 转换为图片
        
        Args:
            base64_str: base64 字符串
            
        Returns:
            PIL Image
        """
        try:
            # 移除可能的 data URL 前缀
            if ',' in base64_str:
                base64_str = base64_str.split(',', 1)[1]
            
            image_data = base64.b64decode(base64_str)
            image = Image.open(BytesIO(image_data))
            
            if image.mode != 'RGBA':
                image = image.convert('RGBA')
            
            return image
            
        except Exception as e:
            self.logger.error(f"base64 转图片失败: {e}")
            return None
    
    def save_image(
        self,
        image: 'Image.Image',
        filename: str,
        format: str = 'PNG',
        quality: int = 95
    ) -> Optional[Path]:
        """
        保存图片到文件
        
        Args:
            image: PIL Image
            filename: 文件名
            format: 图片格式
            quality: 质量
            
        Returns:
            保存路径
        """
        if not self._output_dir:
            self.logger.warning("未设置输出目录")
            return None
        
        try:
            self._output_dir.mkdir(parents=True, exist_ok=True)
            file_path = self._output_dir / filename
            
            save_kwargs = {'format': format}
            if format.upper() in ('JPEG', 'WEBP'):
                save_kwargs['quality'] = quality
            
            image.save(file_path, **save_kwargs)
            self.logger.info(f"图片已保存: {file_path}")
            
            return file_path
            
        except Exception as e:
            self.logger.error(f"保存图片失败: {e}")
            return None
    
    def resize_image(
        self,
        image: 'Image.Image',
        target_size: Tuple[int, int],
        mode: str = 'cover'
    ) -> 'Image.Image':
        """
        调整图片尺寸
        
        Args:
            image: PIL Image
            target_size: 目标尺寸 (width, height)
            mode: 调整模式 (cover, contain, stretch)
            
        Returns:
            调整后的图片
        """
        target_width, target_height = target_size
        
        if mode == 'stretch':
            return image.resize(target_size, Image.Resampling.LANCZOS)
        
        # 计算缩放比例
        scale_x = target_width / image.width
        scale_y = target_height / image.height
        
        if mode == 'cover':
            scale = max(scale_x, scale_y)
        else:  # contain
            scale = min(scale_x, scale_y)
        
        new_width = int(image.width * scale)
        new_height = int(image.height * scale)
        
        resized = image.resize((new_width, new_height), Image.Resampling.LANCZOS)
        
        if mode == 'cover':
            # 裁剪到目标尺寸
            left = (new_width - target_width) // 2
            top = (new_height - target_height) // 2
            return resized.crop((left, top, left + target_width, top + target_height))
        else:
            # 创建目标尺寸画布并居中
            result = Image.new('RGBA', target_size, (255, 255, 255, 255))
            x = (target_width - new_width) // 2
            y = (target_height - new_height) // 2
            result.paste(resized, (x, y))
            return result