KCGL/inventory-backend/app/services/print/label_service.py

import socket
import base64
import os
from io import BytesIO
from PIL import Image, ImageDraw, ImageFont

# 引入条形码生成库
try:
    import barcode
    from barcode.writer import ImageWriter
except ImportError:
    print("❌ 警告: 未安装 python-barcode 库，无法生成真实条形码。请执行: pip install python-barcode")


class LabelPrintService:
    PRINTER_IP = "192.168.9.205"
    PRINTER_PORT = 9100

    # ================= 1. 尺寸与分辨率配置 (300 DPI) =================
    DOTS_PER_MM = 12  # 300 DPI
    LABEL_WIDTH_MM = 40
    LABEL_HEIGHT_MM = 30

    # 画布像素: 40mm -> 480px, 30mm -> 360px
    LABEL_WIDTH = int(LABEL_WIDTH_MM * DOTS_PER_MM)
    LABEL_HEIGHT = int(LABEL_HEIGHT_MM * DOTS_PER_MM)

    # 顶部留白
    TOP_MARGIN_MM = 1.5
    TOP_MARGIN_PX = int(TOP_MARGIN_MM * DOTS_PER_MM)

    # 定义左边距 (3mm) - 用于正文左对齐
    MARGIN_LEFT = int(3 * DOTS_PER_MM)
    # 定义右边距 (防止文字贴边，留 2mm)
    MARGIN_RIGHT = int(2 * DOTS_PER_MM)

    # 计算文字允许的最大像素宽度
    MAX_TEXT_WIDTH = LABEL_WIDTH - MARGIN_LEFT - MARGIN_RIGHT

    @staticmethod
    def _get_font(size):
        """获取字体"""
        # 尝试加载中文字体，否则乱码
        font_names = ["simhei.ttf", "msyh.ttf", "SimHei.ttf", "arial.ttf"]
        base_dirs = [os.getcwd(), os.path.dirname(__file__)]

        for d in base_dirs:
            for name in font_names:
                path = os.path.join(d, name)
                if os.path.exists(path):
                    return ImageFont.truetype(path, size)
        return ImageFont.load_default()

    @staticmethod
    def _generate_barcode_image(content, width_px, height_px):
        """生成真实的条形码图片"""
        try:
            if not content: content = "0000000000"
            code128 = barcode.get('code128', content, writer=ImageWriter())
            buffer = BytesIO()
            code128.write(buffer, options={"write_text": False, "module_height": 10.0, "quiet_zone": 1.0})
            buffer.seek(0)
            bc_img = Image.open(buffer)
            return bc_img.resize((width_px, height_px), Image.Resampling.LANCZOS)
        except Exception as e:
            print(f"条形码生成失败: {e}")
            return Image.new('RGB', (width_px, height_px), color='black')

    @staticmethod
    def draw_text_wrap(draw, text, x, y, font, max_width, line_spacing=0):
        """
        [核心功能] 自动换行绘制文本
        :param line_spacing: 行与行之间的额外像素距离
        :return: 绘制结束后的 Y 坐标
        """
        if not text:
            return y

        lines = []
        current_line = ""

        # 1. 计算折行逻辑
        for char in text:
            # 预测加入新字符后的宽度
            test_line = current_line + char
            width = font.getlength(test_line)

            if width <= max_width:
                current_line = test_line
            else:
                # 宽度超出，将当前行存入，新字符作为下一行开头
                lines.append(current_line)
                current_line = char

        # 将最后剩余的内容加入
        if current_line:
            lines.append(current_line)

        # 2. 绘制每一行
        current_y = y
        font_height = font.size  # 获取字号高度

        for line in lines:
            # 边界检查：如果超出图片高度，停止绘制
            if current_y + font_height > LabelPrintService.LABEL_HEIGHT:
                break

            # 绘制文字 (stroke_width=1 加粗)
            draw.text((x, current_y), line, font=font, fill='black', stroke_width=1, stroke_fill='black')

            # 更新 Y 坐标 (字高 + 行间距)
            current_y += font_height + line_spacing

        return current_y

    @staticmethod
    def _create_image_object(data):
        """
        [绘图层] 生成标签图片
        """
        # 1. 创建画布
        img = Image.new('RGB', (LabelPrintService.LABEL_WIDTH, LabelPrintService.LABEL_HEIGHT), color='white')
        d = ImageDraw.Draw(img)

        # 2. 字体配置
        # [保持] 正文内容维持 24号，以节省空间
        font_body = LabelPrintService._get_font(24)
        # [修改] 编码(SKU)字体设置为 30号
        font_code = LabelPrintService._get_font(30)

        # 3. 数据准备
        sku_code = data.get('sku')
        if not sku_code:
            sku_code = data.get('serial_number') or str(data.get('global_print_id', '0000000000')).zfill(10)

        # ==================== 绘制布局 ====================

        GLOBAL_OFFSET_X = LabelPrintService.MARGIN_LEFT
        CURRENT_Y = LabelPrintService.TOP_MARGIN_PX

        # --- A. 绘制条形码 (居中) ---
        bc_w = int(37 * LabelPrintService.DOTS_PER_MM)
        bc_h = int(8 * LabelPrintService.DOTS_PER_MM)  # 高度

        bc_img = LabelPrintService._generate_barcode_image(sku_code, bc_w, bc_h)

        # [修改核心] 计算条形码的居中 X 坐标
        # 公式：(标签总宽 - 条码宽) / 2
        bc_x_centered = (LabelPrintService.LABEL_WIDTH - bc_w) // 2

        img.paste(bc_img, (bc_x_centered, CURRENT_Y))

        # --- B. 绘制条形码下方数字 (居中 + 30号字) ---
        text_y_pos = CURRENT_Y + bc_h + 2

        # [修改核心] 计算文字宽度 并 居中
        text_width = font_code.getlength(sku_code)
        text_x_centered = (LabelPrintService.LABEL_WIDTH - text_width) // 2

        d.text(
            (text_x_centered, text_y_pos),
            sku_code,
            font=font_code,  # 使用30号字体
            fill='black',
            stroke_width=1,
            stroke_fill='black'
        )

        # 更新 Y 坐标，准备开始绘制正文
        # 30(字高) + 4(间距)
        CURRENT_Y = text_y_pos + 30 + 4

        # --- C. 绘制其余信息 (保持左对齐 + 24号字 + 自动换行) ---

        # 1. 准备完整文本
        name = str(data.get('material_name', '') or '-')
        spec = str(data.get('spec_model', '') or '-')
        loc = str(data.get('warehouse_loc', '') or '-')

        cat = str(data.get('category', '') or '')
        typ = str(data.get('material_type', '') or '')
        attr = f"{cat}/{typ}"

        # 底部文字
        bottom_text = ""
        if data.get('print_no'):
            val = str(data.get('print_no'))
            label_type = data.get('print_label', '')
            bottom_text = f"{'SN' if label_type == '序' else 'BN' if label_type == '批' else 'NO'}: {val}"
        elif data.get('serial_number'):
            bottom_text = f"SN: {data.get('serial_number')}"
        elif data.get('batch_number'):
            bottom_text = f"BN: {data.get('batch_number')}"
        else:
            bottom_text = f"NO: {sku_code}"

        # 2. 依次调用自动换行绘制函数 (使用正文字体 font_body，且坐标使用 GLOBAL_OFFSET_X)

        # 绘制名称
        CURRENT_Y = LabelPrintService.draw_text_wrap(
            d, f"名: {name}", GLOBAL_OFFSET_X, CURRENT_Y, font_body, LabelPrintService.MAX_TEXT_WIDTH, line_spacing=2
        )
        CURRENT_Y += 2

        # 绘制规格
        CURRENT_Y = LabelPrintService.draw_text_wrap(
            d, f"规: {spec}", GLOBAL_OFFSET_X, CURRENT_Y, font_body, LabelPrintService.MAX_TEXT_WIDTH, line_spacing=2
        )
        CURRENT_Y += 2

        # 绘制库位
        CURRENT_Y = LabelPrintService.draw_text_wrap(
            d, f"库: {loc}", GLOBAL_OFFSET_X, CURRENT_Y, font_body, LabelPrintService.MAX_TEXT_WIDTH, line_spacing=2
        )
        CURRENT_Y += 2

        # 绘制属性
        CURRENT_Y = LabelPrintService.draw_text_wrap(
            d, f"属: {attr}", GLOBAL_OFFSET_X, CURRENT_Y, font_body, LabelPrintService.MAX_TEXT_WIDTH, line_spacing=2
        )
        CURRENT_Y += 2

        # 绘制底部编号
        CURRENT_Y = LabelPrintService.draw_text_wrap(
            d, bottom_text, GLOBAL_OFFSET_X, CURRENT_Y, font_body, LabelPrintService.MAX_TEXT_WIDTH, line_spacing=2
        )

        return img

    @staticmethod
    def generate_preview_image(data):
        img = LabelPrintService._create_image_object(data)
        output_buffer = BytesIO()
        img.save(output_buffer, format='JPEG')
        base64_str = base64.b64encode(output_buffer.getvalue()).decode('utf-8')
        return f"data:image/jpeg;base64,{base64_str}"

    @staticmethod
    def send_to_printer(data):
        ip = LabelPrintService.PRINTER_IP
        port = LabelPrintService.PRINTER_PORT

        try:
            img_rgb = LabelPrintService._create_image_object(data)
            img_gray = img_rgb.convert('L')
            img_bw = img_gray.convert('1', dither=Image.Dither.NONE)
            bitmap_data = img_bw.tobytes()
            width_bytes = (img_bw.width + 7) // 8
            height_dots = img_bw.height
            header = (
                f"SIZE {LabelPrintService.LABEL_WIDTH_MM} mm, {LabelPrintService.LABEL_HEIGHT_MM} mm\r\n"
                "GAP 2 mm, 0 mm\r\n"
                "CLS\r\n"
                "DIRECTION 1\r\n"
                "REFERENCE 0, 0\r\n"
            ).encode('gbk')
            bitmap_cmd = f"BITMAP 0,0,{width_bytes},{height_dots},0,".encode('gbk')
            footer = b"\r\nPRINT 1,1\r\n"
            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            s.settimeout(5)
            s.connect((ip, port))
            s.sendall(header + bitmap_cmd + bitmap_data + footer)
            s.close()
            return True
        except Exception as e:
            print(f"❌ 打印异常: {e}")
            raise Exception(f"打印机连接失败: {str(e)}")