Python实现跨平台表格数据分页打印预览处理详解

def calculateScale(self, printer: QPrinter, painter: QPainter) -> float:
        """计算每毫米的逻辑单位"""

        # 获取打印机的 DPI
        ppiPrinterX = printer.resolution()
        ppiPrinterY = ppiPrinterX  # 假设 X 和 Y 方向的 DPI 相同

        # 获取屏幕的 DPI
        screen = QApplication.primaryScreen()
        ppiScreenX = screen.logicalDotsPerInchX()
        ppiScreenY = screen.logicalDotsPerInchY()

        # 计算缩放比例，
        self.logScale = logScale = float(ppiPrinterX) / float(ppiScreenX)

        # 可根据 DPI 比例调整字体大小
        print(f"缩放比例: {logScale}")

        # 获取页面大小和绘制区域大小
        pageRect = printer.pageRect(QPrinter.Unit.DevicePixel)  # 页面大小（像素）
        paintRect = painter.viewport()  # 绘制区域大小（像素）

        # 计算缩放比例
        scale = logScale * float(paintRect.width()) / float(pageRect.width())

        # 设置 QPainter 的缩放比例
        painter.scale(scale, scale)

        # 计算每毫米的逻辑单位
        logUnitsMM = float(ppiPrinterX) / (logScale * 25.4)
        print(f"每毫米的逻辑单位: {logUnitsMM}")
        return logUnitsMM

def print_preview(self, setting: PrintSetting) -> None:
        """打印预览"""

        # print(setting.__dict__)
        printer = QPrinter()  # QPrinter.PrinterMode.HighResolution

        # 打印的处理
        printer.setPageSize(setting.page_size)
        printer.setPageOrientation(setting.page_orientation)
        self.print_cols = setting.print_cols  # 打印指定列的索引列表
        self.print_title = setting.print_title  # 打印标题
        self.settings = setting  # 保存打印设置

        preview_dialog = QPrintPreviewDialog(printer)
        <strong>preview_dialog.paintRequested.connect(self.print_preview_paint)</strong>
        preview_dialog.exec()

def print_preview_paint(self, printer: QPrinter) -> None:
        """打印预览绘制"""
        self.painter = painter = QPainter(printer)

        # 计算每毫米的逻辑单位
        self.logUnitsMM = self.calculateScale(printer, painter)

        # 获取页面大小
        # unit 参数的可选值有：
        # QPrinter.Unit.Point：点（1 点 = 1/72 英寸）
        # QPrinter.Unit.Millimeter：毫米（常用）
        # QPrinter.Unit.Inch：英寸
        # QPrinter.Unit.Pixel：像素

        # 获取页面的可打印区域
        page_rect = printer.pageRect(QPrinter.Unit.Millimeter)
        self.page_height = page_height = page_rect.height() * self.logUnitsMM
        self.page_width = page_width = page_rect.width() * self.logUnitsMM

# 分页打印
        print(f"总行数: {total_rows}, 总页数: {total_pages}")
        for page in range(total_pages):
            if page > 0:  # 非第一页，需要换页
                printer.newPage()
            self.print_page(page, rows_per_page, self.print_cols)

        self.painter.end()

index = 0  # 用来计算递增的列数
        for col in range(self.columnCount()):
            if print_cols and col not in print_cols:
                continue
            header_text = self.GetColLabelValue(col)
            self.painter.drawText(
                int(x_offset + sum(col_widths[:index])),  # 累计不同的列宽
                y_offset,
                header_text,
            )
            index += 1

# 绘制表格内容
        for row in range(
            page * rows_per_page, min((page + 1) * rows_per_page, self.total_rows)
        ):
            y_offset += self.row_height
            index = 0  # 用来计算递增的列数
            for col in range(self.columnCount()):
                if print_cols and col not in print_cols:
                    continue
                # 获取单元格数据
                text = self.GetValue(row, col)
                # 绘制单元格内容
                self.painter.drawText(
                    int(x_offset + sum(col_widths[:index])),  # 累计不同的列宽
                    y_offset,
                    text,
                )
                index += 1