229 lines
9.0 KiB
C#
229 lines
9.0 KiB
C#
// ============================================================
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// PdfiumNative:pdfium.dll 原生库 P/Invoke 封装
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// dll 来源:pypdfium2 win32 wheel(pypdfium2_raw/pdfium.dll,x86)
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// 调用约定:cdecl(pypdfium2 ctypes.CDLL 已验证)
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// ============================================================
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using System;
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using System.Runtime.InteropServices;
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namespace 成套报价软件
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{
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/// <summary>pdfium C API 最小封装(仅本项目用到的函数)。</summary>
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internal static class PdfiumNative
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{
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public const string DllName = "pdfium.dll";
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// 渲染标志:渲染注释/批注
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public const int FPDF_ANNOT = 0x01;
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// FPDF_ERR_* 错误码(GetLastError 返回)
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public const int FPDF_ERR_SUCCESS = 0; // 无错误
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public const int FPDF_ERR_UNKNOWN = 1; // 未知错误
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public const int FPDF_ERR_FILE = 2; // 文件无法打开或读取
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public const int FPDF_ERR_FORMAT = 3; // 文件不是 PDF 或已损坏
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public const int FPDF_ERR_PASSWORD = 4; // 需要密码或密码错误
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public const int FPDF_ERR_SECURITY = 5; // 不支持的安全方案
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public const int FPDF_ERR_PAGE = 6; // 页面无法加载
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private static bool _inited;
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private static readonly object _initLock = new object();
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/// <summary>初始化 pdfium(进程内只需一次,线程安全)。</summary>
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public static void InitLibrary()
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{
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lock (_initLock)
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{
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if (_inited) return;
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FPDF_InitLibrary();
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_inited = true;
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}
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}
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[DllImport(DllName)]
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private static extern void FPDF_InitLibrary();
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[DllImport(DllName)]
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private static extern void FPDF_DestroyLibrary();
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[DllImport(DllName, CharSet = CharSet.Ansi)]
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private static extern IntPtr FPDF_LoadDocument(string file_path, string password);
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[DllImport(DllName)]
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private static extern void FPDF_CloseDocument(IntPtr document);
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[DllImport(DllName)]
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private static extern uint FPDF_GetLastError();
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[DllImport(DllName)]
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private static extern int FPDF_GetPageCount(IntPtr document);
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[DllImport(DllName)]
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private static extern IntPtr FPDF_LoadPage(IntPtr document, int page_index);
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[DllImport(DllName)]
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private static extern void FPDF_ClosePage(IntPtr page);
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// ★ 新版 GetPageSizeByIndexF 是 FS_SIZEF* 参数(易错);用稳定的旧版 double API
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[DllImport(DllName)]
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private static extern int FPDF_GetPageSizeByIndex(IntPtr document, int page_index,
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out double width, out double height);
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[DllImport(DllName)]
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private static extern IntPtr FPDFBitmap_Create(int width, int height, int alpha);
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[DllImport(DllName)]
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private static extern void FPDFBitmap_FillRect(IntPtr bitmap, int left, int top,
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int width, int height, uint color);
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[DllImport(DllName)]
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private static extern void FPDFBitmap_Destroy(IntPtr bitmap);
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[DllImport(DllName)]
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private static extern IntPtr FPDFBitmap_GetBuffer(IntPtr bitmap);
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[DllImport(DllName)]
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private static extern int FPDFBitmap_GetStride(IntPtr bitmap);
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[DllImport(DllName)]
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private static extern void FPDF_RenderPageBitmap(IntPtr bitmap, IntPtr page,
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int start_x, int start_y, int size_x, int size_y,
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int rotate, int flags);
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[DllImport(DllName)]
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private static extern IntPtr FPDF_LoadMemDocument(byte[] data, int size, string password);
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public static IntPtr LoadDocumentFromBytes(byte[] data, string password)
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{
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InitLibrary();
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if (data == null || data.Length == 0) return IntPtr.Zero;
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return FPDF_LoadMemDocument(data, data.Length, string.IsNullOrEmpty(password) ? null : password);
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}
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// ------------------------------------------------------------
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// 上层直接使用的安全包装
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// ------------------------------------------------------------
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/// <summary>打开 PDF 文件。失败返回 IntPtr.Zero,可用 LastErrorText 查原因。</summary>
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public static IntPtr LoadDocument(string path, string password)
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{
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InitLibrary();
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if (string.IsNullOrEmpty(path)) return IntPtr.Zero;
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return FPDF_LoadDocument(path, string.IsNullOrEmpty(password) ? null : password);
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}
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public static void CloseDocument(IntPtr doc)
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{
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if (doc != IntPtr.Zero) FPDF_CloseDocument(doc);
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}
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public static int GetPageCount(IntPtr doc)
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{
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if (doc == IntPtr.Zero) return 0;
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return FPDF_GetPageCount(doc);
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}
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/// <summary>取指定页尺寸(PDF 点,1/72 英寸)。失败返回 false。</summary>
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public static bool GetPageSize(IntPtr doc, int pageIndex, out float widthPt, out float heightPt)
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{
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widthPt = 0; heightPt = 0;
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if (doc == IntPtr.Zero) return false;
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double w, h;
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bool ok = FPDF_GetPageSizeByIndex(doc, pageIndex, out w, out h) != 0;
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widthPt = (float)w;
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heightPt = (float)h;
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return ok;
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}
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public static IntPtr LoadPage(IntPtr doc, int pageIndex)
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{
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if (doc == IntPtr.Zero) return IntPtr.Zero;
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return FPDF_LoadPage(doc, pageIndex);
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}
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public static void ClosePage(IntPtr page)
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{
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if (page != IntPtr.Zero) FPDF_ClosePage(page);
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}
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/// <summary>把整页渲染到 GDI+ 位图(白底不透明)。</summary>
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public static System.Drawing.Bitmap RenderPageToBitmap(IntPtr page, int widthPx, int heightPx)
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{
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return RenderRegionToBitmap(page, 0, 0, widthPx, heightPx, widthPx, heightPx);
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}
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/// <summary>
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/// 把页面局部区域渲染到位图(白底不透明)。
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/// 页面整图尺寸 = fullW×fullH 像素;只取 (startX,startY,wPx,hPx) 矩形。
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/// 用于:OCR 框选区域按任意分辨率高清重渲染(与显示缩放无关)。
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/// </summary>
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public static System.Drawing.Bitmap RenderRegionToBitmap(IntPtr page,
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int startX, int startY, int wPx, int hPx, int fullW, int fullH)
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{
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if (page == IntPtr.Zero || wPx <= 0 || hPx <= 0) return null;
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if (wPx > 16384 || hPx > 16384) return null;
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IntPtr bmp = FPDFBitmap_Create(wPx, hPx, 1);
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if (bmp == IntPtr.Zero) return null;
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try
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{
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// 白底不透明(0xAARRGGBB)
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FPDFBitmap_FillRect(bmp, 0, 0, wPx, hPx, 0xFFFFFFFF);
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// start_x/start_y 为负偏移:位图原点相对页面原点
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FPDF_RenderPageBitmap(bmp, page, -startX, -startY, fullW, fullH, 0, FPDF_ANNOT);
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IntPtr buffer = FPDFBitmap_GetBuffer(bmp);
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int stride = FPDFBitmap_GetStride(bmp);
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if (buffer == IntPtr.Zero || stride <= 0) return null;
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// pdfium BGRA(top-down) → GDI+ Format32bppArgb(BGRA) 逐行拷贝
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var result = new System.Drawing.Bitmap(wPx, hPx,
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System.Drawing.Imaging.PixelFormat.Format32bppArgb);
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var rect = new System.Drawing.Rectangle(0, 0, wPx, hPx);
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var data = result.LockBits(rect,
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System.Drawing.Imaging.ImageLockMode.WriteOnly,
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System.Drawing.Imaging.PixelFormat.Format32bppArgb);
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try
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{
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for (int y = 0; y < hPx; y++)
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{
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IntPtr src = new IntPtr(buffer.ToInt64() + (long)y * stride);
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IntPtr dst = new IntPtr(data.Scan0.ToInt64() + (long)y * data.Stride);
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NativeMethods.CopyMemory(dst, src, (uint)(wPx * 4));
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}
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}
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finally
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{
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result.UnlockBits(data);
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}
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return result;
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}
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finally
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{
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FPDFBitmap_Destroy(bmp);
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}
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}
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public static string LastErrorText()
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{
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uint err = FPDF_GetLastError();
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switch (err)
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{
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case FPDF_ERR_SUCCESS: return "成功";
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case FPDF_ERR_FILE: return "文件无法打开或读取";
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case FPDF_ERR_FORMAT: return "文件不是有效 PDF 或已损坏";
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case FPDF_ERR_PASSWORD: return "PDF 已加密,需要密码";
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case FPDF_ERR_SECURITY: return "不支持的安全方案";
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case FPDF_ERR_PAGE: return "页面内容无法解析";
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default: return "未知错误(" + err + ")";
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}
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}
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private static class NativeMethods
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{
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[DllImport("kernel32.dll", EntryPoint = "RtlMoveMemory", SetLastError = false)]
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public static extern void CopyMemory(IntPtr dest, IntPtr src, uint count);
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}
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}
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}
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