Move helper methods out of pdfium_test.

This CL splits some helper code out of pdfium_test into individual
files. This makes it a bit clearer what each chunk of code is doing and
makes pdfium_test easier to read.

Change-Id: I3dcff5a6a85ac4283336108eb3a24fa5f234284c
Reviewed-on: https://pdfium-review.googlesource.com/28990
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

1 files changed, 644 insertions, 0 deletions

diff --git a/samples/pdfium_test_write_helper.cc b/samples/pdfium_test_write_helper.cc
new file mode 100644
index 0000000000..27f43a64c4
--- /dev/null
+++ b/samples/pdfium_test_write_helper.cc
@@ -0,0 +1,644 @@
+// Copyright 2018 The PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "samples/pdfium_test_write_helper.h"
+
+#include "public/cpp/fpdf_deleters.h"
+#include "public/fpdf_annot.h"
+#include "public/fpdf_attachment.h"
+#include "public/fpdf_edit.h"
+#include "testing/image_diff/image_diff_png.h"
+#include "testing/test_support.h"
+#include "third_party/base/logging.h"
+
+namespace {
+
+bool CheckDimensions(int stride, int width, int height) {
+  if (stride < 0 || width < 0 || height < 0)
+    return false;
+  if (height > 0 && width > INT_MAX / height)
+    return false;
+  return true;
+}
+
+const char* AnnotSubtypeToCString(FPDF_ANNOTATION_SUBTYPE subtype) {
+  if (subtype == FPDF_ANNOT_TEXT)
+    return "Text";
+  if (subtype == FPDF_ANNOT_LINK)
+    return "Link";
+  if (subtype == FPDF_ANNOT_FREETEXT)
+    return "FreeText";
+  if (subtype == FPDF_ANNOT_LINE)
+    return "Line";
+  if (subtype == FPDF_ANNOT_SQUARE)
+    return "Square";
+  if (subtype == FPDF_ANNOT_CIRCLE)
+    return "Circle";
+  if (subtype == FPDF_ANNOT_POLYGON)
+    return "Polygon";
+  if (subtype == FPDF_ANNOT_POLYLINE)
+    return "PolyLine";
+  if (subtype == FPDF_ANNOT_HIGHLIGHT)
+    return "Highlight";
+  if (subtype == FPDF_ANNOT_UNDERLINE)
+    return "Underline";
+  if (subtype == FPDF_ANNOT_SQUIGGLY)
+    return "Squiggly";
+  if (subtype == FPDF_ANNOT_STRIKEOUT)
+    return "StrikeOut";
+  if (subtype == FPDF_ANNOT_STAMP)
+    return "Stamp";
+  if (subtype == FPDF_ANNOT_CARET)
+    return "Caret";
+  if (subtype == FPDF_ANNOT_INK)
+    return "Ink";
+  if (subtype == FPDF_ANNOT_POPUP)
+    return "Popup";
+  if (subtype == FPDF_ANNOT_FILEATTACHMENT)
+    return "FileAttachment";
+  if (subtype == FPDF_ANNOT_SOUND)
+    return "Sound";
+  if (subtype == FPDF_ANNOT_MOVIE)
+    return "Movie";
+  if (subtype == FPDF_ANNOT_WIDGET)
+    return "Widget";
+  if (subtype == FPDF_ANNOT_SCREEN)
+    return "Screen";
+  if (subtype == FPDF_ANNOT_PRINTERMARK)
+    return "PrinterMark";
+  if (subtype == FPDF_ANNOT_TRAPNET)
+    return "TrapNet";
+  if (subtype == FPDF_ANNOT_WATERMARK)
+    return "Watermark";
+  if (subtype == FPDF_ANNOT_THREED)
+    return "3D";
+  if (subtype == FPDF_ANNOT_RICHMEDIA)
+    return "RichMedia";
+  if (subtype == FPDF_ANNOT_XFAWIDGET)
+    return "XFAWidget";
+  NOTREACHED();
+  return "";
+}
+
+void AppendFlagString(const char* flag, std::string* output) {
+  if (!output->empty())
+    *output += ", ";
+  *output += flag;
+}
+
+std::string AnnotFlagsToString(int flags) {
+  std::string str;
+  if (flags & FPDF_ANNOT_FLAG_INVISIBLE)
+    AppendFlagString("Invisible", &str);
+  if (flags & FPDF_ANNOT_FLAG_HIDDEN)
+    AppendFlagString("Hidden", &str);
+  if (flags & FPDF_ANNOT_FLAG_PRINT)
+    AppendFlagString("Print", &str);
+  if (flags & FPDF_ANNOT_FLAG_NOZOOM)
+    AppendFlagString("NoZoom", &str);
+  if (flags & FPDF_ANNOT_FLAG_NOROTATE)
+    AppendFlagString("NoRotate", &str);
+  if (flags & FPDF_ANNOT_FLAG_NOVIEW)
+    AppendFlagString("NoView", &str);
+  if (flags & FPDF_ANNOT_FLAG_READONLY)
+    AppendFlagString("ReadOnly", &str);
+  if (flags & FPDF_ANNOT_FLAG_LOCKED)
+    AppendFlagString("Locked", &str);
+  if (flags & FPDF_ANNOT_FLAG_TOGGLENOVIEW)
+    AppendFlagString("ToggleNoView", &str);
+  return str;
+}
+
+const char* PageObjectTypeToCString(int type) {
+  if (type == FPDF_PAGEOBJ_TEXT)
+    return "Text";
+  if (type == FPDF_PAGEOBJ_PATH)
+    return "Path";
+  if (type == FPDF_PAGEOBJ_IMAGE)
+    return "Image";
+  if (type == FPDF_PAGEOBJ_SHADING)
+    return "Shading";
+  if (type == FPDF_PAGEOBJ_FORM)
+    return "Form";
+  NOTREACHED();
+  return "";
+}
+
+#ifdef _WIN32
+int CALLBACK EnhMetaFileProc(HDC hdc,
+                             HANDLETABLE* handle_table,
+                             const ENHMETARECORD* record,
+                             int objects_count,
+                             LPARAM param) {
+  std::vector<const ENHMETARECORD*>& items =
+      *reinterpret_cast<std::vector<const ENHMETARECORD*>*>(param);
+  items.push_back(record);
+  return 1;
+}
+#endif  // _WIN32
+
+}  // namespace
+
+std::string WritePpm(const char* pdf_name,
+                     int num,
+                     const void* buffer_void,
+                     int stride,
+                     int width,
+                     int height) {
+  const auto* buffer = reinterpret_cast<const char*>(buffer_void);
+
+  if (!CheckDimensions(stride, width, height))
+    return "";
+
+  int out_len = width * height;
+  if (out_len > INT_MAX / 3)
+    return "";
+
+  out_len *= 3;
+
+  char filename[256];
+  snprintf(filename, sizeof(filename), "%s.%d.ppm", pdf_name, num);
+  FILE* fp = fopen(filename, "wb");
+  if (!fp)
+    return "";
+
+  fprintf(fp, "P6\n# PDF test render\n%d %d\n255\n", width, height);
+  // Source data is B, G, R, unused.
+  // Dest data is R, G, B.
+  std::vector<char> result(out_len);
+  for (int h = 0; h < height; ++h) {
+    const char* src_line = buffer + (stride * h);
+    char* dest_line = result.data() + (width * h * 3);
+    for (int w = 0; w < width; ++w) {
+      // R
+      dest_line[w * 3] = src_line[(w * 4) + 2];
+      // G
+      dest_line[(w * 3) + 1] = src_line[(w * 4) + 1];
+      // B
+      dest_line[(w * 3) + 2] = src_line[w * 4];
+    }
+  }
+  if (fwrite(result.data(), out_len, 1, fp) != 1)
+    fprintf(stderr, "Failed to write to %s\n", filename);
+
+  fclose(fp);
+  return std::string(filename);
+}
+
+void WriteText(FPDF_PAGE page, const char* pdf_name, int num) {
+  char filename[256];
+  int chars_formatted =
+      snprintf(filename, sizeof(filename), "%s.%d.txt", pdf_name, num);
+  if (chars_formatted < 0 ||
+      static_cast<size_t>(chars_formatted) >= sizeof(filename)) {
+    fprintf(stderr, "Filename %s is too long\n", filename);
+    return;
+  }
+
+  FILE* fp = fopen(filename, "w");
+  if (!fp) {
+    fprintf(stderr, "Failed to open %s for output\n", filename);
+    return;
+  }
+
+  // Output in UTF32-LE.
+  uint32_t bom = 0x0000FEFF;
+  if (fwrite(&bom, sizeof(bom), 1, fp) != 1) {
+    fprintf(stderr, "Failed to write to %s\n", filename);
+    (void)fclose(fp);
+    return;
+  }
+
+  std::unique_ptr<void, FPDFTextPageDeleter> textpage(FPDFText_LoadPage(page));
+  for (int i = 0; i < FPDFText_CountChars(textpage.get()); i++) {
+    uint32_t c = FPDFText_GetUnicode(textpage.get(), i);
+    if (fwrite(&c, sizeof(c), 1, fp) != 1) {
+      fprintf(stderr, "Failed to write to %s\n", filename);
+      break;
+    }
+  }
+  (void)fclose(fp);
+}
+
+void WriteAnnot(FPDF_PAGE page, const char* pdf_name, int num) {
+  // Open the output text file.
+  char filename[256];
+  int chars_formatted =
+      snprintf(filename, sizeof(filename), "%s.%d.annot.txt", pdf_name, num);
+  if (chars_formatted < 0 ||
+      static_cast<size_t>(chars_formatted) >= sizeof(filename)) {
+    fprintf(stderr, "Filename %s is too long\n", filename);
+    return;
+  }
+
+  FILE* fp = fopen(filename, "w");
+  if (!fp) {
+    fprintf(stderr, "Failed to open %s for output\n", filename);
+    return;
+  }
+
+  int annot_count = FPDFPage_GetAnnotCount(page);
+  fprintf(fp, "Number of annotations: %d\n\n", annot_count);
+
+  // Iterate through all annotations on this page.
+  for (int i = 0; i < annot_count; ++i) {
+    // Retrieve the annotation object and its subtype.
+    fprintf(fp, "Annotation #%d:\n", i + 1);
+    std::unique_ptr<void, FPDFAnnotationDeleter> annot(
+        FPDFPage_GetAnnot(page, i));
+    if (!annot) {
+      fprintf(fp, "Failed to retrieve annotation!\n\n");
+      continue;
+    }
+
+    FPDF_ANNOTATION_SUBTYPE subtype = FPDFAnnot_GetSubtype(annot.get());
+    fprintf(fp, "Subtype: %s\n", AnnotSubtypeToCString(subtype));
+
+    // Retrieve the annotation flags.
+    fprintf(fp, "Flags set: %s\n",
+            AnnotFlagsToString(FPDFAnnot_GetFlags(annot.get())).c_str());
+
+    // Retrieve the annotation's object count and object types.
+    const int obj_count = FPDFAnnot_GetObjectCount(annot.get());
+    fprintf(fp, "Number of objects: %d\n", obj_count);
+    if (obj_count > 0) {
+      fprintf(fp, "Object types: ");
+      for (int j = 0; j < obj_count; ++j) {
+        const char* type = PageObjectTypeToCString(
+            FPDFPageObj_GetType(FPDFAnnot_GetObject(annot.get(), j)));
+        fprintf(fp, "%s  ", type);
+      }
+      fprintf(fp, "\n");
+    }
+
+    // Retrieve the annotation's color and interior color.
+    unsigned int R;
+    unsigned int G;
+    unsigned int B;
+    unsigned int A;
+    if (FPDFAnnot_GetColor(annot.get(), FPDFANNOT_COLORTYPE_Color, &R, &G, &B,
+                           &A)) {
+      fprintf(fp, "Color in RGBA: %d %d %d %d\n", R, G, B, A);
+    } else {
+      fprintf(fp, "Failed to retrieve color.\n");
+    }
+    if (FPDFAnnot_GetColor(annot.get(), FPDFANNOT_COLORTYPE_InteriorColor, &R,
+                           &G, &B, &A)) {
+      fprintf(fp, "Interior color in RGBA: %d %d %d %d\n", R, G, B, A);
+    } else {
+      fprintf(fp, "Failed to retrieve interior color.\n");
+    }
+
+    // Retrieve the annotation's contents and author.
+    static constexpr char kContentsKey[] = "Contents";
+    static constexpr char kAuthorKey[] = "T";
+    unsigned long len =
+        FPDFAnnot_GetStringValue(annot.get(), kContentsKey, nullptr, 0);
+    std::vector<char> buf(len);
+    FPDFAnnot_GetStringValue(annot.get(), kContentsKey, buf.data(), len);
+    fprintf(fp, "Content: %ls\n",
+            GetPlatformWString(reinterpret_cast<unsigned short*>(buf.data()))
+                .c_str());
+    len = FPDFAnnot_GetStringValue(annot.get(), kAuthorKey, nullptr, 0);
+    buf.clear();
+    buf.resize(len);
+    FPDFAnnot_GetStringValue(annot.get(), kAuthorKey, buf.data(), len);
+    fprintf(fp, "Author: %ls\n",
+            GetPlatformWString(reinterpret_cast<unsigned short*>(buf.data()))
+                .c_str());
+
+    // Retrieve the annotation's quadpoints if it is a markup annotation.
+    if (FPDFAnnot_HasAttachmentPoints(annot.get())) {
+      FS_QUADPOINTSF quadpoints;
+      if (FPDFAnnot_GetAttachmentPoints(annot.get(), &quadpoints)) {
+        fprintf(fp,
+                "Quadpoints: (%.3f, %.3f), (%.3f, %.3f), (%.3f, %.3f), (%.3f, "
+                "%.3f)\n",
+                quadpoints.x1, quadpoints.y1, quadpoints.x2, quadpoints.y2,
+                quadpoints.x3, quadpoints.y3, quadpoints.x4, quadpoints.y4);
+      } else {
+        fprintf(fp, "Failed to retrieve quadpoints.\n");
+      }
+    }
+
+    // Retrieve the annotation's rectangle coordinates.
+    FS_RECTF rect;
+    if (FPDFAnnot_GetRect(annot.get(), &rect)) {
+      fprintf(fp, "Rectangle: l - %.3f, b - %.3f, r - %.3f, t - %.3f\n\n",
+              rect.left, rect.bottom, rect.right, rect.top);
+    } else {
+      fprintf(fp, "Failed to retrieve annotation rectangle.\n");
+    }
+  }
+
+  (void)fclose(fp);
+}
+
+std::string WritePng(const char* pdf_name,
+                     int num,
+                     const void* buffer_void,
+                     int stride,
+                     int width,
+                     int height) {
+  if (!CheckDimensions(stride, width, height))
+    return "";
+
+  std::vector<unsigned char> png_encoding;
+  const auto* buffer = static_cast<const unsigned char*>(buffer_void);
+  if (!image_diff_png::EncodeBGRAPNG(buffer, width, height, stride, false,
+                                     &png_encoding)) {
+    fprintf(stderr, "Failed to convert bitmap to PNG\n");
+    return "";
+  }
+
+  char filename[256];
+  int chars_formatted =
+      snprintf(filename, sizeof(filename), "%s.%d.png", pdf_name, num);
+  if (chars_formatted < 0 ||
+      static_cast<size_t>(chars_formatted) >= sizeof(filename)) {
+    fprintf(stderr, "Filename %s is too long\n", filename);
+    return "";
+  }
+
+  FILE* fp = fopen(filename, "wb");
+  if (!fp) {
+    fprintf(stderr, "Failed to open %s for output\n", filename);
+    return "";
+  }
+
+  size_t bytes_written =
+      fwrite(&png_encoding.front(), 1, png_encoding.size(), fp);
+  if (bytes_written != png_encoding.size())
+    fprintf(stderr, "Failed to write to %s\n", filename);
+
+  (void)fclose(fp);
+  return std::string(filename);
+}
+
+#ifdef _WIN32
+std::string WriteBmp(const char* pdf_name,
+                     int num,
+                     const void* buffer,
+                     int stride,
+                     int width,
+                     int height) {
+  if (!CheckDimensions(stride, width, height))
+    return "";
+
+  int out_len = stride * height;
+  if (out_len > INT_MAX / 3)
+    return "";
+
+  char filename[256];
+  snprintf(filename, sizeof(filename), "%s.%d.bmp", pdf_name, num);
+  FILE* fp = fopen(filename, "wb");
+  if (!fp)
+    return "";
+
+  BITMAPINFO bmi = {};
+  bmi.bmiHeader.biSize = sizeof(bmi) - sizeof(RGBQUAD);
+  bmi.bmiHeader.biWidth = width;
+  bmi.bmiHeader.biHeight = -height;  // top-down image
+  bmi.bmiHeader.biPlanes = 1;
+  bmi.bmiHeader.biBitCount = 32;
+  bmi.bmiHeader.biCompression = BI_RGB;
+  bmi.bmiHeader.biSizeImage = 0;
+
+  BITMAPFILEHEADER file_header = {};
+  file_header.bfType = 0x4d42;
+  file_header.bfSize = sizeof(file_header) + bmi.bmiHeader.biSize + out_len;
+  file_header.bfOffBits = file_header.bfSize - out_len;
+
+  if (fwrite(&file_header, sizeof(file_header), 1, fp) != 1 ||
+      fwrite(&bmi, bmi.bmiHeader.biSize, 1, fp) != 1 ||
+      fwrite(buffer, out_len, 1, fp) != 1) {
+    fprintf(stderr, "Failed to write to %s\n", filename);
+  }
+  fclose(fp);
+  return std::string(filename);
+}
+
+void WriteEmf(FPDF_PAGE page, const char* pdf_name, int num) {
+  char filename[256];
+  snprintf(filename, sizeof(filename), "%s.%d.emf", pdf_name, num);
+
+  HDC dc = CreateEnhMetaFileA(nullptr, filename, nullptr, nullptr);
+
+  int width = static_cast<int>(FPDF_GetPageWidth(page));
+  int height = static_cast<int>(FPDF_GetPageHeight(page));
+  HRGN rgn = CreateRectRgn(0, 0, width, height);
+  SelectClipRgn(dc, rgn);
+  DeleteObject(rgn);
+
+  SelectObject(dc, GetStockObject(NULL_PEN));
+  SelectObject(dc, GetStockObject(WHITE_BRUSH));
+  // If a PS_NULL pen is used, the dimensions of the rectangle are 1 pixel less.
+  Rectangle(dc, 0, 0, width + 1, height + 1);
+
+  FPDF_RenderPage(dc, page, 0, 0, width, height, 0,
+                  FPDF_ANNOT | FPDF_PRINTING | FPDF_NO_CATCH);
+
+  DeleteEnhMetaFile(CloseEnhMetaFile(dc));
+}
+
+void WritePS(FPDF_PAGE page, const char* pdf_name, int num) {
+  char filename[256];
+  snprintf(filename, sizeof(filename), "%s.%d.ps", pdf_name, num);
+  FILE* fp = fopen(filename, "wb");
+  if (!fp)
+    return;
+
+  HDC dc = CreateEnhMetaFileA(nullptr, nullptr, nullptr, nullptr);
+
+  int width = static_cast<int>(FPDF_GetPageWidth(page));
+  int height = static_cast<int>(FPDF_GetPageHeight(page));
+  FPDF_RenderPage(dc, page, 0, 0, width, height, 0,
+                  FPDF_ANNOT | FPDF_PRINTING | FPDF_NO_CATCH);
+
+  HENHMETAFILE emf = CloseEnhMetaFile(dc);
+  std::vector<const ENHMETARECORD*> items;
+  EnumEnhMetaFile(nullptr, emf, &EnhMetaFileProc, &items, nullptr);
+  for (const ENHMETARECORD* record : items) {
+    if (record->iType != EMR_GDICOMMENT)
+      continue;
+
+    const auto* comment = reinterpret_cast<const EMRGDICOMMENT*>(record);
+    const char* data = reinterpret_cast<const char*>(comment->Data);
+    uint16_t size = *reinterpret_cast<const uint16_t*>(data);
+    if (fwrite(data + sizeof(uint16_t), size, 1, fp) != 1) {
+      fprintf(stderr, "Failed to write to %s\n", filename);
+      break;
+    }
+  }
+  fclose(fp);
+  DeleteEnhMetaFile(emf);
+}
+#endif  // _WIN32
+
+#ifdef PDF_ENABLE_SKIA
+std::string WriteSkp(const char* pdf_name,
+                     int num,
+                     SkPictureRecorder* recorder) {
+  char filename[256];
+  int chars_formatted =
+      snprintf(filename, sizeof(filename), "%s.%d.skp", pdf_name, num);
+
+  if (chars_formatted < 0 ||
+      static_cast<size_t>(chars_formatted) >= sizeof(filename)) {
+    fprintf(stderr, "Filename %s is too long\n", filename);
+    return "";
+  }
+
+  sk_sp<SkPicture> picture(recorder->finishRecordingAsPicture());
+  SkFILEWStream wStream(filename);
+  picture->serialize(&wStream);
+  return std::string(filename);
+}
+#endif
+
+void WriteAttachments(FPDF_DOCUMENT doc, const std::string& name) {
+  for (int i = 0; i < FPDFDoc_GetAttachmentCount(doc); ++i) {
+    FPDF_ATTACHMENT attachment = FPDFDoc_GetAttachment(doc, i);
+
+    // Retrieve the attachment file name.
+    std::string attachment_name;
+    unsigned long len = FPDFAttachment_GetName(attachment, nullptr, 0);
+    if (len) {
+      std::vector<char> buf(len);
+      unsigned long actual_len =
+          FPDFAttachment_GetName(attachment, buf.data(), len);
+      if (actual_len == len) {
+        attachment_name =
+            GetPlatformString(reinterpret_cast<unsigned short*>(buf.data()));
+      }
+    }
+    if (attachment_name.empty()) {
+      fprintf(stderr, "Attachment #%d has an empty file name.\n", i + 1);
+      continue;
+    }
+
+    // Calculate the full attachment file name.
+    char save_name[256];
+    int chars_formatted =
+        snprintf(save_name, sizeof(save_name), "%s.attachment.%s", name.c_str(),
+                 attachment_name.c_str());
+    if (chars_formatted < 0 ||
+        static_cast<size_t>(chars_formatted) >= sizeof(save_name)) {
+      fprintf(stderr, "Filename %s is too long\n", save_name);
+      continue;
+    }
+
+    // Retrieve the attachment.
+    len = FPDFAttachment_GetFile(attachment, nullptr, 0);
+    std::vector<char> data_buf(len);
+    if (len) {
+      unsigned long actual_len =
+          FPDFAttachment_GetFile(attachment, data_buf.data(), len);
+      if (actual_len != len)
+        data_buf.clear();
+    }
+    if (data_buf.empty()) {
+      fprintf(stderr, "Attachment \"%s\" is empty.\n", attachment_name.c_str());
+      continue;
+    }
+
+    // Write the attachment file.
+    FILE* fp = fopen(save_name, "wb");
+    if (!fp) {
+      fprintf(stderr, "Failed to open %s for saving attachment.\n", save_name);
+      continue;
+    }
+
+    size_t written_len = fwrite(data_buf.data(), 1, len, fp);
+    if (written_len == len) {
+      fprintf(stderr, "Saved attachment \"%s\" as: %s.\n",
+              attachment_name.c_str(), save_name);
+    } else {
+      fprintf(stderr, "Failed to write to %s\n", save_name);
+    }
+    fclose(fp);
+  }
+}
+
+void WriteImages(FPDF_PAGE page, const char* pdf_name, int page_num) {
+  for (int i = 0; i < FPDFPage_CountObjects(page); ++i) {
+    FPDF_PAGEOBJECT obj = FPDFPage_GetObject(page, i);
+    if (FPDFPageObj_GetType(obj) != FPDF_PAGEOBJ_IMAGE)
+      continue;
+
+    std::unique_ptr<void, FPDFBitmapDeleter> bitmap(
+        FPDFImageObj_GetBitmap(obj));
+    if (!bitmap) {
+      fprintf(stderr, "Image object #%d on page #%d has an empty bitmap.\n",
+              i + 1, page_num + 1);
+      continue;
+    }
+
+    int format = FPDFBitmap_GetFormat(bitmap.get());
+    if (format == FPDFBitmap_Unknown) {
+      fprintf(stderr,
+              "Image object #%d on page #%d has a bitmap of unknown format.\n",
+              i + 1, page_num + 1);
+      continue;
+    }
+
+    std::vector<unsigned char> png_encoding;
+    const unsigned char* buffer =
+        static_cast<const unsigned char*>(FPDFBitmap_GetBuffer(bitmap.get()));
+    int width = FPDFBitmap_GetWidth(bitmap.get());
+    int height = FPDFBitmap_GetHeight(bitmap.get());
+    int stride = FPDFBitmap_GetStride(bitmap.get());
+    bool ret = false;
+    switch (format) {
+      case FPDFBitmap_Gray:
+        ret = image_diff_png::EncodeGrayPNG(buffer, width, height, stride,
+                                            &png_encoding);
+        break;
+      case FPDFBitmap_BGR:
+        ret = image_diff_png::EncodeBGRPNG(buffer, width, height, stride,
+                                           &png_encoding);
+        break;
+      case FPDFBitmap_BGRx:
+        ret = image_diff_png::EncodeBGRAPNG(buffer, width, height, stride, true,
+                                            &png_encoding);
+        break;
+      case FPDFBitmap_BGRA:
+        ret = image_diff_png::EncodeBGRAPNG(buffer, width, height, stride,
+                                            false, &png_encoding);
+        break;
+      default:
+        NOTREACHED();
+    }
+    if (!ret) {
+      fprintf(stderr,
+              "Failed to convert image object #%d on page #%d to png.\n", i + 1,
+              page_num + 1);
+      continue;
+    }
+
+    char filename[256];
+    int chars_formatted = snprintf(filename, sizeof(filename), "%s.%d.%d.png",
+                                   pdf_name, page_num, i);
+    if (chars_formatted < 0 ||
+        static_cast<size_t>(chars_formatted) >= sizeof(filename)) {
+      fprintf(stderr, "Filename %s for saving image is too long\n", filename);
+      continue;
+    }
+
+    FILE* fp = fopen(filename, "wb");
+    if (!fp) {
+      fprintf(stderr, "Failed to open %s for saving image.\n", filename);
+      continue;
+    }
+
+    size_t bytes_written =
+        fwrite(&png_encoding.front(), 1, png_encoding.size(), fp);
+    if (bytes_written != png_encoding.size())
+      fprintf(stderr, "Failed to write to %s.\n", filename);
+    else
+      fprintf(stderr, "Successfully wrote embedded image %s.\n", filename);
+
+    (void)fclose(fp);
+  }
+}