Fix some nits in fx_gif.cpp

Change-Id: I7d2d731b8b18d315b5587e1d0d9737c08cbcdead
Reviewed-on: https://pdfium-review.googlesource.com/4710
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

1 files changed, 300 insertions, 775 deletions

diff --git a/core/fxcodec/lgif/fx_gif.cpp b/core/fxcodec/lgif/fx_gif.cpp
index 8c9955f702..82d1bdd35e 100644
--- a/core/fxcodec/lgif/fx_gif.cpp
+++ b/core/fxcodec/lgif/fx_gif.cpp
@@ -9,6 +9,233 @@
 #include "core/fxcodec/lbmp/fx_bmp.h"
 #include "third_party/base/stl_util.h"
 
+namespace {
+
+void gif_error(gif_decompress_struct_p gif_ptr, const char* err_msg) {
+  if (gif_ptr && gif_ptr->gif_error_fn)
+    gif_ptr->gif_error_fn(gif_ptr, err_msg);
+}
+
+void gif_warn(gif_decompress_struct_p gif_ptr, const char* err_msg) {}
+
+void gif_takeover_gce_ptr(gif_decompress_struct_p gif_ptr,
+                          GifGCE** gce_ptr_ptr) {
+  *gce_ptr_ptr = nullptr;
+  if (gif_ptr->gce_ptr && gce_ptr_ptr) {
+    *gce_ptr_ptr = gif_ptr->gce_ptr;
+    gif_ptr->gce_ptr = nullptr;
+  }
+}
+
+uint8_t* gif_read_data(gif_decompress_struct_p gif_ptr,
+                       uint8_t** des_buf_pp,
+                       uint32_t data_size) {
+  if (!gif_ptr || gif_ptr->avail_in < gif_ptr->skip_size + data_size)
+    return nullptr;
+
+  *des_buf_pp = gif_ptr->next_in + gif_ptr->skip_size;
+  gif_ptr->skip_size += data_size;
+  return *des_buf_pp;
+}
+
+void gif_save_decoding_status(gif_decompress_struct_p gif_ptr, int32_t status) {
+  gif_ptr->decode_status = status;
+  gif_ptr->next_in += gif_ptr->skip_size;
+  gif_ptr->avail_in -= gif_ptr->skip_size;
+  gif_ptr->skip_size = 0;
+}
+
+int32_t gif_decode_extension(gif_decompress_struct_p gif_ptr) {
+  uint8_t* data_size_ptr = nullptr;
+  uint8_t* data_ptr = nullptr;
+  uint32_t skip_size_org = gif_ptr->skip_size;
+  switch (gif_ptr->decode_status) {
+    case GIF_D_STATUS_EXT_CE: {
+      if (!gif_read_data(gif_ptr, &data_size_ptr, 1)) {
+        gif_ptr->skip_size = skip_size_org;
+        return 2;
+      }
+      gif_ptr->cmt_data_ptr->clear();
+      while (*data_size_ptr != GIF_BLOCK_TERMINAL) {
+        uint8_t data_size = *data_size_ptr;
+        if (!gif_read_data(gif_ptr, &data_ptr, *data_size_ptr) ||
+            !gif_read_data(gif_ptr, &data_size_ptr, 1)) {
+          gif_ptr->skip_size = skip_size_org;
+          return 2;
+        }
+        *(gif_ptr->cmt_data_ptr) +=
+            CFX_ByteString((const char*)data_ptr, data_size);
+      }
+    } break;
+    case GIF_D_STATUS_EXT_PTE: {
+      ASSERT(sizeof(GifPTE) == 13);
+      GifPTE* gif_pte_ptr = nullptr;
+      if (!gif_read_data(gif_ptr, (uint8_t**)&gif_pte_ptr, 13))
+        return 2;
+
+      GifPlainText* gif_pt_ptr = FX_Alloc(GifPlainText, 1);
+      memset(gif_pt_ptr, 0, sizeof(GifPlainText));
+      gif_takeover_gce_ptr(gif_ptr, &gif_pt_ptr->gce_ptr);
+      gif_pt_ptr->pte_ptr = FX_Alloc(GifPTE, 1);
+      gif_pt_ptr->string_ptr = new CFX_ByteString;
+      gif_pt_ptr->pte_ptr->block_size = gif_pte_ptr->block_size;
+      gif_pt_ptr->pte_ptr->grid_left =
+          GetWord_LSBFirst((uint8_t*)&gif_pte_ptr->grid_left);
+      gif_pt_ptr->pte_ptr->grid_top =
+          GetWord_LSBFirst((uint8_t*)&gif_pte_ptr->grid_top);
+      gif_pt_ptr->pte_ptr->grid_width =
+          GetWord_LSBFirst((uint8_t*)&gif_pte_ptr->grid_width);
+      gif_pt_ptr->pte_ptr->grid_height =
+          GetWord_LSBFirst((uint8_t*)&gif_pte_ptr->grid_height);
+      gif_pt_ptr->pte_ptr->char_width = gif_pte_ptr->char_width;
+      gif_pt_ptr->pte_ptr->char_height = gif_pte_ptr->char_height;
+      gif_pt_ptr->pte_ptr->fc_index = gif_pte_ptr->fc_index;
+      gif_pt_ptr->pte_ptr->bc_index = gif_pte_ptr->bc_index;
+      if (!gif_read_data(gif_ptr, &data_size_ptr, 1)) {
+        gif_ptr->skip_size = skip_size_org;
+        if (gif_pt_ptr) {
+          FX_Free(gif_pt_ptr->gce_ptr);
+          FX_Free(gif_pt_ptr->pte_ptr);
+          delete gif_pt_ptr->string_ptr;
+          FX_Free(gif_pt_ptr);
+        }
+        return 2;
+      }
+      while (*data_size_ptr != GIF_BLOCK_TERMINAL) {
+        uint8_t data_size = *data_size_ptr;
+        if (!gif_read_data(gif_ptr, &data_ptr, *data_size_ptr) ||
+            !gif_read_data(gif_ptr, &data_size_ptr, 1)) {
+          gif_ptr->skip_size = skip_size_org;
+          if (gif_pt_ptr) {
+            FX_Free(gif_pt_ptr->gce_ptr);
+            FX_Free(gif_pt_ptr->pte_ptr);
+            delete gif_pt_ptr->string_ptr;
+            FX_Free(gif_pt_ptr);
+          }
+          return 2;
+        }
+        *(gif_pt_ptr->string_ptr) +=
+            CFX_ByteString((const char*)data_ptr, data_size);
+      }
+      gif_ptr->pt_ptr_arr_ptr->push_back(gif_pt_ptr);
+    } break;
+    case GIF_D_STATUS_EXT_GCE: {
+      ASSERT(sizeof(GifGCE) == 5);
+      GifGCE* gif_gce_ptr = nullptr;
+      if (!gif_read_data(gif_ptr, (uint8_t**)&gif_gce_ptr, 6))
+        return 2;
+
+      if (!gif_ptr->gce_ptr)
+        gif_ptr->gce_ptr = FX_Alloc(GifGCE, 1);
+      gif_ptr->gce_ptr->block_size = gif_gce_ptr->block_size;
+      gif_ptr->gce_ptr->gce_flag = gif_gce_ptr->gce_flag;
+      gif_ptr->gce_ptr->delay_time =
+          GetWord_LSBFirst((uint8_t*)&gif_gce_ptr->delay_time);
+      gif_ptr->gce_ptr->trans_index = gif_gce_ptr->trans_index;
+    } break;
+    default: {
+      if (gif_ptr->decode_status == GIF_D_STATUS_EXT_PTE) {
+        FX_Free(gif_ptr->gce_ptr);
+        gif_ptr->gce_ptr = nullptr;
+      }
+      if (!gif_read_data(gif_ptr, &data_size_ptr, 1))
+        return 2;
+
+      while (*data_size_ptr != GIF_BLOCK_TERMINAL) {
+        if (!gif_read_data(gif_ptr, &data_ptr, *data_size_ptr) ||
+            !gif_read_data(gif_ptr, &data_size_ptr, 1)) {
+          gif_ptr->skip_size = skip_size_org;
+          return 2;
+        }
+      }
+    }
+  }
+  gif_save_decoding_status(gif_ptr, GIF_D_STATUS_SIG);
+  return 1;
+}
+
+int32_t gif_decode_image_info(gif_decompress_struct_p gif_ptr) {
+  if (gif_ptr->width == 0 || gif_ptr->height == 0) {
+    gif_error(gif_ptr, "No Image Header Info");
+    return 0;
+  }
+  uint32_t skip_size_org = gif_ptr->skip_size;
+  ASSERT(sizeof(GifImageInfo) == 9);
+  GifImageInfo* gif_img_info_ptr = nullptr;
+  if (!gif_read_data(gif_ptr, (uint8_t**)&gif_img_info_ptr, 9))
+    return 2;
+
+  GifImage* gif_image_ptr = FX_Alloc(GifImage, 1);
+  memset(gif_image_ptr, 0, sizeof(GifImage));
+  gif_image_ptr->image_info_ptr = FX_Alloc(GifImageInfo, 1);
+  gif_image_ptr->image_info_ptr->left =
+      GetWord_LSBFirst((uint8_t*)&gif_img_info_ptr->left);
+  gif_image_ptr->image_info_ptr->top =
+      GetWord_LSBFirst((uint8_t*)&gif_img_info_ptr->top);
+  gif_image_ptr->image_info_ptr->width =
+      GetWord_LSBFirst((uint8_t*)&gif_img_info_ptr->width);
+  gif_image_ptr->image_info_ptr->height =
+      GetWord_LSBFirst((uint8_t*)&gif_img_info_ptr->height);
+  gif_image_ptr->image_info_ptr->local_flag = gif_img_info_ptr->local_flag;
+  if (gif_image_ptr->image_info_ptr->left +
+              gif_image_ptr->image_info_ptr->width >
+          gif_ptr->width ||
+      gif_image_ptr->image_info_ptr->top +
+              gif_image_ptr->image_info_ptr->height >
+          gif_ptr->height) {
+    FX_Free(gif_image_ptr->image_info_ptr);
+    FX_Free(gif_image_ptr->image_row_buf);
+    FX_Free(gif_image_ptr);
+    gif_error(gif_ptr, "Image Data Out Of LSD, The File May Be Corrupt");
+    return 0;
+  }
+  GifLF* gif_img_info_lf_ptr = (GifLF*)&gif_img_info_ptr->local_flag;
+  if (gif_img_info_lf_ptr->local_pal) {
+    ASSERT(sizeof(GifPalette) == 3);
+    int32_t loc_pal_size = (2 << gif_img_info_lf_ptr->pal_bits) * 3;
+    uint8_t* loc_pal_ptr = nullptr;
+    if (!gif_read_data(gif_ptr, &loc_pal_ptr, loc_pal_size)) {
+      gif_ptr->skip_size = skip_size_org;
+      FX_Free(gif_image_ptr->image_info_ptr);
+      FX_Free(gif_image_ptr->image_row_buf);
+      FX_Free(gif_image_ptr);
+      return 2;
+    }
+    gif_image_ptr->local_pal_ptr =
+        (GifPalette*)gif_ptr->gif_ask_buf_for_pal_fn(gif_ptr, loc_pal_size);
+    if (gif_image_ptr->local_pal_ptr) {
+      memcpy((uint8_t*)gif_image_ptr->local_pal_ptr, loc_pal_ptr, loc_pal_size);
+    }
+  }
+  uint8_t* code_size_ptr = nullptr;
+  if (!gif_read_data(gif_ptr, &code_size_ptr, 1)) {
+    gif_ptr->skip_size = skip_size_org;
+    FX_Free(gif_image_ptr->image_info_ptr);
+    FX_Free(gif_image_ptr->local_pal_ptr);
+    FX_Free(gif_image_ptr->image_row_buf);
+    FX_Free(gif_image_ptr);
+    return 2;
+  }
+  gif_image_ptr->image_code_size = *code_size_ptr;
+  gif_ptr->gif_record_current_position_fn(gif_ptr,
+                                          &gif_image_ptr->image_data_pos);
+  gif_image_ptr->image_data_pos += gif_ptr->skip_size;
+  gif_takeover_gce_ptr(gif_ptr, &gif_image_ptr->image_gce_ptr);
+  gif_ptr->img_ptr_arr_ptr->push_back(gif_image_ptr);
+  gif_save_decoding_status(gif_ptr, GIF_D_STATUS_IMG_DATA);
+  return 1;
+}
+
+void gif_decoding_failure_at_tail_cleanup(gif_decompress_struct_p gif_ptr,
+                                          GifImage* gif_image_ptr) {
+  FX_Free(gif_image_ptr->image_row_buf);
+  gif_image_ptr->image_row_buf = nullptr;
+  gif_save_decoding_status(gif_ptr, GIF_D_STATUS_TAIL);
+  gif_error(gif_ptr, "Decode Image Data Error");
+}
+
+}  // namespace
+
 void CGifLZWDecoder::Input(uint8_t* src_buf, uint32_t src_size) {
   next_in = src_buf;
   avail_in = src_size;
@@ -48,16 +275,17 @@ void CGifLZWDecoder::InitTable(uint8_t code_len) {
   code_first = 0;
   ClearTable();
 }
+
 void CGifLZWDecoder::ClearTable() {
   code_size_cur = code_size + 1;
   code_next = code_end + 1;
-  code_old = (uint16_t)-1;
+  code_old = static_cast<uint16_t>(-1);
   memset(code_table, 0, sizeof(tag_Table) * GIF_MAX_LZW_CODE);
   memset(stack, 0, GIF_MAX_LZW_CODE);
-  for (uint16_t i = 0; i < code_clear; i++) {
-    code_table[i].suffix = (uint8_t)i;
-  }
+  for (uint16_t i = 0; i < code_clear; i++)
+    code_table[i].suffix = static_cast<uint8_t>(i);
 }
+
 void CGifLZWDecoder::DecodeString(uint16_t code) {
   stack_size = 0;
   while (true) {
@@ -67,30 +295,31 @@ void CGifLZWDecoder::DecodeString(uint16_t code) {
     stack[GIF_MAX_LZW_CODE - 1 - stack_size++] = code_table[code].suffix;
     code = code_table[code].prefix;
   }
-  stack[GIF_MAX_LZW_CODE - 1 - stack_size++] = (uint8_t)code;
-  code_first = (uint8_t)code;
+  stack[GIF_MAX_LZW_CODE - 1 - stack_size++] = static_cast<uint8_t>(code);
+  code_first = static_cast<uint8_t>(code);
 }
+
 void CGifLZWDecoder::AddCode(uint16_t prefix_code, uint8_t append_char) {
-  if (code_next == GIF_MAX_LZW_CODE) {
+  if (code_next == GIF_MAX_LZW_CODE)
     return;
-  }
+
   code_table[code_next].prefix = prefix_code;
   code_table[code_next].suffix = append_char;
   if (++code_next < GIF_MAX_LZW_CODE) {
-    if (code_next >> code_size_cur) {
+    if (code_next >> code_size_cur)
       code_size_cur++;
-    }
   }
 }
-int32_t CGifLZWDecoder::Decode(uint8_t* des_buf, uint32_t& des_size) {
-  if (des_size == 0) {
+
+int32_t CGifLZWDecoder::Decode(uint8_t* des_buf, uint32_t* des_size) {
+  if (*des_size == 0)
     return 3;
-  }
+
   uint32_t i = 0;
   if (stack_size != 0) {
-    if (des_size < stack_size) {
-      memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], des_size);
-      stack_size -= (uint16_t)des_size;
+    if (*des_size < stack_size) {
+      memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], *des_size);
+      stack_size -= static_cast<uint16_t>(*des_size);
       return 3;
     }
     memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], stack_size);
@@ -98,294 +327,78 @@ int32_t CGifLZWDecoder::Decode(uint8_t* des_buf, uint32_t& des_size) {
     i += stack_size;
     stack_size = 0;
   }
-  uint16_t code = 0;
-  while (i <= des_size && (avail_in > 0 || bits_left >= code_size_cur)) {
+  ASSERT(err_msg_ptr);
+  while (i <= *des_size && (avail_in > 0 || bits_left >= code_size_cur)) {
     if (code_size_cur > 12) {
-      if (err_msg_ptr) {
-        strncpy(err_msg_ptr, "Code Length Out Of Range",
-                GIF_MAX_ERROR_SIZE - 1);
-      }
+      strncpy(err_msg_ptr, "Code Length Out Of Range", GIF_MAX_ERROR_SIZE - 1);
       return 0;
     }
     if (avail_in > 0) {
       if (bits_left > 31) {
-        if (err_msg_ptr)
-          strncpy(err_msg_ptr, "Decode Error", GIF_MAX_ERROR_SIZE - 1);
+        strncpy(err_msg_ptr, "Decode Error", GIF_MAX_ERROR_SIZE - 1);
         return 0;
       }
       pdfium::base::CheckedNumeric<uint32_t> safe_code = *next_in++;
       safe_code <<= bits_left;
       safe_code |= code_store;
       if (!safe_code.IsValid()) {
-        if (err_msg_ptr) {
-          strncpy(err_msg_ptr, "Code Store Out Of Range",
-                  GIF_MAX_ERROR_SIZE - 1);
-        }
+        strncpy(err_msg_ptr, "Code Store Out Of Range", GIF_MAX_ERROR_SIZE - 1);
         return 0;
       }
       code_store = safe_code.ValueOrDie();
-      avail_in--;
+      --avail_in;
       bits_left += 8;
     }
     while (bits_left >= code_size_cur) {
-      code = (uint16_t)code_store & ((1 << code_size_cur) - 1);
+      uint16_t code =
+          static_cast<uint16_t>(code_store) & ((1 << code_size_cur) - 1);
       code_store >>= code_size_cur;
       bits_left -= code_size_cur;
       if (code == code_clear) {
         ClearTable();
         continue;
-      } else if (code == code_end) {
-        des_size = i;
+      }
+      if (code == code_end) {
+        *des_size = i;
         return 1;
-      } else {
-        if (code_old != (uint16_t)-1) {
-          if (code_next < GIF_MAX_LZW_CODE) {
-            if (code == code_next) {
-              AddCode(code_old, code_first);
-              DecodeString(code);
-            } else if (code > code_next) {
-              if (err_msg_ptr) {
-                strncpy(err_msg_ptr, "Decode Error, Out Of Range",
-                        GIF_MAX_ERROR_SIZE - 1);
-              }
-              return 0;
-            } else {
-              DecodeString(code);
-              uint8_t append_char = stack[GIF_MAX_LZW_CODE - stack_size];
-              AddCode(code_old, append_char);
-            }
+      }
+      if (code_old != static_cast<uint16_t>(-1)) {
+        if (code_next < GIF_MAX_LZW_CODE) {
+          if (code == code_next) {
+            AddCode(code_old, code_first);
+            DecodeString(code);
+          } else if (code > code_next) {
+            strncpy(err_msg_ptr, "Decode Error, Out Of Range",
+                    GIF_MAX_ERROR_SIZE - 1);
+            return 0;
+          } else {
+            DecodeString(code);
+            uint8_t append_char = stack[GIF_MAX_LZW_CODE - stack_size];
+            AddCode(code_old, append_char);
           }
-        } else {
-          DecodeString(code);
-        }
-        code_old = code;
-        if (i + stack_size > des_size) {
-          memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], des_size - i);
-          stack_size -= (uint16_t)(des_size - i);
-          return 3;
         }
-        memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], stack_size);
-        des_buf += stack_size;
-        i += stack_size;
-        stack_size = 0;
+      } else {
+        DecodeString(code);
+      }
+      code_old = code;
+      if (i + stack_size > *des_size) {
+        memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], *des_size - i);
+        stack_size -= static_cast<uint16_t>(*des_size - i);
+        return 3;
       }
+      memcpy(des_buf, &stack[GIF_MAX_LZW_CODE - stack_size], stack_size);
+      des_buf += stack_size;
+      i += stack_size;
+      stack_size = 0;
     }
   }
   if (avail_in == 0) {
-    des_size = i;
+    *des_size = i;
     return 2;
   }
   return 0;
 }
-static bool gif_grow_buf(uint8_t*& dst_buf, uint32_t& dst_len, uint32_t size) {
-  if (dst_len < size) {
-    uint32_t len_org = dst_len;
-    while (dst_buf && dst_len < size) {
-      dst_len <<= 1;
-      // TODO(thestig): Probably should be a try-realloc here.
-      dst_buf = FX_Realloc(uint8_t, dst_buf, dst_len);
-    }
-    if (!dst_buf) {
-      dst_len = size;
-      dst_buf = FX_Realloc(uint8_t, dst_buf, dst_len);
-    }
-    memset(dst_buf + len_org, 0, dst_len - len_org);
-    return !!dst_buf;
-  }
-  return true;
-}
-static inline void gif_cut_index(uint8_t& val,
-                                 uint32_t index,
-                                 uint8_t index_bit,
-                                 uint8_t index_bit_use,
-                                 uint8_t bit_use) {
-  uint32_t cut = ((1 << (index_bit - index_bit_use)) - 1) << index_bit_use;
-  val |= ((index & cut) >> index_bit_use) << bit_use;
-}
-static inline uint8_t gif_cut_buf(const uint8_t* buf,
-                                  uint32_t& offset,
-                                  uint8_t bit_cut,
-                                  uint8_t& bit_offset,
-                                  uint32_t& bit_num) {
-  if (bit_cut != 8) {
-    uint16_t index = 0;
-    index |= ((1 << bit_cut) - 1) << (7 - bit_offset);
-    uint8_t ret = ((index & buf[offset]) >> (7 - bit_offset));
-    bit_offset += bit_cut;
-    if (bit_offset >= 8) {
-      if (bit_offset > 8) {
-        ret |= ((index & (buf[offset + 1] << 8)) >> 8);
-      }
-      bit_offset -= 8;
-      offset++;
-    }
-    bit_num += bit_cut;
-    return ret;
-  }
-  bit_num += bit_cut;
-  return buf[offset++];
-}
-CGifLZWEncoder::CGifLZWEncoder() {
-  memset(this, 0, sizeof(CGifLZWEncoder));
-}
-CGifLZWEncoder::~CGifLZWEncoder() {}
-void CGifLZWEncoder::ClearTable() {
-  index_bit_cur = code_size + 1;
-  index_num = code_end + 1;
-  table_cur = code_end + 1;
-  for (uint16_t i = 0; i < GIF_MAX_LZW_CODE; i++) {
-    code_table[i].prefix = 0;
-    code_table[i].suffix = 0;
-  }
-}
-void CGifLZWEncoder::Start(uint8_t code_len,
-                           const uint8_t* src_buf,
-                           uint8_t*& dst_buf,
-                           uint32_t& offset) {
-  code_size = code_len + 1;
-  ASSERT(code_size < 32);
-  src_bit_cut = code_size;
-  if (code_len == 0) {
-    src_bit_cut = 1;
-    code_size = 2;
-  }
-  code_clear = 1 << code_size;
-  code_end = code_clear + 1;
-  dst_buf[offset++] = code_size;
-  bit_offset = 0;
-  ClearTable();
-  src_offset = 0;
-  src_bit_offset = 0;
-  src_bit_num = 0;
-  code_table[index_num].prefix = gif_cut_buf(src_buf, src_offset, src_bit_cut,
-                                             src_bit_offset, src_bit_num);
-  code_table[index_num].suffix = gif_cut_buf(src_buf, src_offset, src_bit_cut,
-                                             src_bit_offset, src_bit_num);
-}
-void CGifLZWEncoder::WriteBlock(uint8_t*& dst_buf,
-                                uint32_t& dst_len,
-                                uint32_t& offset) {
-  if (!gif_grow_buf(dst_buf, dst_len, offset + GIF_DATA_BLOCK + 1)) {
-    longjmp(jmp, 1);
-  }
-  dst_buf[offset++] = index_buf_len;
-  memcpy(&dst_buf[offset], index_buf, index_buf_len);
-  offset += index_buf_len;
-  memset(index_buf, 0, GIF_DATA_BLOCK);
-  index_buf_len = 0;
-}
-void CGifLZWEncoder::EncodeString(uint32_t index,
-                                  uint8_t*& dst_buf,
-                                  uint32_t& dst_len,
-                                  uint32_t& offset) {
-  uint8_t index_bit_use;
-  index_bit_use = 0;
-  if (index_buf_len == GIF_DATA_BLOCK) {
-    WriteBlock(dst_buf, dst_len, offset);
-  }
-  gif_cut_index(index_buf[index_buf_len], index, index_bit_cur, index_bit_use,
-                bit_offset);
-  if (index_bit_cur <= (8 - bit_offset)) {
-    bit_offset += index_bit_cur;
-  } else if (index_bit_cur <= (16 - bit_offset)) {
-    index_bit_use += (8 - bit_offset);
-    bit_offset = 0;
-    index_buf_len++;
-    if (index_buf_len == GIF_DATA_BLOCK) {
-      WriteBlock(dst_buf, dst_len, offset);
-    }
-    gif_cut_index(index_buf[index_buf_len], index, index_bit_cur, index_bit_use,
-                  bit_offset);
-    bit_offset = index_bit_cur - index_bit_use;
-  } else {
-    index_bit_use += (8 - bit_offset);
-    bit_offset = 0;
-    index_buf_len++;
-    if (index_buf_len == GIF_DATA_BLOCK) {
-      WriteBlock(dst_buf, dst_len, offset);
-    }
-    gif_cut_index(index_buf[index_buf_len], index, index_bit_cur, index_bit_use,
-                  bit_offset);
-    index_bit_use += 8;
-    bit_offset = 0;
-    index_buf_len++;
-    if (index_buf_len == GIF_DATA_BLOCK) {
-      WriteBlock(dst_buf, dst_len, offset);
-    }
-    gif_cut_index(index_buf[index_buf_len], index, index_bit_cur, index_bit_use,
-                  bit_offset);
-    bit_offset = index_bit_cur - index_bit_use;
-  }
-  if (bit_offset == 8) {
-    bit_offset = 0;
-    index_buf_len++;
-    if (index_buf_len == GIF_DATA_BLOCK) {
-      WriteBlock(dst_buf, dst_len, offset);
-    }
-  }
-  if (index == code_end) {
-    index_buf_len++;
-    WriteBlock(dst_buf, dst_len, offset);
-  }
-  if (index_num++ >> index_bit_cur) {
-    index_bit_cur++;
-  }
-}
-bool CGifLZWEncoder::Encode(const uint8_t* src_buf,
-                            uint32_t src_len,
-                            uint8_t*& dst_buf,
-                            uint32_t& dst_len,
-                            uint32_t& offset) {
-  uint8_t suffix;
-  if (setjmp(jmp)) {
-    return false;
-  }
-  while (src_bit_num < src_len) {
-    if (!LookUpInTable(src_buf, src_offset, src_bit_offset)) {
-      EncodeString(code_table[index_num].prefix, dst_buf, dst_len, offset);
-      if (index_num == GIF_MAX_LZW_CODE) {
-        suffix = code_table[index_num - 1].suffix;
-        EncodeString(code_clear, dst_buf, dst_len, offset);
-        ClearTable();
-        code_table[index_num].prefix = suffix;
-        code_table[index_num].suffix = gif_cut_buf(
-            src_buf, src_offset, src_bit_cut, src_bit_offset, src_bit_num);
-      } else {
-        code_table[index_num].prefix = code_table[index_num - 1].suffix;
-        code_table[index_num].suffix = gif_cut_buf(
-            src_buf, src_offset, src_bit_cut, src_bit_offset, src_bit_num);
-      }
-    }
-  }
-  src_offset = 0;
-  src_bit_offset = 0;
-  src_bit_num = 0;
-  return true;
-}
-bool CGifLZWEncoder::LookUpInTable(const uint8_t* buf,
-                                   uint32_t& offset,
-                                   uint8_t& out_bit_offset) {
-  for (uint16_t i = table_cur; i < index_num; i++) {
-    if (code_table[i].prefix == code_table[index_num].prefix &&
-        code_table[i].suffix == code_table[index_num].suffix) {
-      code_table[index_num].prefix = i;
-      code_table[index_num].suffix =
-          gif_cut_buf(buf, offset, src_bit_cut, out_bit_offset, src_bit_num);
-      table_cur = i;
-      return true;
-    }
-  }
-  table_cur = code_end + 1;
-  return false;
-}
-void CGifLZWEncoder::Finish(uint8_t*& dst_buf,
-                            uint32_t& dst_len,
-                            uint32_t& offset) {
-  EncodeString(code_table[index_num].prefix, dst_buf, dst_len, offset);
-  EncodeString(code_end, dst_buf, dst_len, offset);
-  bit_offset = 0;
-  ClearTable();
-}
+
 gif_decompress_struct_p gif_create_decompress() {
   gif_decompress_struct_p gif_ptr = FX_Alloc(gif_decompress_struct, 1);
   memset(gif_ptr, 0, sizeof(gif_decompress_struct));
@@ -395,6 +408,7 @@ gif_decompress_struct_p gif_create_decompress() {
   gif_ptr->pt_ptr_arr_ptr = new std::vector<GifPlainText*>;
   return gif_ptr;
 }
+
 void gif_destroy_decompress(gif_decompress_struct_pp gif_ptr_ptr) {
   if (!gif_ptr_ptr || !*gif_ptr_ptr)
     return;
@@ -410,9 +424,8 @@ void gif_destroy_decompress(gif_decompress_struct_pp gif_ptr_ptr) {
       FX_Free(p->image_info_ptr);
       FX_Free(p->image_gce_ptr);
       FX_Free(p->image_row_buf);
-      if (p->local_pal_ptr && p->local_pal_ptr != gif_ptr->global_pal_ptr) {
+      if (p->local_pal_ptr && p->local_pal_ptr != gif_ptr->global_pal_ptr)
         FX_Free(p->local_pal_ptr);
-      }
       FX_Free(p);
     }
     gif_ptr->img_ptr_arr_ptr->clear();
@@ -434,81 +447,7 @@ void gif_destroy_decompress(gif_decompress_struct_pp gif_ptr_ptr) {
   }
   FX_Free(gif_ptr);
 }
-gif_compress_struct_p gif_create_compress() {
-  gif_compress_struct_p gif_ptr = FX_Alloc(gif_compress_struct, 1);
-  memset(gif_ptr, 0, sizeof(gif_compress_struct));
-  gif_ptr->img_encoder_ptr = new CGifLZWEncoder;
-  gif_ptr->header_ptr = FX_Alloc(GifHeader, 1);
-  if (!gif_ptr->header_ptr) {
-    delete (gif_ptr->img_encoder_ptr);
-    FX_Free(gif_ptr);
-    return nullptr;
-  }
-  memcpy(gif_ptr->header_ptr->signature, GIF_SIGNATURE, 3);
-  memcpy(gif_ptr->header_ptr->version, "89a", 3);
-  gif_ptr->lsd_ptr = FX_Alloc(GifLSD, 1);
-  if (!gif_ptr->lsd_ptr) {
-    FX_Free(gif_ptr->header_ptr);
-    delete (gif_ptr->img_encoder_ptr);
-    FX_Free(gif_ptr);
-    return nullptr;
-  }
-  memset(gif_ptr->lsd_ptr, 0, sizeof(GifLSD));
-  gif_ptr->image_info_ptr = FX_Alloc(GifImageInfo, 1);
-  if (!gif_ptr->image_info_ptr) {
-    FX_Free(gif_ptr->lsd_ptr);
-    FX_Free(gif_ptr->header_ptr);
-    delete (gif_ptr->img_encoder_ptr);
-    FX_Free(gif_ptr);
-    return nullptr;
-  }
-  memset(gif_ptr->image_info_ptr, 0, sizeof(GifImageInfo));
-  gif_ptr->gce_ptr = FX_Alloc(GifGCE, 1);
-  if (!gif_ptr->gce_ptr) {
-    FX_Free(gif_ptr->image_info_ptr);
-    FX_Free(gif_ptr->lsd_ptr);
-    FX_Free(gif_ptr->header_ptr);
-    delete (gif_ptr->img_encoder_ptr);
-    FX_Free(gif_ptr);
-    return nullptr;
-  }
-  gif_ptr->pte_ptr = FX_Alloc(GifPTE, 1);
-  if (!gif_ptr->pte_ptr) {
-    FX_Free(gif_ptr->gce_ptr);
-    FX_Free(gif_ptr->image_info_ptr);
-    FX_Free(gif_ptr->lsd_ptr);
-    FX_Free(gif_ptr->header_ptr);
-    delete (gif_ptr->img_encoder_ptr);
-    FX_Free(gif_ptr);
-    return nullptr;
-  }
-  memset(gif_ptr->pte_ptr, 0, sizeof(GifPTE));
-  gif_ptr->pte_ptr->block_size = 12;
-  return gif_ptr;
-}
-void gif_destroy_compress(gif_compress_struct_pp gif_ptr_ptr) {
-  if (!gif_ptr_ptr || !*gif_ptr_ptr)
-    return;
 
-  gif_compress_struct_p gif_ptr = *gif_ptr_ptr;
-  *gif_ptr_ptr = nullptr;
-  FX_Free(gif_ptr->header_ptr);
-  FX_Free(gif_ptr->lsd_ptr);
-  FX_Free(gif_ptr->global_pal);
-  FX_Free(gif_ptr->image_info_ptr);
-  FX_Free(gif_ptr->local_pal);
-  delete gif_ptr->img_encoder_ptr;
-  FX_Free(gif_ptr->gce_ptr);
-  FX_Free(gif_ptr->cmt_data_ptr);
-  FX_Free(gif_ptr->pte_ptr);
-  FX_Free(gif_ptr);
-}
-void gif_error(gif_decompress_struct_p gif_ptr, const char* err_msg) {
-  if (gif_ptr && gif_ptr->gif_error_fn) {
-    gif_ptr->gif_error_fn(gif_ptr, err_msg);
-  }
-}
-void gif_warn(gif_decompress_struct_p gif_ptr, const char* err_msg) {}
 int32_t gif_read_header(gif_decompress_struct_p gif_ptr) {
   if (!gif_ptr)
     return 0;
@@ -516,7 +455,7 @@ int32_t gif_read_header(gif_decompress_struct_p gif_ptr) {
   uint32_t skip_size_org = gif_ptr->skip_size;
   ASSERT(sizeof(GifHeader) == 6);
   GifHeader* gif_header_ptr = nullptr;
-  if (!gif_read_data(gif_ptr, (uint8_t**)&gif_header_ptr, 6))
+  if (!gif_read_data(gif_ptr, reinterpret_cast<uint8_t**>(&gif_header_ptr), 6))
     return 2;
 
   if (strncmp(gif_header_ptr->signature, GIF_SIGNATURE, 3) != 0 ||
@@ -526,13 +465,13 @@ int32_t gif_read_header(gif_decompress_struct_p gif_ptr) {
   }
   ASSERT(sizeof(GifLSD) == 7);
   GifLSD* gif_lsd_ptr = nullptr;
-  if (!gif_read_data(gif_ptr, (uint8_t**)&gif_lsd_ptr, 7)) {
+  if (!gif_read_data(gif_ptr, reinterpret_cast<uint8_t**>(&gif_lsd_ptr), 7)) {
     gif_ptr->skip_size = skip_size_org;
     return 2;
   }
-  if (((GifGF*)&gif_lsd_ptr->global_flag)->global_pal) {
-    gif_ptr->global_pal_num = 2
-                              << ((GifGF*)&gif_lsd_ptr->global_flag)->pal_bits;
+  if (reinterpret_cast<GifGF*>(&gif_lsd_ptr->global_flag)->global_pal) {
+    gif_ptr->global_pal_num =
+        2 << reinterpret_cast<GifGF*>(&gif_lsd_ptr->global_flag)->pal_bits;
     ASSERT(sizeof(GifPalette) == 3);
     int32_t global_pal_size = gif_ptr->global_pal_num * 3;
     uint8_t* global_pal_ptr = nullptr;
@@ -553,6 +492,7 @@ int32_t gif_read_header(gif_decompress_struct_p gif_ptr) {
   gif_ptr->pixel_aspect = gif_lsd_ptr->pixel_aspect;
   return 1;
 }
+
 int32_t gif_get_frame(gif_decompress_struct_p gif_ptr) {
   if (!gif_ptr)
     return 0;
@@ -641,200 +581,12 @@ int32_t gif_get_frame(gif_decompress_struct_p gif_ptr) {
       }
       default: {
         ret = gif_decode_extension(gif_ptr);
-        if (ret != 1) {
+        if (ret != 1)
           return ret;
-        }
-        continue;
-      }
-    }
-  }
-  return 1;
-}
-void gif_takeover_gce_ptr(gif_decompress_struct_p gif_ptr,
-                          GifGCE** gce_ptr_ptr) {
-  *gce_ptr_ptr = nullptr;
-  if (gif_ptr->gce_ptr && gce_ptr_ptr) {
-    *gce_ptr_ptr = gif_ptr->gce_ptr;
-    gif_ptr->gce_ptr = nullptr;
-  }
-}
-int32_t gif_decode_extension(gif_decompress_struct_p gif_ptr) {
-  uint8_t* data_size_ptr = nullptr;
-  uint8_t* data_ptr = nullptr;
-  uint32_t skip_size_org = gif_ptr->skip_size;
-  switch (gif_ptr->decode_status) {
-    case GIF_D_STATUS_EXT_CE: {
-      if (!gif_read_data(gif_ptr, &data_size_ptr, 1)) {
-        gif_ptr->skip_size = skip_size_org;
-        return 2;
-      }
-      gif_ptr->cmt_data_ptr->clear();
-      while (*data_size_ptr != GIF_BLOCK_TERMINAL) {
-        uint8_t data_size = *data_size_ptr;
-        if (!gif_read_data(gif_ptr, &data_ptr, *data_size_ptr) ||
-            !gif_read_data(gif_ptr, &data_size_ptr, 1)) {
-          gif_ptr->skip_size = skip_size_org;
-          return 2;
-        }
-        *(gif_ptr->cmt_data_ptr) +=
-            CFX_ByteString((const char*)data_ptr, data_size);
-      }
-    } break;
-    case GIF_D_STATUS_EXT_PTE: {
-      ASSERT(sizeof(GifPTE) == 13);
-      GifPTE* gif_pte_ptr = nullptr;
-      if (!gif_read_data(gif_ptr, (uint8_t**)&gif_pte_ptr, 13)) {
-        return 2;
-      }
-      GifPlainText* gif_pt_ptr = FX_Alloc(GifPlainText, 1);
-      memset(gif_pt_ptr, 0, sizeof(GifPlainText));
-      gif_takeover_gce_ptr(gif_ptr, &gif_pt_ptr->gce_ptr);
-      gif_pt_ptr->pte_ptr = FX_Alloc(GifPTE, 1);
-      gif_pt_ptr->string_ptr = new CFX_ByteString;
-      gif_pt_ptr->pte_ptr->block_size = gif_pte_ptr->block_size;
-      gif_pt_ptr->pte_ptr->grid_left =
-          GetWord_LSBFirst((uint8_t*)&gif_pte_ptr->grid_left);
-      gif_pt_ptr->pte_ptr->grid_top =
-          GetWord_LSBFirst((uint8_t*)&gif_pte_ptr->grid_top);
-      gif_pt_ptr->pte_ptr->grid_width =
-          GetWord_LSBFirst((uint8_t*)&gif_pte_ptr->grid_width);
-      gif_pt_ptr->pte_ptr->grid_height =
-          GetWord_LSBFirst((uint8_t*)&gif_pte_ptr->grid_height);
-      gif_pt_ptr->pte_ptr->char_width = gif_pte_ptr->char_width;
-      gif_pt_ptr->pte_ptr->char_height = gif_pte_ptr->char_height;
-      gif_pt_ptr->pte_ptr->fc_index = gif_pte_ptr->fc_index;
-      gif_pt_ptr->pte_ptr->bc_index = gif_pte_ptr->bc_index;
-      if (!gif_read_data(gif_ptr, &data_size_ptr, 1)) {
-        gif_ptr->skip_size = skip_size_org;
-        if (gif_pt_ptr) {
-          FX_Free(gif_pt_ptr->gce_ptr);
-          FX_Free(gif_pt_ptr->pte_ptr);
-          delete gif_pt_ptr->string_ptr;
-          FX_Free(gif_pt_ptr);
-        }
-        return 2;
-      }
-      while (*data_size_ptr != GIF_BLOCK_TERMINAL) {
-        uint8_t data_size = *data_size_ptr;
-        if (!gif_read_data(gif_ptr, &data_ptr, *data_size_ptr) ||
-            !gif_read_data(gif_ptr, &data_size_ptr, 1)) {
-          gif_ptr->skip_size = skip_size_org;
-          if (gif_pt_ptr) {
-            FX_Free(gif_pt_ptr->gce_ptr);
-            FX_Free(gif_pt_ptr->pte_ptr);
-            delete gif_pt_ptr->string_ptr;
-            FX_Free(gif_pt_ptr);
-          }
-          return 2;
-        }
-        *(gif_pt_ptr->string_ptr) +=
-            CFX_ByteString((const char*)data_ptr, data_size);
-      }
-      gif_ptr->pt_ptr_arr_ptr->push_back(gif_pt_ptr);
-    } break;
-    case GIF_D_STATUS_EXT_GCE: {
-      ASSERT(sizeof(GifGCE) == 5);
-      GifGCE* gif_gce_ptr = nullptr;
-      if (!gif_read_data(gif_ptr, (uint8_t**)&gif_gce_ptr, 6))
-        return 2;
-
-      if (!gif_ptr->gce_ptr)
-        gif_ptr->gce_ptr = FX_Alloc(GifGCE, 1);
-      gif_ptr->gce_ptr->block_size = gif_gce_ptr->block_size;
-      gif_ptr->gce_ptr->gce_flag = gif_gce_ptr->gce_flag;
-      gif_ptr->gce_ptr->delay_time =
-          GetWord_LSBFirst((uint8_t*)&gif_gce_ptr->delay_time);
-      gif_ptr->gce_ptr->trans_index = gif_gce_ptr->trans_index;
-    } break;
-    default: {
-      if (gif_ptr->decode_status == GIF_D_STATUS_EXT_PTE) {
-        FX_Free(gif_ptr->gce_ptr);
-        gif_ptr->gce_ptr = nullptr;
-      }
-      if (!gif_read_data(gif_ptr, &data_size_ptr, 1))
-        return 2;
-
-      while (*data_size_ptr != GIF_BLOCK_TERMINAL) {
-        if (!gif_read_data(gif_ptr, &data_ptr, *data_size_ptr) ||
-            !gif_read_data(gif_ptr, &data_size_ptr, 1)) {
-          gif_ptr->skip_size = skip_size_org;
-          return 2;
-        }
+        break;
       }
     }
   }
-  gif_save_decoding_status(gif_ptr, GIF_D_STATUS_SIG);
-  return 1;
-}
-int32_t gif_decode_image_info(gif_decompress_struct_p gif_ptr) {
-  if (gif_ptr->width == 0 || gif_ptr->height == 0) {
-    gif_error(gif_ptr, "No Image Header Info");
-    return 0;
-  }
-  uint32_t skip_size_org = gif_ptr->skip_size;
-  ASSERT(sizeof(GifImageInfo) == 9);
-  GifImageInfo* gif_img_info_ptr = nullptr;
-  if (!gif_read_data(gif_ptr, (uint8_t**)&gif_img_info_ptr, 9))
-    return 2;
-
-  GifImage* gif_image_ptr = FX_Alloc(GifImage, 1);
-  memset(gif_image_ptr, 0, sizeof(GifImage));
-  gif_image_ptr->image_info_ptr = FX_Alloc(GifImageInfo, 1);
-  gif_image_ptr->image_info_ptr->left =
-      GetWord_LSBFirst((uint8_t*)&gif_img_info_ptr->left);
-  gif_image_ptr->image_info_ptr->top =
-      GetWord_LSBFirst((uint8_t*)&gif_img_info_ptr->top);
-  gif_image_ptr->image_info_ptr->width =
-      GetWord_LSBFirst((uint8_t*)&gif_img_info_ptr->width);
-  gif_image_ptr->image_info_ptr->height =
-      GetWord_LSBFirst((uint8_t*)&gif_img_info_ptr->height);
-  gif_image_ptr->image_info_ptr->local_flag = gif_img_info_ptr->local_flag;
-  if (gif_image_ptr->image_info_ptr->left +
-              gif_image_ptr->image_info_ptr->width >
-          gif_ptr->width ||
-      gif_image_ptr->image_info_ptr->top +
-              gif_image_ptr->image_info_ptr->height >
-          gif_ptr->height) {
-    FX_Free(gif_image_ptr->image_info_ptr);
-    FX_Free(gif_image_ptr->image_row_buf);
-    FX_Free(gif_image_ptr);
-    gif_error(gif_ptr, "Image Data Out Of LSD, The File May Be Corrupt");
-    return 0;
-  }
-  GifLF* gif_img_info_lf_ptr = (GifLF*)&gif_img_info_ptr->local_flag;
-  if (gif_img_info_lf_ptr->local_pal) {
-    ASSERT(sizeof(GifPalette) == 3);
-    int32_t loc_pal_size = (2 << gif_img_info_lf_ptr->pal_bits) * 3;
-    uint8_t* loc_pal_ptr = nullptr;
-    if (!gif_read_data(gif_ptr, &loc_pal_ptr, loc_pal_size)) {
-      gif_ptr->skip_size = skip_size_org;
-      FX_Free(gif_image_ptr->image_info_ptr);
-      FX_Free(gif_image_ptr->image_row_buf);
-      FX_Free(gif_image_ptr);
-      return 2;
-    }
-    gif_image_ptr->local_pal_ptr =
-        (GifPalette*)gif_ptr->gif_ask_buf_for_pal_fn(gif_ptr, loc_pal_size);
-    if (gif_image_ptr->local_pal_ptr) {
-      memcpy((uint8_t*)gif_image_ptr->local_pal_ptr, loc_pal_ptr, loc_pal_size);
-    }
-  }
-  uint8_t* code_size_ptr = nullptr;
-  if (!gif_read_data(gif_ptr, &code_size_ptr, 1)) {
-    gif_ptr->skip_size = skip_size_org;
-    FX_Free(gif_image_ptr->image_info_ptr);
-    FX_Free(gif_image_ptr->local_pal_ptr);
-    FX_Free(gif_image_ptr->image_row_buf);
-    FX_Free(gif_image_ptr);
-    return 2;
-  }
-  gif_image_ptr->image_code_size = *code_size_ptr;
-  gif_ptr->gif_record_current_position_fn(gif_ptr,
-                                          &gif_image_ptr->image_data_pos);
-  gif_image_ptr->image_data_pos += gif_ptr->skip_size;
-  gif_takeover_gce_ptr(gif_ptr, &gif_image_ptr->image_gce_ptr);
-  gif_ptr->img_ptr_arr_ptr->push_back(gif_image_ptr);
-  gif_save_decoding_status(gif_ptr, GIF_D_STATUS_IMG_DATA);
   return 1;
 }
 
@@ -935,7 +687,7 @@ int32_t gif_load_frame(gif_decompress_struct_p gif_ptr, int32_t frame_num) {
       gif_ptr->img_row_avail_size = gif_img_row_bytes - gif_ptr->img_row_offset;
       int32_t ret = img_decoder_ptr->Decode(
           gif_image_ptr->image_row_buf + gif_ptr->img_row_offset,
-          gif_ptr->img_row_avail_size);
+          &gif_ptr->img_row_avail_size);
       if (ret == 0) {
         gif_decoding_failure_at_tail_cleanup(gif_ptr, gif_image_ptr);
         return 0;
@@ -967,7 +719,7 @@ int32_t gif_load_frame(gif_decompress_struct_p gif_ptr, int32_t frame_num) {
                 gif_img_row_bytes - gif_ptr->img_row_offset;
             ret = img_decoder_ptr->Decode(
                 gif_image_ptr->image_row_buf + gif_ptr->img_row_offset,
-                gif_ptr->img_row_avail_size);
+                &gif_ptr->img_row_avail_size);
           }
         }
         if (ret == 3) {
@@ -994,7 +746,7 @@ int32_t gif_load_frame(gif_decompress_struct_p gif_ptr, int32_t frame_num) {
           gif_ptr->img_row_avail_size = gif_img_row_bytes;
           ret = img_decoder_ptr->Decode(
               gif_image_ptr->image_row_buf + gif_ptr->img_row_offset,
-              gif_ptr->img_row_avail_size);
+              &gif_ptr->img_row_avail_size);
         }
         if (ret == 0) {
           gif_decoding_failure_at_tail_cleanup(gif_ptr, gif_image_ptr);
@@ -1007,29 +759,7 @@ int32_t gif_load_frame(gif_decompress_struct_p gif_ptr, int32_t frame_num) {
   gif_error(gif_ptr, "Decode Image Data Error");
   return 0;
 }
-void gif_decoding_failure_at_tail_cleanup(gif_decompress_struct_p gif_ptr,
-                                          GifImage* gif_image_ptr) {
-  FX_Free(gif_image_ptr->image_row_buf);
-  gif_image_ptr->image_row_buf = nullptr;
-  gif_save_decoding_status(gif_ptr, GIF_D_STATUS_TAIL);
-  gif_error(gif_ptr, "Decode Image Data Error");
-}
-void gif_save_decoding_status(gif_decompress_struct_p gif_ptr, int32_t status) {
-  gif_ptr->decode_status = status;
-  gif_ptr->next_in += gif_ptr->skip_size;
-  gif_ptr->avail_in -= gif_ptr->skip_size;
-  gif_ptr->skip_size = 0;
-}
-uint8_t* gif_read_data(gif_decompress_struct_p gif_ptr,
-                       uint8_t** des_buf_pp,
-                       uint32_t data_size) {
-  if (!gif_ptr || gif_ptr->avail_in < gif_ptr->skip_size + data_size)
-    return nullptr;
 
-  *des_buf_pp = gif_ptr->next_in + gif_ptr->skip_size;
-  gif_ptr->skip_size += data_size;
-  return *des_buf_pp;
-}
 void gif_input_buffer(gif_decompress_struct_p gif_ptr,
                       uint8_t* src_buf,
                       uint32_t src_size) {
@@ -1037,222 +767,17 @@ void gif_input_buffer(gif_decompress_struct_p gif_ptr,
   gif_ptr->avail_in = src_size;
   gif_ptr->skip_size = 0;
 }
+
 uint32_t gif_get_avail_input(gif_decompress_struct_p gif_ptr,
                              uint8_t** avail_buf_ptr) {
   if (avail_buf_ptr) {
     *avail_buf_ptr = nullptr;
-    if (gif_ptr->avail_in > 0) {
+    if (gif_ptr->avail_in > 0)
       *avail_buf_ptr = gif_ptr->next_in;
-    }
   }
   return gif_ptr->avail_in;
 }
+
 int32_t gif_get_frame_num(gif_decompress_struct_p gif_ptr) {
   return pdfium::CollectionSize<int32_t>(*gif_ptr->img_ptr_arr_ptr);
 }
-static bool gif_write_header(gif_compress_struct_p gif_ptr,
-                             uint8_t*& dst_buf,
-                             uint32_t& dst_len) {
-  if (gif_ptr->cur_offset) {
-    return true;
-  }
-  dst_len = sizeof(GifHeader) + sizeof(GifLSD) + sizeof(GifGF);
-  dst_buf = FX_TryAlloc(uint8_t, dst_len);
-  if (!dst_buf)
-    return false;
-
-  memset(dst_buf, 0, dst_len);
-  memcpy(dst_buf, gif_ptr->header_ptr, sizeof(GifHeader));
-  gif_ptr->cur_offset += sizeof(GifHeader);
-  SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset, gif_ptr->lsd_ptr->width);
-  gif_ptr->cur_offset += 2;
-  SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset, gif_ptr->lsd_ptr->height);
-  gif_ptr->cur_offset += 2;
-  dst_buf[gif_ptr->cur_offset++] = gif_ptr->lsd_ptr->global_flag;
-  dst_buf[gif_ptr->cur_offset++] = gif_ptr->lsd_ptr->bc_index;
-  dst_buf[gif_ptr->cur_offset++] = gif_ptr->lsd_ptr->pixel_aspect;
-  if (gif_ptr->global_pal) {
-    uint16_t size = sizeof(GifPalette) * gif_ptr->gpal_num;
-    if (!gif_grow_buf(dst_buf, dst_len, gif_ptr->cur_offset + size)) {
-      return false;
-    }
-    memcpy(&dst_buf[gif_ptr->cur_offset], gif_ptr->global_pal, size);
-    gif_ptr->cur_offset += size;
-  }
-  return true;
-}
-void interlace_buf(const uint8_t* buf, uint32_t pitch, uint32_t height) {
-  std::vector<uint8_t*> pass[4];
-  uint32_t row = 0;
-  uint8_t* temp;
-  while (row < height) {
-    size_t j;
-    if (row % 8 == 0) {
-      j = 0;
-    } else if (row % 4 == 0) {
-      j = 1;
-    } else if (row % 2 == 0) {
-      j = 2;
-    } else {
-      j = 3;
-    }
-    temp = FX_Alloc(uint8_t, pitch);
-    memcpy(temp, &buf[pitch * row], pitch);
-    pass[j].push_back(temp);
-    row++;
-  }
-  for (size_t i = 0, row = 0; i < 4; i++) {
-    for (size_t j = 0; j < pass[i].size(); j++, row++) {
-      memcpy((uint8_t*)&buf[pitch * row], pass[i][j], pitch);
-      FX_Free(pass[i][j]);
-    }
-  }
-}
-static void gif_write_block_data(const uint8_t* src_buf,
-                                 uint32_t src_len,
-                                 uint8_t*& dst_buf,
-                                 uint32_t& dst_len,
-                                 uint32_t& dst_offset) {
-  uint32_t src_offset = 0;
-  while (src_len > GIF_DATA_BLOCK) {
-    dst_buf[dst_offset++] = GIF_DATA_BLOCK;
-    memcpy(&dst_buf[dst_offset], &src_buf[src_offset], GIF_DATA_BLOCK);
-    dst_offset += GIF_DATA_BLOCK;
-    src_offset += GIF_DATA_BLOCK;
-    src_len -= GIF_DATA_BLOCK;
-  }
-  dst_buf[dst_offset++] = (uint8_t)src_len;
-  memcpy(&dst_buf[dst_offset], &src_buf[src_offset], src_len);
-  dst_offset += src_len;
-}
-static bool gif_write_data(gif_compress_struct_p gif_ptr,
-                           uint8_t*& dst_buf,
-                           uint32_t& dst_len) {
-  if (!gif_grow_buf(dst_buf, dst_len, gif_ptr->cur_offset + GIF_DATA_BLOCK)) {
-    return false;
-  }
-  if (memcmp(gif_ptr->header_ptr->version, "89a", 3) == 0) {
-    dst_buf[gif_ptr->cur_offset++] = GIF_SIG_EXTENSION;
-    dst_buf[gif_ptr->cur_offset++] = GIF_BLOCK_GCE;
-    gif_ptr->gce_ptr->block_size = 4;
-    dst_buf[gif_ptr->cur_offset++] = gif_ptr->gce_ptr->block_size;
-    gif_ptr->gce_ptr->gce_flag = 0;
-    dst_buf[gif_ptr->cur_offset++] = gif_ptr->gce_ptr->gce_flag;
-    gif_ptr->gce_ptr->delay_time = 10;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                     gif_ptr->gce_ptr->delay_time);
-    gif_ptr->cur_offset += 2;
-    gif_ptr->gce_ptr->trans_index = 0;
-    dst_buf[gif_ptr->cur_offset++] = gif_ptr->gce_ptr->trans_index;
-    dst_buf[gif_ptr->cur_offset++] = 0;
-  }
-  dst_buf[gif_ptr->cur_offset++] = GIF_SIG_IMAGE;
-  SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                   gif_ptr->image_info_ptr->left);
-  gif_ptr->cur_offset += 2;
-  SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset, gif_ptr->image_info_ptr->top);
-  gif_ptr->cur_offset += 2;
-  SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                   gif_ptr->image_info_ptr->width);
-  gif_ptr->cur_offset += 2;
-  SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                   gif_ptr->image_info_ptr->height);
-  gif_ptr->cur_offset += 2;
-  GifLF& lf = (GifLF&)gif_ptr->image_info_ptr->local_flag;
-  dst_buf[gif_ptr->cur_offset++] = gif_ptr->image_info_ptr->local_flag;
-  if (gif_ptr->local_pal) {
-    uint32_t pal_size = sizeof(GifPalette) * gif_ptr->lpal_num;
-    if (!gif_grow_buf(dst_buf, dst_len, pal_size + gif_ptr->cur_offset)) {
-      return false;
-    }
-    memcpy(&dst_buf[gif_ptr->cur_offset], gif_ptr->local_pal, pal_size);
-    gif_ptr->cur_offset += pal_size;
-  }
-  if (lf.interlace) {
-    interlace_buf(gif_ptr->src_buf, gif_ptr->src_pitch,
-                  gif_ptr->image_info_ptr->height);
-  }
-  uint8_t code_bit = lf.pal_bits;
-  if (lf.local_pal == 0) {
-    GifGF& gf = (GifGF&)gif_ptr->lsd_ptr->global_flag;
-    code_bit = gf.pal_bits;
-  }
-  if (code_bit >= 31)
-    return false;
-  gif_ptr->img_encoder_ptr->Start(code_bit, gif_ptr->src_buf, dst_buf,
-                                  gif_ptr->cur_offset);
-  uint32_t i;
-  for (i = 0; i < gif_ptr->src_row; i++) {
-    if (!gif_ptr->img_encoder_ptr->Encode(
-            &gif_ptr->src_buf[i * gif_ptr->src_pitch],
-            gif_ptr->src_width * (code_bit + 1), dst_buf, dst_len,
-            gif_ptr->cur_offset)) {
-      return false;
-    }
-  }
-  gif_ptr->img_encoder_ptr->Finish(dst_buf, dst_len, gif_ptr->cur_offset);
-  dst_buf[gif_ptr->cur_offset++] = 0;
-  if (memcmp(gif_ptr->header_ptr->version, "89a", 3) == 0 &&
-      gif_ptr->cmt_data_ptr) {
-    dst_buf[gif_ptr->cur_offset++] = GIF_SIG_EXTENSION;
-    dst_buf[gif_ptr->cur_offset++] = GIF_BLOCK_CE;
-    gif_write_block_data(gif_ptr->cmt_data_ptr, gif_ptr->cmt_data_len, dst_buf,
-                         dst_len, gif_ptr->cur_offset);
-    dst_buf[gif_ptr->cur_offset++] = 0;
-  }
-  if (memcmp(gif_ptr->header_ptr->version, "89a", 3) == 0 &&
-      gif_ptr->pte_data_ptr) {
-    dst_buf[gif_ptr->cur_offset++] = GIF_SIG_EXTENSION;
-    dst_buf[gif_ptr->cur_offset++] = GIF_BLOCK_PTE;
-    dst_buf[gif_ptr->cur_offset++] = gif_ptr->pte_ptr->block_size;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                     gif_ptr->pte_ptr->grid_left);
-    gif_ptr->cur_offset += 2;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset, gif_ptr->pte_ptr->grid_top);
-    gif_ptr->cur_offset += 2;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                     gif_ptr->pte_ptr->grid_width);
-    gif_ptr->cur_offset += 2;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                     gif_ptr->pte_ptr->grid_height);
-    gif_ptr->cur_offset += 2;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                     gif_ptr->pte_ptr->char_width);
-    gif_ptr->cur_offset += 2;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset,
-                     gif_ptr->pte_ptr->char_height);
-    gif_ptr->cur_offset += 2;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset, gif_ptr->pte_ptr->fc_index);
-    gif_ptr->cur_offset += 2;
-    SetWord_LSBFirst(dst_buf + gif_ptr->cur_offset, gif_ptr->pte_ptr->bc_index);
-    gif_ptr->cur_offset += 2;
-    gif_write_block_data(gif_ptr->pte_data_ptr, gif_ptr->pte_data_len, dst_buf,
-                         dst_len, gif_ptr->cur_offset);
-    gif_ptr->cur_offset += gif_ptr->pte_data_len;
-    dst_buf[gif_ptr->cur_offset++] = 0;
-  }
-  dst_buf[gif_ptr->cur_offset++] = GIF_SIG_TRAILER;
-  return true;
-}
-bool gif_encode(gif_compress_struct_p gif_ptr,
-                uint8_t*& dst_buf,
-                uint32_t& dst_len) {
-  if (!gif_write_header(gif_ptr, dst_buf, dst_len)) {
-    return false;
-  }
-  uint32_t cur_offset = gif_ptr->cur_offset;
-  bool res = true;
-  if (gif_ptr->frames) {
-    gif_ptr->cur_offset--;
-  }
-  if (!gif_write_data(gif_ptr, dst_buf, dst_len)) {
-    gif_ptr->cur_offset = cur_offset;
-    res = false;
-  }
-  dst_len = gif_ptr->cur_offset;
-  dst_buf[dst_len - 1] = GIF_SIG_TRAILER;
-  if (res) {
-    gif_ptr->frames++;
-  }
-  return res;
-}