diff --git a/libs/androidfw/Png.cpp b/libs/androidfw/Png.cpp
new file mode 100644
index 0000000..fb45cd9
--- /dev/null
+++ b/libs/androidfw/Png.cpp
@@ -0,0 +1,1259 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "androidfw/Png.h"
+
+#include <png.h>
+#include <zlib.h>
+
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include "android-base/strings.h"
+#include "androidfw/BigBuffer.h"
+#include "androidfw/ResourceTypes.h"
+#include "androidfw/Source.h"
+
+namespace android {
+
+constexpr bool kDebug = false;
+
+struct PngInfo {
+  ~PngInfo() {
+    for (png_bytep row : rows) {
+      if (row != nullptr) {
+        delete[] row;
+      }
+    }
+
+    delete[] xDivs;
+    delete[] yDivs;
+  }
+
+  void* serialize9Patch() {
+    void* serialized = Res_png_9patch::serialize(info9Patch, xDivs, yDivs, colors.data());
+    reinterpret_cast<Res_png_9patch*>(serialized)->deviceToFile();
+    return serialized;
+  }
+
+  uint32_t width = 0;
+  uint32_t height = 0;
+  std::vector<png_bytep> rows;
+
+  bool is9Patch = false;
+  Res_png_9patch info9Patch;
+  int32_t* xDivs = nullptr;
+  int32_t* yDivs = nullptr;
+  std::vector<uint32_t> colors;
+
+  // Layout padding.
+  bool haveLayoutBounds = false;
+  int32_t layoutBoundsLeft;
+  int32_t layoutBoundsTop;
+  int32_t layoutBoundsRight;
+  int32_t layoutBoundsBottom;
+
+  // Round rect outline description.
+  int32_t outlineInsetsLeft;
+  int32_t outlineInsetsTop;
+  int32_t outlineInsetsRight;
+  int32_t outlineInsetsBottom;
+  float outlineRadius;
+  uint8_t outlineAlpha;
+};
+
+static void readDataFromStream(png_structp readPtr, png_bytep data, png_size_t length) {
+  std::istream* input = reinterpret_cast<std::istream*>(png_get_io_ptr(readPtr));
+  if (!input->read(reinterpret_cast<char*>(data), length)) {
+    png_error(readPtr, strerror(errno));
+  }
+}
+
+static void writeDataToStream(png_structp writePtr, png_bytep data, png_size_t length) {
+  BigBuffer* outBuffer = reinterpret_cast<BigBuffer*>(png_get_io_ptr(writePtr));
+  png_bytep buf = outBuffer->NextBlock<png_byte>(length);
+  memcpy(buf, data, length);
+}
+
+static void flushDataToStream(png_structp /*writePtr*/) {
+}
+
+static void logWarning(png_structp readPtr, png_const_charp warningMessage) {
+  IDiagnostics* diag = reinterpret_cast<IDiagnostics*>(png_get_error_ptr(readPtr));
+  diag->Warn(DiagMessage() << warningMessage);
+}
+
+static bool readPng(IDiagnostics* diag, png_structp readPtr, png_infop infoPtr, PngInfo* outInfo) {
+  if (setjmp(png_jmpbuf(readPtr))) {
+    diag->Error(DiagMessage() << "failed reading png");
+    return false;
+  }
+
+  png_set_sig_bytes(readPtr, kPngSignatureSize);
+  png_read_info(readPtr, infoPtr);
+
+  int colorType, bitDepth, interlaceType, compressionType;
+  png_get_IHDR(readPtr, infoPtr, &outInfo->width, &outInfo->height, &bitDepth, &colorType,
+               &interlaceType, &compressionType, nullptr);
+
+  if (colorType == PNG_COLOR_TYPE_PALETTE) {
+    png_set_palette_to_rgb(readPtr);
+  }
+
+  if (colorType == PNG_COLOR_TYPE_GRAY && bitDepth < 8) {
+    png_set_expand_gray_1_2_4_to_8(readPtr);
+  }
+
+  if (png_get_valid(readPtr, infoPtr, PNG_INFO_tRNS)) {
+    png_set_tRNS_to_alpha(readPtr);
+  }
+
+  if (bitDepth == 16) {
+    png_set_strip_16(readPtr);
+  }
+
+  if (!(colorType & PNG_COLOR_MASK_ALPHA)) {
+    png_set_add_alpha(readPtr, 0xFF, PNG_FILLER_AFTER);
+  }
+
+  if (colorType == PNG_COLOR_TYPE_GRAY || colorType == PNG_COLOR_TYPE_GRAY_ALPHA) {
+    png_set_gray_to_rgb(readPtr);
+  }
+
+  png_set_interlace_handling(readPtr);
+  png_read_update_info(readPtr, infoPtr);
+
+  const uint32_t rowBytes = png_get_rowbytes(readPtr, infoPtr);
+  outInfo->rows.resize(outInfo->height);
+  for (size_t i = 0; i < outInfo->height; i++) {
+    outInfo->rows[i] = new png_byte[rowBytes];
+  }
+
+  png_read_image(readPtr, outInfo->rows.data());
+  png_read_end(readPtr, infoPtr);
+  return true;
+}
+
+static void checkNinePatchSerialization(Res_png_9patch* inPatch, void* data) {
+  size_t patchSize = inPatch->serializedSize();
+  void* newData = malloc(patchSize);
+  memcpy(newData, data, patchSize);
+  Res_png_9patch* outPatch = inPatch->deserialize(newData);
+  outPatch->fileToDevice();
+  // deserialization is done in place, so outPatch == newData
+  assert(outPatch == newData);
+  assert(outPatch->numXDivs == inPatch->numXDivs);
+  assert(outPatch->numYDivs == inPatch->numYDivs);
+  assert(outPatch->paddingLeft == inPatch->paddingLeft);
+  assert(outPatch->paddingRight == inPatch->paddingRight);
+  assert(outPatch->paddingTop == inPatch->paddingTop);
+  assert(outPatch->paddingBottom == inPatch->paddingBottom);
+  /*    for (int i = 0; i < outPatch->numXDivs; i++) {
+          assert(outPatch->getXDivs()[i] == inPatch->getXDivs()[i]);
+      }
+      for (int i = 0; i < outPatch->numYDivs; i++) {
+          assert(outPatch->getYDivs()[i] == inPatch->getYDivs()[i]);
+      }
+      for (int i = 0; i < outPatch->numColors; i++) {
+          assert(outPatch->getColors()[i] == inPatch->getColors()[i]);
+      }*/
+  free(newData);
+}
+
+/*static void dump_image(int w, int h, const png_byte* const* rows, int
+color_type) {
+    int i, j, rr, gg, bb, aa;
+
+    int bpp;
+    if (color_type == PNG_COLOR_TYPE_PALETTE || color_type ==
+PNG_COLOR_TYPE_GRAY) {
+        bpp = 1;
+    } else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
+        bpp = 2;
+    } else if (color_type == PNG_COLOR_TYPE_RGB || color_type ==
+PNG_COLOR_TYPE_RGB_ALPHA) {
+        // We use a padding byte even when there is no alpha
+        bpp = 4;
+    } else {
+        printf("Unknown color type %d.\n", color_type);
+    }
+
+    for (j = 0; j < h; j++) {
+        const png_byte* row = rows[j];
+        for (i = 0; i < w; i++) {
+            rr = row[0];
+            gg = row[1];
+            bb = row[2];
+            aa = row[3];
+            row += bpp;
+
+            if (i == 0) {
+                printf("Row %d:", j);
+            }
+            switch (bpp) {
+            case 1:
+                printf(" (%d)", rr);
+                break;
+            case 2:
+                printf(" (%d %d", rr, gg);
+                break;
+            case 3:
+                printf(" (%d %d %d)", rr, gg, bb);
+                break;
+            case 4:
+                printf(" (%d %d %d %d)", rr, gg, bb, aa);
+                break;
+            }
+            if (i == (w - 1)) {
+                printf("\n");
+            }
+        }
+    }
+}*/
+
+#ifdef MAX
+#undef MAX
+#endif
+#ifdef ABS
+#undef ABS
+#endif
+
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define ABS(a) ((a) < 0 ? -(a) : (a))
+
+static void analyze_image(IDiagnostics* diag, const PngInfo& imageInfo, int grayscaleTolerance,
+                          png_colorp rgbPalette, png_bytep alphaPalette, int* paletteEntries,
+                          bool* hasTransparency, int* colorType, png_bytepp outRows) {
+  int w = imageInfo.width;
+  int h = imageInfo.height;
+  int i, j, rr, gg, bb, aa, idx;
+  uint32_t colors[256], col;
+  int num_colors = 0;
+  int maxGrayDeviation = 0;
+
+  bool isOpaque = true;
+  bool isPalette = true;
+  bool isGrayscale = true;
+
+  // Scan the entire image and determine if:
+  // 1. Every pixel has R == G == B (grayscale)
+  // 2. Every pixel has A == 255 (opaque)
+  // 3. There are no more than 256 distinct RGBA colors
+
+  if (kDebug) {
+    printf("Initial image data:\n");
+    // dump_image(w, h, imageInfo.rows.data(), PNG_COLOR_TYPE_RGB_ALPHA);
+  }
+
+  for (j = 0; j < h; j++) {
+    const png_byte* row = imageInfo.rows[j];
+    png_bytep out = outRows[j];
+    for (i = 0; i < w; i++) {
+      rr = *row++;
+      gg = *row++;
+      bb = *row++;
+      aa = *row++;
+
+      int odev = maxGrayDeviation;
+      maxGrayDeviation = MAX(ABS(rr - gg), maxGrayDeviation);
+      maxGrayDeviation = MAX(ABS(gg - bb), maxGrayDeviation);
+      maxGrayDeviation = MAX(ABS(bb - rr), maxGrayDeviation);
+      if (maxGrayDeviation > odev) {
+        if (kDebug) {
+          printf("New max dev. = %d at pixel (%d, %d) = (%d %d %d %d)\n", maxGrayDeviation, i, j,
+                 rr, gg, bb, aa);
+        }
+      }
+
+      // Check if image is really grayscale
+      if (isGrayscale) {
+        if (rr != gg || rr != bb) {
+          if (kDebug) {
+            printf("Found a non-gray pixel at %d, %d = (%d %d %d %d)\n", i, j, rr, gg, bb, aa);
+          }
+          isGrayscale = false;
+        }
+      }
+
+      // Check if image is really opaque
+      if (isOpaque) {
+        if (aa != 0xff) {
+          if (kDebug) {
+            printf("Found a non-opaque pixel at %d, %d = (%d %d %d %d)\n", i, j, rr, gg, bb, aa);
+          }
+          isOpaque = false;
+        }
+      }
+
+      // Check if image is really <= 256 colors
+      if (isPalette) {
+        col = (uint32_t)((rr << 24) | (gg << 16) | (bb << 8) | aa);
+        bool match = false;
+        for (idx = 0; idx < num_colors; idx++) {
+          if (colors[idx] == col) {
+            match = true;
+            break;
+          }
+        }
+
+        // Write the palette index for the pixel to outRows optimistically
+        // We might overwrite it later if we decide to encode as gray or
+        // gray + alpha
+        *out++ = idx;
+        if (!match) {
+          if (num_colors == 256) {
+            if (kDebug) {
+              printf("Found 257th color at %d, %d\n", i, j);
+            }
+            isPalette = false;
+          } else {
+            colors[num_colors++] = col;
+          }
+        }
+      }
+    }
+  }
+
+  *paletteEntries = 0;
+  *hasTransparency = !isOpaque;
+  int bpp = isOpaque ? 3 : 4;
+  int paletteSize = w * h + bpp * num_colors;
+
+  if (kDebug) {
+    printf("isGrayscale = %s\n", isGrayscale ? "true" : "false");
+    printf("isOpaque = %s\n", isOpaque ? "true" : "false");
+    printf("isPalette = %s\n", isPalette ? "true" : "false");
+    printf("Size w/ palette = %d, gray+alpha = %d, rgb(a) = %d\n", paletteSize, 2 * w * h,
+           bpp * w * h);
+    printf("Max gray deviation = %d, tolerance = %d\n", maxGrayDeviation, grayscaleTolerance);
+  }
+
+  // Choose the best color type for the image.
+  // 1. Opaque gray - use COLOR_TYPE_GRAY at 1 byte/pixel
+  // 2. Gray + alpha - use COLOR_TYPE_PALETTE if the number of distinct
+  // combinations
+  //     is sufficiently small, otherwise use COLOR_TYPE_GRAY_ALPHA
+  // 3. RGB(A) - use COLOR_TYPE_PALETTE if the number of distinct colors is
+  // sufficiently
+  //     small, otherwise use COLOR_TYPE_RGB{_ALPHA}
+  if (isGrayscale) {
+    if (isOpaque) {
+      *colorType = PNG_COLOR_TYPE_GRAY;  // 1 byte/pixel
+    } else {
+      // Use a simple heuristic to determine whether using a palette will
+      // save space versus using gray + alpha for each pixel.
+      // This doesn't take into account chunk overhead, filtering, LZ
+      // compression, etc.
+      if (isPalette && (paletteSize < 2 * w * h)) {
+        *colorType = PNG_COLOR_TYPE_PALETTE;  // 1 byte/pixel + 4 bytes/color
+      } else {
+        *colorType = PNG_COLOR_TYPE_GRAY_ALPHA;  // 2 bytes per pixel
+      }
+    }
+  } else if (isPalette && (paletteSize < bpp * w * h)) {
+    *colorType = PNG_COLOR_TYPE_PALETTE;
+  } else {
+    if (maxGrayDeviation <= grayscaleTolerance) {
+      diag->Note(DiagMessage() << "forcing image to gray (max deviation = " << maxGrayDeviation
+                               << ")");
+      *colorType = isOpaque ? PNG_COLOR_TYPE_GRAY : PNG_COLOR_TYPE_GRAY_ALPHA;
+    } else {
+      *colorType = isOpaque ? PNG_COLOR_TYPE_RGB : PNG_COLOR_TYPE_RGB_ALPHA;
+    }
+  }
+
+  // Perform postprocessing of the image or palette data based on the final
+  // color type chosen
+
+  if (*colorType == PNG_COLOR_TYPE_PALETTE) {
+    // Create separate RGB and Alpha palettes and set the number of colors
+    *paletteEntries = num_colors;
+
+    // Create the RGB and alpha palettes
+    for (int idx = 0; idx < num_colors; idx++) {
+      col = colors[idx];
+      rgbPalette[idx].red = (png_byte)((col >> 24) & 0xff);
+      rgbPalette[idx].green = (png_byte)((col >> 16) & 0xff);
+      rgbPalette[idx].blue = (png_byte)((col >> 8) & 0xff);
+      alphaPalette[idx] = (png_byte)(col & 0xff);
+    }
+  } else if (*colorType == PNG_COLOR_TYPE_GRAY || *colorType == PNG_COLOR_TYPE_GRAY_ALPHA) {
+    // If the image is gray or gray + alpha, compact the pixels into outRows
+    for (j = 0; j < h; j++) {
+      const png_byte* row = imageInfo.rows[j];
+      png_bytep out = outRows[j];
+      for (i = 0; i < w; i++) {
+        rr = *row++;
+        gg = *row++;
+        bb = *row++;
+        aa = *row++;
+
+        if (isGrayscale) {
+          *out++ = rr;
+        } else {
+          *out++ = (png_byte)(rr * 0.2126f + gg * 0.7152f + bb * 0.0722f);
+        }
+        if (!isOpaque) {
+          *out++ = aa;
+        }
+      }
+    }
+  }
+}
+
+static bool writePng(IDiagnostics* diag, png_structp writePtr, png_infop infoPtr, PngInfo* info,
+                     int grayScaleTolerance) {
+  if (setjmp(png_jmpbuf(writePtr))) {
+    diag->Error(DiagMessage() << "failed to write png");
+    return false;
+  }
+
+  uint32_t width, height;
+  int colorType, bitDepth, interlaceType, compressionType;
+
+  png_unknown_chunk unknowns[3];
+  unknowns[0].data = nullptr;
+  unknowns[1].data = nullptr;
+  unknowns[2].data = nullptr;
+
+  png_bytepp outRows = (png_bytepp)malloc((int)info->height * sizeof(png_bytep));
+  if (outRows == (png_bytepp)0) {
+    printf("Can't allocate output buffer!\n");
+    exit(1);
+  }
+  for (uint32_t i = 0; i < info->height; i++) {
+    outRows[i] = (png_bytep)malloc(2 * (int)info->width);
+    if (outRows[i] == (png_bytep)0) {
+      printf("Can't allocate output buffer!\n");
+      exit(1);
+    }
+  }
+
+  png_set_compression_level(writePtr, Z_BEST_COMPRESSION);
+
+  if (kDebug) {
+    diag->Note(DiagMessage() << "writing image: w = " << info->width << ", h = " << info->height);
+  }
+
+  png_color rgbPalette[256];
+  png_byte alphaPalette[256];
+  bool hasTransparency;
+  int paletteEntries;
+
+  analyze_image(diag, *info, grayScaleTolerance, rgbPalette, alphaPalette, &paletteEntries,
+                &hasTransparency, &colorType, outRows);
+
+  // If the image is a 9-patch, we need to preserve it as a ARGB file to make
+  // sure the pixels will not be pre-dithered/clamped until we decide they are
+  if (info->is9Patch && (colorType == PNG_COLOR_TYPE_RGB || colorType == PNG_COLOR_TYPE_GRAY ||
+                         colorType == PNG_COLOR_TYPE_PALETTE)) {
+    colorType = PNG_COLOR_TYPE_RGB_ALPHA;
+  }
+
+  if (kDebug) {
+    switch (colorType) {
+      case PNG_COLOR_TYPE_PALETTE:
+        diag->Note(DiagMessage() << "has " << paletteEntries << " colors"
+                                 << (hasTransparency ? " (with alpha)" : "")
+                                 << ", using PNG_COLOR_TYPE_PALLETTE");
+        break;
+      case PNG_COLOR_TYPE_GRAY:
+        diag->Note(DiagMessage() << "is opaque gray, using PNG_COLOR_TYPE_GRAY");
+        break;
+      case PNG_COLOR_TYPE_GRAY_ALPHA:
+        diag->Note(DiagMessage() << "is gray + alpha, using PNG_COLOR_TYPE_GRAY_ALPHA");
+        break;
+      case PNG_COLOR_TYPE_RGB:
+        diag->Note(DiagMessage() << "is opaque RGB, using PNG_COLOR_TYPE_RGB");
+        break;
+      case PNG_COLOR_TYPE_RGB_ALPHA:
+        diag->Note(DiagMessage() << "is RGB + alpha, using PNG_COLOR_TYPE_RGB_ALPHA");
+        break;
+    }
+  }
+
+  png_set_IHDR(writePtr, infoPtr, info->width, info->height, 8, colorType, PNG_INTERLACE_NONE,
+               PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+
+  if (colorType == PNG_COLOR_TYPE_PALETTE) {
+    png_set_PLTE(writePtr, infoPtr, rgbPalette, paletteEntries);
+    if (hasTransparency) {
+      png_set_tRNS(writePtr, infoPtr, alphaPalette, paletteEntries, (png_color_16p)0);
+    }
+    png_set_filter(writePtr, 0, PNG_NO_FILTERS);
+  } else {
+    png_set_filter(writePtr, 0, PNG_ALL_FILTERS);
+  }
+
+  if (info->is9Patch) {
+    int chunkCount = 2 + (info->haveLayoutBounds ? 1 : 0);
+    int pIndex = info->haveLayoutBounds ? 2 : 1;
+    int bIndex = 1;
+    int oIndex = 0;
+
+    // Chunks ordered thusly because older platforms depend on the base 9 patch
+    // data being last
+    png_bytep chunkNames =
+        info->haveLayoutBounds ? (png_bytep) "npOl\0npLb\0npTc\0" : (png_bytep) "npOl\0npTc";
+
+    // base 9 patch data
+    if (kDebug) {
+      diag->Note(DiagMessage() << "adding 9-patch info..");
+    }
+    memcpy((char*)unknowns[pIndex].name, "npTc", 5);
+    unknowns[pIndex].data = (png_byte*)info->serialize9Patch();
+    unknowns[pIndex].size = info->info9Patch.serializedSize();
+    // TODO: remove the check below when everything works
+    checkNinePatchSerialization(&info->info9Patch, unknowns[pIndex].data);
+
+    // automatically generated 9 patch outline data
+    int chunkSize = sizeof(png_uint_32) * 6;
+    memcpy((char*)unknowns[oIndex].name, "npOl", 5);
+    unknowns[oIndex].data = (png_byte*)calloc(chunkSize, 1);
+    png_byte outputData[chunkSize];
+    memcpy(&outputData, &info->outlineInsetsLeft, 4 * sizeof(png_uint_32));
+    ((float*)outputData)[4] = info->outlineRadius;
+    ((png_uint_32*)outputData)[5] = info->outlineAlpha;
+    memcpy(unknowns[oIndex].data, &outputData, chunkSize);
+    unknowns[oIndex].size = chunkSize;
+
+    // optional optical inset / layout bounds data
+    if (info->haveLayoutBounds) {
+      int chunkSize = sizeof(png_uint_32) * 4;
+      memcpy((char*)unknowns[bIndex].name, "npLb", 5);
+      unknowns[bIndex].data = (png_byte*)calloc(chunkSize, 1);
+      memcpy(unknowns[bIndex].data, &info->layoutBoundsLeft, chunkSize);
+      unknowns[bIndex].size = chunkSize;
+    }
+
+    for (int i = 0; i < chunkCount; i++) {
+      unknowns[i].location = PNG_HAVE_PLTE;
+    }
+    png_set_keep_unknown_chunks(writePtr, PNG_HANDLE_CHUNK_ALWAYS, chunkNames, chunkCount);
+    png_set_unknown_chunks(writePtr, infoPtr, unknowns, chunkCount);
+
+#if PNG_LIBPNG_VER < 10600
+    // Deal with unknown chunk location bug in 1.5.x and earlier.
+    png_set_unknown_chunk_location(writePtr, infoPtr, 0, PNG_HAVE_PLTE);
+    if (info->haveLayoutBounds) {
+      png_set_unknown_chunk_location(writePtr, infoPtr, 1, PNG_HAVE_PLTE);
+    }
+#endif
+  }
+
+  png_write_info(writePtr, infoPtr);
+
+  png_bytepp rows;
+  if (colorType == PNG_COLOR_TYPE_RGB || colorType == PNG_COLOR_TYPE_RGB_ALPHA) {
+    if (colorType == PNG_COLOR_TYPE_RGB) {
+      png_set_filler(writePtr, 0, PNG_FILLER_AFTER);
+    }
+    rows = info->rows.data();
+  } else {
+    rows = outRows;
+  }
+  png_write_image(writePtr, rows);
+
+  if (kDebug) {
+    printf("Final image data:\n");
+    // dump_image(info->width, info->height, rows, colorType);
+  }
+
+  png_write_end(writePtr, infoPtr);
+
+  for (uint32_t i = 0; i < info->height; i++) {
+    free(outRows[i]);
+  }
+  free(outRows);
+  free(unknowns[0].data);
+  free(unknowns[1].data);
+  free(unknowns[2].data);
+
+  png_get_IHDR(writePtr, infoPtr, &width, &height, &bitDepth, &colorType, &interlaceType,
+               &compressionType, nullptr);
+
+  if (kDebug) {
+    diag->Note(DiagMessage() << "image written: w = " << width << ", h = " << height
+                             << ", d = " << bitDepth << ", colors = " << colorType
+                             << ", inter = " << interlaceType << ", comp = " << compressionType);
+  }
+  return true;
+}
+
+constexpr uint32_t kColorWhite = 0xffffffffu;
+constexpr uint32_t kColorTick = 0xff000000u;
+constexpr uint32_t kColorLayoutBoundsTick = 0xff0000ffu;
+
+enum class TickType { kNone, kTick, kLayoutBounds, kBoth };
+
+static TickType tickType(png_bytep p, bool transparent, const char** outError) {
+  png_uint_32 color = p[0] | (p[1] << 8) | (p[2] << 16) | (p[3] << 24);
+
+  if (transparent) {
+    if (p[3] == 0) {
+      return TickType::kNone;
+    }
+    if (color == kColorLayoutBoundsTick) {
+      return TickType::kLayoutBounds;
+    }
+    if (color == kColorTick) {
+      return TickType::kTick;
+    }
+
+    // Error cases
+    if (p[3] != 0xff) {
+      *outError =
+          "Frame pixels must be either solid or transparent "
+          "(not intermediate alphas)";
+      return TickType::kNone;
+    }
+
+    if (p[0] != 0 || p[1] != 0 || p[2] != 0) {
+      *outError = "Ticks in transparent frame must be black or red";
+    }
+    return TickType::kTick;
+  }
+
+  if (p[3] != 0xFF) {
+    *outError = "White frame must be a solid color (no alpha)";
+  }
+  if (color == kColorWhite) {
+    return TickType::kNone;
+  }
+  if (color == kColorTick) {
+    return TickType::kTick;
+  }
+  if (color == kColorLayoutBoundsTick) {
+    return TickType::kLayoutBounds;
+  }
+
+  if (p[0] != 0 || p[1] != 0 || p[2] != 0) {
+    *outError = "Ticks in white frame must be black or red";
+    return TickType::kNone;
+  }
+  return TickType::kTick;
+}
+
+enum class TickState { kStart, kInside1, kOutside1 };
+
+static bool getHorizontalTicks(png_bytep row, int width, bool transparent, bool required,
+                               int32_t* outLeft, int32_t* outRight, const char** outError,
+                               uint8_t* outDivs, bool multipleAllowed) {
+  *outLeft = *outRight = -1;
+  TickState state = TickState::kStart;
+  bool found = false;
+
+  for (int i = 1; i < width - 1; i++) {
+    if (tickType(row + i * 4, transparent, outError) == TickType::kTick) {
+      if (state == TickState::kStart || (state == TickState::kOutside1 && multipleAllowed)) {
+        *outLeft = i - 1;
+        *outRight = width - 2;
+        found = true;
+        if (outDivs != NULL) {
+          *outDivs += 2;
+        }
+        state = TickState::kInside1;
+      } else if (state == TickState::kOutside1) {
+        *outError = "Can't have more than one marked region along edge";
+        *outLeft = i;
+        return false;
+      }
+    } else if (!*outError) {
+      if (state == TickState::kInside1) {
+        // We're done with this div.  Move on to the next.
+        *outRight = i - 1;
+        outRight += 2;
+        outLeft += 2;
+        state = TickState::kOutside1;
+      }
+    } else {
+      *outLeft = i;
+      return false;
+    }
+  }
+
+  if (required && !found) {
+    *outError = "No marked region found along edge";
+    *outLeft = -1;
+    return false;
+  }
+  return true;
+}
+
+static bool getVerticalTicks(png_bytepp rows, int offset, int height, bool transparent,
+                             bool required, int32_t* outTop, int32_t* outBottom,
+                             const char** outError, uint8_t* outDivs, bool multipleAllowed) {
+  *outTop = *outBottom = -1;
+  TickState state = TickState::kStart;
+  bool found = false;
+
+  for (int i = 1; i < height - 1; i++) {
+    if (tickType(rows[i] + offset, transparent, outError) == TickType::kTick) {
+      if (state == TickState::kStart || (state == TickState::kOutside1 && multipleAllowed)) {
+        *outTop = i - 1;
+        *outBottom = height - 2;
+        found = true;
+        if (outDivs != NULL) {
+          *outDivs += 2;
+        }
+        state = TickState::kInside1;
+      } else if (state == TickState::kOutside1) {
+        *outError = "Can't have more than one marked region along edge";
+        *outTop = i;
+        return false;
+      }
+    } else if (!*outError) {
+      if (state == TickState::kInside1) {
+        // We're done with this div.  Move on to the next.
+        *outBottom = i - 1;
+        outTop += 2;
+        outBottom += 2;
+        state = TickState::kOutside1;
+      }
+    } else {
+      *outTop = i;
+      return false;
+    }
+  }
+
+  if (required && !found) {
+    *outError = "No marked region found along edge";
+    *outTop = -1;
+    return false;
+  }
+  return true;
+}
+
+static bool getHorizontalLayoutBoundsTicks(png_bytep row, int width, bool transparent,
+                                           bool /* required */, int32_t* outLeft, int32_t* outRight,
+                                           const char** outError) {
+  *outLeft = *outRight = 0;
+
+  // Look for left tick
+  if (tickType(row + 4, transparent, outError) == TickType::kLayoutBounds) {
+    // Starting with a layout padding tick
+    int i = 1;
+    while (i < width - 1) {
+      (*outLeft)++;
+      i++;
+      if (tickType(row + i * 4, transparent, outError) != TickType::kLayoutBounds) {
+        break;
+      }
+    }
+  }
+
+  // Look for right tick
+  if (tickType(row + (width - 2) * 4, transparent, outError) == TickType::kLayoutBounds) {
+    // Ending with a layout padding tick
+    int i = width - 2;
+    while (i > 1) {
+      (*outRight)++;
+      i--;
+      if (tickType(row + i * 4, transparent, outError) != TickType::kLayoutBounds) {
+        break;
+      }
+    }
+  }
+  return true;
+}
+
+static bool getVerticalLayoutBoundsTicks(png_bytepp rows, int offset, int height, bool transparent,
+                                         bool /* required */, int32_t* outTop, int32_t* outBottom,
+                                         const char** outError) {
+  *outTop = *outBottom = 0;
+
+  // Look for top tick
+  if (tickType(rows[1] + offset, transparent, outError) == TickType::kLayoutBounds) {
+    // Starting with a layout padding tick
+    int i = 1;
+    while (i < height - 1) {
+      (*outTop)++;
+      i++;
+      if (tickType(rows[i] + offset, transparent, outError) != TickType::kLayoutBounds) {
+        break;
+      }
+    }
+  }
+
+  // Look for bottom tick
+  if (tickType(rows[height - 2] + offset, transparent, outError) == TickType::kLayoutBounds) {
+    // Ending with a layout padding tick
+    int i = height - 2;
+    while (i > 1) {
+      (*outBottom)++;
+      i--;
+      if (tickType(rows[i] + offset, transparent, outError) != TickType::kLayoutBounds) {
+        break;
+      }
+    }
+  }
+  return true;
+}
+
+static void findMaxOpacity(png_bytepp rows, int startX, int startY, int endX, int endY, int dX,
+                           int dY, int* outInset) {
+  uint8_t maxOpacity = 0;
+  int inset = 0;
+  *outInset = 0;
+  for (int x = startX, y = startY; x != endX && y != endY; x += dX, y += dY, inset++) {
+    png_byte* color = rows[y] + x * 4;
+    uint8_t opacity = color[3];
+    if (opacity > maxOpacity) {
+      maxOpacity = opacity;
+      *outInset = inset;
+    }
+    if (opacity == 0xff) return;
+  }
+}
+
+static uint8_t maxAlphaOverRow(png_bytep row, int startX, int endX) {
+  uint8_t maxAlpha = 0;
+  for (int x = startX; x < endX; x++) {
+    uint8_t alpha = (row + x * 4)[3];
+    if (alpha > maxAlpha) maxAlpha = alpha;
+  }
+  return maxAlpha;
+}
+
+static uint8_t maxAlphaOverCol(png_bytepp rows, int offsetX, int startY, int endY) {
+  uint8_t maxAlpha = 0;
+  for (int y = startY; y < endY; y++) {
+    uint8_t alpha = (rows[y] + offsetX * 4)[3];
+    if (alpha > maxAlpha) maxAlpha = alpha;
+  }
+  return maxAlpha;
+}
+
+static void getOutline(PngInfo* image) {
+  int midX = image->width / 2;
+  int midY = image->height / 2;
+  int endX = image->width - 2;
+  int endY = image->height - 2;
+
+  // find left and right extent of nine patch content on center row
+  if (image->width > 4) {
+    findMaxOpacity(image->rows.data(), 1, midY, midX, -1, 1, 0, &image->outlineInsetsLeft);
+    findMaxOpacity(image->rows.data(), endX, midY, midX, -1, -1, 0, &image->outlineInsetsRight);
+  } else {
+    image->outlineInsetsLeft = 0;
+    image->outlineInsetsRight = 0;
+  }
+
+  // find top and bottom extent of nine patch content on center column
+  if (image->height > 4) {
+    findMaxOpacity(image->rows.data(), midX, 1, -1, midY, 0, 1, &image->outlineInsetsTop);
+    findMaxOpacity(image->rows.data(), midX, endY, -1, midY, 0, -1, &image->outlineInsetsBottom);
+  } else {
+    image->outlineInsetsTop = 0;
+    image->outlineInsetsBottom = 0;
+  }
+
+  int innerStartX = 1 + image->outlineInsetsLeft;
+  int innerStartY = 1 + image->outlineInsetsTop;
+  int innerEndX = endX - image->outlineInsetsRight;
+  int innerEndY = endY - image->outlineInsetsBottom;
+  int innerMidX = (innerEndX + innerStartX) / 2;
+  int innerMidY = (innerEndY + innerStartY) / 2;
+
+  // assuming the image is a round rect, compute the radius by marching
+  // diagonally from the top left corner towards the center
+  image->outlineAlpha =
+      std::max(maxAlphaOverRow(image->rows[innerMidY], innerStartX, innerEndX),
+               maxAlphaOverCol(image->rows.data(), innerMidX, innerStartY, innerStartY));
+
+  int diagonalInset = 0;
+  findMaxOpacity(image->rows.data(), innerStartX, innerStartY, innerMidX, innerMidY, 1, 1,
+                 &diagonalInset);
+
+  /* Determine source radius based upon inset:
+   *     sqrt(r^2 + r^2) = sqrt(i^2 + i^2) + r
+   *     sqrt(2) * r = sqrt(2) * i + r
+   *     (sqrt(2) - 1) * r = sqrt(2) * i
+   *     r = sqrt(2) / (sqrt(2) - 1) * i
+   */
+  image->outlineRadius = 3.4142f * diagonalInset;
+
+  if (kDebug) {
+    printf("outline insets %d %d %d %d, rad %f, alpha %x\n", image->outlineInsetsLeft,
+           image->outlineInsetsTop, image->outlineInsetsRight, image->outlineInsetsBottom,
+           image->outlineRadius, image->outlineAlpha);
+  }
+}
+
+static uint32_t getColor(png_bytepp rows, int left, int top, int right, int bottom) {
+  png_bytep color = rows[top] + left * 4;
+
+  if (left > right || top > bottom) {
+    return Res_png_9patch::TRANSPARENT_COLOR;
+  }
+
+  while (top <= bottom) {
+    for (int i = left; i <= right; i++) {
+      png_bytep p = rows[top] + i * 4;
+      if (color[3] == 0) {
+        if (p[3] != 0) {
+          return Res_png_9patch::NO_COLOR;
+        }
+      } else if (p[0] != color[0] || p[1] != color[1] || p[2] != color[2] || p[3] != color[3]) {
+        return Res_png_9patch::NO_COLOR;
+      }
+    }
+    top++;
+  }
+
+  if (color[3] == 0) {
+    return Res_png_9patch::TRANSPARENT_COLOR;
+  }
+  return (color[3] << 24) | (color[0] << 16) | (color[1] << 8) | color[2];
+}
+
+static bool do9Patch(PngInfo* image, std::string* outError) {
+  image->is9Patch = true;
+
+  int W = image->width;
+  int H = image->height;
+  int i, j;
+
+  const int maxSizeXDivs = W * sizeof(int32_t);
+  const int maxSizeYDivs = H * sizeof(int32_t);
+  int32_t* xDivs = image->xDivs = new int32_t[W];
+  int32_t* yDivs = image->yDivs = new int32_t[H];
+  uint8_t numXDivs = 0;
+  uint8_t numYDivs = 0;
+
+  int8_t numColors;
+  int numRows;
+  int numCols;
+  int top;
+  int left;
+  int right;
+  int bottom;
+  memset(xDivs, -1, maxSizeXDivs);
+  memset(yDivs, -1, maxSizeYDivs);
+  image->info9Patch.paddingLeft = image->info9Patch.paddingRight = -1;
+  image->info9Patch.paddingTop = image->info9Patch.paddingBottom = -1;
+  image->layoutBoundsLeft = image->layoutBoundsRight = 0;
+  image->layoutBoundsTop = image->layoutBoundsBottom = 0;
+
+  png_bytep p = image->rows[0];
+  bool transparent = p[3] == 0;
+  bool hasColor = false;
+
+  const char* errorMsg = nullptr;
+  int errorPixel = -1;
+  const char* errorEdge = nullptr;
+
+  int colorIndex = 0;
+  std::vector<png_bytep> newRows;
+
+  // Validate size...
+  if (W < 3 || H < 3) {
+    errorMsg = "Image must be at least 3x3 (1x1 without frame) pixels";
+    goto getout;
+  }
+
+  // Validate frame...
+  if (!transparent && (p[0] != 0xFF || p[1] != 0xFF || p[2] != 0xFF || p[3] != 0xFF)) {
+    errorMsg = "Must have one-pixel frame that is either transparent or white";
+    goto getout;
+  }
+
+  // Find left and right of sizing areas...
+  if (!getHorizontalTicks(p, W, transparent, true, &xDivs[0], &xDivs[1], &errorMsg, &numXDivs,
+                          true)) {
+    errorPixel = xDivs[0];
+    errorEdge = "top";
+    goto getout;
+  }
+
+  // Find top and bottom of sizing areas...
+  if (!getVerticalTicks(image->rows.data(), 0, H, transparent, true, &yDivs[0], &yDivs[1],
+                        &errorMsg, &numYDivs, true)) {
+    errorPixel = yDivs[0];
+    errorEdge = "left";
+    goto getout;
+  }
+
+  // Copy patch size data into image...
+  image->info9Patch.numXDivs = numXDivs;
+  image->info9Patch.numYDivs = numYDivs;
+
+  // Find left and right of padding area...
+  if (!getHorizontalTicks(image->rows[H - 1], W, transparent, false, &image->info9Patch.paddingLeft,
+                          &image->info9Patch.paddingRight, &errorMsg, nullptr, false)) {
+    errorPixel = image->info9Patch.paddingLeft;
+    errorEdge = "bottom";
+    goto getout;
+  }
+
+  // Find top and bottom of padding area...
+  if (!getVerticalTicks(image->rows.data(), (W - 1) * 4, H, transparent, false,
+                        &image->info9Patch.paddingTop, &image->info9Patch.paddingBottom, &errorMsg,
+                        nullptr, false)) {
+    errorPixel = image->info9Patch.paddingTop;
+    errorEdge = "right";
+    goto getout;
+  }
+
+  // Find left and right of layout padding...
+  getHorizontalLayoutBoundsTicks(image->rows[H - 1], W, transparent, false,
+                                 &image->layoutBoundsLeft, &image->layoutBoundsRight, &errorMsg);
+
+  getVerticalLayoutBoundsTicks(image->rows.data(), (W - 1) * 4, H, transparent, false,
+                               &image->layoutBoundsTop, &image->layoutBoundsBottom, &errorMsg);
+
+  image->haveLayoutBounds = image->layoutBoundsLeft != 0 || image->layoutBoundsRight != 0 ||
+                            image->layoutBoundsTop != 0 || image->layoutBoundsBottom != 0;
+
+  if (image->haveLayoutBounds) {
+    if (kDebug) {
+      printf("layoutBounds=%d %d %d %d\n", image->layoutBoundsLeft, image->layoutBoundsTop,
+             image->layoutBoundsRight, image->layoutBoundsBottom);
+    }
+  }
+
+  // use opacity of pixels to estimate the round rect outline
+  getOutline(image);
+
+  // If padding is not yet specified, take values from size.
+  if (image->info9Patch.paddingLeft < 0) {
+    image->info9Patch.paddingLeft = xDivs[0];
+    image->info9Patch.paddingRight = W - 2 - xDivs[1];
+  } else {
+    // Adjust value to be correct!
+    image->info9Patch.paddingRight = W - 2 - image->info9Patch.paddingRight;
+  }
+  if (image->info9Patch.paddingTop < 0) {
+    image->info9Patch.paddingTop = yDivs[0];
+    image->info9Patch.paddingBottom = H - 2 - yDivs[1];
+  } else {
+    // Adjust value to be correct!
+    image->info9Patch.paddingBottom = H - 2 - image->info9Patch.paddingBottom;
+  }
+
+  /*    if (kDebug) {
+          printf("Size ticks for %s: x0=%d, x1=%d, y0=%d, y1=%d\n", imageName,
+                  xDivs[0], xDivs[1],
+                  yDivs[0], yDivs[1]);
+          printf("padding ticks for %s: l=%d, r=%d, t=%d, b=%d\n", imageName,
+                  image->info9Patch.paddingLeft, image->info9Patch.paddingRight,
+                  image->info9Patch.paddingTop,
+     image->info9Patch.paddingBottom);
+      }*/
+
+  // Remove frame from image.
+  newRows.resize(H - 2);
+  for (i = 0; i < H - 2; i++) {
+    newRows[i] = image->rows[i + 1];
+    memmove(newRows[i], newRows[i] + 4, (W - 2) * 4);
+  }
+  image->rows.swap(newRows);
+
+  image->width -= 2;
+  W = image->width;
+  image->height -= 2;
+  H = image->height;
+
+  // Figure out the number of rows and columns in the N-patch
+  numCols = numXDivs + 1;
+  if (xDivs[0] == 0) {  // Column 1 is strechable
+    numCols--;
+  }
+  if (xDivs[numXDivs - 1] == W) {
+    numCols--;
+  }
+  numRows = numYDivs + 1;
+  if (yDivs[0] == 0) {  // Row 1 is strechable
+    numRows--;
+  }
+  if (yDivs[numYDivs - 1] == H) {
+    numRows--;
+  }
+
+  // Make sure the amount of rows and columns will fit in the number of
+  // colors we can use in the 9-patch format.
+  if (numRows * numCols > 0x7F) {
+    errorMsg = "Too many rows and columns in 9-patch perimeter";
+    goto getout;
+  }
+
+  numColors = numRows * numCols;
+  image->info9Patch.numColors = numColors;
+  image->colors.resize(numColors);
+
+  // Fill in color information for each patch.
+
+  uint32_t c;
+  top = 0;
+
+  // The first row always starts with the top being at y=0 and the bottom
+  // being either yDivs[1] (if yDivs[0]=0) of yDivs[0].  In the former case
+  // the first row is stretchable along the Y axis, otherwise it is fixed.
+  // The last row always ends with the bottom being bitmap.height and the top
+  // being either yDivs[numYDivs-2] (if yDivs[numYDivs-1]=bitmap.height) or
+  // yDivs[numYDivs-1]. In the former case the last row is stretchable along
+  // the Y axis, otherwise it is fixed.
+  //
+  // The first and last columns are similarly treated with respect to the X
+  // axis.
+  //
+  // The above is to help explain some of the special casing that goes on the
+  // code below.
+
+  // The initial yDiv and whether the first row is considered stretchable or
+  // not depends on whether yDiv[0] was zero or not.
+  for (j = (yDivs[0] == 0 ? 1 : 0); j <= numYDivs && top < H; j++) {
+    if (j == numYDivs) {
+      bottom = H;
+    } else {
+      bottom = yDivs[j];
+    }
+    left = 0;
+    // The initial xDiv and whether the first column is considered
+    // stretchable or not depends on whether xDiv[0] was zero or not.
+    for (i = xDivs[0] == 0 ? 1 : 0; i <= numXDivs && left < W; i++) {
+      if (i == numXDivs) {
+        right = W;
+      } else {
+        right = xDivs[i];
+      }
+      c = getColor(image->rows.data(), left, top, right - 1, bottom - 1);
+      image->colors[colorIndex++] = c;
+      if (kDebug) {
+        if (c != Res_png_9patch::NO_COLOR) {
+          hasColor = true;
+        }
+      }
+      left = right;
+    }
+    top = bottom;
+  }
+
+  assert(colorIndex == numColors);
+
+  if (kDebug && hasColor) {
+    for (i = 0; i < numColors; i++) {
+      if (i == 0) printf("Colors:\n");
+      printf(" #%08x", image->colors[i]);
+      if (i == numColors - 1) printf("\n");
+    }
+  }
+getout:
+  if (errorMsg) {
+    std::stringstream err;
+    err << "9-patch malformed: " << errorMsg;
+    if (errorEdge) {
+      err << "." << std::endl;
+      if (errorPixel >= 0) {
+        err << "Found at pixel #" << errorPixel << " along " << errorEdge << " edge";
+      } else {
+        err << "Found along " << errorEdge << " edge";
+      }
+    }
+    *outError = err.str();
+    return false;
+  }
+  return true;
+}
+
+bool Png::process(const Source& source, std::istream* input, BigBuffer* outBuffer,
+                  const PngOptions& options) {
+  png_byte signature[kPngSignatureSize];
+
+  // Read the PNG signature first.
+  if (!input->read(reinterpret_cast<char*>(signature), kPngSignatureSize)) {
+    mDiag->Error(DiagMessage() << strerror(errno));
+    return false;
+  }
+
+  // If the PNG signature doesn't match, bail early.
+  if (png_sig_cmp(signature, 0, kPngSignatureSize) != 0) {
+    mDiag->Error(DiagMessage() << "not a valid png file");
+    return false;
+  }
+
+  bool result = false;
+  png_structp readPtr = nullptr;
+  png_infop infoPtr = nullptr;
+  png_structp writePtr = nullptr;
+  png_infop writeInfoPtr = nullptr;
+  PngInfo pngInfo = {};
+
+  readPtr = png_create_read_struct(PNG_LIBPNG_VER_STRING, 0, nullptr, nullptr);
+  if (!readPtr) {
+    mDiag->Error(DiagMessage() << "failed to allocate read ptr");
+    goto bail;
+  }
+
+  infoPtr = png_create_info_struct(readPtr);
+  if (!infoPtr) {
+    mDiag->Error(DiagMessage() << "failed to allocate info ptr");
+    goto bail;
+  }
+
+  png_set_error_fn(readPtr, reinterpret_cast<png_voidp>(mDiag), nullptr, logWarning);
+
+  // Set the read function to read from std::istream.
+  png_set_read_fn(readPtr, (png_voidp)input, readDataFromStream);
+
+  if (!readPng(mDiag, readPtr, infoPtr, &pngInfo)) {
+    goto bail;
+  }
+
+  if (android::base::EndsWith(source.path, ".9.png")) {
+    std::string errorMsg;
+    if (!do9Patch(&pngInfo, &errorMsg)) {
+      mDiag->Error(DiagMessage() << errorMsg);
+      goto bail;
+    }
+  }
+
+  writePtr = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, nullptr, nullptr);
+  if (!writePtr) {
+    mDiag->Error(DiagMessage() << "failed to allocate write ptr");
+    goto bail;
+  }
+
+  writeInfoPtr = png_create_info_struct(writePtr);
+  if (!writeInfoPtr) {
+    mDiag->Error(DiagMessage() << "failed to allocate write info ptr");
+    goto bail;
+  }
+
+  png_set_error_fn(writePtr, nullptr, nullptr, logWarning);
+
+  // Set the write function to write to std::ostream.
+  png_set_write_fn(writePtr, (png_voidp)outBuffer, writeDataToStream, flushDataToStream);
+
+  if (!writePng(mDiag, writePtr, writeInfoPtr, &pngInfo, options.grayscale_tolerance)) {
+    goto bail;
+  }
+
+  result = true;
+bail:
+  if (readPtr) {
+    png_destroy_read_struct(&readPtr, &infoPtr, nullptr);
+  }
+
+  if (writePtr) {
+    png_destroy_write_struct(&writePtr, &writeInfoPtr);
+  }
+  return result;
+}
+
+}  // namespace android