AAPT2: Refactor PngCrunching
PngCrunching now has a slightly better heuristic of choosing to encode
an image as a palette or RGB. For small images, RGB compresses much better
than a palette.
The original PNG is used as-is (minus some optional chunks being stripped)
if the resulting crunched PNG is larger than the original.
9-patch handling is abstracted away from PNGs, paving the way
for other 9-patches, like WebP.
TODO: handle PNGs with 9-patch chunks already present, which
should just be passed through. This will allow for 3rd party
tools to generate 9-patches.
TODO: implement cheap transparency: when one color is used to represent
transparent, and all other colors are opaque.
Bug:30053276
Change-Id: I5167f53b91d1efa462d9f03d6b9108d9b541c0c1
diff --git a/tools/aapt2/compile/Compile.cpp b/tools/aapt2/compile/Compile.cpp
index e0f37ec..dbd8062 100644
--- a/tools/aapt2/compile/Compile.cpp
+++ b/tools/aapt2/compile/Compile.cpp
@@ -36,6 +36,8 @@
#include <google/protobuf/io/zero_copy_stream_impl_lite.h>
#include <google/protobuf/io/coded_stream.h>
+#include <android-base/errors.h>
+#include <android-base/file.h>
#include <dirent.h>
#include <fstream>
#include <string>
@@ -359,6 +361,9 @@
static bool compileXml(IAaptContext* context, const CompileOptions& options,
const ResourcePathData& pathData, IArchiveWriter* writer,
const std::string& outputPath) {
+ if (context->verbose()) {
+ context->getDiagnostics()->note(DiagMessage(pathData.source) << "compiling XML");
+ }
std::unique_ptr<xml::XmlResource> xmlRes;
{
@@ -431,9 +436,43 @@
return true;
}
+class BigBufferOutputStream : public io::OutputStream {
+public:
+ explicit BigBufferOutputStream(BigBuffer* buffer) : mBuffer(buffer) {
+ }
+
+ bool Next(void** data, int* len) override {
+ size_t count;
+ *data = mBuffer->nextBlock(&count);
+ *len = static_cast<int>(count);
+ return true;
+ }
+
+ void BackUp(int count) override {
+ mBuffer->backUp(count);
+ }
+
+ int64_t ByteCount() const override {
+ return mBuffer->size();
+ }
+
+ bool HadError() const override {
+ return false;
+ }
+
+private:
+ BigBuffer* mBuffer;
+
+ DISALLOW_COPY_AND_ASSIGN(BigBufferOutputStream);
+};
+
static bool compilePng(IAaptContext* context, const CompileOptions& options,
const ResourcePathData& pathData, IArchiveWriter* writer,
const std::string& outputPath) {
+ if (context->verbose()) {
+ context->getDiagnostics()->note(DiagMessage(pathData.source) << "compiling PNG");
+ }
+
BigBuffer buffer(4096);
ResourceFile resFile;
resFile.name = ResourceName({}, *parseResourceType(pathData.resourceDir), pathData.name);
@@ -441,16 +480,90 @@
resFile.source = pathData.source;
{
- std::ifstream fin(pathData.source.path, std::ifstream::binary);
- if (!fin) {
- context->getDiagnostics()->error(DiagMessage(pathData.source) << strerror(errno));
+ std::string content;
+ if (!android::base::ReadFileToString(pathData.source.path, &content)) {
+ context->getDiagnostics()->error(DiagMessage(pathData.source)
+ << android::base::SystemErrorCodeToString(errno));
return false;
}
- Png png(context->getDiagnostics());
- if (!png.process(pathData.source, &fin, &buffer, {})) {
+ BigBuffer crunchedPngBuffer(4096);
+ BigBufferOutputStream crunchedPngBufferOut(&crunchedPngBuffer);
+
+ // Ensure that we only keep the chunks we care about if we end up
+ // using the original PNG instead of the crunched one.
+ PngChunkFilter pngChunkFilter(content);
+ std::unique_ptr<Image> image = readPng(context, &pngChunkFilter);
+ if (!image) {
return false;
}
+
+ std::unique_ptr<NinePatch> ninePatch;
+ if (pathData.extension == "9.png") {
+ std::string err;
+ ninePatch = NinePatch::create(image->rows.get(), image->width, image->height, &err);
+ if (!ninePatch) {
+ context->getDiagnostics()->error(DiagMessage() << err);
+ return false;
+ }
+
+ // Remove the 1px border around the NinePatch.
+ // Basically the row array is shifted up by 1, and the length is treated
+ // as height - 2.
+ // For each row, shift the array to the left by 1, and treat the length as width - 2.
+ image->width -= 2;
+ image->height -= 2;
+ memmove(image->rows.get(), image->rows.get() + 1, image->height * sizeof(uint8_t**));
+ for (int32_t h = 0; h < image->height; h++) {
+ memmove(image->rows[h], image->rows[h] + 4, image->width * 4);
+ }
+
+ if (context->verbose()) {
+ context->getDiagnostics()->note(DiagMessage(pathData.source)
+ << "9-patch: " << *ninePatch);
+ }
+ }
+
+ // Write the crunched PNG.
+ if (!writePng(context, image.get(), ninePatch.get(), &crunchedPngBufferOut, {})) {
+ return false;
+ }
+
+ if (ninePatch != nullptr
+ || crunchedPngBufferOut.ByteCount() <= pngChunkFilter.ByteCount()) {
+ // No matter what, we must use the re-encoded PNG, even if it is larger.
+ // 9-patch images must be re-encoded since their borders are stripped.
+ buffer.appendBuffer(std::move(crunchedPngBuffer));
+ } else {
+ // The re-encoded PNG is larger than the original, and there is
+ // no mandatory transformation. Use the original.
+ if (context->verbose()) {
+ context->getDiagnostics()->note(DiagMessage(pathData.source)
+ << "original PNG is smaller than crunched PNG"
+ << ", using original");
+ }
+
+ PngChunkFilter pngChunkFilterAgain(content);
+ BigBuffer filteredPngBuffer(4096);
+ BigBufferOutputStream filteredPngBufferOut(&filteredPngBuffer);
+ io::copy(&filteredPngBufferOut, &pngChunkFilterAgain);
+ buffer.appendBuffer(std::move(filteredPngBuffer));
+ }
+
+ if (context->verbose()) {
+ // For debugging only, use the legacy PNG cruncher and compare the resulting file sizes.
+ // This will help catch exotic cases where the new code may generate larger PNGs.
+ std::stringstream legacyStream(content);
+ BigBuffer legacyBuffer(4096);
+ Png png(context->getDiagnostics());
+ if (!png.process(pathData.source, &legacyStream, &legacyBuffer, {})) {
+ return false;
+ }
+
+ context->getDiagnostics()->note(DiagMessage(pathData.source)
+ << "legacy=" << legacyBuffer.size()
+ << " new=" << buffer.size());
+ }
}
if (!writeHeaderAndBufferToWriter(outputPath, resFile, buffer, writer,
@@ -463,6 +576,10 @@
static bool compileFile(IAaptContext* context, const CompileOptions& options,
const ResourcePathData& pathData, IArchiveWriter* writer,
const std::string& outputPath) {
+ if (context->verbose()) {
+ context->getDiagnostics()->note(DiagMessage(pathData.source) << "compiling file");
+ }
+
BigBuffer buffer(256);
ResourceFile resFile;
resFile.name = ResourceName({}, *parseResourceType(pathData.resourceDir), pathData.name);