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/io/Io.h b/tools/aapt2/io/Io.h
new file mode 100644
index 0000000..e1e9107
--- /dev/null
+++ b/tools/aapt2/io/Io.h
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#ifndef AAPT_IO_IO_H
+#define AAPT_IO_IO_H
+
+#include <google/protobuf/io/zero_copy_stream_impl_lite.h>
+#include <string>
+
+namespace aapt {
+namespace io {
+
+/**
+ * InputStream interface that inherits from protobuf's ZeroCopyInputStream,
+ * but adds error handling methods to better report issues.
+ *
+ * The code style here matches the protobuf style.
+ */
+class InputStream : public google::protobuf::io::ZeroCopyInputStream {
+public:
+ virtual std::string GetError() const {
+ return {};
+ }
+
+ virtual bool HadError() const = 0;
+};
+
+/**
+ * OutputStream interface that inherits from protobuf's ZeroCopyOutputStream,
+ * but adds error handling methods to better report issues.
+ *
+ * The code style here matches the protobuf style.
+ */
+class OutputStream : public google::protobuf::io::ZeroCopyOutputStream {
+public:
+ virtual std::string GetError() const {
+ return {};
+ }
+
+ virtual bool HadError() const = 0;
+};
+
+/**
+ * Copies the data from in to out. Returns true if there was no error.
+ * If there was an error, check the individual streams' HadError/GetError
+ * methods.
+ */
+bool copy(OutputStream* out, InputStream* in);
+
+} // namespace io
+} // namespace aapt
+
+#endif /* AAPT_IO_IO_H */