[rust png] Hoist `PngDecoder::Delegate` into a top-level class.
This CL moves the declaration of the abstract `PngDecoder::Delegate`
interface into a separate `png_decoder_delegate.h` header (renaming the
interface into `PngDecoderDelegate`). This is desirable for follow-up
CLs, where the interface will be used from a future
`skia_png_decoder.cc` without having to reach for the current,
`libpng`-related `png_decoder.cc`.
Bug: 444045690
Change-Id: I546c8da2c8f6d90894cef9af8bd6df54c13d358f
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/135653
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
diff --git a/core/fxcodec/png/png_decoder.cpp b/core/fxcodec/png/png_decoder.cpp
index 950e28a..60a70a2 100644
--- a/core/fxcodec/png/png_decoder.cpp
+++ b/core/fxcodec/png/png_decoder.cpp
@@ -12,6 +12,7 @@
#include "core/fxcodec/cfx_codec_memory.h"
#include "core/fxcodec/fx_codec.h"
#include "core/fxcodec/fx_codec_def.h"
+#include "core/fxcodec/png/png_decoder_delegate.h"
#include "core/fxcrt/compiler_specific.h"
#include "core/fxcrt/notreached.h"
#include "core/fxcrt/unowned_ptr.h"
@@ -24,17 +25,18 @@
#define PNG_ERROR_SIZE 256
-using DecodedColorType = fxcodec::PngDecoder::Delegate::DecodedColorType;
-using EncodedColorType = fxcodec::PngDecoder::Delegate::EncodedColorType;
+using PngDecoderDelegate = fxcodec::PngDecoderDelegate;
+using DecodedColorType = PngDecoderDelegate::DecodedColorType;
+using EncodedColorType = PngDecoderDelegate::EncodedColorType;
class CPngContext final : public ProgressiveDecoderIface::Context {
public:
- explicit CPngContext(PngDecoder::Delegate* pDelegate);
+ explicit CPngContext(PngDecoderDelegate* pDelegate);
~CPngContext() override;
png_structp png_ = nullptr;
png_infop info_ = nullptr;
- UnownedPtr<PngDecoder::Delegate> const delegate_;
+ UnownedPtr<PngDecoderDelegate> const delegate_;
char last_error_[PNG_ERROR_SIZE] = {};
};
@@ -203,7 +205,7 @@
} // extern "C"
-CPngContext::CPngContext(PngDecoder::Delegate* pDelegate)
+CPngContext::CPngContext(PngDecoderDelegate* pDelegate)
: delegate_(pDelegate) {}
CPngContext::~CPngContext() {
@@ -215,7 +217,7 @@
// static
std::unique_ptr<ProgressiveDecoderIface::Context> PngDecoder::StartDecode(
- Delegate* pDelegate) {
+ PngDecoderDelegate* pDelegate) {
auto p = std::make_unique<CPngContext>(pDelegate);
p->png_ =
png_create_read_struct(PNG_LIBPNG_VER_STRING, nullptr, nullptr, nullptr);
diff --git a/core/fxcodec/png/png_decoder.h b/core/fxcodec/png/png_decoder.h
index d1f1cb6..635c05a 100644
--- a/core/fxcodec/png/png_decoder.h
+++ b/core/fxcodec/png/png_decoder.h
@@ -19,66 +19,12 @@
namespace fxcodec {
class CFX_DIBAttribute;
+class PngDecoderDelegate;
class PngDecoder {
public:
- class Delegate {
- public:
- // Color type specified in the PNG IHDR chunk. See also
- // https://www.w3.org/TR/png-3/#6Colour-values and
- // https://www.w3.org/TR/png-3/#11IHDR
- //
- // The enumerator values below have been picked to match 1) the PNG spec and
- // 2) `PNG_COLOR_TYPE_...` constants from `libpng/png.h`.
- enum class EncodedColorType : int {
- kGrayscale = 0,
- kTruecolor = 2,
- kIndexedColor = 3,
- kGrayscaleWithAlpha = 4,
- kTruecolorWithAlpha = 6,
- };
-
- // Color format to decode into.
- enum class DecodedColorType {
- kBgr,
- kBgra,
- };
-
- // Called by `PngDecoder` after decoding the image header:
- //
- // * `width` and `height` specify image dimensions in pixels
- // * `bpc` is number of bits per component (e.g. per red, or per alpha)
- // * `src_color_type` is the color type the image has been encoded with
- //
- // Implementation should:
- //
- // * Return `true` upon success (and `false` otherwise)
- // * Set `*dst_color_type` to the color type to decode into
- // * Set `*gamma` to the target gamma to decode with
- // * TODO(crbug.com/355630556): Add out parameter for desired alpha-premul.
- virtual bool PngReadHeader(int width,
- int height,
- int bpc,
- int pass,
- EncodedColorType src_color_type,
- DecodedColorType* dst_color_type,
- double* gamma) = 0;
-
- // Called by `PngDecoder` to ask where to write decoded pixels.
- // Implementation should return a pointer to the buffer where the
- // decoded pixels should be written to.
- //
- // `PngDecoder` guarantees that `0 <= line && line < height`
- // (`height` that was earlier passed to `PngReadHeader`).
- virtual uint8_t* PngAskScanlineBuf(int line) = 0;
-
- // Called by `PngDecoder` Communicates that `line`th row has been decoded
- // enough to be displayed.
- virtual void PngFillScanlineBufCompleted(int line) = 0;
- };
-
static std::unique_ptr<ProgressiveDecoderIface::Context> StartDecode(
- Delegate* pDelegate);
+ PngDecoderDelegate* pDelegate);
static bool ContinueDecode(ProgressiveDecoderIface::Context* pContext,
RetainPtr<CFX_CodecMemory> codec_memory,
diff --git a/core/fxcodec/png/png_decoder_delegate.h b/core/fxcodec/png/png_decoder_delegate.h
new file mode 100644
index 0000000..a28e18c
--- /dev/null
+++ b/core/fxcodec/png/png_decoder_delegate.h
@@ -0,0 +1,75 @@
+// Copyright 2025 The PDFium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CORE_FXCODEC_PNG_PNG_DECODER_DELEGATE_H_
+#define CORE_FXCODEC_PNG_PNG_DECODER_DELEGATE_H_
+
+#include <stdint.h>
+
+namespace fxcodec {
+
+// Abstract interface used by the `libpng`-based decoder from `png_decoder.h`
+// (in the future by Skia-based decoder from `skia_png_decoder.h`).
+//
+// TODO(https://crbug.com/444045690): Update the comment above once the
+// Skia-based decoder is implemented and/or the `libpng`-based decoder moved
+// to renamed .h/.cc files.
+class PngDecoderDelegate {
+ public:
+ // Color type specified in the PNG IHDR chunk. See also
+ // https://www.w3.org/TR/png-3/#6Colour-values and
+ // https://www.w3.org/TR/png-3/#11IHDR
+ //
+ // The enumerator values below have been picked to match 1) the PNG spec and
+ // 2) `PNG_COLOR_TYPE_...` constants from `libpng/png.h`.
+ enum class EncodedColorType : int {
+ kGrayscale = 0,
+ kTruecolor = 2,
+ kIndexedColor = 3,
+ kGrayscaleWithAlpha = 4,
+ kTruecolorWithAlpha = 6,
+ };
+
+ // Color format to decode into.
+ enum class DecodedColorType {
+ kBgr,
+ kBgra,
+ };
+
+ // Called by `PngDecoder` after decoding the image header:
+ //
+ // * `width` and `height` specify image dimensions in pixels
+ // * `bpc` is number of bits per component (e.g. per red, or per alpha)
+ // * `src_color_type` is the color type the image has been encoded with
+ //
+ // Implementation should:
+ //
+ // * Return `true` upon success (and `false` otherwise)
+ // * Set `*dst_color_type` to the color type to decode into
+ // * Set `*gamma` to the target gamma to decode with
+ // * TODO(crbug.com/355630556): Add out parameter for desired alpha-premul.
+ virtual bool PngReadHeader(int width,
+ int height,
+ int bpc,
+ int pass,
+ EncodedColorType src_color_type,
+ DecodedColorType* dst_color_type,
+ double* gamma) = 0;
+
+ // Called by `PngDecoder` to ask where to write decoded pixels.
+ // Implementation should return a pointer to the buffer where the
+ // decoded pixels should be written to.
+ //
+ // `PngDecoder` guarantees that `0 <= line && line < height`
+ // (`height` that was earlier passed to `PngReadHeader`).
+ virtual uint8_t* PngAskScanlineBuf(int line) = 0;
+
+ // Called by `PngDecoder` Communicates that `line`th row has been decoded
+ // enough to be displayed.
+ virtual void PngFillScanlineBufCompleted(int line) = 0;
+};
+
+} // namespace fxcodec
+
+#endif // CORE_FXCODEC_PNG_PNG_DECODER_DELEGATE_H_
diff --git a/core/fxcodec/progressive_decoder.cpp b/core/fxcodec/progressive_decoder.cpp
index 4fa0e8e..d38aa72 100644
--- a/core/fxcodec/progressive_decoder.cpp
+++ b/core/fxcodec/progressive_decoder.cpp
@@ -48,8 +48,8 @@
constexpr size_t kBlockSize = 4096;
#ifdef PDF_ENABLE_XFA_PNG
-using PngDecodedColorType = fxcodec::PngDecoder::Delegate::DecodedColorType;
-using PngEncodedColorType = fxcodec::PngDecoder::Delegate::EncodedColorType;
+using PngDecodedColorType = fxcodec::PngDecoderDelegate::DecodedColorType;
+using PngEncodedColorType = fxcodec::PngDecoderDelegate::EncodedColorType;
#if BUILDFLAG(IS_APPLE)
const double kPngGamma = 1.7;
#else
diff --git a/core/fxcodec/progressive_decoder.h b/core/fxcodec/progressive_decoder.h
index 3589dfb..c96138c 100644
--- a/core/fxcodec/progressive_decoder.h
+++ b/core/fxcodec/progressive_decoder.h
@@ -33,6 +33,7 @@
#ifdef PDF_ENABLE_XFA_PNG
#include "core/fxcodec/png/png_decoder.h"
+#include "core/fxcodec/png/png_decoder_delegate.h"
#endif // PDF_ENABLE_XFA_PNG
class CFX_DIBitmap;
@@ -52,7 +53,7 @@
public GifDecoder::Delegate,
#endif // PDF_ENABLE_XFA_GIF
#ifdef PDF_ENABLE_XFA_PNG
- public PngDecoder::Delegate,
+ public PngDecoderDelegate,
#endif // PDF_ENABLE_XFA_PNG
public Dummy {
public:
@@ -85,13 +86,13 @@
FXCODEC_STATUS ContinueDecode();
#ifdef PDF_ENABLE_XFA_PNG
- // PngDecoder::Delegate
+ // PngDecoderDelegate
bool PngReadHeader(int width,
int height,
int bpc,
int pass,
- PngDecoder::Delegate::EncodedColorType src_color_type,
- PngDecoder::Delegate::DecodedColorType* dst_color_type,
+ PngDecoderDelegate::EncodedColorType src_color_type,
+ PngDecoderDelegate::DecodedColorType* dst_color_type,
double* gamma) override;
uint8_t* PngAskScanlineBuf(int line) override;
void PngFillScanlineBufCompleted(int line) override;
