Add SkCodec, including PNG implementation.

src/codec/SkCodec_libpng.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCodec_libpng.h"
+#include "SkColorPriv.h"
+#include "SkColorTable.h"
+#include "SkBitmap.h"
+#include "SkMath.h"
+#include "SkSize.h"
+#include "SkStream.h"
+#include "SkSwizzler.h"
+
+///////////////////////////////////////////////////////////////////////////////
+// Helper macros
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef png_jmpbuf
+#  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
+#endif
+
+/* These were dropped in libpng >= 1.4 */
+#ifndef png_infopp_NULL
+    #define png_infopp_NULL NULL
+#endif
+
+#ifndef png_bytepp_NULL
+    #define png_bytepp_NULL NULL
+#endif
+
+#ifndef int_p_NULL
+    #define int_p_NULL NULL
+#endif
+
+#ifndef png_flush_ptr_NULL
+    #define png_flush_ptr_NULL NULL
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+// Callback functions
+///////////////////////////////////////////////////////////////////////////////
+
+static void sk_error_fn(png_structp png_ptr, png_const_charp msg) {
+    SkDEBUGF(("------ png error %s\n", msg));

[djsollen, 2015/02/25 16:02:20]

I think we may want to always log this error not just in debug mode.

[scroggo, 2015/02/25 18:00:55]

Oops, copied from SkImageDecoder. Done.

FWIW, by the time we replace SkImageDecoder, I actually want to make it
optional, since some users may not want to see it...

+    longjmp(png_jmpbuf(png_ptr), 1);
+}
+
+static void sk_read_fn(png_structp png_ptr, png_bytep data,
+                       png_size_t length) {
+    SkStream* stream = static_cast<SkStream*>(png_get_io_ptr(png_ptr));
+    const size_t bytes = stream->read(data, length);
+    if (bytes != length) {
+        // FIXME: We want to report the fact that the stream was truncated.
+        // One way to do that might be to pass a enum to longjmp so setjmp can
+        // specify the failure.
+        png_error(png_ptr, "Read Error!");
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Helpers
+///////////////////////////////////////////////////////////////////////////////
+
+class AutoCleanPng : public SkNoncopyable {
+public:
+    AutoCleanPng(png_structp png_ptr)
+        : fPng_ptr(png_ptr)
+        , fInfo_ptr(NULL) {}
+
+    ~AutoCleanPng() {
+        // fInfo_ptr will never be non-NULL unless fPng_ptr is.
+        if (fPng_ptr) {
+            png_infopp info_pp = fInfo_ptr ? &fInfo_ptr : NULL;
+            png_destroy_read_struct(&fPng_ptr, info_pp, png_infopp_NULL);
+        }
+    }
+
+    void setInfoPtr(png_infop info_ptr) {
+        SkASSERT(NULL == fInfo_ptr);
+        fInfo_ptr = info_ptr;
+    }
+
+    void detach() {
+        fPng_ptr = NULL;
+        fInfo_ptr = NULL;
+    }
+
+private:
+    png_structp     fPng_ptr;
+    png_infop       fInfo_ptr;
+};
+#define AutoCleanPng(...) SK_REQUIRE_LOCAL_VAR(AutoCleanPng)
+
+// call only if color_type is PALETTE. Returns true if the ctable has alpha
+static bool has_transparency_in_palette(png_structp png_ptr,
+                                        png_infop info_ptr) {
+    if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
+        return false;
+    }
+
+    png_bytep trans;
+    int num_trans;
+    png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, NULL);
+    return num_trans > 0;
+}
+
+// Method for coverting to either an SkPMColor or a similarly packed
+// unpremultiplied color.
+typedef uint32_t (*PackColorProc)(U8CPU a, U8CPU r, U8CPU g, U8CPU b);
+
+// Note: SkColorTable claims to store SkPMColors, which is not necessarily
+// the case here.
+SkColorTable* decode_palette(png_structp png_ptr, png_infop info_ptr,
+                             bool premultiply, SkAlphaType* outAlphaType) {
+    SkASSERT(outAlphaType != NULL);
+    int numPalette;
+    png_colorp palette;
+    png_bytep trans;
+
+    if (!png_get_PLTE(png_ptr, info_ptr, &palette, &numPalette)) {
+        return NULL;
+    }
+
+    /*  BUGGY IMAGE WORKAROUND
+
+        We hit some images (e.g. fruit_.png) who contain bytes that are == colortable_count
+        which is a problem since we use the byte as an index. To work around this we grow
+        the colortable by 1 (if its < 256) and duplicate the last color into that slot.
+    */
+    const int colorCount = numPalette + (numPalette < 256);
+    // Note: These are not necessarily SkPMColors.
+    SkPMColor colorStorage[256];    // worst-case storage
+    SkPMColor* colorPtr = colorStorage;
+
+    int numTrans;
+    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
+        png_get_tRNS(png_ptr, info_ptr, &trans, &numTrans, NULL);
+    } else {
+        numTrans = 0;
+    }
+
+    // check for bad images that might make us crash
+    if (numTrans > numPalette) {
+        numTrans = numPalette;
+    }
+
+    int index = 0;
+    int transLessThanFF = 0;
+
+    // Choose which function to use to create the color table. If the final destination's
+    // colortype is unpremultiplied, the color table will store unpremultiplied colors.
+    PackColorProc proc;
+    if (premultiply) {
+        proc = &SkPreMultiplyARGB;
+    } else {
+        proc = &SkPackARGB32NoCheck;
+    }
+    for (; index < numTrans; index++) {
+        transLessThanFF |= (int)*trans - 0xFF;
+        *colorPtr++ = proc(*trans++, palette->red, palette->green, palette->blue);
+        palette++;
+    }
+
+    if (transLessThanFF < 0) {
+        *outAlphaType = premultiply ? kPremul_SkAlphaType : kUnpremul_SkAlphaType;
+    } else {
+        *outAlphaType = kOpaque_SkAlphaType;
+    }
+
+    for (; index < numPalette; index++) {
+        *colorPtr++ = SkPackARGB32(0xFF, palette->red, palette->green, palette->blue);
+        palette++;
+    }
+
+    // see BUGGY IMAGE WORKAROUND comment above
+    if (numPalette < 256) {
+        *colorPtr = colorPtr[-1];
+    }
+
+    return SkNEW_ARGS(SkColorTable, (colorStorage, colorCount));
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Creation
+///////////////////////////////////////////////////////////////////////////////
+
+#define PNG_BYTES_TO_CHECK 4
+
+bool SkPngCodec::IsPng(SkStream* stream) {
+    char buf[PNG_BYTES_TO_CHECK];
+    if (stream->read(buf, PNG_BYTES_TO_CHECK) != PNG_BYTES_TO_CHECK) {
+        return false;
+    }
+    if (png_sig_cmp((png_bytep) buf, (png_size_t)0, PNG_BYTES_TO_CHECK)) {
+        return false;
+    }
+    return true;
+}
+
+SkCodec* SkPngCodec::NewFromStream(SkStream* stream) {
+    // The image is known to be a PNG. Decode enough to know the SkImageInfo.
+    // FIXME: Allow silencing warnings.
+    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
+                                                 sk_error_fn, NULL);
+    if (!png_ptr) {
+        return NULL;
+    }
+
+    AutoCleanPng autoClean(png_ptr);
+
+    png_infop info_ptr = png_create_info_struct(png_ptr);
+    if (info_ptr == NULL) {
+        return NULL;
+    }
+
+    autoClean.setInfoPtr(info_ptr);
+
+    // FIXME: Could we use the return value of setjmp to specify the type of
+    // error?
+    if (setjmp(png_jmpbuf(png_ptr))) {
+        return NULL;
+    }
+
+    png_set_read_fn(png_ptr, static_cast<void*>(stream), sk_read_fn);
+
+    // FIXME: This is where the old code hooks up the Peeker. Does it need to
+    // be set this early? (i.e. where are the user chunks? early in the stream,
+    // potentially?)
+    // If it does, we need to figure out a way to set it here.
+
+    // The call to png_read_info() gives us all of the information from the
+    // PNG file before the first IDAT (image data chunk).
+    png_read_info(png_ptr, info_ptr);
+    png_uint_32 origWidth, origHeight;
+    int bitDepth, colorType;
+    png_get_IHDR(png_ptr, info_ptr, &origWidth, &origHeight, &bitDepth,
+                 &colorType, int_p_NULL, int_p_NULL, int_p_NULL);
+
+    // sanity check for size
+    {
+        int64_t size = sk_64_mul(origWidth, origHeight);
+        // now check that if we are 4-bytes per pixel, we also don't overflow
+        if (size < 0 || size > (0x7FFFFFFF >> 2)) {
+            return NULL;
+        }
+    }
+
+    // Tell libpng to strip 16 bit/color files down to 8 bits/color
+    if (bitDepth == 16) {
+        png_set_strip_16(png_ptr);
+    }
+#ifdef PNG_READ_PACK_SUPPORTED
+    // Extract multiple pixels with bit depths of 1, 2, and 4 from a single
+    // byte into separate bytes (useful for paletted and grayscale images).
+    if (bitDepth < 8) {
+        png_set_packing(png_ptr);
+    }
+#endif
+    // Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel.
+    if (colorType == PNG_COLOR_TYPE_GRAY && bitDepth < 8) {
+        png_set_expand_gray_1_2_4_to_8(png_ptr);
+    }
+
+
+    // Now determine the default SkColorType and SkAlphaType.
+    SkColorType skColorType;
+    SkAlphaType skAlphaType;
+    switch (colorType) {
+        case PNG_COLOR_TYPE_PALETTE:
+            // Technically, this is true of the data, but I don't think we want
+            // to support it.
+            // skColorType = kIndex8_SkColorType;
+            skColorType = kN32_SkColorType;
+            skAlphaType = has_transparency_in_palette(png_ptr, info_ptr) ?
+                    kUnpremul_SkAlphaType : kOpaque_SkAlphaType;
+            break;
+        case PNG_COLOR_TYPE_GRAY:
+            if (false) {
+                // FIXME: Is this the wrong default behavior? This means if the
+                // caller supplies the info we gave them, they'll get Alpha 8.
+                skColorType = kAlpha_8_SkColorType;
+                // FIXME: Strangely, the canonical type for Alpha 8 is Premul.
+                skAlphaType = kPremul_SkAlphaType;
+            } else {
+                skColorType = kN32_SkColorType;
+                skAlphaType = kOpaque_SkAlphaType;
+            }
+            break;
+        default:
+            // Note: This *almost* mimics the code in SkImageDecoder_libpng.
+            // has_transparency_in_palette makes an additional check - whether
+            // numTrans is greater than 0. Why does the other code not make that
+            // check?
+            if (has_transparency_in_palette(png_ptr, info_ptr)
+                || PNG_COLOR_TYPE_RGB_ALPHA == colorType
+                || PNG_COLOR_TYPE_GRAY_ALPHA == colorType)
+            {
+                skAlphaType = kUnpremul_SkAlphaType;
+            } else {
+                skAlphaType = kOpaque_SkAlphaType;
+            }
+            skColorType = kN32_SkColorType;
+            break;
+    }
+
+    {
+        // FIXME: Again, this block needs to go into onGetPixels.
+        bool convertGrayToRGB = PNG_COLOR_TYPE_GRAY == colorType && skColorType != kAlpha_8_SkColorType;
+
+        // Unless the user is requesting A8, convert a grayscale image into RGB.
+        // GRAY_ALPHA will always be converted to RGB
+        if (convertGrayToRGB || colorType == PNG_COLOR_TYPE_GRAY_ALPHA) {
+            png_set_gray_to_rgb(png_ptr);
+        }
+
+        // Add filler (or alpha) byte (after each RGB triplet) if necessary.
+        // FIXME: It seems like we could just use RGB as the SrcConfig here.
+        if (colorType == PNG_COLOR_TYPE_RGB || convertGrayToRGB) {
+            png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
+        }
+    }
+
+    // FIXME: Also need to check for sRGB (skbug.com/3471).
+
+    SkImageInfo info = SkImageInfo::Make(origWidth, origHeight, skColorType,
+                                         skAlphaType);
+    SkCodec* codec = SkNEW_ARGS(SkPngCodec, (info, stream, png_ptr, info_ptr));
+    autoClean.detach();
+    return codec;
+}
+
+SkPngCodec::SkPngCodec(const SkImageInfo& info, SkStream* stream,
+                       png_structp png_ptr, png_infop info_ptr)
+    : INHERITED(info, stream)
+    , fPng_ptr(png_ptr)
+    , fInfo_ptr(info_ptr) {}
+
+SkPngCodec::~SkPngCodec() {
+    png_destroy_read_struct(&fPng_ptr, &fInfo_ptr, png_infopp_NULL);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Getting the pixels
+///////////////////////////////////////////////////////////////////////////////
+
+static bool premul_and_unpremul(SkAlphaType A, SkAlphaType B) {
+    return kPremul_SkAlphaType == A && kUnpremul_SkAlphaType == B;
+}
+
+static bool conversion_possible(const SkImageInfo& A, const SkImageInfo& B) {
+    // TODO: Support other conversions
+    if (A.colorType() != B.colorType()) {
+        return false;
+    }
+    if (A.profileType() != B.profileType()) {
+        return false;
+    }
+    if (A.alphaType() == B.alphaType()) {
+        return true;
+    }
+    return premul_and_unpremul(A.alphaType(), B.alphaType())
+            || premul_and_unpremul(B.alphaType(), A.alphaType());
+}
+
+SkCodec::Result SkPngCodec::onGetPixels(const SkImageInfo& requestedInfo, void* dst,
+                                        size_t rowBytes, SkPMColor ctable[],
+                                        int* ctableCount) {
+    if (!this->couldRewindIfNeeded()) {
+        return kCouldNotRewind;
+    }
+    if (requestedInfo.dimensions() != this->getOriginalInfo().dimensions()) {
+        return kInvalidScale;
+    }
+    if (!conversion_possible(requestedInfo, this->getOriginalInfo())) {
+        return kInvalidConversion;
+    }
+
+    SkBitmap decodedBitmap;
+    // If installPixels would have failed, getPixels should have failed before
+    // calling onGetPixels.
+    SkAssertResult(decodedBitmap.installPixels(requestedInfo, dst, rowBytes));
+
+    // Initialize all non-trivial objects before setjmp.
+    SkAutoTUnref<SkColorTable> colorTable;
+    SkAutoTDelete<SkSwizzler> swizzler;
+    SkAutoMalloc storage;                   // Scratch memory for pre-swizzled rows.
+
+    // FIXME: Could we use the return value of setjmp to specify the type of
+    // error?
+    if (setjmp(png_jmpbuf(fPng_ptr))) {
+        SkDebugf("setjmp long jump!\n");
+        return kInvalidInput;
+    }
+
+    // FIXME: We already retrieved this information. Store it in SkPngCodec?
+    png_uint_32 origWidth, origHeight;
+    int bitDepth, pngColorType, interlaceType;
+    png_get_IHDR(fPng_ptr, fInfo_ptr, &origWidth, &origHeight, &bitDepth,
+                 &pngColorType, &interlaceType, int_p_NULL, int_p_NULL);
+
+    const int numberPasses = (interlaceType != PNG_INTERLACE_NONE) ?
+            png_set_interlace_handling(fPng_ptr) : 1;
+
+    SkSwizzler::SrcConfig sc;
+    bool reallyHasAlpha = false;
+    if (PNG_COLOR_TYPE_PALETTE == pngColorType) {
+        sc = SkSwizzler::kIndex;
+        SkAlphaType at = requestedInfo.alphaType();
+        colorTable.reset(decode_palette(fPng_ptr, fInfo_ptr,
+                                        kPremul_SkAlphaType == at,
+                                        &at));
+        if (!colorTable) {
+            return kInvalidInput;
+        }
+
+        reallyHasAlpha = (at != kOpaque_SkAlphaType);
+
+        if (at != requestedInfo.alphaType()) {
+            // It turns out the image is opaque.
+            SkASSERT(kOpaque_SkAlphaType == at);
+        }
+    } else if (kAlpha_8_SkColorType == requestedInfo.colorType()) {
+        // Note: we check the destination, since otherwise we would have
+        // told png to upscale.
+        SkASSERT(PNG_COLOR_TYPE_GRAY == pngColorType);
+        sc = SkSwizzler::kGray;
+    } else if (this->getOriginalInfo().alphaType() == kOpaque_SkAlphaType) {
+        sc = SkSwizzler::kRGBX;
+    } else {
+        sc = SkSwizzler::kRGBA;
+    }
+    const SkPMColor* colors = colorTable ? colorTable->readColors() : NULL;
+    // TODO: Support skipZeroes.
+    swizzler.reset(SkSwizzler::CreateSwizzler(sc, colors, requestedInfo,
+                                              dst, rowBytes, false));
+    if (!swizzler) {
+        // FIXME: CreateSwizzler could fail for another reason.
+        return kUnimplemented;
+    }
+
+    // FIXME: Here is where we should likely insert some of the modifications
+    // made in the factory.
+    png_read_update_info(fPng_ptr, fInfo_ptr);
+
+    if (numberPasses > 1) {
+        const int width = requestedInfo.width();
+        const int height = requestedInfo.height();
+        const int bpp = SkSwizzler::BytesPerPixel(sc);
+        const size_t rowBytes = width * bpp;
+
+        storage.reset(width * height * bpp);
+        uint8_t* const base = static_cast<uint8_t*>(storage.get());
+
+        for (int i = 0; i < numberPasses; i++) {
+            uint8_t* row = base;
+            for (png_uint_32 y = 0; y < height; y++) {
+                uint8_t* bmRow = row;
+                png_read_rows(fPng_ptr, &bmRow, png_bytepp_NULL, 1);
+                row += rowBytes;
+            }
+        }
+
+        // Now swizzle it.
+        uint8_t* row = base;
+        for (int y = 0; y < height; y++) {
+            reallyHasAlpha |= swizzler->next(row);
+            row += rowBytes;
+        }
+    } else {
+        storage.reset(requestedInfo.width() * SkSwizzler::BytesPerPixel(sc));
+        uint8_t* srcRow = static_cast<uint8_t*>(storage.get());
+        for (int y = 0; y < requestedInfo.height(); y++) {
+            png_read_rows(fPng_ptr, &srcRow, png_bytepp_NULL, 1);
+            reallyHasAlpha |= swizzler->next(srcRow);
+        }
+    }
+
+    /* read rest of file, and get additional chunks in info_ptr - REQUIRED */
+    png_read_end(fPng_ptr, fInfo_ptr);
+
+    // FIXME: do we need substituteTranspColor?
+
+    if (reallyHasAlpha && requestedInfo.alphaType() != kOpaque_SkAlphaType) {
+        // FIXME: We want to alert the caller. Is this the right way?
+        SkImageInfo* modInfo = const_cast<SkImageInfo*>(&requestedInfo);
+        *modInfo = requestedInfo.makeAlphaType(kOpaque_SkAlphaType);
+    }
+    return kSuccess;
+}