/* * @file llpngwrapper.cpp * @brief Encapsulates libpng read/write functionality. * * $LicenseInfo:firstyear=2007&license=viewerlgpl$ * Second Life Viewer Source Code * Copyright (C) 2010, Linden Research, Inc. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; * version 2.1 of the License only. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA * $/LicenseInfo$ */ #include "linden_common.h" #include "stdtypes.h" #include "llerror.h" #include "llimage.h" #include "llpngwrapper.h" // --------------------------------------------------------------------------- // LLPngWrapper // --------------------------------------------------------------------------- LLPngWrapper::LLPngWrapper() : mReadPngPtr( NULL ), mReadInfoPtr( NULL ), mWritePngPtr( NULL ), mWriteInfoPtr( NULL ), mRowPointers( NULL ), mWidth( 0 ), mHeight( 0 ), mBitDepth( 0 ), mColorType( 0 ), mChannels( 0 ), mInterlaceType( 0 ), mCompressionType( 0 ), mFilterMethod( 0 ), mFinalSize( 0 ), mHasBKGD(false), mBackgroundColor(), mGamma(0.f) { } LLPngWrapper::~LLPngWrapper() { releaseResources(); } // Checks the src for a valid PNG header BOOL LLPngWrapper::isValidPng(U8* src) { const int PNG_BYTES_TO_CHECK = 8; int sig = png_sig_cmp((png_bytep)src, (png_size_t)0, PNG_BYTES_TO_CHECK); if (sig != 0) { mErrorMessage = "Invalid or corrupt PNG file"; return FALSE; } return TRUE; } // Called by the libpng library when a fatal encoding or decoding error // occurs. We simply throw the error message and let our try/catch // block clean up. void LLPngWrapper::errorHandler(png_structp png_ptr, png_const_charp msg) { throw msg; } // Called by the libpng library when reading (decoding) the PNG file. We // copy the PNG data from our internal buffer into the PNG's data buffer. void LLPngWrapper::readDataCallback(png_structp png_ptr, png_bytep dest, png_size_t length) { PngDataInfo *dataInfo = (PngDataInfo *) png_get_io_ptr(png_ptr); U8 *src = &dataInfo->mData[dataInfo->mOffset]; memcpy(dest, src, length); dataInfo->mOffset += static_cast<U32>(length); } // Called by the libpng library when writing (encoding) the PNG file. We // copy the encoded result into our data buffer. void LLPngWrapper::writeDataCallback(png_structp png_ptr, png_bytep src, png_size_t length) { PngDataInfo *dataInfo = (PngDataInfo *) png_get_io_ptr(png_ptr); U8 *dest = &dataInfo->mData[dataInfo->mOffset]; memcpy(dest, src, length); dataInfo->mOffset += static_cast<U32>(length); } // Flush the write output pointer void LLPngWrapper::writeFlush(png_structp png_ptr) { // no-op since we're just writing to memory } // Read the PNG file using the libpng. The low-level interface is used here // because we want to do various transformations (including setting the // matte background if any, and applying gama) which can't be done with // the high-level interface. The scanline also begins at the bottom of // the image (per SecondLife conventions) instead of at the top, so we // must assign row-pointers in "reverse" order. BOOL LLPngWrapper::readPng(U8* src, LLImageRaw* rawImage, ImageInfo *infop) { try { // Create and initialize the png structures mReadPngPtr = png_create_read_struct(PNG_LIBPNG_VER_STRING, this, &errorHandler, NULL); if (mReadPngPtr == NULL) { throw "Problem creating png read structure"; } // Allocate/initialize the memory for image information. mReadInfoPtr = png_create_info_struct(mReadPngPtr); // Set up the input control PngDataInfo dataPtr; dataPtr.mData = src; dataPtr.mOffset = 0; png_set_read_fn(mReadPngPtr, &dataPtr, &readDataCallback); png_set_sig_bytes(mReadPngPtr, 0); // setup low-level read and get header information png_read_info(mReadPngPtr, mReadInfoPtr); png_get_IHDR(mReadPngPtr, mReadInfoPtr, &mWidth, &mHeight, &mBitDepth, &mColorType, &mInterlaceType, &mCompressionType, &mFilterMethod); // Normalize the image, then get updated image information // after transformations have been applied normalizeImage(); updateMetaData(); // If a raw object is supplied, read the PNG image into its // data space if (rawImage != NULL) { rawImage->resize(static_cast<U16>(mWidth), static_cast<U16>(mHeight), mChannels); U8 *dest = rawImage->getData(); int offset = mWidth * mChannels; // Set up the row pointers and read the image mRowPointers = new U8* [mHeight]; for (U32 i=0; i < mHeight; i++) { mRowPointers[i] = &dest[(mHeight-i-1)*offset]; } png_read_image(mReadPngPtr, mRowPointers); // Finish up, ensures all metadata are updated png_read_end(mReadPngPtr, NULL); } // If an info object is supplied, copy the relevant info if (infop != NULL) { infop->mHeight = static_cast<U16>(mHeight); infop->mWidth = static_cast<U16>(mWidth); infop->mComponents = mChannels; } mFinalSize = dataPtr.mOffset; } catch (png_const_charp msg) { mErrorMessage = msg; releaseResources(); return (FALSE); } // Clean up and return releaseResources(); return (TRUE); } // Do transformations to normalize the input to 8-bpp RGBA void LLPngWrapper::normalizeImage() { // 1. Expand any palettes // 2. Convert grayscales to RGB // 3. Create alpha layer from transparency // 4. Ensure 8-bpp for all images // 5. Apply background matte if any // 6. Set (or guess) gamma if (mColorType == PNG_COLOR_TYPE_PALETTE) { png_set_palette_to_rgb(mReadPngPtr); } if (mColorType == PNG_COLOR_TYPE_GRAY && mBitDepth < 8) { png_set_expand_gray_1_2_4_to_8(mReadPngPtr); } if (mColorType == PNG_COLOR_TYPE_GRAY || mColorType == PNG_COLOR_TYPE_GRAY_ALPHA) { png_set_gray_to_rgb(mReadPngPtr); } if (png_get_valid(mReadPngPtr, mReadInfoPtr, PNG_INFO_tRNS)) { png_set_tRNS_to_alpha(mReadPngPtr); } if (mBitDepth < 8) { png_set_packing(mReadPngPtr); } else if (mBitDepth == 16) { png_set_strip_16(mReadPngPtr); } mHasBKGD = png_get_bKGD(mReadPngPtr, mReadInfoPtr, &mBackgroundColor); if (mHasBKGD) { png_set_background(mReadPngPtr, mBackgroundColor, PNG_BACKGROUND_GAMMA_FILE, 1, 1.0); } #if LL_DARWIN const F64 SCREEN_GAMMA = 1.8; #else const F64 SCREEN_GAMMA = 2.2; #endif if (png_get_gAMA(mReadPngPtr, mReadInfoPtr, &mGamma)) { png_set_gamma(mReadPngPtr, SCREEN_GAMMA, mGamma); } else { png_set_gamma(mReadPngPtr, SCREEN_GAMMA, 1/SCREEN_GAMMA); } } // Read out the image meta-data void LLPngWrapper::updateMetaData() { png_read_update_info(mReadPngPtr, mReadInfoPtr); mWidth = png_get_image_width(mReadPngPtr, mReadInfoPtr); mHeight = png_get_image_height(mReadPngPtr, mReadInfoPtr); mBitDepth = png_get_bit_depth(mReadPngPtr, mReadInfoPtr); mColorType = png_get_color_type(mReadPngPtr, mReadInfoPtr); mChannels = png_get_channels(mReadPngPtr, mReadInfoPtr); mHasBKGD = png_get_bKGD(mReadPngPtr, mReadInfoPtr, &mBackgroundColor); } // Method to write raw image into PNG at dest. The raw scanline begins // at the bottom of the image per SecondLife conventions. BOOL LLPngWrapper::writePng(const LLImageRaw* rawImage, U8* dest) { try { S8 numComponents = rawImage->getComponents(); switch (numComponents) { case 1: mColorType = PNG_COLOR_TYPE_GRAY; break; case 2: mColorType = PNG_COLOR_TYPE_GRAY_ALPHA; break; case 3: mColorType = PNG_COLOR_TYPE_RGB; break; case 4: mColorType = PNG_COLOR_TYPE_RGB_ALPHA; break; default: mColorType = -1; } if (mColorType == -1) { throw "Unsupported image: unexpected number of channels"; } mWritePngPtr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, &errorHandler, NULL); if (!mWritePngPtr) { throw "Problem creating png write structure"; } mWriteInfoPtr = png_create_info_struct(mWritePngPtr); // Setup write function PngDataInfo dataPtr; dataPtr.mData = dest; dataPtr.mOffset = 0; png_set_write_fn(mWritePngPtr, &dataPtr, &writeDataCallback, &writeFlush); // Setup image params mWidth = rawImage->getWidth(); mHeight = rawImage->getHeight(); mBitDepth = 8; // Fixed to 8-bpp in SL mChannels = numComponents; mInterlaceType = PNG_INTERLACE_NONE; mCompressionType = PNG_COMPRESSION_TYPE_DEFAULT; mFilterMethod = PNG_FILTER_TYPE_DEFAULT; // Write header png_set_IHDR(mWritePngPtr, mWriteInfoPtr, mWidth, mHeight, mBitDepth, mColorType, mInterlaceType, mCompressionType, mFilterMethod); // Get data and compute row size const U8* data = rawImage->getData(); int offset = mWidth * mChannels; // Ready to write, start with the header png_write_info(mWritePngPtr, mWriteInfoPtr); // Write image (sorry, must const-cast for libpng) const U8 * rowPointer; for (U32 i=0; i < mHeight; i++) { rowPointer = &data[(mHeight-1-i)*offset]; png_write_row(mWritePngPtr, const_cast<png_bytep>(rowPointer)); } // Finish up png_write_end(mWritePngPtr, mWriteInfoPtr); mFinalSize = dataPtr.mOffset; } catch (png_const_charp msg) { mErrorMessage = msg; releaseResources(); return (FALSE); } releaseResources(); return TRUE; } // Cleanup various internal structures void LLPngWrapper::releaseResources() { if (mReadPngPtr || mReadInfoPtr) { png_destroy_read_struct(&mReadPngPtr, &mReadInfoPtr, NULL); mReadPngPtr = NULL; mReadInfoPtr = NULL; } if (mWritePngPtr || mWriteInfoPtr) { png_destroy_write_struct(&mWritePngPtr, &mWriteInfoPtr); mWritePngPtr = NULL; mWriteInfoPtr = NULL; } if (mRowPointers) { delete[] mRowPointers; mRowPointers = NULL; } } // Get final image size after compression U32 LLPngWrapper::getFinalSize() { return mFinalSize; } // Get last error message, if any const std::string& LLPngWrapper::getErrorMessage() { return mErrorMessage; }