| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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. |
| */ |
| |
| #include "config.h" |
| #include "jpeg.h" |
| #include "log.h" |
| |
| #include <stdio.h> |
| #include <unistd.h> |
| |
| #include <cairo/cairo.h> |
| #include <jpeglib.h> |
| |
| #include <stdlib.h> |
| |
| /** |
| * Translates libjpeg's 24-bit RGB format into Cairo's 32-bit ARGB32 / RGB24 |
| * format. The red, green, and blue components from the libjpeg pixel are |
| * copied verbatim, while the extra high byte used within Cairo is set to 0xFF. |
| * |
| * @param src |
| * A pointer to the first byte of the 24-bit RGB pixel within a libjpeg |
| * scanline buffer. |
| * |
| * @return |
| * A 32-bit Cairo ARGB32 / RGB24 pixel value equivalent to the libjpeg |
| * pixel at the given pointer. |
| */ |
| static uint32_t guacenc_jpeg_translate_rgb(const unsigned char* src) { |
| |
| /* Pull components from source */ |
| int r = *(src++); |
| int g = *(src++); |
| int b = *(src++); |
| |
| /* Translate to 32-bit integer compatible with Cairo */ |
| return 0xFF000000 | (r << 16) | (g << 8) | b; |
| |
| } |
| |
| /** |
| * Copies the data from a libjpeg scanline buffer into a row of image data |
| * within a Cairo surface, translating each pixel as necessary. |
| * |
| * @param dst |
| * The destination buffer into which the scanline should be copied. |
| * |
| * @param src |
| * The libjpeg scanline buffer that should be copied into the |
| * destination buffer. |
| * |
| * @param width |
| * The number of pixels available within both the scanline buffer and the |
| * destination buffer. |
| */ |
| static void guacenc_jpeg_copy_scanline(unsigned char* dst, |
| const unsigned char* src, int width) { |
| |
| uint32_t* current = (uint32_t*) dst; |
| |
| /* Copy all pixels from source to destination, translating for Cairo */ |
| for (; width > 0; width--, src += 3) { |
| *(current++) = guacenc_jpeg_translate_rgb(src); |
| } |
| |
| } |
| |
| cairo_surface_t* guacenc_jpeg_decoder(unsigned char* data, int length) { |
| |
| struct jpeg_decompress_struct cinfo; |
| struct jpeg_error_mgr jerr; |
| |
| /* Create decompressor with standard error handling */ |
| jpeg_create_decompress(&cinfo); |
| cinfo.err = jpeg_std_error(&jerr); |
| |
| /* Read JPEG directly from memory buffer */ |
| jpeg_mem_src(&cinfo, data, length); |
| |
| /* Read and validate JPEG header */ |
| if (!jpeg_read_header(&cinfo, TRUE)) { |
| guacenc_log(GUAC_LOG_WARNING, "Invalid JPEG data"); |
| jpeg_destroy_decompress(&cinfo); |
| return NULL; |
| } |
| |
| /* Begin decompression */ |
| cinfo.out_color_space = JCS_RGB; |
| jpeg_start_decompress(&cinfo); |
| |
| /* Pull JPEG dimensions from decompressor */ |
| int width = cinfo.output_width; |
| int height = cinfo.output_height; |
| |
| /* Allocate sufficient buffer space for one JPEG scanline */ |
| unsigned char* jpeg_scanline = malloc(width * 3); |
| |
| /* Create blank Cairo surface (no transparency in JPEG) */ |
| cairo_surface_t* surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24, |
| width, height); |
| |
| /* Pull underlying buffer and its stride */ |
| int stride = cairo_image_surface_get_stride(surface); |
| unsigned char* row = cairo_image_surface_get_data(surface); |
| |
| /* Read JPEG into surface */ |
| while (cinfo.output_scanline < height) { |
| |
| /* Read single scanline */ |
| unsigned char* buffers[1] = { jpeg_scanline }; |
| jpeg_read_scanlines(&cinfo, buffers, 1); |
| |
| /* Copy scanline to Cairo surface */ |
| guacenc_jpeg_copy_scanline(row, jpeg_scanline, width); |
| |
| /* Advance to next row of Cairo surface */ |
| row += stride; |
| |
| } |
| |
| /* Scanline buffer is no longer needed */ |
| free(jpeg_scanline); |
| |
| /* End decompression */ |
| jpeg_finish_decompress(&cinfo); |
| |
| /* Free decompressor */ |
| jpeg_destroy_decompress(&cinfo); |
| |
| /* JPEG was read successfully */ |
| return surface; |
| |
| } |
| |