| /* |
| * 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 "log.h" |
| #include "png.h" |
| |
| #include <cairo/cairo.h> |
| |
| #include <stdlib.h> |
| #include <string.h> |
| |
| /** |
| * The current state of the PNG decoder. |
| */ |
| typedef struct guacenc_png_read_state { |
| |
| /** |
| * The buffer of unread image data. This pointer will be updated to point |
| * to the next unread byte when data is read. |
| */ |
| unsigned char* data; |
| |
| /** |
| * The number of bytes remaining to be read within the buffer. |
| */ |
| unsigned int length; |
| |
| } guacenc_png_read_state; |
| |
| /** |
| * Attempts to fill the given buffer with read image data. The behavior of |
| * this function is dictated by cairo_read_t. |
| * |
| * @param closure |
| * The current state of the PNG decoding process (an instance of |
| * guacenc_png_read_state). |
| * |
| * @param data |
| * The data buffer to fill. |
| * |
| * @param length |
| * The number of bytes to fill within the data buffer. |
| * |
| * @return |
| * CAIRO_STATUS_SUCCESS if all data was read successfully (the entire |
| * buffer was filled), CAIRO_STATUS_READ_ERROR otherwise. |
| */ |
| static cairo_status_t guacenc_png_read(void* closure, unsigned char* data, |
| unsigned int length) { |
| |
| guacenc_png_read_state* state = (guacenc_png_read_state*) closure; |
| |
| /* If more data is requested than is available in buffer, fail */ |
| if (length > state->length) |
| return CAIRO_STATUS_READ_ERROR; |
| |
| /* Read chunk into buffer */ |
| memcpy(data, state->data, length); |
| |
| /* Advance to next chunk */ |
| state->length -= length; |
| state->data += length; |
| |
| /* Read was successful */ |
| return CAIRO_STATUS_SUCCESS; |
| |
| } |
| |
| cairo_surface_t* guacenc_png_decoder(unsigned char* data, int length) { |
| |
| guacenc_png_read_state state = { |
| .data = data, |
| .length = length |
| }; |
| |
| /* Read PNG from data */ |
| cairo_surface_t* surface = |
| cairo_image_surface_create_from_png_stream(guacenc_png_read, &state); |
| |
| /* If surface returned with an error, just return NULL */ |
| if (surface != NULL && |
| cairo_surface_status(surface) != CAIRO_STATUS_SUCCESS) { |
| guacenc_log(GUAC_LOG_WARNING, "Invalid PNG data"); |
| cairo_surface_destroy(surface); |
| return NULL; |
| } |
| |
| /* PNG was read successfully */ |
| return surface; |
| |
| } |
| |