110 lines
3.0 KiB
C
110 lines
3.0 KiB
C
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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#include "config.h"
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#include "log.h"
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#include "png.h"
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#include <cairo/cairo.h>
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#include <stdlib.h>
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#include <string.h>
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/**
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* The current state of the PNG decoder.
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*/
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typedef struct guacenc_png_read_state {
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/**
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* The buffer of unread image data. This pointer will be updated to point
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* to the next unread byte when data is read.
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*/
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unsigned char* data;
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/**
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* The number of bytes remaining to be read within the buffer.
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*/
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unsigned int length;
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} guacenc_png_read_state;
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/**
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* Attempts to fill the given buffer with read image data. The behavior of
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* this function is dictated by cairo_read_t.
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*
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* @param closure
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* The current state of the PNG decoding process (an instance of
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* guacenc_png_read_state).
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*
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* @param data
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* The data buffer to fill.
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*
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* @param length
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* The number of bytes to fill within the data buffer.
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*
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* @return
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* CAIRO_STATUS_SUCCESS if all data was read successfully (the entire
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* buffer was filled), CAIRO_STATUS_READ_ERROR otherwise.
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*/
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static cairo_status_t guacenc_png_read(void* closure, unsigned char* data,
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unsigned int length) {
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guacenc_png_read_state* state = (guacenc_png_read_state*) closure;
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/* If more data is requested than is available in buffer, fail */
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if (length > state->length)
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return CAIRO_STATUS_READ_ERROR;
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/* Read chunk into buffer */
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memcpy(data, state->data, length);
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/* Advance to next chunk */
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state->length -= length;
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state->data += length;
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/* Read was successful */
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return CAIRO_STATUS_SUCCESS;
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}
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cairo_surface_t* guacenc_png_decoder(unsigned char* data, int length) {
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guacenc_png_read_state state = {
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.data = data,
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.length = length
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};
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/* Read PNG from data */
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cairo_surface_t* surface =
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cairo_image_surface_create_from_png_stream(guacenc_png_read, &state);
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/* If surface returned with an error, just return NULL */
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if (surface != NULL &&
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cairo_surface_status(surface) != CAIRO_STATUS_SUCCESS) {
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guacenc_log(GUAC_LOG_WARNING, "Invalid PNG data");
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cairo_surface_destroy(surface);
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return NULL;
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}
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/* PNG was read successfully */
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return surface;
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}
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