mirror of https://github.com/axmolengine/axmol.git
78 lines
2.9 KiB
C++
78 lines
2.9 KiB
C++
// Copyright 2009 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// 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, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "base/etc1.h"
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#include <string.h>
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static const char kMagic[] = { 'P', 'K', 'M', ' ', '1', '0' };
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static const etc1_uint32 ETC1_PKM_FORMAT_OFFSET = 6;
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static const etc1_uint32 ETC1_PKM_ENCODED_WIDTH_OFFSET = 8;
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static const etc1_uint32 ETC1_PKM_ENCODED_HEIGHT_OFFSET = 10;
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static const etc1_uint32 ETC1_PKM_WIDTH_OFFSET = 12;
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static const etc1_uint32 ETC1_PKM_HEIGHT_OFFSET = 14;
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static const etc1_uint32 ETC1_RGB_NO_MIPMAPS = 0;
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//static void writeBEUint16(etc1_byte* pOut, etc1_uint32 data) {
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// pOut[0] = (etc1_byte) (data >> 8);
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// pOut[1] = (etc1_byte) data;
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//}
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static etc1_uint32 readBEUint16(const etc1_byte* pIn) {
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return (pIn[0] << 8) | pIn[1];
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}
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// Format a PKM header
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//void etc1_pkm_format_header(etc1_byte* pHeader, etc1_uint32 width, etc1_uint32 height) {
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// memcpy(pHeader, kMagic, sizeof(kMagic));
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// etc1_uint32 encodedWidth = (width + 3) & ~3;
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// etc1_uint32 encodedHeight = (height + 3) & ~3;
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// writeBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET, ETC1_RGB_NO_MIPMAPS);
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// writeBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET, encodedWidth);
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// writeBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET, encodedHeight);
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// writeBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET, width);
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// writeBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET, height);
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//}
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// Check if a PKM header is correctly formatted.
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etc1_bool etc1_pkm_is_valid(const etc1_byte* pHeader) {
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if (memcmp(pHeader, kMagic, sizeof(kMagic))) {
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return false;
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}
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etc1_uint32 format = readBEUint16(pHeader + ETC1_PKM_FORMAT_OFFSET);
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etc1_uint32 encodedWidth = readBEUint16(pHeader + ETC1_PKM_ENCODED_WIDTH_OFFSET);
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etc1_uint32 encodedHeight = readBEUint16(pHeader + ETC1_PKM_ENCODED_HEIGHT_OFFSET);
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etc1_uint32 width = readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET);
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etc1_uint32 height = readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET);
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return format == ETC1_RGB_NO_MIPMAPS &&
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encodedWidth >= width && encodedWidth - width < 4 &&
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encodedHeight >= height && encodedHeight - height < 4;
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}
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// Read the image width from a PKM header
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etc1_uint32 etc1_pkm_get_width(const etc1_byte* pHeader) {
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return readBEUint16(pHeader + ETC1_PKM_WIDTH_OFFSET);
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}
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// Read the image height from a PKM header
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etc1_uint32 etc1_pkm_get_height(const etc1_byte* pHeader){
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return readBEUint16(pHeader + ETC1_PKM_HEIGHT_OFFSET);
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}
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