66 lines
1.9 KiB
C
66 lines
1.9 KiB
C
/*
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* Copyright (c) 2014 Vittorio Giovara <vittorio.giovara@gmail.com>
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <stdint.h>
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#include <string.h>
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#include <math.h>
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#include "display.h"
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#include "mathematics.h"
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// fixed point to double
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#define CONV_FP(x) ((double) (x)) / (1 << 16)
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// double to fixed point
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#define CONV_DB(x) (int32_t) ((x) * (1 << 16))
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double av_display_rotation_get(const int32_t matrix[9])
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{
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double rotation, scale[2];
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scale[0] = sqrt(CONV_FP(matrix[0]) * CONV_FP(matrix[0]) +
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CONV_FP(matrix[3]) * CONV_FP(matrix[3]));
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scale[1] = sqrt(CONV_FP(matrix[1]) * CONV_FP(matrix[1]) +
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CONV_FP(matrix[4]) * CONV_FP(matrix[4]));
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if (scale[0] == 0.0 || scale[1] == 0.0)
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return NAN;
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rotation = atan2(CONV_FP(matrix[1]) / scale[1],
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CONV_FP(matrix[0]) / scale[0]) * 180 / M_PI;
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return rotation;
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}
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void av_display_rotation_set(int32_t matrix[9], double angle)
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{
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double radians = angle * M_PI / 180.0f;
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double c = cos(radians);
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double s = sin(radians);
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memset(matrix, 0, 9 * sizeof(int32_t));
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matrix[0] = CONV_DB(c);
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matrix[1] = CONV_DB(-s);
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matrix[3] = CONV_DB(s);
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matrix[4] = CONV_DB(c);
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matrix[8] = 1 << 30;
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}
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