skia2/include/codec/SkEncodedOrigin.h

/*
 * Copyright 2017 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkEncodedOrigin_DEFINED
#define SkEncodedOrigin_DEFINED

#include "SkMatrix.h"

// These values match the orientation www.exif.org/Exif2-2.PDF.
enum SkEncodedOrigin {
    kTopLeft_SkEncodedOrigin     = 1, // Default
    kTopRight_SkEncodedOrigin    = 2, // Reflected across y-axis
    kBottomRight_SkEncodedOrigin = 3, // Rotated 180
    kBottomLeft_SkEncodedOrigin  = 4, // Reflected across x-axis
    kLeftTop_SkEncodedOrigin     = 5, // Reflected across x-axis, Rotated 90 CCW
    kRightTop_SkEncodedOrigin    = 6, // Rotated 90 CW
    kRightBottom_SkEncodedOrigin = 7, // Reflected across x-axis, Rotated 90 CW
    kLeftBottom_SkEncodedOrigin  = 8, // Rotated 90 CCW
    kDefault_SkEncodedOrigin     = kTopLeft_SkEncodedOrigin,
    kLast_SkEncodedOrigin        = kLeftBottom_SkEncodedOrigin,
};

/**
 * Given an encoded origin and the width and height of the source data, returns a matrix
 * that transforms the source rectangle [0, 0, w, h] to a correctly oriented destination
 * rectangle, with the upper left corner still at [0, 0].
 */
static inline SkMatrix SkEncodedOriginToMatrix(SkEncodedOrigin origin, int w, int h) {
    switch (origin) {
        case     kTopLeft_SkEncodedOrigin: return SkMatrix::I();
        case    kTopRight_SkEncodedOrigin: return SkMatrix::MakeAll(-1,  0, w,  0,  1, 0, 0, 0, 1);
        case kBottomRight_SkEncodedOrigin: return SkMatrix::MakeAll(-1,  0, w,  0, -1, h, 0, 0, 1);
        case  kBottomLeft_SkEncodedOrigin: return SkMatrix::MakeAll( 1,  0, 0,  0, -1, h, 0, 0, 1);
        case     kLeftTop_SkEncodedOrigin: return SkMatrix::MakeAll( 0,  1, 0,  1,  0, 0, 0, 0, 1);
        case    kRightTop_SkEncodedOrigin: return SkMatrix::MakeAll( 0, -1, h,  1,  0, 0, 0, 0, 1);
        case kRightBottom_SkEncodedOrigin: return SkMatrix::MakeAll( 0, -1, h, -1,  0, w, 0, 0, 1);
        case  kLeftBottom_SkEncodedOrigin: return SkMatrix::MakeAll( 0,  1, 0, -1,  0, w, 0, 0, 1);
    }
    SK_ABORT("Unexpected origin");
    return SkMatrix::I();
}


#endif // SkEncodedOrigin_DEFINED