Clean up
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parent
33251eaca7
commit
d5b2e43364
41
fiv-io.c
41
fiv-io.c
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@ -4225,43 +4225,22 @@ fiv_io_orientation_apply(cairo_surface_t *surface,
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FivIoOrientation
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fiv_io_exif_orientation(const guint8 *tiff, gsize len)
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{
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// libtiff also knows how to do this, but it's not a lot of code.
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// The "Orientation" tag/field is part of Baseline TIFF 6.0 (1992),
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// it just so happens that Exif is derived from this format.
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// There is no other meaningful placement for this than right in IFD0,
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// describing the main image.
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const uint8_t *end = tiff + len,
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le[4] = {'I', 'I', 42, 0},
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be[4] = {'M', 'M', 0, 42};
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uint16_t (*u16)(const uint8_t *) = NULL;
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uint32_t (*u32)(const uint8_t *) = NULL;
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if (tiff + 8 > end) {
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return FivIoOrientationUnknown;
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} else if (!memcmp(tiff, le, sizeof le)) {
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u16 = wuffs_base__peek_u16le__no_bounds_check;
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u32 = wuffs_base__peek_u32le__no_bounds_check;
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} else if (!memcmp(tiff, be, sizeof be)) {
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u16 = wuffs_base__peek_u16be__no_bounds_check;
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u32 = wuffs_base__peek_u32be__no_bounds_check;
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} else {
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return FivIoOrientationUnknown;
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}
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const uint8_t *ifd0 = tiff + u32(tiff + 4);
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if (ifd0 + 2 > end)
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struct tiffer T = {};
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if (!tiffer_init(&T, tiff, len) || !tiffer_next_ifd(&T))
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return FivIoOrientationUnknown;
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uint16_t fields = u16(ifd0);
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enum { BYTE = 1, ASCII, SHORT, LONG, RATIONAL,
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SBYTE, UNDEFINED, SSHORT, SLONG, SRATIONAL, FLOAT, DOUBLE };
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enum { Orientation = 274 };
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for (const guint8 *p = ifd0 + 2; fields-- && p + 12 <= end; p += 12) {
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uint16_t tag = u16(p), type = u16(p + 2), value16 = u16(p + 8);
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uint32_t count = u32(p + 4);
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if (G_UNLIKELY(tag == Orientation && type == SHORT && count == 1 &&
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value16 >= 1 && value16 <= 8))
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return value16;
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struct tiffer_entry entry = {};
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while (tiffer_next_entry(&T, &entry)) {
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int64_t orientation = 0;
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if (G_UNLIKELY(entry.tag == TIFF_Orientation) &&
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entry.type == SHORT && entry.remaining_count == 1 &&
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tiffer_integer(&T, &entry, &orientation) &&
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orientation >= 1 && orientation <= 8)
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return orientation;
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}
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return FivIoOrientationUnknown;
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}
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