WIP - add extractor, generate snippet_data

node_modules/probe-image-size/lib/parse_sync/tiff.js

@@ -0,0 +1,86 @@
+'use strict';
+
+/* eslint-disable consistent-return */
+
+var str2arr = require('../common').str2arr;
+var sliceEq = require('../common').sliceEq;
+var readUInt16LE = require('../common').readUInt16LE;
+var readUInt16BE = require('../common').readUInt16BE;
+var readUInt32LE = require('../common').readUInt32LE;
+var readUInt32BE = require('../common').readUInt32BE;
+
+
+var SIG_1 = str2arr('II\x2A\0');
+var SIG_2 = str2arr('MM\0\x2A');
+
+
+function readUInt16(buffer, offset, is_big_endian) {
+  return is_big_endian ? readUInt16BE(buffer, offset) : readUInt16LE(buffer, offset);
+}
+
+function readUInt32(buffer, offset, is_big_endian) {
+  return is_big_endian ? readUInt32BE(buffer, offset) : readUInt32LE(buffer, offset);
+}
+
+function readIFDValue(data, data_offset, is_big_endian) {
+  var type       = readUInt16(data, data_offset + 2, is_big_endian);
+  var values     = readUInt32(data, data_offset + 4, is_big_endian);
+
+  if (values !== 1 || (type !== 3 && type !== 4)) return null;
+
+  if (type === 3) {
+    return readUInt16(data, data_offset + 8, is_big_endian);
+  }
+
+  return readUInt32(data, data_offset + 8, is_big_endian);
+}
+
+module.exports = function (data) {
+  if (data.length < 8) return;
+
+  // check TIFF signature
+  if (!sliceEq(data, 0, SIG_1) && !sliceEq(data, 0, SIG_2)) return;
+
+  var is_big_endian = (data[0] === 77 /* 'MM' */);
+  var count = readUInt32(data, 4, is_big_endian) - 8;
+
+  if (count < 0) return;
+
+  // skip until IFD
+  var offset = count + 8;
+
+  if (data.length - offset < 2) return;
+
+  // read number of IFD entries
+  var ifd_size = readUInt16(data, offset + 0, is_big_endian) * 12;
+
+  if (ifd_size <= 0) return;
+
+  offset += 2;
+
+  // read all IFD entries
+  if (data.length - offset < ifd_size) return;
+
+  var i, width, height, tag;
+
+  for (i = 0; i < ifd_size; i += 12) {
+    tag = readUInt16(data, offset + i, is_big_endian);
+
+    if (tag === 256) {
+      width = readIFDValue(data, offset + i, is_big_endian);
+    } else if (tag === 257) {
+      height = readIFDValue(data, offset + i, is_big_endian);
+    }
+  }
+
+  if (width && height) {
+    return {
+      width:  width,
+      height: height,
+      type:   'tiff',
+      mime:   'image/tiff',
+      wUnits: 'px',
+      hUnits: 'px'
+    };
+  }
+};