WIP - add extractor, generate snippet_data

node_modules/probe-image-size/lib/parse_stream/webp.js

@@ -0,0 +1,104 @@
+'use strict';
+
+/* eslint-disable no-bitwise */
+
+var ParserStream = require('../common').ParserStream;
+var str2arr      = require('../common').str2arr;
+var sliceEq      = require('../common').sliceEq;
+
+
+var SIG_RIFF    = str2arr('RIFF');
+var SIG_WEBPVP8 = str2arr('WEBPVP8');
+
+
+function parseVP8(parser) {
+  parser._bytes(14, function (data) {
+    parser._skipBytes(Infinity);
+
+    if (data[7] !== 0x9D || data[8] !== 0x01 || data[9] !== 0x2A) {
+      // bad code block signature
+      parser.push(null);
+      return;
+    }
+
+    parser.push({
+      width:  data.readUInt16LE(10) & 0x3FFF,
+      height: data.readUInt16LE(12) & 0x3FFF,
+      type:   'webp',
+      mime:   'image/webp',
+      wUnits: 'px',
+      hUnits: 'px'
+    });
+
+    parser.push(null);
+  });
+}
+
+
+function parseVP8L(parser) {
+  parser._bytes(9, function (data) {
+    parser._skipBytes(Infinity);
+
+    if (data[4] !== 0x2F) {
+      // bad code block signature
+      parser.push(null);
+      return;
+    }
+
+    var bits = data.readUInt32LE(5);
+
+    parser.push({
+      width:  (bits & 0x3FFF) + 1,
+      height: ((bits >> 14) & 0x3FFF) + 1,
+      type:   'webp',
+      mime:   'image/webp',
+      wUnits: 'px',
+      hUnits: 'px'
+    });
+
+    parser.push(null);
+  });
+}
+
+
+function parseVP8X(parser) {
+  parser._bytes(14, function (data) {
+    parser._skipBytes(Infinity);
+
+    parser.push({
+      // TODO: replace with `data.readUIntLE(8, 3) + 1`
+      //       when 0.10 support is dropped
+      width:  ((data[10] << 16) | (data[9] << 8) | data[8]) + 1,
+      height: ((data[13] << 16) | (data[12] << 8) | data[11]) + 1,
+      type:   'webp',
+      mime:   'image/webp',
+      wUnits: 'px',
+      hUnits: 'px'
+    });
+
+    parser.push(null);
+  });
+}
+
+
+module.exports = function () {
+  var parser = new ParserStream();
+
+  parser._bytes(16, function (data) {
+
+    // check /^RIFF....WEBPVP8([ LX])$/ signature
+
+    if (sliceEq(data, 0, SIG_RIFF) && sliceEq(data, 8, SIG_WEBPVP8)) {
+      switch (data[15]) {
+        case 32/*' '*/: parseVP8(parser); return;
+        case 76/* L */: parseVP8L(parser); return;
+        case 88/* X */: parseVP8X(parser); return;
+      }
+    } else {
+      parser._skipBytes(Infinity);
+      parser.push(null);
+    }
+  });
+
+  return parser;
+};