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build/node_modules/pngjs/lib/bitmapper.js

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+'use strict';
+
+var interlaceUtils = require('./interlace');
+
+var pixelBppMap = {
+  1: { // L
+    0: 0,
+    1: 0,
+    2: 0,
+    3: 0xff
+  },
+  2: { // LA
+    0: 0,
+    1: 0,
+    2: 0,
+    3: 1
+  },
+  3: { // RGB
+    0: 0,
+    1: 1,
+    2: 2,
+    3: 0xff
+  },
+  4: { // RGBA
+    0: 0,
+    1: 1,
+    2: 2,
+    3: 3
+  }
+};
+
+function bitRetriever(data, depth) {
+
+  var leftOver = [];
+  var i = 0;
+
+  function split() {
+    if (i === data.length) {
+      throw new Error('Ran out of data');
+    }
+    var byte = data[i];
+    i++;
+    var byte8, byte7, byte6, byte5, byte4, byte3, byte2, byte1;
+    switch (depth) {
+      default:
+        throw new Error('unrecognised depth');
+      case 16:
+        byte2 = data[i];
+        i++;
+        leftOver.push(((byte << 8) + byte2));
+        break;
+      case 4:
+        byte2 = byte & 0x0f;
+        byte1 = byte >> 4;
+        leftOver.push(byte1, byte2);
+        break;
+      case 2:
+        byte4 = byte & 3;
+        byte3 = byte >> 2 & 3;
+        byte2 = byte >> 4 & 3;
+        byte1 = byte >> 6 & 3;
+        leftOver.push(byte1, byte2, byte3, byte4);
+        break;
+      case 1:
+        byte8 = byte & 1;
+        byte7 = byte >> 1 & 1;
+        byte6 = byte >> 2 & 1;
+        byte5 = byte >> 3 & 1;
+        byte4 = byte >> 4 & 1;
+        byte3 = byte >> 5 & 1;
+        byte2 = byte >> 6 & 1;
+        byte1 = byte >> 7 & 1;
+        leftOver.push(byte1, byte2, byte3, byte4, byte5, byte6, byte7, byte8);
+        break;
+    }
+  }
+
+  return {
+    get: function(count) {
+      while (leftOver.length < count) {
+        split();
+      }
+      var returner = leftOver.slice(0, count);
+      leftOver = leftOver.slice(count);
+      return returner;
+    },
+    resetAfterLine: function() {
+      leftOver.length = 0;
+    },
+    end: function() {
+      if (i !== data.length) {
+        throw new Error('extra data found');
+      }
+    }
+  };
+}
+
+function mapImage8Bit(image, pxData, getPxPos, bpp, data, rawPos) { // eslint-disable-line max-params
+  var imageWidth = image.width;
+  var imageHeight = image.height;
+  var imagePass = image.index;
+  for (var y = 0; y < imageHeight; y++) {
+    for (var x = 0; x < imageWidth; x++) {
+      var pxPos = getPxPos(x, y, imagePass);
+
+      for (var i = 0; i < 4; i++) {
+        var idx = pixelBppMap[bpp][i];
+        if (idx === 0xff) {
+          pxData[pxPos + i] = 0xff;
+        } else {
+          var dataPos = idx + rawPos;
+          if (dataPos === data.length) {
+            throw new Error('Ran out of data');
+          }
+          pxData[pxPos + i] = data[dataPos];
+        }
+      }
+      rawPos += bpp; //eslint-disable-line no-param-reassign
+    }
+  }
+  return rawPos;
+}
+
+function mapImageCustomBit(image, pxData, getPxPos, bpp, bits, maxBit) { // eslint-disable-line max-params
+  var imageWidth = image.width;
+  var imageHeight = image.height;
+  var imagePass = image.index;
+  for (var y = 0; y < imageHeight; y++) {
+    for (var x = 0; x < imageWidth; x++) {
+      var pixelData = bits.get(bpp);
+      var pxPos = getPxPos(x, y, imagePass);
+
+      for (var i = 0; i < 4; i++) {
+        var idx = pixelBppMap[bpp][i];
+        pxData[pxPos + i] = idx !== 0xff ? pixelData[idx] : maxBit;
+      }
+    }
+    bits.resetAfterLine();
+  }
+}
+
+exports.dataToBitMap = function(data, bitmapInfo) {
+
+  var width = bitmapInfo.width;
+  var height = bitmapInfo.height;
+  var depth = bitmapInfo.depth;
+  var bpp = bitmapInfo.bpp;
+  var interlace = bitmapInfo.interlace;
+
+  if (depth !== 8) {
+    var bits = bitRetriever(data, depth);
+  }
+  var pxData;
+  if (depth <= 8) {
+    pxData = new Buffer(width * height * 4);
+  }
+  else {
+    pxData = new Uint16Array(width * height * 4);
+  }
+  var maxBit = Math.pow(2, depth) - 1;
+  var rawPos = 0;
+  var images;
+  var getPxPos;
+
+  if (interlace) {
+    images = interlaceUtils.getImagePasses(width, height);
+    getPxPos = interlaceUtils.getInterlaceIterator(width, height);
+  }
+  else {
+    var nonInterlacedPxPos = 0;
+    getPxPos = function() {
+      var returner = nonInterlacedPxPos;
+      nonInterlacedPxPos += 4;
+      return returner;
+    };
+    images = [{ width: width, height: height }];
+  }
+
+  for (var imageIndex = 0; imageIndex < images.length; imageIndex++) {
+    if (depth === 8) {
+      rawPos = mapImage8Bit(images[imageIndex], pxData, getPxPos, bpp, data, rawPos);
+    }
+    else {
+      mapImageCustomBit(images[imageIndex], pxData, getPxPos, bpp, bits, maxBit);
+    }
+  }
+  if (depth === 8) {
+    if (rawPos !== data.length) {
+      throw new Error('extra data found');
+    }
+  }
+  else {
+    bits.end();
+  }
+
+  return pxData;
+};