Refactors shared/pattern.js into core/ and display/

src/core/pattern.js

@@ -0,0 +1,241 @@
+/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
+/* Copyright 2012 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/* globals ColorSpace, PDFFunction, Util, error, warn, info, isArray, isStream,
+           isPDFFunction, UnsupportedManager, UNSUPPORTED_FEATURES */
+
+'use strict';
+
+var PatternType = {
+  AXIAL: 2,
+  RADIAL: 3
+};
+
+var Pattern = (function PatternClosure() {
+  // Constructor should define this.getPattern
+  function Pattern() {
+    error('should not call Pattern constructor');
+  }
+
+  Pattern.prototype = {
+    // Input: current Canvas context
+    // Output: the appropriate fillStyle or strokeStyle
+    getPattern: function Pattern_getPattern(ctx) {
+      error('Should not call Pattern.getStyle: ' + ctx);
+    }
+  };
+
+  Pattern.parseShading = function Pattern_parseShading(shading, matrix, xref,
+                                                       res) {
+
+    var dict = isStream(shading) ? shading.dict : shading;
+    var type = dict.get('ShadingType');
+
+    switch (type) {
+      case PatternType.AXIAL:
+      case PatternType.RADIAL:
+        // Both radial and axial shadings are handled by RadialAxial shading.
+        return new Shadings.RadialAxial(dict, matrix, xref, res);
+      default:
+        UnsupportedManager.notify(UNSUPPORTED_FEATURES.shadingPattern);
+        return new Shadings.Dummy();
+    }
+  };
+  return Pattern;
+})();
+
+var Shadings = {};
+
+// A small number to offset the first/last color stops so we can insert ones to
+// support extend.  Number.MIN_VALUE appears to be too small and breaks the
+// extend. 1e-7 works in FF but chrome seems to use an even smaller sized number
+// internally so we have to go bigger.
+Shadings.SMALL_NUMBER = 1e-2;
+
+// Radial and axial shading have very similar implementations
+// If needed, the implementations can be broken into two classes
+Shadings.RadialAxial = (function RadialAxialClosure() {
+  function RadialAxial(dict, matrix, xref, res) {
+    this.matrix = matrix;
+    this.coordsArr = dict.get('Coords');
+    this.shadingType = dict.get('ShadingType');
+    this.type = 'Pattern';
+    var cs = dict.get('ColorSpace', 'CS');
+    cs = ColorSpace.parse(cs, xref, res);
+    this.cs = cs;
+
+    var t0 = 0.0, t1 = 1.0;
+    if (dict.has('Domain')) {
+      var domainArr = dict.get('Domain');
+      t0 = domainArr[0];
+      t1 = domainArr[1];
+    }
+
+    var extendStart = false, extendEnd = false;
+    if (dict.has('Extend')) {
+      var extendArr = dict.get('Extend');
+      extendStart = extendArr[0];
+      extendEnd = extendArr[1];
+    }
+
+    if (this.shadingType === PatternType.RADIAL &&
+       (!extendStart || !extendEnd)) {
+      // Radial gradient only currently works if either circle is fully within
+      // the other circle.
+      var x1 = this.coordsArr[0];
+      var y1 = this.coordsArr[1];
+      var r1 = this.coordsArr[2];
+      var x2 = this.coordsArr[3];
+      var y2 = this.coordsArr[4];
+      var r2 = this.coordsArr[5];
+      var distance = Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
+      if (r1 <= r2 + distance &&
+          r2 <= r1 + distance) {
+        warn('Unsupported radial gradient.');
+      }
+    }
+
+    this.extendStart = extendStart;
+    this.extendEnd = extendEnd;
+
+    var fnObj = dict.get('Function');
+    var fn;
+    if (isArray(fnObj)) {
+      var fnArray = [];
+      for (var j = 0, jj = fnObj.length; j < jj; j++) {
+        var obj = xref.fetchIfRef(fnObj[j]);
+        if (!isPDFFunction(obj)) {
+          error('Invalid function');
+        }
+        fnArray.push(PDFFunction.parse(xref, obj));
+      }
+      fn = function radialAxialColorFunction(arg) {
+        var out = [];
+        for (var i = 0, ii = fnArray.length; i < ii; i++) {
+          out.push(fnArray[i](arg)[0]);
+        }
+        return out;
+      };
+    } else {
+      if (!isPDFFunction(fnObj)) {
+        error('Invalid function');
+      }
+      fn = PDFFunction.parse(xref, fnObj);
+    }
+
+    // 10 samples seems good enough for now, but probably won't work
+    // if there are sharp color changes. Ideally, we would implement
+    // the spec faithfully and add lossless optimizations.
+    var diff = t1 - t0;
+    var step = diff / 10;
+
+    var colorStops = this.colorStops = [];
+
+    // Protect against bad domains so we don't end up in an infinte loop below.
+    if (t0 >= t1 || step <= 0) {
+      // Acrobat doesn't seem to handle these cases so we'll ignore for
+      // now.
+      info('Bad shading domain.');
+      return;
+    }
+
+    for (var i = t0; i <= t1; i += step) {
+      var rgbColor = cs.getRgb(fn([i]), 0);
+      var cssColor = Util.makeCssRgb(rgbColor);
+      colorStops.push([(i - t0) / diff, cssColor]);
+    }
+
+    var background = 'transparent';
+    if (dict.has('Background')) {
+      var rgbColor = cs.getRgb(dict.get('Background'), 0);
+      background = Util.makeCssRgb(rgbColor);
+    }
+
+    if (!extendStart) {
+      // Insert a color stop at the front and offset the first real color stop
+      // so it doesn't conflict with the one we insert.
+      colorStops.unshift([0, background]);
+      colorStops[1][0] += Shadings.SMALL_NUMBER;
+    }
+    if (!extendEnd) {
+      // Same idea as above in extendStart but for the end.
+      colorStops[colorStops.length - 1][0] -= Shadings.SMALL_NUMBER;
+      colorStops.push([1, background]);
+    }
+
+    this.colorStops = colorStops;
+  }
+
+  RadialAxial.prototype = {
+    getIR: function RadialAxial_getIR() {
+      var coordsArr = this.coordsArr;
+      var shadingType = this.shadingType;
+      var type, p0, p1, r0, r1;
+      if (shadingType == PatternType.AXIAL) {
+        p0 = [coordsArr[0], coordsArr[1]];
+        p1 = [coordsArr[2], coordsArr[3]];
+        r0 = null;
+        r1 = null;
+        type = 'axial';
+      } else if (shadingType == PatternType.RADIAL) {
+        p0 = [coordsArr[0], coordsArr[1]];
+        p1 = [coordsArr[3], coordsArr[4]];
+        r0 = coordsArr[2];
+        r1 = coordsArr[5];
+        type = 'radial';
+      } else {
+        error('getPattern type unknown: ' + shadingType);
+      }
+
+      var matrix = this.matrix;
+      if (matrix) {
+        p0 = Util.applyTransform(p0, matrix);
+        p1 = Util.applyTransform(p1, matrix);
+      }
+
+      return ['RadialAxial', type, this.colorStops, p0, p1, r0, r1];
+    }
+  };
+
+  return RadialAxial;
+})();
+
+Shadings.Dummy = (function DummyClosure() {
+  function Dummy() {
+    this.type = 'Pattern';
+  }
+
+  Dummy.prototype = {
+    getIR: function Dummy_getIR() {
+      return ['Dummy'];
+    }
+  };
+  return Dummy;
+})();
+
+function getTilingPatternIR(operatorList, dict, args) {
+  var matrix = dict.get('Matrix');
+  var bbox = dict.get('BBox');
+  var xstep = dict.get('XStep');
+  var ystep = dict.get('YStep');
+  var paintType = dict.get('PaintType');
+  var tilingType = dict.get('TilingType');
+
+  return [
+    'TilingPattern', args, operatorList, matrix, bbox, xstep, ystep,
+    paintType, tilingType
+  ];
+}