pdf.js/src/display/pattern_helper.js

/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
/* Copyright 2014 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 CanvasGraphics, CachedCanvases, ColorSpace, Util, error, info,
           isArray */

'use strict';

var ShadingIRs = {};

ShadingIRs.RadialAxial = {
  fromIR: function RadialAxial_fromIR(raw) {
    var type = raw[1];
    var colorStops = raw[2];
    var p0 = raw[3];
    var p1 = raw[4];
    var r0 = raw[5];
    var r1 = raw[6];
    return {
      type: 'Pattern',
      getPattern: function RadialAxial_getPattern(ctx) {
        var grad;
        if (type === 'axial') {
          grad = ctx.createLinearGradient(p0[0], p0[1], p1[0], p1[1]);
        } else if (type === 'radial') {
          grad = ctx.createRadialGradient(p0[0], p0[1], r0, p1[0], p1[1], r1);
        }

        for (var i = 0, ii = colorStops.length; i < ii; ++i) {
          var c = colorStops[i];
          grad.addColorStop(c[0], c[1]);
        }
        return grad;
      }
    };
  }
};

ShadingIRs.Dummy = {
  fromIR: function Dummy_fromIR() {
    return {
      type: 'Pattern',
      getPattern: function Dummy_fromIR_getPattern() {
        return 'hotpink';
      }
    };
  }
};

function getShadingPatternFromIR(raw) {
  return ShadingIRs[raw[0]].fromIR(raw);
}

var TilingPattern = (function TilingPatternClosure() {
  var PaintType = {
    COLORED: 1,
    UNCOLORED: 2
  };

  var MAX_PATTERN_SIZE = 3000; // 10in @ 300dpi shall be enough

  function TilingPattern(IR, color, ctx, objs, commonObjs, baseTransform) {
    this.name = IR[1][0].name;
    this.operatorList = IR[2];
    this.matrix = IR[3] || [1, 0, 0, 1, 0, 0];
    this.bbox = IR[4];
    this.xstep = IR[5];
    this.ystep = IR[6];
    this.paintType = IR[7];
    this.tilingType = IR[8];
    this.color = color;
    this.objs = objs;
    this.commonObjs = commonObjs;
    this.baseTransform = baseTransform;
    this.type = 'Pattern';
    this.ctx = ctx;
  }

  TilingPattern.prototype = {
    createPatternCanvas: function TilinPattern_createPatternCanvas(owner) {
      var operatorList = this.operatorList;
      var bbox = this.bbox;
      var xstep = this.xstep;
      var ystep = this.ystep;
      var paintType = this.paintType;
      var tilingType = this.tilingType;
      var color = this.color;
      var objs = this.objs;
      var commonObjs = this.commonObjs;
      var ctx = this.ctx;

      info('TilingType: ' + tilingType);

      var x0 = bbox[0], y0 = bbox[1], x1 = bbox[2], y1 = bbox[3];

      var topLeft = [x0, y0];
      // we want the canvas to be as large as the step size
      var botRight = [x0 + xstep, y0 + ystep];

      var width = botRight[0] - topLeft[0];
      var height = botRight[1] - topLeft[1];

      // Obtain scale from matrix and current transformation matrix.
      var matrixScale = Util.singularValueDecompose2dScale(this.matrix);
      var curMatrixScale = Util.singularValueDecompose2dScale(
        this.baseTransform);
      var combinedScale = [matrixScale[0] * curMatrixScale[0],
        matrixScale[1] * curMatrixScale[1]];

      // MAX_PATTERN_SIZE is used to avoid OOM situation.
      // Use width and height values that are as close as possible to the end
      // result when the pattern is used. Too low value makes the pattern look
      // blurry. Too large value makes it look too crispy.
      width = Math.min(Math.ceil(Math.abs(width * combinedScale[0])),
        MAX_PATTERN_SIZE);

      height = Math.min(Math.ceil(Math.abs(height * combinedScale[1])),
        MAX_PATTERN_SIZE);

      var tmpCanvas = CachedCanvases.getCanvas('pattern', width, height, true);
      var tmpCtx = tmpCanvas.context;
      var graphics = new CanvasGraphics(tmpCtx, commonObjs, objs);
      graphics.groupLevel = owner.groupLevel;

      this.setFillAndStrokeStyleToContext(tmpCtx, paintType, color);

      this.setScale(width, height, xstep, ystep);
      this.transformToScale(graphics);

      // transform coordinates to pattern space
      var tmpTranslate = [1, 0, 0, 1, -topLeft[0], -topLeft[1]];
      graphics.transform.apply(graphics, tmpTranslate);

      this.clipBbox(graphics, bbox, x0, y0, x1, y1);

      graphics.executeOperatorList(operatorList);
      return tmpCanvas.canvas;
    },

    setScale: function TilingPattern_setScale(width, height, xstep, ystep) {
      this.scale = [width / xstep, height / ystep];
    },

    transformToScale: function TilingPattern_transformToScale(graphics) {
      var scale = this.scale;
      var tmpScale = [scale[0], 0, 0, scale[1], 0, 0];
      graphics.transform.apply(graphics, tmpScale);
    },

    scaleToContext: function TilingPattern_scaleToContext() {
      var scale = this.scale;
      this.ctx.scale(1 / scale[0], 1 / scale[1]);
    },

    clipBbox: function clipBbox(graphics, bbox, x0, y0, x1, y1) {
      if (bbox && isArray(bbox) && 4 == bbox.length) {
        var bboxWidth = x1 - x0;
        var bboxHeight = y1 - y0;
        graphics.rectangle(x0, y0, bboxWidth, bboxHeight);
        graphics.clip();
        graphics.endPath();
      }
    },

    setFillAndStrokeStyleToContext:
      function setFillAndStrokeStyleToContext(context, paintType, color) {
        switch (paintType) {
          case PaintType.COLORED:
            var ctx = this.ctx;
            context.fillStyle = ctx.fillStyle;
            context.strokeStyle = ctx.strokeStyle;
            break;
          case PaintType.UNCOLORED:
            var rgbColor = ColorSpace.singletons.rgb.getRgb(color, 0);
            var cssColor = Util.makeCssRgb(rgbColor);
            context.fillStyle = cssColor;
            context.strokeStyle = cssColor;
            break;
          default:
            error('Unsupported paint type: ' + paintType);
        }
      },

    getPattern: function TilingPattern_getPattern(ctx, owner) {
      var temporaryPatternCanvas = this.createPatternCanvas(owner);

      var ctx = this.ctx;
      ctx.setTransform.apply(ctx, this.baseTransform);
      ctx.transform.apply(ctx, this.matrix);
      this.scaleToContext();

      return ctx.createPattern(temporaryPatternCanvas, 'repeat');
    }
  };

  return TilingPattern;
})();