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openlayers

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Build tools and sources for developing OpenLayers based mapping applications

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goog.provide('ol.reproj.Triangulation'); goog.require('ol'); goog.require('ol.extent'); goog.require('ol.math'); goog.require('ol.proj'); /** * @classdesc * Class containing triangulation of the given target extent. * Used for determining source data and the reprojection itself. * * @param {ol.proj.Projection} sourceProj Source projection. * @param {ol.proj.Projection} targetProj Target projection. * @param {ol.Extent} targetExtent Target extent to triangulate. * @param {ol.Extent} maxSourceExtent Maximal source extent that can be used. * @param {number} errorThreshold Acceptable error (in source units). * @constructor */ ol.reproj.Triangulation = function(sourceProj, targetProj, targetExtent, maxSourceExtent, errorThreshold) { /** * @type {ol.proj.Projection} * @private */ this.sourceProj_ = sourceProj; /** * @type {ol.proj.Projection} * @private */ this.targetProj_ = targetProj; /** @type {!Object.<string, ol.Coordinate>} */ var transformInvCache = {}; var transformInv = ol.proj.getTransform(this.targetProj_, this.sourceProj_); /** * @param {ol.Coordinate} c A coordinate. * @return {ol.Coordinate} Transformed coordinate. * @private */ this.transformInv_ = function(c) { var key = c[0] + '/' + c[1]; if (!transformInvCache[key]) { transformInvCache[key] = transformInv(c); } return transformInvCache[key]; }; /** * @type {ol.Extent} * @private */ this.maxSourceExtent_ = maxSourceExtent; /** * @type {number} * @private */ this.errorThresholdSquared_ = errorThreshold * errorThreshold; /** * @type {Array.<ol.ReprojTriangle>} * @private */ this.triangles_ = []; /** * Indicates that the triangulation crosses edge of the source projection. * @type {boolean} * @private */ this.wrapsXInSource_ = false; /** * @type {boolean} * @private */ this.canWrapXInSource_ = this.sourceProj_.canWrapX() && !!maxSourceExtent && !!this.sourceProj_.getExtent() && (ol.extent.getWidth(maxSourceExtent) == ol.extent.getWidth(this.sourceProj_.getExtent())); /** * @type {?number} * @private */ this.sourceWorldWidth_ = this.sourceProj_.getExtent() ? ol.extent.getWidth(this.sourceProj_.getExtent()) : null; /** * @type {?number} * @private */ this.targetWorldWidth_ = this.targetProj_.getExtent() ? ol.extent.getWidth(this.targetProj_.getExtent()) : null; var destinationTopLeft = ol.extent.getTopLeft(targetExtent); var destinationTopRight = ol.extent.getTopRight(targetExtent); var destinationBottomRight = ol.extent.getBottomRight(targetExtent); var destinationBottomLeft = ol.extent.getBottomLeft(targetExtent); var sourceTopLeft = this.transformInv_(destinationTopLeft); var sourceTopRight = this.transformInv_(destinationTopRight); var sourceBottomRight = this.transformInv_(destinationBottomRight); var sourceBottomLeft = this.transformInv_(destinationBottomLeft); this.addQuad_( destinationTopLeft, destinationTopRight, destinationBottomRight, destinationBottomLeft, sourceTopLeft, sourceTopRight, sourceBottomRight, sourceBottomLeft, ol.RASTER_REPROJECTION_MAX_SUBDIVISION); if (this.wrapsXInSource_) { // Fix coordinates (ol.proj returns wrapped coordinates, "unwrap" here). // This significantly simplifies the rest of the reprojection process. ol.DEBUG && console.assert(this.sourceWorldWidth_ !== null); var leftBound = Infinity; this.triangles_.forEach(function(triangle, i, arr) { leftBound = Math.min(leftBound, triangle.source[0][0], triangle.source[1][0], triangle.source[2][0]); }); // Shift triangles to be as close to `leftBound` as possible // (if the distance is more than `worldWidth / 2` it can be closer. this.triangles_.forEach(function(triangle) { if (Math.max(triangle.source[0][0], triangle.source[1][0], triangle.source[2][0]) - leftBound > this.sourceWorldWidth_ / 2) { var newTriangle = [[triangle.source[0][0], triangle.source[0][1]], [triangle.source[1][0], triangle.source[1][1]], [triangle.source[2][0], triangle.source[2][1]]]; if ((newTriangle[0][0] - leftBound) > this.sourceWorldWidth_ / 2) { newTriangle[0][0] -= this.sourceWorldWidth_; } if ((newTriangle[1][0] - leftBound) > this.sourceWorldWidth_ / 2) { newTriangle[1][0] -= this.sourceWorldWidth_; } if ((newTriangle[2][0] - leftBound) > this.sourceWorldWidth_ / 2) { newTriangle[2][0] -= this.sourceWorldWidth_; } // Rarely (if the extent contains both the dateline and prime meridian) // the shift can in turn break some triangles. // Detect this here and don't shift in such cases. var minX = Math.min( newTriangle[0][0], newTriangle[1][0], newTriangle[2][0]); var maxX = Math.max( newTriangle[0][0], newTriangle[1][0], newTriangle[2][0]); if ((maxX - minX) < this.sourceWorldWidth_ / 2) { triangle.source = newTriangle; } } }, this); } transformInvCache = {}; }; /** * Adds triangle to the triangulation. * @param {ol.Coordinate} a The target a coordinate. * @param {ol.Coordinate} b The target b coordinate. * @param {ol.Coordinate} c The target c coordinate. * @param {ol.Coordinate} aSrc The source a coordinate. * @param {ol.Coordinate} bSrc The source b coordinate. * @param {ol.Coordinate} cSrc The source c coordinate. * @private */ ol.reproj.Triangulation.prototype.addTriangle_ = function(a, b, c, aSrc, bSrc, cSrc) { this.triangles_.push({ source: [aSrc, bSrc, cSrc], target: [a, b, c] }); }; /** * Adds quad (points in clock-wise order) to the triangulation * (and reprojects the vertices) if valid. * Performs quad subdivision if needed to increase precision. * * @param {ol.Coordinate} a The target a coordinate. * @param {ol.Coordinate} b The target b coordinate. * @param {ol.Coordinate} c The target c coordinate. * @param {ol.Coordinate} d The target d coordinate. * @param {ol.Coordinate} aSrc The source a coordinate. * @param {ol.Coordinate} bSrc The source b coordinate. * @param {ol.Coordinate} cSrc The source c coordinate. * @param {ol.Coordinate} dSrc The source d coordinate. * @param {number} maxSubdivision Maximal allowed subdivision of the quad. * @private */ ol.reproj.Triangulation.prototype.addQuad_ = function(a, b, c, d, aSrc, bSrc, cSrc, dSrc, maxSubdivision) { var sourceQuadExtent = ol.extent.boundingExtent([aSrc, bSrc, cSrc, dSrc]); var sourceCoverageX = this.sourceWorldWidth_ ? ol.extent.getWidth(sourceQuadExtent) / this.sourceWorldWidth_ : null; var sourceWorldWidth = /** @type {number} */ (this.sourceWorldWidth_); // when the quad is wrapped in the source projection // it covers most of the projection extent, but not fully var wrapsX = this.sourceProj_.canWrapX() && sourceCoverageX > 0.5 && sourceCoverageX < 1; var needsSubdivision = false; if (maxSubdivision > 0) { if (this.targetProj_.isGlobal() && this.targetWorldWidth_) { var targetQuadExtent = ol.extent.boundingExtent([a, b, c, d]); var targetCoverageX = ol.extent.getWidth(targetQuadExtent) / this.targetWorldWidth_; needsSubdivision |= targetCoverageX > ol.RASTER_REPROJECTION_MAX_TRIANGLE_WIDTH; } if (!wrapsX && this.sourceProj_.isGlobal() && sourceCoverageX) { needsSubdivision |= sourceCoverageX > ol.RASTER_REPROJECTION_MAX_TRIANGLE_WIDTH; } } if (!needsSubdivision && this.maxSourceExtent_) { if (!ol.extent.intersects(sourceQuadExtent, this.maxSourceExtent_)) { // whole quad outside source projection extent -> ignore return; } } if (!needsSubdivision) { if (!isFinite(aSrc[0]) || !isFinite(aSrc[1]) || !isFinite(bSrc[0]) || !isFinite(bSrc[1]) || !isFinite(cSrc[0]) || !isFinite(cSrc[1]) || !isFinite(dSrc[0]) || !isFinite(dSrc[1])) { if (maxSubdivision > 0) { needsSubdivision = true; } else { return; } } } if (maxSubdivision > 0) { if (!needsSubdivision) { var center = [(a[0] + c[0]) / 2, (a[1] + c[1]) / 2]; var centerSrc = this.transformInv_(center); var dx; if (wrapsX) { var centerSrcEstimX = (ol.math.modulo(aSrc[0], sourceWorldWidth) + ol.math.modulo(cSrc[0], sourceWorldWidth)) / 2; dx = centerSrcEstimX - ol.math.modulo(centerSrc[0], sourceWorldWidth); } else { dx = (aSrc[0] + cSrc[0]) / 2 - centerSrc[0]; } var dy = (aSrc[1] + cSrc[1]) / 2 - centerSrc[1]; var centerSrcErrorSquared = dx * dx + dy * dy; needsSubdivision = centerSrcErrorSquared > this.errorThresholdSquared_; } if (needsSubdivision) { if (Math.abs(a[0] - c[0]) <= Math.abs(a[1] - c[1])) { // split horizontally (top & bottom) var bc = [(b[0] + c[0]) / 2, (b[1] + c[1]) / 2]; var bcSrc = this.transformInv_(bc); var da = [(d[0] + a[0]) / 2, (d[1] + a[1]) / 2]; var daSrc = this.transformInv_(da); this.addQuad_( a, b, bc, da, aSrc, bSrc, bcSrc, daSrc, maxSubdivision - 1); this.addQuad_( da, bc, c, d, daSrc, bcSrc, cSrc, dSrc, maxSubdivision - 1); } else { // split vertically (left & right) var ab = [(a[0] + b[0]) / 2, (a[1] + b[1]) / 2]; var abSrc = this.transformInv_(ab); var cd = [(c[0] + d[0]) / 2, (c[1] + d[1]) / 2]; var cdSrc = this.transformInv_(cd); this.addQuad_( a, ab, cd, d, aSrc, abSrc, cdSrc, dSrc, maxSubdivision - 1); this.addQuad_( ab, b, c, cd, abSrc, bSrc, cSrc, cdSrc, maxSubdivision - 1); } return; } } if (wrapsX) { if (!this.canWrapXInSource_) { return; } this.wrapsXInSource_ = true; } this.addTriangle_(a, c, d, aSrc, cSrc, dSrc); this.addTriangle_(a, b, c, aSrc, bSrc, cSrc); }; /** * Calculates extent of the 'source' coordinates from all the triangles. * * @return {ol.Extent} Calculated extent. */ ol.reproj.Triangulation.prototype.calculateSourceExtent = function() { var extent = ol.extent.createEmpty(); this.triangles_.forEach(function(triangle, i, arr) { var src = triangle.source; ol.extent.extendCoordinate(extent, src[0]); ol.extent.extendCoordinate(extent, src[1]); ol.extent.extendCoordinate(extent, src[2]); }); return extent; }; /** * @return {Array.<ol.ReprojTriangle>} Array of the calculated triangles. */ ol.reproj.Triangulation.prototype.getTriangles = function() { return this.triangles_; };