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301 lines
14 KiB
JavaScript
301 lines
14 KiB
JavaScript
/**
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* @module ol/reproj
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*/
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import { IMAGE_SMOOTHING_DISABLED } from './renderer/canvas/common.js';
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import { assign } from './obj.js';
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import { containsCoordinate, createEmpty, extend, forEachCorner, getCenter, getHeight, getTopLeft, getWidth, } from './extent.js';
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import { createCanvasContext2D } from './dom.js';
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import { getPointResolution, transform } from './proj.js';
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import { solveLinearSystem } from './math.js';
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var brokenDiagonalRendering_;
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/**
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* @type {Array<HTMLCanvasElement>}
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*/
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export var canvasPool = [];
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/**
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* This draws a small triangle into a canvas by setting the triangle as the clip region
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* and then drawing a (too large) rectangle
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*
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* @param {CanvasRenderingContext2D} ctx The context in which to draw the triangle
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* @param {number} u1 The x-coordinate of the second point. The first point is 0,0.
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* @param {number} v1 The y-coordinate of the second point.
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* @param {number} u2 The x-coordinate of the third point.
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* @param {number} v2 The y-coordinate of the third point.
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*/
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function drawTestTriangle(ctx, u1, v1, u2, v2) {
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ctx.beginPath();
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ctx.moveTo(0, 0);
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ctx.lineTo(u1, v1);
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ctx.lineTo(u2, v2);
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ctx.closePath();
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ctx.save();
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ctx.clip();
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ctx.fillRect(0, 0, Math.max(u1, u2) + 1, Math.max(v1, v2));
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ctx.restore();
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}
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/**
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* Given the data from getImageData, see if the right values appear at the provided offset.
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* Returns true if either the color or transparency is off
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*
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* @param {Uint8ClampedArray} data The data returned from getImageData
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* @param {number} offset The pixel offset from the start of data.
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* @return {boolean} true if the diagonal rendering is broken
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*/
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function verifyBrokenDiagonalRendering(data, offset) {
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// the values ought to be close to the rgba(210, 0, 0, 0.75)
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return (Math.abs(data[offset * 4] - 210) > 2 ||
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Math.abs(data[offset * 4 + 3] - 0.75 * 255) > 2);
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}
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/**
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* Determines if the current browser configuration can render triangular clip regions correctly.
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* This value is cached so the function is only expensive the first time called.
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* Firefox on Windows (as of now) does not if HWA is enabled. See https://bugzilla.mozilla.org/show_bug.cgi?id=1606976
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* IE also doesn't. Chrome works, and everything seems to work on OSX and Android. This function caches the
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* result. I suppose that it is conceivably possible that a browser might flip modes while the app is
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* running, but lets hope not.
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*
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* @return {boolean} true if the Diagonal Rendering is broken.
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*/
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function isBrokenDiagonalRendering() {
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if (brokenDiagonalRendering_ === undefined) {
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var ctx = document.createElement('canvas').getContext('2d');
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ctx.globalCompositeOperation = 'lighter';
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ctx.fillStyle = 'rgba(210, 0, 0, 0.75)';
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drawTestTriangle(ctx, 4, 5, 4, 0);
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drawTestTriangle(ctx, 4, 5, 0, 5);
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var data = ctx.getImageData(0, 0, 3, 3).data;
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brokenDiagonalRendering_ =
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verifyBrokenDiagonalRendering(data, 0) ||
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verifyBrokenDiagonalRendering(data, 4) ||
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verifyBrokenDiagonalRendering(data, 8);
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}
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return brokenDiagonalRendering_;
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}
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/**
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* Calculates ideal resolution to use from the source in order to achieve
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* pixel mapping as close as possible to 1:1 during reprojection.
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* The resolution is calculated regardless of what resolutions
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* are actually available in the dataset (TileGrid, Image, ...).
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*
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* @param {import("./proj/Projection.js").default} sourceProj Source projection.
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* @param {import("./proj/Projection.js").default} targetProj Target projection.
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* @param {import("./coordinate.js").Coordinate} targetCenter Target center.
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* @param {number} targetResolution Target resolution.
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* @return {number} The best resolution to use. Can be +-Infinity, NaN or 0.
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*/
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export function calculateSourceResolution(sourceProj, targetProj, targetCenter, targetResolution) {
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var sourceCenter = transform(targetCenter, targetProj, sourceProj);
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// calculate the ideal resolution of the source data
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var sourceResolution = getPointResolution(targetProj, targetResolution, targetCenter);
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var targetMetersPerUnit = targetProj.getMetersPerUnit();
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if (targetMetersPerUnit !== undefined) {
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sourceResolution *= targetMetersPerUnit;
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}
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var sourceMetersPerUnit = sourceProj.getMetersPerUnit();
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if (sourceMetersPerUnit !== undefined) {
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sourceResolution /= sourceMetersPerUnit;
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}
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// Based on the projection properties, the point resolution at the specified
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// coordinates may be slightly different. We need to reverse-compensate this
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// in order to achieve optimal results.
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var sourceExtent = sourceProj.getExtent();
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if (!sourceExtent || containsCoordinate(sourceExtent, sourceCenter)) {
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var compensationFactor = getPointResolution(sourceProj, sourceResolution, sourceCenter) /
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sourceResolution;
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if (isFinite(compensationFactor) && compensationFactor > 0) {
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sourceResolution /= compensationFactor;
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}
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}
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return sourceResolution;
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}
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/**
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* Calculates ideal resolution to use from the source in order to achieve
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* pixel mapping as close as possible to 1:1 during reprojection.
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* The resolution is calculated regardless of what resolutions
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* are actually available in the dataset (TileGrid, Image, ...).
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*
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* @param {import("./proj/Projection.js").default} sourceProj Source projection.
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* @param {import("./proj/Projection.js").default} targetProj Target projection.
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* @param {import("./extent.js").Extent} targetExtent Target extent
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* @param {number} targetResolution Target resolution.
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* @return {number} The best resolution to use. Can be +-Infinity, NaN or 0.
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*/
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export function calculateSourceExtentResolution(sourceProj, targetProj, targetExtent, targetResolution) {
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var targetCenter = getCenter(targetExtent);
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var sourceResolution = calculateSourceResolution(sourceProj, targetProj, targetCenter, targetResolution);
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if (!isFinite(sourceResolution) || sourceResolution <= 0) {
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forEachCorner(targetExtent, function (corner) {
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sourceResolution = calculateSourceResolution(sourceProj, targetProj, corner, targetResolution);
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return isFinite(sourceResolution) && sourceResolution > 0;
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});
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}
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return sourceResolution;
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}
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/**
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* @typedef {Object} ImageExtent
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* @property {import("./extent.js").Extent} extent Extent.
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* @property {HTMLCanvasElement|HTMLImageElement|HTMLVideoElement} image Image.
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*/
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/**
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* Renders the source data into new canvas based on the triangulation.
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*
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* @param {number} width Width of the canvas.
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* @param {number} height Height of the canvas.
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* @param {number} pixelRatio Pixel ratio.
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* @param {number} sourceResolution Source resolution.
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* @param {import("./extent.js").Extent} sourceExtent Extent of the data source.
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* @param {number} targetResolution Target resolution.
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* @param {import("./extent.js").Extent} targetExtent Target extent.
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* @param {import("./reproj/Triangulation.js").default} triangulation Calculated triangulation.
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* @param {Array<ImageExtent>} sources Array of sources.
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* @param {number} gutter Gutter of the sources.
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* @param {boolean} [opt_renderEdges] Render reprojection edges.
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* @param {boolean} [opt_interpolate] Use linear interpolation when resampling.
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* @return {HTMLCanvasElement} Canvas with reprojected data.
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*/
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export function render(width, height, pixelRatio, sourceResolution, sourceExtent, targetResolution, targetExtent, triangulation, sources, gutter, opt_renderEdges, opt_interpolate) {
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var context = createCanvasContext2D(Math.round(pixelRatio * width), Math.round(pixelRatio * height), canvasPool);
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if (!opt_interpolate) {
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assign(context, IMAGE_SMOOTHING_DISABLED);
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}
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if (sources.length === 0) {
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return context.canvas;
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}
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context.scale(pixelRatio, pixelRatio);
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function pixelRound(value) {
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return Math.round(value * pixelRatio) / pixelRatio;
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}
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context.globalCompositeOperation = 'lighter';
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var sourceDataExtent = createEmpty();
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sources.forEach(function (src, i, arr) {
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extend(sourceDataExtent, src.extent);
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});
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var canvasWidthInUnits = getWidth(sourceDataExtent);
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var canvasHeightInUnits = getHeight(sourceDataExtent);
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var stitchContext = createCanvasContext2D(Math.round((pixelRatio * canvasWidthInUnits) / sourceResolution), Math.round((pixelRatio * canvasHeightInUnits) / sourceResolution));
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if (!opt_interpolate) {
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assign(stitchContext, IMAGE_SMOOTHING_DISABLED);
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}
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var stitchScale = pixelRatio / sourceResolution;
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sources.forEach(function (src, i, arr) {
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var xPos = src.extent[0] - sourceDataExtent[0];
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var yPos = -(src.extent[3] - sourceDataExtent[3]);
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var srcWidth = getWidth(src.extent);
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var srcHeight = getHeight(src.extent);
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// This test should never fail -- but it does. Need to find a fix the upstream condition
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if (src.image.width > 0 && src.image.height > 0) {
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stitchContext.drawImage(src.image, gutter, gutter, src.image.width - 2 * gutter, src.image.height - 2 * gutter, xPos * stitchScale, yPos * stitchScale, srcWidth * stitchScale, srcHeight * stitchScale);
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}
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});
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var targetTopLeft = getTopLeft(targetExtent);
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triangulation.getTriangles().forEach(function (triangle, i, arr) {
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/* Calculate affine transform (src -> dst)
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* Resulting matrix can be used to transform coordinate
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* from `sourceProjection` to destination pixels.
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*
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* To optimize number of context calls and increase numerical stability,
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* we also do the following operations:
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* trans(-topLeftExtentCorner), scale(1 / targetResolution), scale(1, -1)
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* here before solving the linear system so [ui, vi] are pixel coordinates.
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*
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* Src points: xi, yi
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* Dst points: ui, vi
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* Affine coefficients: aij
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*
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* | x0 y0 1 0 0 0 | |a00| |u0|
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* | x1 y1 1 0 0 0 | |a01| |u1|
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* | x2 y2 1 0 0 0 | x |a02| = |u2|
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* | 0 0 0 x0 y0 1 | |a10| |v0|
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* | 0 0 0 x1 y1 1 | |a11| |v1|
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* | 0 0 0 x2 y2 1 | |a12| |v2|
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*/
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var source = triangle.source;
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var target = triangle.target;
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var x0 = source[0][0], y0 = source[0][1];
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var x1 = source[1][0], y1 = source[1][1];
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var x2 = source[2][0], y2 = source[2][1];
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// Make sure that everything is on pixel boundaries
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var u0 = pixelRound((target[0][0] - targetTopLeft[0]) / targetResolution);
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var v0 = pixelRound(-(target[0][1] - targetTopLeft[1]) / targetResolution);
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var u1 = pixelRound((target[1][0] - targetTopLeft[0]) / targetResolution);
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var v1 = pixelRound(-(target[1][1] - targetTopLeft[1]) / targetResolution);
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var u2 = pixelRound((target[2][0] - targetTopLeft[0]) / targetResolution);
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var v2 = pixelRound(-(target[2][1] - targetTopLeft[1]) / targetResolution);
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// Shift all the source points to improve numerical stability
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// of all the subsequent calculations. The [x0, y0] is used here.
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// This is also used to simplify the linear system.
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var sourceNumericalShiftX = x0;
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var sourceNumericalShiftY = y0;
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x0 = 0;
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y0 = 0;
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x1 -= sourceNumericalShiftX;
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y1 -= sourceNumericalShiftY;
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x2 -= sourceNumericalShiftX;
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y2 -= sourceNumericalShiftY;
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var augmentedMatrix = [
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[x1, y1, 0, 0, u1 - u0],
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[x2, y2, 0, 0, u2 - u0],
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[0, 0, x1, y1, v1 - v0],
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[0, 0, x2, y2, v2 - v0],
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];
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var affineCoefs = solveLinearSystem(augmentedMatrix);
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if (!affineCoefs) {
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return;
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}
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context.save();
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context.beginPath();
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if (isBrokenDiagonalRendering() || !opt_interpolate) {
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// Make sure that all lines are horizontal or vertical
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context.moveTo(u1, v1);
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// This is the diagonal line. Do it in 4 steps
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var steps = 4;
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var ud = u0 - u1;
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var vd = v0 - v1;
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for (var step = 0; step < steps; step++) {
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// Go horizontally
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context.lineTo(u1 + pixelRound(((step + 1) * ud) / steps), v1 + pixelRound((step * vd) / (steps - 1)));
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// Go vertically
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if (step != steps - 1) {
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context.lineTo(u1 + pixelRound(((step + 1) * ud) / steps), v1 + pixelRound(((step + 1) * vd) / (steps - 1)));
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}
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}
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// We are almost at u0r, v0r
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context.lineTo(u2, v2);
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}
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else {
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context.moveTo(u1, v1);
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context.lineTo(u0, v0);
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context.lineTo(u2, v2);
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}
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context.clip();
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context.transform(affineCoefs[0], affineCoefs[2], affineCoefs[1], affineCoefs[3], u0, v0);
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context.translate(sourceDataExtent[0] - sourceNumericalShiftX, sourceDataExtent[3] - sourceNumericalShiftY);
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context.scale(sourceResolution / pixelRatio, -sourceResolution / pixelRatio);
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context.drawImage(stitchContext.canvas, 0, 0);
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context.restore();
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});
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if (opt_renderEdges) {
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context.save();
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context.globalCompositeOperation = 'source-over';
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context.strokeStyle = 'black';
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context.lineWidth = 1;
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triangulation.getTriangles().forEach(function (triangle, i, arr) {
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var target = triangle.target;
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var u0 = (target[0][0] - targetTopLeft[0]) / targetResolution;
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var v0 = -(target[0][1] - targetTopLeft[1]) / targetResolution;
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var u1 = (target[1][0] - targetTopLeft[0]) / targetResolution;
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var v1 = -(target[1][1] - targetTopLeft[1]) / targetResolution;
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var u2 = (target[2][0] - targetTopLeft[0]) / targetResolution;
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var v2 = -(target[2][1] - targetTopLeft[1]) / targetResolution;
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context.beginPath();
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context.moveTo(u1, v1);
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context.lineTo(u0, v0);
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context.lineTo(u2, v2);
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context.closePath();
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context.stroke();
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});
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context.restore();
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}
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return context.canvas;
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}
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//# sourceMappingURL=reproj.js.map
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