147 lines
3.4 KiB
JavaScript
147 lines
3.4 KiB
JavaScript
goog.require('ol.Map');
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goog.require('ol.View2D');
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goog.require('ol.layer.Tile');
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goog.require('ol.proj');
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goog.require('ol.source.BingMaps');
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var key = 'Ak-dzM4wZjSqTlzveKz5u0d4IQ4bRzVI309GxmkgSVr1ewS6iPSrOvOKhA-CJlm3';
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var imagery = new ol.layer.Tile({
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source: new ol.source.BingMaps({key: key, imagerySet: 'Aerial'})
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});
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var map = new ol.Map({
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layers: [imagery],
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target: 'map',
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view: new ol.View2D({
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center: ol.proj.transform([-120, 50], 'EPSG:4326', 'EPSG:3857'),
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zoom: 6
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})
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});
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var kernels = {
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none: [
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0, 0, 0,
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0, 1, 0,
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0, 0, 0
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],
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sharpen: [
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0, -1, 0,
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-1, 5, -1,
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0, -1, 0
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],
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sharpenless: [
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0, -1, 0,
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-1, 10, -1,
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0, -1, 0
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],
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blur: [
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1, 1, 1,
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1, 1, 1,
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1, 1, 1
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],
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shadow: [
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1, 2, 1,
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0, 1, 0,
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-1, -2, -1
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],
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emboss: [
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-2, 1, 0,
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-1, 1, 1,
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0, 1, 2
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],
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edge: [
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0, 1, 0,
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1, -4, 1,
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0, 1, 0
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]
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};
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function normalize(kernel) {
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var len = kernel.length;
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var normal = new Array(len);
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var i, sum = 0;
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for (i = 0; i < len; ++i) {
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sum += kernel[i];
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}
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if (sum <= 0) {
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normal.normalized = false;
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sum = 1;
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} else {
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normal.normalized = true;
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}
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for (i = 0; i < len; ++i) {
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normal[i] = kernel[i] / sum;
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}
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return normal;
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}
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var select = document.getElementById('kernel');
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var selectedKernel = normalize(kernels[select.value]);
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/**
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* Update the kernel and re-render on change.
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*/
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select.onchange = function() {
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selectedKernel = normalize(kernels[select.value]);
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map.render();
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};
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/**
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* Apply a filter on "postcompose" events.
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* @param {ol.render.Event} event Render event.
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*/
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imagery.on('postcompose', function(event) {
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convolve(event.context, selectedKernel);
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});
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/**
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* Apply a convolution kernel to canvas. This works for any size kernel, but
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* performance starts degrading above 3 x 3.
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* @param {CanvasRenderingContext2D} context Canvas 2d context.
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* @param {Array.<number>} kernel Kernel.
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*/
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function convolve(context, kernel) {
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var canvas = context.canvas;
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var width = canvas.width;
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var height = canvas.height;
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var size = Math.sqrt(kernel.length);
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var half = Math.floor(size / 2);
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var inputData = context.getImageData(0, 0, width, height).data;
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var output = context.createImageData(width, height);
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var outputData = output.data;
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for (var pixelY = 0; pixelY < height; ++pixelY) {
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var pixelsAbove = pixelY * width;
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for (var pixelX = 0; pixelX < width; ++pixelX) {
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var r = 0, g = 0, b = 0, a = 0;
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for (var kernelY = 0; kernelY < size; ++kernelY) {
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for (var kernelX = 0; kernelX < size; ++kernelX) {
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var weight = kernel[kernelY * size + kernelX];
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var neighborY = Math.min(
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height - 1, Math.max(0, pixelY + kernelY - half));
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var neighborX = Math.min(
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width - 1, Math.max(0, pixelX + kernelX - half));
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var inputIndex = (neighborY * width + neighborX) * 4;
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r += inputData[inputIndex] * weight;
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g += inputData[inputIndex + 1] * weight;
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b += inputData[inputIndex + 2] * weight;
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a += inputData[inputIndex + 3] * weight;
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}
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}
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var outputIndex = (pixelsAbove + pixelX) * 4;
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outputData[outputIndex] = r;
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outputData[outputIndex + 1] = g;
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outputData[outputIndex + 2] = b;
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outputData[outputIndex + 3] = kernel.normalized ? a : 255;
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}
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}
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context.putImageData(output, 0, 0);
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}
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