使重叠的 d3.js 雷达图元素透明
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【中文标题】使重叠的 d3.js 雷达图元素透明【英文标题】:Make overlapping d3.js radar chart elements transparent 【发布时间】:2018-01-08 06:38:36 【问题描述】:如何使 d3.js 雷达图中的重叠部分透明。
下面的雷达图 blob 是使用 d3.js 创建的。红色和绿色相交的空间应该是透明的(这将用于比较之前的 之后)。图表下方的 sn-p 包含用于创建雷达图表的代码。为简单起见,我没有包括 5 个轴:
/* Original radar chart design created by Nadieh Bremer - VisualCinnamon.com */
////////////////////////// Data //////////////////////////////
var data = [
[//Before - red
axis:"First",value:0.49,
axis:"Banana",value:0.79,
axis:"Scratch",value:0.70,
axis:"Wheelie",value:0.09,
axis:"Pantalon",value:0.37,
],[//After - green
axis:"First",value:0.64,
axis:"Banana",value:0.44,
axis:"Scratch",value:0.37,
axis:"Wheelie",value:0.84,
axis:"Pantalon",value:0.81,
]
];
//////////////////////// Setup ////////////////////////////////
var margin = top: 50, right: 50, bottom: 50, left: 50,
width = 300,
height = 300;
var color = d3.scale.ordinal().range(["#CC333F","#53e87d"]);
var radarChartOptions =
w: width, //Width of the circle
h: height, //Height of the circle
margin: margin, //The margins of the SVG
opacityArea: 0.7, //The opacity of the area of the blob
color: color //Color function
;
//////////////////////// RadarChart ///////////////////////////
RadarChart("#radarChart1", data, radarChartOptions);
/////////////////////////////////////////////////////////
/////////////// The Radar Chart Function ////////////////
/////////////// Written by Nadieh Bremer ////////////////
////////////////// VisualCinnamon.com ///////////////////
/////////// Inspired by the code of alangrafu ///////////
/////////////////////////////////////////////////////////
function RadarChart(id, data, options)
/////////////////////////////////////////////////////////
/////////////// Prep ////////////////
/////////////////////////////////////////////////////////
var cfg = radarChartOptions;
var allAxis = (data[0].map(function(i, j)return i.axis)), //Names of each axis
total = allAxis.length, //The number of different axes
radius = Math.min(cfg.w/2, cfg.h/2), //Radius of the outermost circle
Format = d3.format('%'), //Percentage formatting
angleSlice = Math.PI * 2 / total; //The width in radians of each "slice"
var rScale = d3.scale.linear() //Scale for the radius
.range([0, radius]);
//////////// Create the container SVG and g /////////////
var svg = d3.select(id).append("svg") //Initiate the radar chart SVG
.attr("width", cfg.w + cfg.margin.left + cfg.margin.right)
.attr("height", cfg.h + cfg.margin.top + cfg.margin.bottom)
.attr("class", "radar"+id);
var g = svg.append("g") //Append a g element
.attr("transform", "translate(" + (cfg.w/2 + cfg.margin.left) + "," + (cfg.h/2 + cfg.margin.top) + ")");
/////////////////////////////////////////////////////////
///////////// Draw the radar chart blobs ////////////////
/////////////////////////////////////////////////////////
//The radial line function
var radarLine = d3.svg.line.radial()
.interpolate("cardinal-closed")
.radius(function(d) return rScale(d.value); )
.angle(function(d,i) return i*angleSlice; );
//Create a wrapper for the blobs
var blobWrapper = g.selectAll(".radarWrapper")
.data(data)
.enter().append("g")
.attr("class", "radarWrapper");
//Append the backgrounds
blobWrapper
.append("path")
.attr("class", "radarArea")
.attr("d", function(d,i) return radarLine(d); )
.style("fill", function(d,i) return cfg.color(i);)
.style("fill-opacity", cfg.opacityArea);
//RadarChart function
<script src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<!-- Radar Chart -->
<div class="radar-chart" id="radarChart1"></div>
我发现在 html5-Canvas 中重叠的元素可以变成透明的 (1)。它还可以用于将 d3 节点绑定到它 (2),并且它们可以通过这种方式变得透明。然而,对于像上面的雷达图斑点这样的更复杂的对象,这似乎非常复杂。在d3中有一个简单的解决方案吗? (chart.js中好像有(3))
附录 - 我已经找到的内容:
-
通过将
globalCompositeOperation
模式设置为'xor'
,可以使用HTML5-Canvas 使重叠(非d3)元素透明:
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
ctx.globalCompositeOperation = 'xor';
// WITHOUT overlap:
ctx.fillStyle = 'blue';
ctx.fillRect(10, 10, 100, 100);
ctx.fillStyle = 'red';
ctx.fillRect(110, 50, 100, 100);
// WITH (transparent) overlap:
ctx.fillStyle = 'blue';
ctx.fillRect(250, 10, 100, 100);
ctx.fillStyle = 'red';
ctx.fillRect(300, 50, 100, 100);
<!-- Original from https://developer.mozilla.org/en-US/docs/Web/API/CanvasRenderingContext2D/globalCompositeOperation -->
<style>
body
background-image: url("http://www.scri8e.com/stars/PNG_Clouds/zc06.png?filename=./zc06.png");
</style>
<canvas id="canvas" ></canvas>
d3.js 节点也可以通过 HTML5-Canvas 使用 getContext("2d") 进行可视化。可以按照与上述 (1) 相同的方式实现重叠。但是,据我了解,这需要 重新创建 javascript 中的每个元素,然后在其上绑定 d3 数据。例如对于圆形,必须在 HTML5-Canvas 上下文中重新创建弧元素,如 this example by Mike Bostock:
context = canvas.getContext("2d"); ...
context.arc(element.getAttribute("x"), element.getAttribute("y"), element.getAttribute("radius"), 0, 2 * Math.PI);
这是chartjs 中可能的实现(见下图)
【问题讨论】:
这可能会有所帮助:"What is the best approach for overlapping SVG elements area fill?". 【参考方案1】:您的描述暗示您将始终有两个图表(“之前 -> 之后”)。
此解决方案使用 SVG 蒙版。虽然它可以使用更多图表,但它变得更加复杂。您必须动态构造 <mask>
元素。
/* Original radar chart design created by Nadieh Bremer - VisualCinnamon.com */
////////////////////////// Data //////////////////////////////
var data = [
[//Before - red
axis:"First",value:0.49,
axis:"Banana",value:0.79,
axis:"Scratch",value:0.70,
axis:"Wheelie",value:0.09,
axis:"Pantalon",value:0.37,
],[//After - green
axis:"First",value:0.64,
axis:"Banana",value:0.44,
axis:"Scratch",value:0.37,
axis:"Wheelie",value:0.84,
axis:"Pantalon",value:0.81,
]
];
//////////////////////// Setup ////////////////////////////////
var margin = top: 50, right: 50, bottom: 50, left: 50,
width = 300,
height = 300;
var color = d3.scale.ordinal().range(["#CC333F","#53e87d"]);
var radarChartOptions =
w: width, //Width of the circle
h: height, //Height of the circle
margin: margin, //The margins of the SVG
opacityArea: 0.7, //The opacity of the area of the blob
color: color //Color function
;
//////////////////////// RadarChart ///////////////////////////
RadarChart("radarChart", data, radarChartOptions);
function RadarChart(id, data, options)
var cfg = radarChartOptions;
var allAxis = (data[0].map(function(i, j)return i.axis)), //Names of each axis
total = allAxis.length, //The number of different axes
radius = Math.min(cfg.w/2, cfg.h/2), //Radius of the outermost circle
Format = d3.format('%'), //Percentage formatting
angleSlice = Math.PI * 2 / total; //The width in radians of each "slice"
var rScale = d3.scale.linear() //Scale for the radius
.range([0, radius]);
var svg = d3.select('#' + id) //Initiate the radar chart SVG
.attr("width", cfg.w + cfg.margin.left + cfg.margin.right)
.attr("height", cfg.h + cfg.margin.top + cfg.margin.bottom)
.attr("class", "radar"+id);
svg.select('#bg').attr('r', radius);
var dx = cfg.w/2 + cfg.margin.left,
dy = cfg.h/2 + cfg.margin.top;
svg.selectAll('mask')
.attr('x', -dx)
.attr('y', -dy);
var source = svg.select('#radarSource')
var wrapper = svg.select('#radarWrapper')
.attr("transform", "translate(" + dx + "," + dy + ")");
//The radial line function
var radarLine = d3.svg.line.radial()
.interpolate("cardinal-closed")
.radius(function(d) return rScale(d.value); )
.angle(function(d,i) return i*angleSlice; );
//Draw the blobs
source.selectAll("path")
.data(data)
.enter().append("path")
.attr("id", function(d,i) return 'area' + i;)
.attr("d", function(d,i) return radarLine(d); );
//render and apply masks
wrapper.selectAll("use")
.data(data)
.enter().append("use")
.attr("xlink:href", function(d,i) return '#area' + i;)
.attr("mask", function(d,i) return 'url(#mask' + i + ')';)
.style("fill", function(d,i) return cfg.color(i);)
.style("fill-opacity", cfg.opacityArea);
//RadarChart function
<script src="https://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<!-- Radar Chart -->
<svg id="radarChart" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
<defs>
<circle id="bg" />
<g id="radarSource" />
<mask id="mask0" maskUnits="userSpaceOnUse">
<use xlink:href="#bg" fill="white" />
<use xlink:href="#area1" fill="black" />
</mask>
<mask id="mask1" maskUnits="userSpaceOnUse">
<use xlink:href="#bg" fill="white" />
<use xlink:href="#area0" fill="black" />
</mask>
</defs>
<g id="radarWrapper" />
</svg>
【讨论】:
感谢您的精彩回答!这对我帮助很大! :)以上是关于使重叠的 d3.js 雷达图元素透明的主要内容,如果未能解决你的问题,请参考以下文章