处理重叠SVG图层中的鼠标事件

Question

我正在使用d3.js构建地图可视化.我正为美国各州和县绘制填充多边形.县的SVG层位于州的层下.填充状态,但填充不透明度设置为0; 需要填充(我认为)来捕获点击事件.

我想在州一级捕获点击事件,但我想在县一级捕捉鼠标悬停事件.

但是,mouseover事件由状态捕获,而不是传递给各个县.

有没有办法将事件传递到一个层或以其他方式触发县上的鼠标悬停事件？

Answer 1

这是一个d3功能,可以满足您的需求.

它通过暂时禁用顶层的指针事件并在下一层上手动触发鼠标事件,将事件传递给较低层.

function passThruEvents(g) {
    g   .on('mousemove.passThru', passThru)
        .on('mousedown.passThru', passThru)
    ;

    function passThru(d) {
        var e = d3.event;

        var prev = this.style.pointerEvents;
        this.style.pointerEvents = 'none';

        var el = document.elementFromPoint(d3.event.x, d3.event.y);

        var e2 = document.createEvent('MouseEvent');
        e2.initMouseEvent(e.type,e.bubbles,e.cancelable,e.view, e.detail,e.screenX,e.screenY,e.clientX,e.clientY,e.ctrlKey,e.altKey,e.shiftKey,e.metaKey,e.button,e.relatedTarget);

        el.dispatchEvent(e2);

        this.style.pointerEvents = prev;
    }
}

Answer 2

如果您想在单击一个州时执行某些操作，例如更改边框样式或形状的不透明度，您可以利用每个县都属于一个州的事实，只需将州中的县分组，捕获“点击”县中的事件，选择相应的状态元素并更改其视觉属性。该策略的模型：

// Setup the visualization, assuming that you have a div with id 'chart'
var width = 300,
    height = 300,
    div = d3.select('#chart'),
    svg = div.append('svg')
        .attr('width', width)
        .attr('height', height);

// Array of states, each one containing one or more counties. In this example,
// the states are rectangles, but you get the idea
var states = [
    {
        width: 300,
        height: 300,
        name: 'Fake State',
        counties: [
            {x:   5, y: 5, width:  95, height: 290, fill: '#b4a0a0'},
            {x: 100, y: 5, width: 150, height: 290, fill: '#b4c0a0'},
            {x: 250, y: 5, width:  45, height: 290, fill: '#a4a0c0'}
        ]
    }];

// Create a group for each state, with class state
var gstates = svg.selectAll('g.state')
    .data(states)
    .enter()
    .append('g')
    .classed('state', true);

// Add the state background, in this case, a transparent rectangle
gstates
    .append('rect')
    .classed('state', true)
    .attr('width', function(d) { return d.width; })
    .attr('height', function(d) { return d.height; })
    .attr('fill', '#444')
    .attr('fill-opacity', 0.0);

// For each group, add rectangles for each county, binding them to the
// county array of each state.
gstates.selectAll('rect.county')
    .data(function(d) { return d.counties; })
    .enter()
    .append('rect')
    .classed('county', true)
        .attr('x', function(d) { return d.x; })
        .attr('y', function(d) { return d.y; })
        .attr('width', function(d) { return d.width; })
        .attr('height', function(d) { return d.height; })
        .attr('fill', function(d) { return d.fill; })
        .on('mouseover', function() {
            d3.select(this).attr('fill-opacity', 0.5);
        })
        .on('mouseout', function() {
            d3.select(this).attr('fill-opacity', 0.9);
        })
        .on('click', function() {
            // Retrive the parent group of each county, and then select
            // the shape corresponding to the state and alter its properties
            // you can also access the state data
            var parent = d3.select(d3.select(this).node().parentNode),
                state = parent.select('rect.state');
                // Output 'Fake State'
                console.log(parent[0][0].__data__.name);
                state.attr('fill-opacity', 1.0);
        });

这里有一个工作小提琴：http://jsfiddle.net/pnavarrc/PGTCM/5/。问候，