08.js

进行ajax开发sdsd s d sd s

/**
 * Draw a pie chart into an <svg> element.
 * Arguments:
 *   canvas: the SVG element (or the id of that element) to draw into.
 *   data: an array of numbers to chart, one for each wedge of the pie.
 *   cx, cy, r: the center and radius of the pie
 *   colors: an array of HTML color strings, one for each wedge
 *   labels: an array of labels to appear in the legend, one for each wedge
 *   lx, ly: the upper-left corner of the chart legend
 */
function pieChart(canvas, data, cx, cy, r, colors, labels, lx, ly) {
    // Locate canvas if specified by id instead of element
    if (typeof canvas == "string") canvas = document.getElementById(canvas);
    
    // Add up the data values so we know how big the pie is
    var total = 0;
    for(var i = 0; i < data.length; i++) total += data[i];
    
    // Now figure out how big each slice of pie is.  Angles in radians.
    var angles = []
    for(var i = 0; i < data.length; i++) angles[i] = data[i]/total*Math.PI*2;

    // Loop through each slice of pie.
    startangle = 0;
    for(var i = 0; i < data.length; i++) {
        // This is where the wedge ends
        var endangle = startangle + angles[i];

        // Compute the two points where our wedge intersects the circle
        // These formulas are chosen so that an angle of 0 is at 12 o'clock
        // and positive angles increase clockwise.
        var x1 = cx + r * Math.sin(startangle);
        var y1 = cy - r * Math.cos(startangle);
        var x2 = cx + r * Math.sin(endangle);
        var y2 = cy - r * Math.cos(endangle);
        
        // This is a flag for angles larger than than a half circle
        var big = 0;
        if (endangle - startangle > Math.PI) big = 1;
        
        // We describe a wedge with an <svg:path> element
        // Notice that we create this with createElementNS()
        var path = document.createElementNS(SVG.ns, "path");
        
        // This string holds the path details
        var d = "M " + cx + "," + cy +  // Start at circle center
            " L " + x1 + "," + y1 +     // Draw line to (x1,y1)
            " A " + r + "," + r +       // Draw an arc of radius r
            " 0 " + big + " 1 " +       // Arc details...
            x2 + "," + y2 +             // Arc goes to to (x2,y2)
            " Z";                       // Close path back to (cx,cy)
        // This is an XML element, so all attributes must be set
        // with setAttribute().  We can't just use JavaScript properties
        path.setAttribute("d", d);              // Set this path 
        path.setAttribute("fill", colors[i]);   // Set wedge color
        path.setAttribute("stroke", "black");   // Outline wedge in black
        path.setAttribute("stroke-width", "2"); // 2 units thick
        canvas.appendChild(path);               // Add wedge to canvas

        // The next wedge begins where this one ends
        startangle = endangle;

        // Now draw a little matching square for the key
        var icon = document.createElementNS(SVG.ns, "rect");
        icon.setAttribute("x", lx);             // Position the square
        icon.setAttribute("y", ly + 30*i);
        icon.setAttribute("width", 20);         // Size the square
        icon.setAttribute("height", 20);
        icon.setAttribute("fill", colors[i]);   // Same fill color as wedge
        icon.setAttribute("stroke", "black");   // Same outline, too.
        icon.setAttribute("stroke-width", "2");
        canvas.appendChild(icon);               // Add to the canvas

        // And add a label to the right of the rectangle
        var label = document.createElementNS(SVG.ns, "text");
        label.setAttribute("x", lx + 30);       // Position the text
        label.setAttribute("y", ly + 30*i + 18);
        // Text style attributes could also be set via CSS
        label.setAttribute("font-family", "sans-serif");
        label.setAttribute("font-size", "16");
        // Add a DOM text node to the <svg:text> element
        label.appendChild(document.createTextNode(labels[i]));
        canvas.appendChild(label);              // Add text to the canvas
    }
}