没有理由不能为 svg 对象的视图框设置动画 - Raphael 根本没有提供开箱即用的此类功能。但是,创建插件相当简单。例如:
Raphael.fn.animateViewBox = function animateViewBox( x, y, w, h, duration, easing_function, callback )
{
var cx = this._viewBox ? this._viewBox[0] : 0,
dx = x - cx,
cy = this._viewBox ? this._viewBox[1] : 0,
dy = y - cy,
cw = this._viewBox ? this._viewBox[2] : this.width,
dw = w - cw,
ch = this._viewBox ? this._viewBox[3] : this.height,
dh = h - ch,
self = this;;
easing_function = easing_function || "linear";
var interval = 25;
var steps = duration / interval;
var current_step = 0;
var easing_formula = Raphael.easing_formulas[easing_function];
var intervalID = setInterval( function()
{
var ratio = current_step / steps;
self.setViewBox( cx + dx * easing_formula( ratio ),
cy + dy * easing_formula( ratio ),
cw + dw * easing_formula( ratio ),
ch + dh * easing_formula( ratio ), false );
if ( current_step++ >= steps )
{
clearInterval( intervalID );
callback && callback();
}
}, interval );
}
安装此插件后实例化的任何纸张都可以使用与 Raphael 内置的 animate 方法完全相同的方法使用 animateViewBox。比如……
var paper = Raphael( 0, 0, 640, 480 );
paper.animateViewBox( 100, 100, 320, 240, 5000, '<>', function()
{
alert("View box updated! What's next?" );
} );
演示已上演here。