如何使用canvas和Kinetic.js裁剪图像

Question

我的函数绘制一个图像,另一个图像在另一个图层上使用Kinetic.js,但我想裁剪第二个图像,名为smsTopBg_image

    window.onload = function() {
        //INITIALISATION
        var stage = new Kinetic.Stage({
            container: "iPhone",
            width: 480,
            height: 720
        });
        //LAYERS
        var background_layer = new Kinetic.Layer();
        var sms_layer = new Kinetic.Layer();
        var text_layer = new Kinetic.Layer();

        //ELEMENTS
        var iPhoneBg = new Image();
        iPhoneBg.onload = function() {
                var iPhoneBg_image = new Kinetic.Image({
                image: iPhoneBg
            });
            background_layer.add(iPhoneBg_image);
            stage.add(background_layer);
        }
        iPhoneBg.src = "iPhoneBg.jpg";
        //--------------------------------------------------
        var smsTopBg = new Image();
            smsTopBg.onload = function() {
                var smsTopBg_image = new Kinetic.Image({
                image: smsTopBg,
                x: 10,
                y: 10,
            });
            sms_layer.add(smsTopBg_image);
            stage.add(sms_layer);
        }
        smsTopBg.src = "iPhoneBg.jpg";
    };

谢谢 !

Answer 1

您可以将可选的裁剪对象添加到Image构造函数中的主要属性对象.它有一个x, y, width and height属性.

var smsTopBg_image = new Kinetic.Image({
    image: smsTopBg,
    x: 10,
    y: 10,
    // random values, choose your own :
    crop: {
        x: 20,
        y: 3,
        width: 100,
        height: 42
    }
});