创建图像区域，用于不透明度> 0 的像素，而不仅仅是 1

Question

因此，createImageRegion方法忽略所有具有少量alpha/不透明度的像素。

如何使此功能也可用于命中检测，以便不透明度为 .5 或其他像素的像素也计入命中检测？

我研究了KineticJS。颜色键被添加到命中区域，但它会将键转换为没有字母的十六进制键。我想不出如何使这项工作的方法。

帮助非常感激！

这就是魔术发生的地方。但是我不明白我如何包含任何类型的跨性别的像素，但 0

createImageHitRegion: function (callback) {
    var canvas = new Kinetic.Canvas(this.attrs.width, this.attrs.height);
    var context = canvas.getContext();
    context.drawImage(this.attrs.image, 0, 0);
    try {
        var imageData = context.getImageData(0, 0, canvas.getWidth(), canvas.getHeight());
        var data = imageData.data;
        var rgbColorKey = Kinetic.Type._hexToRgb(this.colorKey);
        // replace non transparent pixels with color key
        for (var i = 0, n = data.length; i < n; i += 4) {
            data[i] = rgbColorKey.r;
            data[i + 1] = rgbColorKey.g;
            data[i + 2] = rgbColorKey.b;
            // i+3 is alpha (the fourth element)
        }
        var that = this;
        Kinetic.Type._getImage(imageData, function (imageObj) {
            that.imageHitRegion = imageObj;
            if (callback) {
                callback();
            }
        });
    }
    catch (e) {
        Kinetic.Global.warn('Unable to create image hit region. ' + e.message);
    }
}

当我包括：data[i + 3] = 255 （rgbColorKey.a） 不删除时，所有图像事件都不再起作用

Answer 1

我找到了答案：

       for (var i = 0, n = data.length; i < n; i += 4) {
            data[i] = rgbColorKey.r;
            data[i + 1] = rgbColorKey.g;
            data[i + 2] = rgbColorKey.b;
            if (!ignoreAlpha && data[i + 3] > 0) {
                data[i + 3] = 255;
            }
        }

这样，每个还剩下一点透明度的像素都会得到一个完整的颜色。因此，如果您将其原型化为 kinetixJS，它应该可以工作：

Kinetic.Image.prototype.createImageHitRegion = function (callback, ignoreTransparantPixels) {
var canvas = new Kinetic.Canvas(this.attrs.width, this.attrs.height);
var context = canvas.getContext();
var _ignoreTransparantPixels;
if(typeof ignoreTransparantPixels == 'undefined'){
    _ignoreTransparantPixels = false;
}
context.drawImage(this.attrs.image, 0, 0);
try {
    var imageData = context.getImageData(0, 0, canvas.getWidth(), canvas.getHeight());
    var data = imageData.data;
    var rgbColorKey = Kinetic.Type._hexToRgb(this.colorKey);
    // replace non transparent pixels with color key
    for (var i = 0, n = data.length; i < n; i += 4) {
        data[i] = rgbColorKey.r;
        data[i + 1] = rgbColorKey.g;
        data[i + 2] = rgbColorKey.b;
        if (!_ignoreTransparantPixels && data[i + 3] > 0) {
            data[i + 3] = 255;
        }
        //trace(data[i + 3]);
        // i+3 is alpha (the fourth element)
    }
    var that = this;
    Kinetic.Type._getImage(imageData, function (imageObj) {
        that.imageHitRegion = imageObj;
        if (callback) {
            callback();
        }
    });
}
catch (e) {
    Kinetic.Global.warn('Unable to create image hit region. ' + e.message);
}

}