Sketch.js pageX未定义错误 [英] Sketch.js pageX undefined error

问题描述

我在我的phonegap应用程序中使用通过intridea的sketch.js。它可以直接修改

I am using sketch.js by intridea in my phonegap application.It works allright with the modification

 case 'touchstart':
            if (this.painting) {//add
                this.stopPainting();
                //add
            }//add
            this.startPainting();
            break;

通过将以上行添加到代码。但我得到一个pageX未定义的错误，这是崩溃我的app。

by adding the above lines to the code.But I am getting a pageX undefined error which is crashing my app.

01-23 19:53:59.342: E/Web Console(31932): Uncaught TypeError: Cannot read property 'pageX' of undefined at file:///android_asset/www/js/external_libs/sketch.js:107

如何克服这个问题，任何帮助将不胜感激。

How to overcome this issue,any help would be appreciated.Thanks

推荐答案

似乎每个人都swfhed到jqscribbel .js，但是要直接用sketch.js回答这个问题，你需要检查是否定义了 e.originalEvent.targetTouches [0] 。我还没有挖掘sketch.js太多，但似乎当触发事件被触发， e.originalEvent.targetTouches [0] 不再定义，因此试图找到 .pageX of undefined会出错。此错误导致整个画布被重新绘制，因此您无法在画布上绘制超过1个草图。要修复此错误，只需添加以下两行代码（在第100/101行附近）：

It seems as if everyone has swtiched over to jqscribbel.js, but to directly answer this question with sketch.js, you need to check if e.originalEvent.targetTouches[0] is defined. I haven't dug into sketch.js too much yet, but it seems that when a touchup event is triggered, e.originalEvent.targetTouches[0] is no longer defined, so trying to find .pageX of undefined gives an error. This error causes the entire canvas to be re-drawn, so you cannot draw more than 1 sketch on the canvas. To fix this error, simply add find the following two lines of code (around line 100/101):

e.pageX = e.originalEvent.targetTouches[0].pageX;
e.pageY = e.originalEvent.targetTouches[0].pageY;

并替换为

if (e.originalEvent.targetTouches[0] !== undefined && e.originalEvent.targetTouches[0].pageX !== undefined){
    e.pageX = e.originalEvent.targetTouches[0].pageX;
}
if (e.originalEvent.targetTouches[0] !== undefined && e.originalEvent.targetTouches[0].pageY !==undefined){
    e.pageY = e.originalEvent.targetTouches[0].pageY;
}

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