检测画布文本API支持（Opera Mini） [英] Detecting canvas text API support (Opera Mini)

问题描述

虽然Opera Mini不显示画布文本，但是典型的测试表明它具有文本API函数的实现。是否有其他技术来检查支持？

Although Opera Mini does not display canvas text, a typical test indicates that it has an implementation of the text API functions. Is there an alternative technique to check for support?

当前方法：

var context = document.createElement("canvas").getContext("2d");
var canvasTextSupport = typeof context.fillText == "function"; // true in Opera Mini

您可以使用示例来查看是否显示文本： tutorialspoint

An example you can use to see if text shown: tutorialspoint

推荐答案

根据@kangax的建议，您可以通过将文本绘制到画布上，然后确保已绘制像素来进行测试。

As suggested by @kangax, you can test by drawing text to a canvas and then making sure that pixels have been drawn.

var canvasTextSupported = function() {
  var canvas = document.createElement("canvas");  
  var context = canvas.getContext("2d");

  context.fillText("X", 5, 5);     
  var imageData = context.getImageData(0, 0, 10, 10);

  for(var i = 0, l = imageData.data.length; i < l; i++) {
    if(imageData.data[i] !== 0)
      return true;
  }
  return false;
}

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