如何检查是否有东西在画布上绘制 [英] How to check if something is drawn on canvas

问题描述

如何检查画布上是否有资料或绘画？

How do I check if there is data or something drawn on a canvas?

我有这个< canvas id =my- canvas>< / canvas> 元素，我想检查我的画布是否有绘制的东西。

I have this <canvas id="my-canvas"></canvas> element, and I want to check if my canvas has something drawn on it.

推荐答案

一旦填充完成，而不是检查每个像素，它可能会更有效率地记录每次画布被填充或描边。或中风或已经发生，那么你知道已经绘制了一些东西。

Once a fill or stroke or has happened, then you know that something has been drawn.

当然'how'是非常特定的应用程序，因为我们不知道你的画布在第一个地方画。

Of course 'how' is very application specific, since we don't know how your canvas is getting drawn on in the first place.

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