在canvas中移动由drawImage创建的图像 [英] Moving image that was created by drawImage in canvas

问题描述

如何在画布中移动图像？没有可以通过+ =或 - =改变的x \y坐标。

How just move image in canvas? There are no x\y coordinates which I can change by += or -=.

推荐答案

Canvas是一个immedate绘图表面。当你进行 drawImage 调用时，画布将位图渲染到上下文中，然后忘记所有发生的事情。它没有任何记录。

Canvas is an immedate drawing surface. When you make a call like drawImage the canvas renders the bitmap to the context and then forgets that anything ever happened. It keeps track of nothing.

这意味着你需要跟踪一切。如果你想要移动的图像，你需要清除画布，并重新绘制图像（和场景中的一切）在不同的位置，比以前。

That means you need to keep track of everything. If you want the image you move, you need to clear the canvas and redraw the image (and everything else in the scene) at a different location than before.

我在各个方面做了很多，所以我做了一个教程管理绘制对象的状态，帆布交互性，作为这个主题的一个体面的介绍。本教程使用矩形，您可以在屏幕上拖动，但使用图像几乎相同。

This comes up a lot in various ways so I made a tutorial on managing the state of drawn objects and canvas interactivity that serves as a decent introduction to this topic. The tutorial uses rectangles that you can drag around the screen, but using images is nearly identical.

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