为什么您可以直接更改ImageView的srccompat？
我正在关注Kotlin Android教程，目前正在Dice Roller应用程序教程中。为了更改图像，教程说要写：
diceImage.setImageResource(drawableResource)
我的问题是，为什么我们不能直接更改图像？就像说：
diceImage.srcCompat = drawableResource
我认为我们不能这样做的原因可能是srccompat变量是私人的，但是后来教程写道：
diceImage.contentDescription = diceRoll.toString()
内容描述在与srccompat的“常见属性”标签下，这可能意味着srccompat issn'' t私人。虽然我可能错了。
我的问题是：
为什么我们不能直接设置SRCCOMPAT？
SetImageresource函数的确切作用是什么？
I am following the Kotlin Android tutorial and am currently on the Dice Roller App tutorial. For changing the image, the tutorial says to write:
diceImage.setImageResource(drawableResource)
My question is, why can't we change the image directly? Like say:
diceImage.srcCompat = drawableResource
I thought that maybe the reason we couldn't do that was that the srcCompat variable was private, but later the tutorial writes:
diceImage.contentDescription = diceRoll.toString()
The content description is under the same "common attributes" tab as srcCompat, which probably means srcCompat isn't private. Although I'm probably wrong.
My questions are:
Why can't we set srcCompat directly?
What is the setImageResource function doing exactly?
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在ImageView内部，实际图像是可绘制的。当您设置Immageresource时，您将设置一个INT ID。然后，图像视图将通过调用Context.Resources.getDrawable（ID）查找与ID相关联的内容，并将其保存在变量中。因此，您不能仅仅通过属性集进行操作，因为您存储的值与将其设置为的值不同。因此，您需要一个功能。
请注意，您可以在图像上设置图像的几种不同方法 - 从可绘制的资源ID，位图等。如果您有多种方式，则需要是函数而不是属性。 ContextDeScription可以起作用，因为您只将其设置为charsequence。
Inside the ImageView, the actual image is a Drawable. When you setImageResource, you're setting an int id. The ImageView will then look up what Drawable is associated with the id by calling context.resources.getDrawable(id) and save that in a variable. So you can't just do it via a property set, because the value you'd be storing isn't the same type as the value you'd be setting it to. Thus you need a function.
Notice there are several different ways you can set the image on an image view- from a Drawable, a resource id, a Bitmap, etc. If you have more than one way, it needs to be a function and not a property. ContextDescription can work because you're only ever setting it to a CharSequence.