Android: SurfaceView and Z-Level Question

I have a FrameLayout containing first a SurfaceView, and second a RelativeLayout which in turn contians various Buttons and TextViews.

Upon the canvas of the SurfaceView I am drawing numerous Bitmaps, and, via Touch and Motion Events am allowing the user to drag them around.

These Bitmaps, when dragged around pass underneath the Buttons etc that are inside the RelativeLayout.

Now, it's my (possibly mistaken) understanding that the "Z-level" of the SurfaceView, or whatever it has开发者_运维知识库 that passes for it, is entirely unrelated to the actual Z-level of the rest of the Layout. Is this the case? If so, how may I get around it, so that dragged Bitmaps are drawn ontop of other Views? Or what other way can I implement a full-screen canvas and yet not have my buttons etc act like the controls of an overlay.

I guess what I actually need is an underlay, where touch events can still be picked up by the Buttons etc underneath. But I don't know how to achieve this, as, when redrawing my Canvas, I have to also redraw the background.

Can I swap the order of the RelativeLayout and the SurfaceView inside the FrameLayout, and then make the background of the Canvas transparent? If so how? Will touch events still "fall through" to the buttons underneath?

Thanks for bearing with me, I know I'm a bit of a waffler.

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SurfaceView doesn't work that way.

SurfaceView has two parts, the "view" part and the "surface" part. The "view" part is a transparent hole that is laid out with the other view elements, and composited onto the view layer. The "surface" part is a completely separate layer that will be positioned and scaled to match the "view" part, and composited by the system compositor rather than the app.

You can control the Z-order of the "surface" layer when the SurfaceView is first created, but it's going to be above or below all View elements. It can't go above some Views and below others because they're completely independent layers. The "surface" layer does not catch input events, so having it on top (via SurfaceView#setZOrderOnTop()) doesn't affect input focus.

For API 14+, you can use a TextureView, which behaves in a more View-friendly way.

Edit: for full details, see the much longer explanation.

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Can you clarify a little bit more? In your SurfaceView do you have a background assigned? If not, you could probably also use AbsoluteView if your intention is to simply drag pieces around. If there is no background, you should be able to place the entire view above the RelativeView that you have and only have the various Buttons and such drawn on the view on top, which would be draggable and remain above everything else.