Provide picture to image support?

[jtdaugherty]

Would it be possible for vty to provide a function with this type?

composite :: Picture -> (Int, Int) -> Image

This function would convert the layers in the Picture to an Image suitable for composing with other Images or as a layer in another Picture, subject to the width and height expectations provided as a parameter.

I am working on a new terminal UI library similar (in spirit) to vty-ui, and one operation I thought would be cool would be to composite layers as an intermediate step in building interfaces. Specifically I was modifying the Vty Rogue demo application and thought it would be nice to be able to build a minimap by compositing the player and geography images and then compose that with other images in the UI.

What do you think?

[coreyoconnor]

I cannot start dev on this now, but here's some notes:

The code that is responsible for compositing the layers is from:

• https://github.com/coreyoconnor/vty/blob/master/src/Graphics/Vty/PictureToSpans.hs#L94

to:

• https://github.com/coreyoconnor/vty/blob/master/src/Graphics/Vty/PictureToSpans.hs#L178

First each layer is transformed from the Image representation to an array of SpanOp s. These arrays of SpanOps are then composed together by the code above.

I see no reason the composition could not be done before. That would likely be simpler than compositing the SpanOps as well.

A verification test for no regressions would be:

forall p < Picture. displayOpsForPic p displayRegion == displayOpsForPic (composite p displayRegion) displayRegion

[jtdaugherty]

Okay, thank you for the context. If I get time, I will work on this.