Feature request: `make-bitmap` method of `dc<%>`

I would like to request that a make-bitmap method be added to dc<%>. I would like it to behave like the existing make-bitmap function, with the following differences:

• The backing scale is automatically inherited from the dc it is created from, and

• it automatically chooses between make-bitmap, make-platform-bitmap, and make-screen-bitmap depending on what is most appropriate for the drawing context (if relevant).

For example, the drawing context produced by the get-dc method of canvas<%> would presumably use make-screen-bitmap to create a bitmap, while drawing contexts that don’t actually draw to bitmaps like post-script-dc% and record-dc% would just return a bitmap created with the make-bitmap function. Instances of bitmap-dc% would create bitmaps with the same properties as the currently-installed bitmap.

This would make it significantly easier for functions like blur from pict to do the right thing, avoiding bugs like racket/pict#52. I’m not sure it’s currently even possible to handle the second point with the existing interface.

Start with the existing make-bitmap function and the dc<%> interface, then compare the get-dc method of canvas<%>, bitmap-dc%, post-script-dc%, and record-dc%. Done would mean a dc<%>-level make-bitmap that inherits backing scale and selects the appropriate bitmap constructor, but the issue leaves the feasibility and design of the second behavior unresolved.