Core Graphics–driven style layer

[1ec5]

Subclassing MGLOpenGLStyleLayer requires skill with OpenGL, but a developer may want to be able to programmatically generate a style layer using familiar Core Graphics or Core Animation APIs. As far as I can tell, if you attempt to use Core Graphics within MGLOpenGLStyleLayer, a crash occurs (but correct me if I’m wrong). A more natural approach to custom style layers would allow the developer to subclass MGLRasterStyleLayer and implement -drawInRect: or similar. (-drawInRect: is the standard way to implement a custom-drawn view in Cocoa and Cocoa Touch.)

Perhaps the developer could also implement -isAnimated. If it returns false, or perhaps even if it returns true, the SDK can upload a static MGLRasterStyleLayer to an OpenGL texture. @incanus previously experimented with a similar approach for layer-backed annotations in #1125 (comment).

Unlike the programmatically generated raster source proposed in #7471, a Core Graphics–driven style layer would redraw on every frame, not just when moving between integer zoom levels. I have no idea what this feature would look like at the mbgl level, but I believe it makes more sense as a Layer than as a Source. As with MGLOpenGLStyleLayer and the MGLComputedShapeSource being introduced in #6940, I don’t think we should expose this feature in the style specification in any form. So I don’t think this feature would integrate with mapbox/mapbox-gl-style-spec#656.

/cc @jfirebaugh @lucaswoj @lbud

[1ec5]

This feature and #7471 would probably eliminate any demand to make MGLOpenGLStyleLayer an officially supported API.

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.

[1ec5]

MGLOpenGLStyleLayer is still too hard to use for the average developer. An API based on Core Graphics would have much, much less of a learning curve.

[stale]

This issue has been automatically detected as stale because it has not had recent activity and will be archived. Thank you for your contributions.