Repaint when the picture changed and nothing else did - #842
Merged
Conversation
The Windows head repaints only when the new screen differs from the last one, because ScreenBuilder allocates a fresh Screen every frame and record equality would repaint sixty times a second. That comparison never looked at the image pane, and an image pane said only where the file was and how big it was. An image side's rows are format, dimensions and byte count, so a re-run that rewrites a received image at the same size changes nothing in the model - for BMP, being uncompressed, that is every re-run. Apply returned before invalidating, the canvas never repainted, and the pane kept the previous picture. The stamp based freshness check in ImageCache was never even consulted, since nothing asked it to paint. ImagePane carries the content hash the model already had, and the pane comparison includes the image. The hash is not for drawing - a head reads the file - but for telling one picture from another at the same path and size.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The Windows head repaints only when the new screen differs from the last one,
because ScreenBuilder allocates a fresh Screen every frame and record equality
would repaint sixty times a second. That comparison never looked at the image
pane, and an image pane said only where the file was and how big it was.
An image side's rows are format, dimensions and byte count, so a re-run that
rewrites a received image at the same size changes nothing in the model - for BMP,
being uncompressed, that is every re-run. Apply returned before invalidating, the
canvas never repainted, and the pane kept the previous picture. The stamp based
freshness check in ImageCache was never even consulted, since nothing asked it to
paint.
ImagePane carries the content hash the model already had, and the pane comparison
includes the image. The hash is not for drawing - a head reads the file - but for
telling one picture from another at the same path and size.