Closed antonfirsov closed 4 years ago
I feel we should also take the opportunity to remove the passing of a Rectangle
into IImageProcessingContext.ApplyProcessor()
& IImageProcessor.CreatePixelSpecificProcessor()
the rectangle feels like it should be a concern of individual processors configuration as not all processors honor the rectangle so it becomes a bit of a lie to have it always passed.
@tocsoft Yeah, I had a good dig through the code there and I don't think there's any reason why we cannot do that.
Been looking at the open PR regarding this and we need to fix up the way we use the term Clone
and DeepClone
in the library. Currently we use both for what is a deep clone. I suggest we always use DeepClone
everywhere
@tocsoft good idea. We need to provide specific guidance for #983 to make it happen. I'll also have a dig through the code to see what we can do.
@tocsoft @JimBobSquarePants I had a deeper look at the source, now I'm unsure whether this is the right thing to do.
In my understanding the majority of the processors actually do honor SourceRectangle
. Drawing processors are an exception, but it would probably make sense to respect sourceRectangle
in drawing. (Eg: user wants to draw to a given subarea of an image masking out the rest, even if some drawing artifacts go outside the bounds.)
I think we could even generalize this logic, and introduce ImageArea
and ImageFrameArea<T>
types:
class ImageFrameArea<T>
{
public ImageFrame<T> Frame { get; }
public Rectangle Rectangle { get; }
public Span<T> GetPixelRowSpan(int y); // gets the subspan inside the area.
// y = 0 is at row Rectangle.Top
// etc.
}
Am I missing an important point? Are there other exceptions?
Added an update to the issue description.
@antonfirsov having had a good dig through via refactoring I tend to agree. We can handle that once I finish implementing IDisposable
Just pushed a PR to clean up the way we were implementing IDisposable
. I'm gonna have a look at moving the visitor extensions now.
I've started working on exposing the pixel blenders. The lack of method documentation is a chore though!
Great news! I will be available for reviews in the next days.
These APIs are basically the last two methods I think we should expose. They're not currently used in Drawing but I think would be very useful elsewhere.
I'm definitely going to rename anything Helper to Utils for the sake of my sanity anyway.
I think we can close this since ImageSharp.Drawing is now in an external repository with no internal access.
Plans to externalize SixLabors.ImageSharp.Drawing
The main library, SixLabors.ImageSharp almost reached Release Candidate quality, however we realized, that it will take much more time to bring SixLabors.ImageSharp.Drawing and it's base libraries SixLabors.Shapes and SixLabors.Fonts to the same level.
In order to unblock the release of ImageSharp, we decided to externalize SixLabors.ImageSharp.Drawing. It shall be:
We are afraid that Drawing, Shapes, Fonts will reach RC status only after the 1.0 release of the main library.
Blockers
Unfortunately, externalizing ImageSharp.Drawing is not a trivial job, since it depends on certain internals of the main library by using
[InternalsVisibleTo(...)]
, namely:Buffer2D<T>
ImageProcessor<T>
PixelBlender<T>
andPixelOperations<T>.GetPixelBlender(...)
IImageVisitor
andImage.AcceptVisitor(...)
ParallelExecutionSettings
,configuration.GetParallelSettings()
andParallelHelper
These issues are actually well-known to anyone trying to implement Image Processors, and complaining about classes being internal. (Hi there @Sergio0694 😄!) This turns the issue of ImageSharp.Drawing into an API-cleanup problem.
Suggested solution
Buffer2D<T>
with a minimal subset of public methods. KeepMemorySource<T>
hidden. Consider reintroducingIBuffer2D<T>
.ImageProcessor<T>
but consider refactoring the "processor application" logic. See follow-up explanation.PixelBlender<T>
andPixelOperations<T>.GetPixelBlender(...)
IImageVisitor
to theAdvanced
subnamespace, exposeIImageVisitor
andImage.AcceptVisitor(...)
Proposal to refactor current ImageProcessor logic
IQuantizer
is a good example for the interaction and lifecycle rules of non-generic (pixel agnostic) objects and their generic (pixel-specific) counterparts:I think we should fully adapt this pattern for Image Processors:
BeforeImageApply
should be replaced with~ constructor logic:IImageProcessor.CreatePixelSpecificProcessor()
should takeImage<T>
and aRectangle
which is then passed toImageProcessor<T>
constructor, initialization and resource allocation could be done here.AfterImageApply
should be replaced with~Dispose()
(to clean up temporary resources)Image<T>
,SourceRectangle
andConfiguration
can be membersIImageProcessor<TPixel>.Apply()
should be non-parametric. Consider renaming it toExecute()
UPDATE: I no longer think that constructor/
Dispose
are replacements forBefore/After ImageApply
. Those should exist side-by side.UPDATE 2:
Further, "nice to have" points
SourceRectangle
(and maybeTargetRectangle
) behavior. See: commentsIImageProcessor
vsICloningImageProcessor
behavior. Expose(I)CloningImageProcessor
UPDATE 3:
PixelOperations<T>.To/FromVector4(...)
(nice to have, currently not used by Drawing)To avoid a longer delay, I'm fine if we can't address them within the current API cleanup process, since these are no trivial topics.