Raster that was created with NewRasterFromImage renders from Bounds.Min instead of from zero

[ltlaitoff]

Checklist

• I have searched the issue tracker for open issues that relate to the same problem, before opening a new one.
• This issue only relates to a single bug. I will open new issues for any other problems.

Describe the bug

I have an image that was created with SubImage(aka a tile from a tileset for application in pixel-art style) and, because of that, Bounds().Min is actually not equal to zero

According to the Go blog: The Go image package, it's a normal situation: "A common mistake is assuming that an Image’s bounds start at (0, 0)"

But when I'm trying to render that image, after transforming it to the Raster via NewRasterFromImage, on the canvas it actually renders starting from this Bounds().Min

Expected behaviour was that the image inside the Raster renders from zero, because after that we can position it however we want on the screen, like any other CanvasObject

How to reproduce

1. Run the code snippet

Screenshots

Example code

func main() {
	application := app.NewWithID("Test image position")
	window := application.NewWindow("Test image position")

	img := image.NewRGBA(image.Rect(150, 200, 300, 400))
	bounds := img.Bounds()
	uniform := image.Uniform{C: color.RGBA{R: 0, G: 0, B: 0, A: 255}}
	draw.Draw(img, bounds, &uniform, bounds.Min, draw.Src)

	rasterImage := canvas.NewRasterFromImage(img)

	window.SetContent(rasterImage)
	window.ShowAndRun()
}

Fyne version

2.8.0

Go compiler version

1.25.0

Operating system and version

Arch Linux x86_64

Additional Information

No response

[dweymouth]

I agree that this is unexpected behavior but apparently it's documented:

https://github.com/fyne-io/fyne/blob/develop/canvas/raster.go#L131

// Rasters returned from this method will map pixel for pixel to the screen
// starting img.Bounds().Min pixels from the top left of the canvas object.

It seems like it was an intentional decision, though I don't know why. @andydotxyz What do you think? The most idiomatic Go way to do it would be to always start drawing at 0, 0 relative to the canvas.Raster's position, because a sub-image in Go whose bounds don't start at the pixel origin should behave as if it were a regular smaller image whose pixel data is just that rectangle. But since it's documented, changing it seems like a potentially breaking change that would have to be put off until Fyne 3.0

[andydotxyz]

It is perhaps a little ambiguous, but looking at the width and height checks the image bounds delta should fill then space.
I think that perhaps the documents should have read more like "the top left pixel is at img.Bounds().Min and from there image pixels map to output pixels." (And then the note about padding as before).