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[kipcole9]

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[RyoWakabayashi]

Wouldn't it be better if the Image tab was displayed by default?

[kipcole9]

I submitted this PR to vix upstream to reorder the tabs and I expect it will be in the next Vix release.

[RyoWakabayashi]

The current implementation of Image.Kino.show() does not apply well to Kino.Layout.grid()

It would be better to do the following

lib/kino.ex

  def show(%Vimage{} = image, opts \\ []) do
    image = maybe_resize_image(image, opts)

    {:ok, image_bin} = Vimage.write_to_buffer(image, ".png")
    apply(Kino.Image, :new, [image_bin, "image/png"])
  end

[kipcole9]

I just published Image version 0.23.1 with this fix and changelog entry:

Bug Fixes

• Kino.show/2 returns the image instead of :ok so that it works correctly in a grid. Thanks to @RyoWakabayashi for the suggestion.

Thanks for the suggestion!

[RyoWakabayashi]

Why not add thickness to the Image.Draw.rect parameter as follows

draw_rect = fn img, left, top, width, height, thickness ->
  img
  |> Image.Draw.rect!(left, top, thickness, height, color: :blue, fill: true)
  |> Image.Draw.rect!(left, top, width, thickness, color: :blue, fill: true)
  |> Image.Draw.rect!(left + width - thickness, top, thickness, height, color: :blue, fill: true)
  |> Image.Draw.rect!(left, top + height - thickness, width, thickness, color: :blue, fill: true)
end

[kipcole9]

That's a very creative solution. I'm reluctant to add it to Image.Draw.rect/5 only because I don't also have a solution for Image.Draw.circle or Image.Draw.line. I think there is a roadmap item to add thickness in libvips for these mutations - if not I'll add a feature request there.

[RyoWakabayashi]

It's solution for Image.Draw.circle

img
|> Image.Draw.circle!(center_x, center_y, radius, color: color, fill: false)
|> Image.Draw.circle!(
  center_x,
  center_y,
  radius - thickness,
  color: color,
  fill: false
)
|> Image.Draw.flood(center_x - radius + 1, center_y, color: color)
|> elem(1)
|> elem(0)

[kipcole9]

That would work well - unless there are adjacent pixels the same colour as the circle. Probably that's not so common and documenting the behaviour will be enough. And the same approach can be used for Image.Draw.line/5. I will work on this over the weekend.

[kipcole9]

I also added Image.Draw.flood!/3 to the main branch.

[kipcole9]

I've push a commit that adds the :stroke_width option to Image.Draw.rect/6 using your code example above. I've not yet added tests but I'd welcome you giving it a try to see if it does what you expect. I'll work on Image.Draw.circle/5 next.

[RyoWakabayashi]

How about a function to add the alpha band

add_alpha = fn rgb_img ->
  alpha_band = Image.new!(rgb_img, bands: 1, color: Image.Color.max_opacity())
  Vix.Vips.Operation.bandjoin!([rgb_img, alpha_band])
end

[kipcole9]

Yes, makes sense. I'll add that to the weekend work.

[kipcole9]

You can do that today with:

use Image.Math
alpha_band = Image.new!(rgb_img, bands: 1, color: Image.Color.max_opacity())
with_alpha = rgb_img + alpha_band

But I agree, a more explicit "Image.add_alpha/2` would be valuable.

[kipcole9]

I added Image.add_alpha/2 and `Image.add_alpha!/2" to the main branch.