refactor(tvix): move logo to //tvix:logo

Also expose both formats, then use it from
users/tazjin/presentations/tvix-eval-2023.

Change-Id: Id906e8aff5510a7a4f33336326472e86db18ea32
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9280
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/README.md

@@ -1,5 +1,5 @@
 <div align="center">
-  <img src="https://tvix.dev/tvix-logo.webp">
+  <img src="https://tvix.dev/logo.webp">
 </div>
 
 -----------------

tvix/default.nix

@@ -58,6 +58,16 @@ in
     ${depot.tools.depotfmt}/bin/depotfmt Cargo.nix
   '';
 
+  # Provide the Tvix logo in both .webp and .png format.
+  logo = pkgs.runCommand "logo"
+    {
+      nativeBuildInputs = [ pkgs.imagemagick ];
+    } ''
+    mkdir -p $out
+    cp ${./logo.webp} $out/logo.webp
+    convert $out/logo.webp $out/logo.png
+  '';
+
   # Provide a shell for the combined dependencies of all Tvix Rust
   # projects. Note that as this is manually maintained it may be
   # lacking something, but it is required for some people's workflows.

tvix/website/default.nix

@@ -28,5 +28,5 @@ in
 pkgs.runCommand "tvix-website" { } ''
   mkdir $out
   cp ${landing} $out/index.html
-  cp ${./tvix-logo.webp} $out/tvix-logo.webp
+  cp ${depot.tvix.logo}/logo.webp $out/
 ''

tvix/website/landing-en.md

@@ -1,4 +1,4 @@
-<img class="tvl-logo" src="./tvix-logo.webp"
+<img class="tvl-logo" src="./logo.webp"
      alt="A candy bar in different shades of blue that says 'Tvix by TVL' on it">
 
 ------------------

users/tazjin/presentations/tvix-eval-2023/default.nix

@@ -47,8 +47,7 @@ stdenv.mkDerivation {
     mkdir home
     export HOME=$PWD/home
 
-    # webp images can't be included directly, need to convert to PNG
-    convert ${depot.tvix.website}/tvix-logo.webp tvix-logo.png
+    cp ${depot.tvix.logo}/logo.png tvix-logo.png
     cp ${linksQrCode} qrcode.png
 
     # As usual, TeX needs to be run twice ...