Add ability to remove default args via config (#314)

CHANGELOG.md

@@ -1,3 +1,9 @@
+## Unreleased
+
+### Added
+
+- Extend `chrome_args` to allow removal of conflicting default args. Allows for use cases which were previously blocked by defaults such as rendering WebGL images. See #314 (@walter)
+
 ## [1.16.0] - 2024-06-25
 
 ### Changed

lib/chromic_pdf.ex

@@ -278,6 +278,24 @@ defmodule ChromicPDF do
         [chrome_args: "--font-render-hinting=none"]
       end
 
+  In some cases, chromic_pdf's default args may conflict with the ones you would like to add.
+
+  E.g. `--disable-gpu`
+
+  The problem is that you can't simply override them like so:
+
+  E.g. in default args within chromic_pdf's code, `--disable-gpu` and then
+  passing `chrome_args: "--enable-gpu"` won't work.
+
+  In this case, use Keyword form of the `:chrome_args` option which
+  allows targeted removing of problematic default args so that they don't
+  disrupt your chrome configuration.
+
+      defp chromic_pdf_opts do
+        [chrome_args: [append: "--headless=new --angle=swiftshader",
+                       remove: ["--headless", "--disable-gpu"]]]
+      end
+
   The `:chrome_executable` option allows to specify a custom Chrome/Chromium executable.
 
       defp chromic_pdf_opts do

lib/chromic_pdf/pdf/chrome_runner.ex

@@ -148,13 +148,28 @@ defmodule ChromicPDF.ChromeRunner do
   defp args(extra, opts) do
     default_args()
     |> append_if("--no-sandbox", no_sandbox?(opts))
-    |> append_if(to_string(opts[:chrome_args]), !!opts[:chrome_args])
+    |> apply_chrome_args(opts[:chrome_args])
     |> Kernel.++(List.wrap(extra))
     |> append_if("2>/dev/null 3<&0 4>&1", discard_stderr?(opts))
   end
 
   defp append_if(list, _value, false), do: list
-  defp append_if(list, value, true), do: list ++ [value]
+  defp append_if(list, value, true), do: list ++ List.wrap(value)
+
+  defp apply_chrome_args(list, nil), do: list
+
+  defp apply_chrome_args(list, chrome_args) when is_binary(chrome_args) do
+    append_if(list, chrome_args, true)
+  end
+
+  defp apply_chrome_args(list, extended) when is_list(extended) do
+    conflicting = List.wrap(Keyword.get(extended, :remove, []))
+    append = List.wrap(Keyword.get(extended, :append, []))
+
+    list
+    |> Enum.reject(&Enum.member?(conflicting, &1))
+    |> append_if(append, true)
+  end
 
   defp no_sandbox?(opts), do: Keyword.get(opts, :no_sandbox, false)
   defp discard_stderr?(opts), do: Keyword.get(opts, :discard_stderr, true)

lib/chromic_pdf/supervisor.ex

@@ -220,13 +220,17 @@ defmodule ChromicPDF.Supervisor do
 
       @type ghostscript_pool_option :: {:size, non_neg_integer()}
 
+      @type extended_chrome_args :: [
+              {:append, binary() | [binary()]} | {:remove, binary() | [binary()]}
+            ]
+
       @typedoc """
       These options apply to local Chrome instances only.
       """
       @type local_chrome_option ::
               {:no_sandbox, boolean()}
               | {:discard_stderr, boolean()}
-              | {:chrome_args, binary()}
+              | {:chrome_args, binary() | extended_chrome_args()}
               | {:chrome_executable, binary()}
 
       @typedoc """