Add ability to remove default args via config

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 +278,26 @@ 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
+
+  _Note: `:append` expects a string whereas `:remove` expects a list._
+
   The `:chrome_executable` option allows to specify a custom Chrome/Chromium executable.
 
       defp chromic_pdf_opts do

lib/chromic_pdf/pdf/chrome_runner.ex

@@ -147,15 +147,37 @@ defmodule ChromicPDF.ChromeRunner do
   # https://github.com/bitcrowd/chromic_pdf/issues/76
   defp args(extra, opts) do
     default_args()
+    |> remove_conflicting_args(opts[:chrome_args])
     |> append_if("--no-sandbox", no_sandbox?(opts))
-    |> append_if(to_string(opts[:chrome_args]), !!opts[:chrome_args])
+    |> append_chrome_args_if(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_chrome_args_if(list, ""), do: list
+
+  defp append_chrome_args_if(list, chrome_args) when is_binary(chrome_args) do
+    append_if(list, chrome_args, true)
+  end
+
+  defp append_chrome_args_if(list, [{_, _} | _] = chrome_args) do
+    append = Keyword.get(chrome_args, :append)
+
+    append_if(list, append, !!append)
+  end
+
+  defp append_chrome_args_if(list, _), do: list
+
   defp no_sandbox?(opts), do: Keyword.get(opts, :no_sandbox, false)
   defp discard_stderr?(opts), do: Keyword.get(opts, :discard_stderr, true)
+
+  defp remove_conflicting_args(defaults, [{_, _} | _] = chrome_args) do
+    conflicting = Keyword.get(chrome_args, :remove, [])
+    Enum.reject(defaults, &Enum.member?(conflicting, &1))
+  end
+
+  defp remove_conflicting_args(defaults, _), do: defaults
 end

lib/chromic_pdf/supervisor.ex

@@ -226,7 +226,7 @@ defmodule ChromicPDF.Supervisor do
       @type local_chrome_option ::
               {:no_sandbox, boolean()}
               | {:discard_stderr, boolean()}
-              | {:chrome_args, binary()}
+              | {:chrome_args, binary() | map()}
               | {:chrome_executable, binary()}
 
       @typedoc """