Add Support for ALD Option

Implement Parsing of (yes|no) options and add --ald to the command builder
of scanimage. The feature is to turn on scanning when the automatic document
feeder detects the start of the page.

--ald[=(yes|no)] [no] [advanced]'
     Scanner detects paper lower edge. May confuse some frontends.'

packages/server/src/classes/feature.js

@@ -36,6 +36,14 @@ module.exports = class Feature {
     this.interval = steps ? Number(steps[1]) : 1;
   }
 
+  asEnum() {
+    // Example: [=(yes|no)]
+    const match = /^\[=\((.*)\)\]$/.exec(this.parameters);
+    if (match !== null) {
+      this.options = match[1].split('|');
+    }
+  }
+
   asResolution() {
     if (this.parameters.indexOf('|') > -1) {
       this.options = splitNumbers(this.parameters, '|');
@@ -97,6 +105,10 @@ module.exports = class Feature {
         case '--contrast':
           this.asLighting();
           break;
+
+        case '--ald':
+          this.asEnum();
+          break;
       }
     }
   }

packages/server/src/classes/request.js

@@ -98,6 +98,10 @@ module.exports = class Request {
         ? data.params.dynamicLineart
         : true;
     }
+    if ('--ald' in features) {
+      this.params.ald = data.params.ald || features['--ald'].default;
+      assertContains(features['--ald'].options, this.params.ald, 'Invalid --ald');
+    }
 
     log.trace(LogFormatter.format().full(this));
   }

packages/server/src/classes/scanimage-command.js

@@ -108,6 +108,9 @@ module.exports = class ScanimageCommand {
 
     cmdBuilder.arg('--format', params.format);
 
+    if ('ald' in params) {
+      cmdBuilder.arg(`--ald=${params.ald}`);
+    }
     if ('depth' in params) {
       cmdBuilder.arg('--depth', params.depth);
     }

packages/server/src/swagger.yml

@@ -572,6 +572,9 @@ definitions:
       dynamicLineart:
         type: boolean
         example: false
+      ald:
+        type: string
+        example: 'yes'
     required:
       - deviceId
       - resolution