Added a small command to set the volume of the master gain in the audio mixer.

git-svn-id: file:///srv/svn/repos/haiku/trunk/current@10592 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/apps/bin/Jamfile

@@ -77,6 +77,7 @@ StdBinCommands
 # standard commands that need libbe.so, libmedia.so
 StdBinCommands
 	installsound.cpp
+	setvolume.cpp
 	: be libmedia.so
 	;
 

src/apps/bin/setvolume.cpp

@@ -0,0 +1,93 @@
+/*
+ * Copyright 2005, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include <Application.h>
+#include <MediaRoster.h>
+#include <ParameterWeb.h>
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+
+extern const char *__progname;
+static const char *sProgramName = __progname;
+
+
+int
+main(int argc, char **argv)
+{
+	BApplication app("application/x-vnd.haiku.setvolume");
+
+	BMediaRoster *roster = BMediaRoster::Roster();
+	if (roster == NULL) {
+		fprintf(stderr, "%s: media roster not available\n", sProgramName);
+		return 1;
+	}
+
+	media_node mixer;
+	status_t status = roster->GetAudioMixer(&mixer);
+	if (status != B_OK) {
+		fprintf(stderr, "%s: cannot get audio mixer: %s\n", sProgramName, strerror(status));
+		return 1;
+	}
+
+	BParameterWeb *web;
+	status = roster->GetParameterWebFor(mixer, &web);
+
+	roster->ReleaseNode(mixer);
+		// the web is all we need :-)
+
+	if (status != B_OK) {
+		fprintf(stderr, "%s: cannot get parameter web for audio mixer: %s\n",
+			sProgramName, strerror(status));
+		return 1;
+	}
+
+	BContinuousParameter *gain = NULL;
+
+	BParameter *parameter;
+	for (int32 index = 0; (parameter = web->ParameterAt(index)) != NULL; index++) {
+		if (!strcmp(parameter->Kind(), B_MASTER_GAIN)) {
+			gain = dynamic_cast<BContinuousParameter *>(parameter);
+			break;
+		}
+	}
+
+	if (gain == NULL) {
+		fprintf(stderr, "%s: could not found master gain!\n", sProgramName);
+		delete web;
+		return 1;
+	}
+
+	float volume = 0.0;
+
+	if (argc > 1) {
+		char *end;
+		volume = strtod(argv[1], &end);
+		if (end == argv[1]) {
+			fprintf(stderr, "usage: %s <volume>\n", sProgramName);
+		} else {
+			// make sure our parameter is in range
+			if (volume > gain->MaxValue())
+				volume = gain->MaxValue();
+			else if (volume < gain->MinValue())
+				volume = gain->MinValue();
+
+			gain->SetValue(&volume, sizeof(volume), system_time());
+		}
+	}
+
+	bigtime_t when;
+	size_t size = sizeof(volume);
+	gain->GetValue(&volume, &size, &when);
+
+	printf("Current volume: %g (min = %g, max = %g)\n", volume, gain->MinValue(), gain->MaxValue());
+
+	delete web;
+	return 0;
+}
+