api: get_streams (#886)

## Link to GitHub Issue or related Pull Request, if one exists
#0

## Description of change
MSE method of streaming video needs the dimensions up front. This new
api delivers that. Also provides an easier way to determine which
screens are available and a way to discover port number.

## Testing
See pending changes in substream project

src/spice2x/api/resources/dart/spiceapi-websocket/spiceapi.dart

@@ -11,6 +11,7 @@ part "src/exceptions.dart";
 part "src/rc4.dart";
 part "src/wrappers/analogs.dart";
 part "src/wrappers/buttons.dart";
+part "src/wrappers/capture.dart";
 part "src/wrappers/card.dart";
 part "src/wrappers/coin.dart";
 part "src/wrappers/control.dart";

src/spice2x/api/resources/dart/spiceapi-websocket/src/connection.dart

@@ -4,8 +4,8 @@ part of spiceapi;
 class Connection {
 
   // settings
-  static const _TIMEOUT = Duration(seconds: 2);
-  static const _BUFFER_SIZE = 1024 * 8;
+  static const _TIMEOUT = Duration(seconds: 3);
+  static const _BUFFER_SIZE = 1024 * 1024 * 8;
 
   // state
   final String host, pass;

src/spice2x/api/resources/dart/spiceapi-websocket/src/wrappers/capture.dart

@@ -0,0 +1,47 @@
+part of spiceapi;
+
+class CaptureData {
+  int timestamp;
+  int width, height;
+  Uint8List data;
+}
+
+var _base64DecoderInstance = Base64Decoder();
+
+Future<List> captureGetScreens(Connection con) {
+  var req = Request("capture", "get_screens");
+  return con.request(req).then((res) {
+    return res.getData();
+  });
+}
+
+Future<CaptureData> captureGetJPG(Connection con, {
+  int screen = 0,
+  int quality = 70,
+  int divide = 1,
+}) {
+  var req = Request("capture", "get_jpg");
+  req.addParam(screen);
+  req.addParam(quality);
+  req.addParam(divide);
+  return con.request(req).then((res) {
+    var captureData = CaptureData();
+    var data = res.getData();
+    if (data.length > 0) captureData.timestamp = data[0];
+    if (data.length > 1) captureData.width = data[1];
+    if (data.length > 2) captureData.height = data[2];
+    if (data.length > 3) {
+      captureData.data = _base64DecoderInstance.convert(data[3]);
+    }
+    return captureData;
+  });
+}
+
+/// Describes the HTTP video stream, or null when this spice2x serves none.
+Future<Map> captureGetStreams(Connection con) {
+  var req = Request("capture", "get_streams");
+  return con.request(req).then((res) {
+    var data = res.getData();
+    return data.length > 0 ? data[0] : null;
+  });
+}

src/spice2x/api/resources/dart/spiceapi/src/wrappers/capture.dart

@@ -17,7 +17,7 @@ Future<List> captureGetScreens(Connection con) {
 
 Future<CaptureData> captureGetJPG(Connection con, {
   int screen = 0,
-  int quality = 60,
+  int quality = 70,
   int divide = 1,
 }) {
   var req = Request("capture", "get_jpg");
@@ -36,3 +36,12 @@ Future<CaptureData> captureGetJPG(Connection con, {
     return captureData;
   });
 }
+
+/// Describes the HTTP video stream, or null when this spice2x serves none.
+Future<Map> captureGetStreams(Connection con) {
+  var req = Request("capture", "get_streams");
+  return con.request(req).then((res) {
+    var data = res.getData();
+    return data.length > 0 ? data[0] : null;
+  });
+}