Added few methods to subtitle plugin

Author: sandeep-vedam

src/Subtitles/index.js

@@ -81,6 +81,22 @@ export default {
     subtitles.viewportW = w
     subtitles.viewportH = h
   },
+  viewportW(w) {
+    const subtitles = getOrCreateSubtitlesComponent()
+    subtitles.viewportW = w
+  },
+  viewportH(h) {
+    const subtitles = getOrCreateSubtitlesComponent()
+    subtitles.viewportH = h
+  },
+  xPos(v) {
+    const subtitles = getOrCreateSubtitlesComponent()
+    subtitles.xPos = v
+  },
+  yPos(v) {
+    const subtitles = getOrCreateSubtitlesComponent()
+    subtitles.yPos = v
+  },
   position(x, y) {
     const subtitles = getOrCreateSubtitlesComponent()
     subtitles.xPos = x