screen sharing: fix limited screen sharing offset on win32

- Offset isn't passed the same ways for gdigrab and x11grab

Change-Id: I5b48e8c40ff7f60e5d8e875835330d7b225a7175
Tuleap: #319

src/media/media_decoder.cpp

@@ -77,6 +77,10 @@ int MediaDecoder::openInput(const DeviceParams& params)
     if (params.framerate)
         av_dict_set(&options_, "framerate", ring::to_string(params.framerate.real()).c_str(), 0);
 #endif
+    if (params.offset_x || params.offset_y) {
+        av_dict_set(&options_, "offset_x", ring::to_string(params.offset_x).c_str(), 0);
+        av_dict_set(&options_, "offset_y", ring::to_string(params.offset_y).c_str(), 0);
+    }
     if (params.channel)
         av_dict_set(&options_, "channel", ring::to_string(params.channel).c_str(), 0);
     av_dict_set(&options_, "loop", params.loop.c_str(), 0);

src/media/media_device.h

@@ -40,6 +40,8 @@ struct DeviceParams {
     unsigned channel {}; // Channel number
     std::string loop {};
     std::string sdp_flags {};
+    unsigned offset_x {};
+    unsigned offset_y {};
 };
 
 }

src/media/video/video_input.cpp

@@ -245,6 +245,10 @@ VideoInput::initGdiGrab(std::string params)
         iss >> w >> sep >> h;
         decOpts_.width = round2pow(w, 3);
         decOpts_.height = round2pow(h, 3);
+
+        size_t plus = params.find('+');
+        std::istringstream dss(params.substr(plus + 1, space - plus));
+        dss >> decOpts_.offset_x >> sep >> decOpts_.offset_y;
     } else {
         decOpts_.width = default_grab_width;
         decOpts_.height = default_grab_height;