Add a frame generator that allows scrolling images

webrtc/video/screenshare_loopback.cc

Index: webrtc/video/screenshare_loopback.cc
diff --git a/webrtc/video/screenshare_loopback.cc b/webrtc/video/screenshare_loopback.cc
index f2133a211b8a947fbcecb543c103561e3cdef8cd..a3084249811d8b205a8ef96ed748c529eebdfc0f 100644
--- a/webrtc/video/screenshare_loopback.cc
+++ b/webrtc/video/screenshare_loopback.cc
@@ -15,6 +15,7 @@
 #include "gflags/gflags.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+#include "webrtc/base/checks.h"
 #include "webrtc/test/field_trial.h"
 #include "webrtc/test/frame_generator.h"
 #include "webrtc/test/frame_generator_capturer.h"
@@ -27,12 +28,14 @@
 namespace webrtc {
 namespace flags {
 
-// Fixed for prerecorded screenshare content.
+DEFINE_int32(width, 1850, "Video width (crops source).");
 size_t Width() {
-  return 1850;
+  return static_cast<size_t>(FLAGS_width);
 }
+
+DEFINE_int32(height, 1110, "Video height (crops source).");
 size_t Height() {
-  return 1110;
+  return static_cast<size_t>(FLAGS_height);
 }
 
 DEFINE_int32(fps, 5, "Frames per second.");
@@ -40,6 +43,21 @@ int Fps() {
   return static_cast<int>(FLAGS_fps);
 }
 
+DEFINE_int32(slide_change_interval,
+             10,
+             "Interval (in seconds) between simulated slide changes.");
+int SlideChangeInterval() {
+  return static_cast<int>(FLAGS_slide_change_interval);
+}
+
+DEFINE_int32(
+    scroll_duration,
+    0,
+    "Duration (in seconds) during which a slide will be scrolled into place.");
+int ScrollDuration() {
+  return static_cast<int>(FLAGS_scroll_duration);
+}
+
 DEFINE_int32(min_bitrate, 50, "Minimum video bitrate.");
 size_t MinBitrate() {
   return static_cast<size_t>(FLAGS_min_bitrate);
@@ -138,9 +156,21 @@ class ScreenshareLoopback : public test::Loopback {
     slides.push_back(test::ResourcePath("photo_1850_1110", "yuv"));
     slides.push_back(test::ResourcePath("difficult_photo_1850_1110", "yuv"));
 
+    // Fixed for input resolution for prerecorded screenshare content.
+    const size_t kWidth = 1850;
+    const size_t kHeight = 1110;
+    CHECK_LE(flags::Width(), kWidth);
+    CHECK_LE(flags::Height(), kHeight);
+    CHECK_GT(flags::SlideChangeInterval(), 0);
+    const int kPauseDurationMs =
+        (flags::SlideChangeInterval() - flags::ScrollDuration()) * 1000;
+    CHECK_LE(flags::ScrollDuration(), flags::SlideChangeInterval());
+
     test::FrameGenerator* frame_generator =
-        test::FrameGenerator::CreateFromYuvFile(
-            slides, flags::Width(), flags::Height(), 10 * flags::Fps());
+        test::FrameGenerator::CreateScrollingInputFromYuvFiles(
+            Clock::GetRealTimeClock(), slides, kWidth, kHeight, flags::Width(),
+            flags::Height(), flags::ScrollDuration() * 1000, kPauseDurationMs);
+
     test::FrameGeneratorCapturer* capturer(new test::FrameGeneratorCapturer(
         clock_, send_stream->Input(), frame_generator, flags::Fps()));
     EXPECT_TRUE(capturer->Init());