Add a scrolling frame generator and use it in loopback test

webrtc/test/frame_generator.cc

Index: webrtc/test/frame_generator.cc
diff --git a/webrtc/test/frame_generator.cc b/webrtc/test/frame_generator.cc
index 55e5a41548a5192361f090a8d20dc906eba8f60c..9a14ff14d75f6156b4d98055491d25e70cc90f60 100644
--- a/webrtc/test/frame_generator.cc
+++ b/webrtc/test/frame_generator.cc
@@ -15,6 +15,7 @@
 
 #include "webrtc/base/checks.h"
 #include "webrtc/common_video/libyuv/include/webrtc_libyuv.h"
+#include "webrtc/system_wrappers/interface/clock.h"
 
 namespace webrtc {
 namespace test {
@@ -126,6 +127,108 @@ class YuvFileGenerator : public FrameGenerator {
   VideoFrame last_read_frame_;
   VideoFrame temp_frame_copy_;
 };
+
+class ScrollingImageFrameGenerator : public FrameGenerator {
+ public:
+  ScrollingImageFrameGenerator(Clock* clock,
+                               const std::vector<FILE*>& files,
+                               size_t source_width,
+                               size_t source_height,
+                               size_t target_width,
+                               size_t target_height,
+                               int64_t scroll_time_ms,
+                               int64_t pause_time_ms)
+      : clock_(clock),
+        start_time_(clock->TimeInMilliseconds()),
+        scroll_time_(scroll_time_ms),
+        pause_time_(pause_time_ms),
+        num_frames_(files.size()),
+        current_frame_num_(num_frames_ - 1),
+        current_source_frame_(nullptr),
+        file_generator_(files, source_width, source_height, 1) {
+    DCHECK(clock_ != nullptr);
+    DCHECK_GT(num_frames_, 0u);
+    DCHECK_GE(source_height, target_height);
+    DCHECK_GE(source_width, target_width);
+    DCHECK_GE(scroll_time_ms, 0);
+    DCHECK_GE(pause_time_ms, 0);
+    DCHECK_GT(scroll_time_ms + pause_time_ms, 0);
+    current_frame_.CreateEmptyFrame(target_width, target_height, target_width,
+                                    (target_width + 1) / 2,
+                                    (target_width + 1) / 2);
+  }
+
+  virtual ~ScrollingImageFrameGenerator() {}
+
+  VideoFrame* NextFrame() override {
+    const int64_t kFrameDisplayTime = scroll_time_ + pause_time_;
+    const int64_t now = clock_->TimeInMilliseconds();
+    int64_t ms_since_start = now - start_time_;
+
+    size_t frame_num = (ms_since_start / kFrameDisplayTime) % num_frames_;
+    UpdateSourceFrame(frame_num);
+
+    double scroll_factor;
+    int64_t time_into_frame = ms_since_start % kFrameDisplayTime;
+    if (time_into_frame < scroll_time_) {
+      scroll_factor = static_cast<double>(time_into_frame) / scroll_time_;
+    } else {
+      scroll_factor = 1.0;
+    }
+    CropSourceToScrolledImage(scroll_factor);
+
+    return &current_frame_;
+  }
+
+  void UpdateSourceFrame(size_t frame_num) {
+    while (current_frame_num_ != frame_num) {
+      current_source_frame_ = file_generator_.NextFrame();
+      current_frame_num_ = (current_frame_num_ + 1) % num_frames_;
+    }
+    DCHECK(current_source_frame_ != nullptr);
+  }
+
+  void CropSourceToScrolledImage(double scroll_factor) {
+    const int kTargetWidth = current_frame_.width();
+    const int kTargetHeight = current_frame_.height();
+    int scroll_margin_x = current_source_frame_->width() - kTargetWidth;
+    int pixels_scrolled_x =
+        static_cast<int>(scroll_margin_x * scroll_factor + 0.5);
+    int scroll_margin_y = current_source_frame_->height() - kTargetHeight;
+    int pixels_scrolled_y =
+        static_cast<int>(scroll_margin_y * scroll_factor + 0.5);
+
+    int offset_y = (current_source_frame_->stride(PlaneType::kYPlane) *
+                    pixels_scrolled_y) +
+                   pixels_scrolled_x;
+    int offset_u = (current_source_frame_->stride(PlaneType::kUPlane) *
+                    (pixels_scrolled_y / 2)) +
+                   (pixels_scrolled_x / 2);
+    int offset_v = (current_source_frame_->stride(PlaneType::kVPlane) *
+                    (pixels_scrolled_y / 2)) +
+                   (pixels_scrolled_x / 2);
+
+    current_frame_.CreateFrame(
+        &current_source_frame_->buffer(PlaneType::kYPlane)[offset_y],
+        &current_source_frame_->buffer(PlaneType::kUPlane)[offset_u],
+        &current_source_frame_->buffer(PlaneType::kVPlane)[offset_v],
+        kTargetWidth, kTargetHeight,
+        current_source_frame_->stride(PlaneType::kYPlane),
+        current_source_frame_->stride(PlaneType::kUPlane),
+        current_source_frame_->stride(PlaneType::kVPlane));
+  }
+
+  Clock* const clock_;
+  const int64_t start_time_;
+  const int64_t scroll_time_;
+  const int64_t pause_time_;
+  const size_t num_frames_;
+  size_t current_frame_num_;
+  VideoFrame* current_source_frame_;
+  VideoFrame current_frame_;
+  YuvFileGenerator file_generator_;
+};
+
 }  // namespace
 
 FrameGenerator* FrameGenerator::CreateChromaGenerator(size_t width,
@@ -149,5 +252,27 @@ FrameGenerator* FrameGenerator::CreateFromYuvFile(
   return new YuvFileGenerator(files, width, height, frame_repeat_count);
 }
 
+FrameGenerator* FrameGenerator::CreateScrollingInputFromYuvFiles(
+    Clock* clock,
+    std::vector<std::string> filenames,
+    size_t source_width,
+    size_t source_height,
+    size_t target_width,
+    size_t target_height,
+    int64_t scroll_time_ms,
+    int64_t pause_time_ms) {
+  assert(!filenames.empty());
+  std::vector<FILE*> files;
+  for (const std::string& filename : filenames) {
+    FILE* file = fopen(filename.c_str(), "rb");
+    DCHECK(file != nullptr);
+    files.push_back(file);
+  }
+
+  return new ScrollingImageFrameGenerator(
+      clock, files, source_width, source_height, target_width, target_height,
+      scroll_time_ms, pause_time_ms);
+}
+
 }  // namespace test
 }  // namespace webrtc