Remove differ from ScreenCapturer implementations

webrtc/modules/desktop_capture/differ.cc

-/*
- *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
- *
- *  Use of this source code is governed by a BSD-style license
- *  that can be found in the LICENSE file in the root of the source
- *  tree. An additional intellectual property rights grant can be found
- *  in the file PATENTS.  All contributing project authors may
- *  be found in the AUTHORS file in the root of the source tree.
- */
-
-#include "webrtc/modules/desktop_capture/differ.h"
-
-#include "string.h"
-
-#include "webrtc/modules/desktop_capture/differ_block.h"
-#include "webrtc/system_wrappers/include/logging.h"
-
-namespace webrtc {
-
-Differ::Differ(int width, int height, int bpp, int stride) {
-  // Dimensions of screen.
-  width_ = width;
-  height_ = height;
-  bytes_per_pixel_ = bpp;
-  bytes_per_row_ = stride;
-
-  // Calc number of blocks (full and partial) required to cover entire image.
-  // One additional row/column is added as a boundary on the right & bottom.
-  diff_info_width_ = ((width_ + kBlockSize - 1) / kBlockSize) + 1;
-  diff_info_height_ = ((height_ + kBlockSize - 1) / kBlockSize) + 1;
-  diff_info_size_ = diff_info_width_ * diff_info_height_ * sizeof(bool);
-  diff_info_.reset(new bool[diff_info_size_]);
-}
-
-Differ::~Differ() {}
-
-void Differ::CalcDirtyRegion(const uint8_t* prev_buffer,
-                             const uint8_t* curr_buffer,
-                             DesktopRegion* region) {
-  // Identify all the blocks that contain changed pixels.
-  MarkDirtyBlocks(prev_buffer, curr_buffer);
-
-  // Now that we've identified the blocks that have changed, merge adjacent
-  // blocks to minimize the number of rects that we return.
-  MergeBlocks(region);
-}
-
-void Differ::MarkDirtyBlocks(const uint8_t* prev_buffer,
-                             const uint8_t* curr_buffer) {
-  memset(diff_info_.get(), 0, diff_info_size_);
-
-  // Calc number of full blocks.
-  int x_full_blocks = width_ / kBlockSize;
-  int y_full_blocks = height_ / kBlockSize;
-
-  // Calc size of partial blocks which may be present on right and bottom edge.
-  int partial_column_width = width_ - (x_full_blocks * kBlockSize);
-  int partial_row_height = height_ - (y_full_blocks * kBlockSize);
-
-  // Offset from the start of one block-column to the next.
-  int block_x_offset = bytes_per_pixel_ * kBlockSize;
-  // Offset from the start of one block-row to the next.
-  int block_y_stride = (width_ * bytes_per_pixel_) * kBlockSize;
-  // Offset from the start of one diff_info row to the next.
-  int diff_info_stride = diff_info_width_ * sizeof(bool);
-
-  const uint8_t* prev_block_row_start = prev_buffer;
-  const uint8_t* curr_block_row_start = curr_buffer;
-  bool* diff_info_row_start = diff_info_.get();
-
-  for (int y = 0; y < y_full_blocks; y++) {
-    const uint8_t* prev_block = prev_block_row_start;
-    const uint8_t* curr_block = curr_block_row_start;
-    bool* diff_info = diff_info_row_start;
-
-    for (int x = 0; x < x_full_blocks; x++) {
-      // Mark this block as being modified so that it gets incorporated into
-      // a dirty rect.
-      *diff_info = BlockDifference(prev_block, curr_block, bytes_per_row_);
-      prev_block += block_x_offset;
-      curr_block += block_x_offset;
-      diff_info += sizeof(bool);
-    }
-
-    // If there is a partial column at the end, handle it.
-    // This condition should rarely, if ever, occur.
-    if (partial_column_width != 0) {
-      *diff_info = !PartialBlocksEqual(prev_block, curr_block, bytes_per_row_,
-                                       partial_column_width, kBlockSize);
-      diff_info += sizeof(bool);
-    }
-
-    // Update pointers for next row.
-    prev_block_row_start += block_y_stride;
-    curr_block_row_start += block_y_stride;
-    diff_info_row_start += diff_info_stride;
-  }
-
-  // If the screen height is not a multiple of the block size, then this
-  // handles the last partial row. This situation is far more common than the
-  // 'partial column' case.
-  if (partial_row_height != 0) {
-    const uint8_t* prev_block = prev_block_row_start;
-    const uint8_t* curr_block = curr_block_row_start;
-    bool* diff_info = diff_info_row_start;
-    for (int x = 0; x < x_full_blocks; x++) {
-      *diff_info = !PartialBlocksEqual(prev_block, curr_block,
-                                       bytes_per_row_,
-                                       kBlockSize, partial_row_height);
-      prev_block += block_x_offset;
-      curr_block += block_x_offset;
-      diff_info += sizeof(bool);
-    }
-    if (partial_column_width != 0) {
-      *diff_info = !PartialBlocksEqual(prev_block, curr_block, bytes_per_row_,
-                                       partial_column_width,
-                                       partial_row_height);
-      diff_info += sizeof(bool);
-    }
-  }
-}
-
-bool Differ::PartialBlocksEqual(const uint8_t* prev_buffer,
-                                const uint8_t* curr_buffer,
-                                int stride, int width, int height) {
-  int width_bytes = width * bytes_per_pixel_;
-  for (int y = 0; y < height; y++) {
-    if (memcmp(prev_buffer, curr_buffer, width_bytes) != 0)
-      return false;
-    prev_buffer += bytes_per_row_;
-    curr_buffer += bytes_per_row_;
-  }
-  return true;
-}
-
-void Differ::MergeBlocks(DesktopRegion* region) {
-  region->Clear();
-
-  bool* diff_info_row_start = diff_info_.get();
-  int diff_info_stride = diff_info_width_ * sizeof(bool);
-
-  for (int y = 0; y < diff_info_height_; y++) {
-    bool* diff_info = diff_info_row_start;
-    for (int x = 0; x < diff_info_width_; x++) {
-      if (*diff_info) {
-        // We've found a modified block. Look at blocks to the right and below
-        // to group this block with as many others as we can.
-        int left = x * kBlockSize;
-        int top = y * kBlockSize;
-        int width = 1;
-        int height = 1;
-        *diff_info = false;
-
-        // Group with blocks to the right.
-        // We can keep looking until we find an unchanged block because we
-        // have a boundary block which is never marked as having diffs.
-        bool* right = diff_info + 1;
-        while (*right) {
-          *right++ = false;
-          width++;
-        }
-
-        // Group with blocks below.
-        // The entire width of blocks that we matched above much match for
-        // each row that we add.
-        bool* bottom = diff_info;
-        bool found_new_row;
-        do {
-          found_new_row = true;
-          bottom += diff_info_stride;
-          right = bottom;
-          for (int x2 = 0; x2 < width; x2++) {
-            if (!*right++) {
-              found_new_row = false;
-            }
-          }
-
-          if (found_new_row) {
-            height++;
-
-            // We need to go back and erase the diff markers so that we don't
-            // try to add these blocks a second time.
-            right = bottom;
-            for (int x2 = 0; x2 < width; x2++) {
-              *right++ = false;
-            }
-          }
-        } while (found_new_row);
-
-        // Add rect to list of dirty rects.
-        width *= kBlockSize;
-        if (left + width > width_) {
-          width = width_ - left;
-        }
-        height *= kBlockSize;
-        if (top + height > height_) {
-          height = height_ - top;
-        }
-        region->AddRect(DesktopRect::MakeXYWH(left, top, width, height));
-      }
-
-      // Increment to next block in this row.
-      diff_info++;
-    }
-
-    // Go to start of next row.
-    diff_info_row_start += diff_info_stride;
-  }
-}
-
-}  // namespace webrtc