1 files changed, 80 insertions, 0 deletions
diff --git a/libraries/pake/source/dirtiable-image.cpp b/libraries/pake/source/dirtiable-image.cpp
new file mode 100644
index 0000000..9e5c979
--- /dev/null
+++ b/libraries/pake/source/dirtiable-image.cpp
@@ -0,0 +1,80 @@
+#include <pake/dirtiable-image.hpp>
+
+namespace pake {
+
+  struct dirty_region_builder {
+
+    std::vector<region> regions_not_on_bottom;
+    std::list<region> regions_on_bottom;
+
+    void add_row(const std::vector<region> &row) {
+
+      std::list<region> new_regions_on_bottom;
+
+      for (auto i = row.begin(); i < row.end(); ++i) {
+        bool expanded = false;
+        for (auto j = regions_on_bottom.begin(); j != regions_on_bottom.end(); ++j)
+          if (i->start_x == j->start_x && i->width == j->width) {
+            j->height += i->height;
+            new_regions_on_bottom.push_back(*j);
+            regions_on_bottom.erase(j);
+            expanded = true;
+            break;
+          }
+        if (!expanded)
+          new_regions_on_bottom.push_back(*i);
+      }
+
+      for (auto i = regions_on_bottom.begin(); i != regions_on_bottom.end(); ++i)
+        regions_not_on_bottom.push_back(*i);
+
+      regions_on_bottom = std::move(new_regions_on_bottom);
+
+    }
+
+  };
+
+  std::vector<region> dirtiable_image::get_dirty_regions() {
+
+    dirty_region_builder builder;
+
+    std::vector<region> row;
+
+    for (int y = 0; y < dirty.height; ++y) {
+
+      int r = 0;
+      for (int x = 0; x < dirty.width; ++x)
+        if (!dirty.at(x, y)) {
+          if (r != x)
+            row.push_back({
+              .start_x = r, .start_y = y,
+              .width = x - r, .height = 1
+            });
+          r = x + 1;
+        }
+      if (r != dirty.width)
+        row.push_back({
+          .start_x = r, .start_y = y,
+          .width = dirty.width - r, .height = 1
+        });
+
+      builder.add_row(row);
+      row.clear();
+
+    }
+
+    builder.add_row(row);
+    return builder.regions_not_on_bottom;
+
+  }
+
+  void dirtiable_image::clear_dirty() {
+    dirty.fill(false);
+  }
+
+  dirtiable_image::dirtiable_image(int width, int height)
+  : image(width, height), dirty(width, height) {
+    dirty.fill(false);
+  }
+
+}