damageRing: move to hyprland impl

A small wlroots utility we were still using.

src/helpers/DamageRing.cpp

@@ -0,0 +1,52 @@
+#include "DamageRing.hpp"
+
+void CDamageRing::setSize(const Vector2D& size_) {
+    if (size_ == size)
+        return;
+
+    size = size_;
+
+    damageEntire();
+}
+
+bool CDamageRing::damage(const CRegion& rg) {
+    CRegion clipped = rg.copy().intersect(CBox{{}, size});
+    if (clipped.empty())
+        return false;
+
+    current.add(clipped);
+    return true;
+}
+
+void CDamageRing::damageEntire() {
+    damage(CBox{{}, size});
+}
+
+void CDamageRing::rotate() {
+    previousIdx = (previousIdx + DAMAGE_RING_PREVIOUS_LEN - 1) % DAMAGE_RING_PREVIOUS_LEN;
+
+    previous[previousIdx] = current;
+    current.clear();
+}
+
+CRegion CDamageRing::getBufferDamage(int age) {
+    if (age <= 0 || age > DAMAGE_RING_PREVIOUS_LEN + 1)
+        return CBox{{}, size};
+
+    CRegion damage = current;
+
+    for (int i = 0; i < age - 1; ++i) {
+        int j = (previousIdx + i) % DAMAGE_RING_PREVIOUS_LEN;
+        damage.add(previous.at(j));
+    }
+
+    // don't return a ludicrous amount of rects
+    if (damage.getRects().size() > 8)
+        return damage.getExtents();
+
+    return damage;
+}
+
+bool CDamageRing::hasChanged() {
+    return !current.empty();
+}