1 files changed, 76 insertions, 0 deletions
diff --git a/libs/ui/include/ui/StretchEffect.h b/libs/ui/include/ui/StretchEffect.h
new file mode 100644
index 0000000000..cf08acb359
--- /dev/null
+++ b/libs/ui/include/ui/StretchEffect.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <utils/Flattenable.h>
+#include "FloatRect.h"
+
+#include <math.h>
+#include <type_traits>
+
+namespace android {
+
+struct StretchEffect : public LightFlattenablePod<StretchEffect> {
+  constexpr static const float CONTENT_DISTANCE_STRETCHED = 1.f;
+
+  float width = 0;
+  float height = 0;
+  float vectorX = 0;
+  float vectorY = 0;
+  float maxAmountX = 0;
+  float maxAmountY = 0;
+  FloatRect mappedChildBounds = {0, 0, 0, 0};
+
+  bool operator==(const StretchEffect& other) const {
+    return width == other.width && height == other.height &&
+        vectorX == other.vectorX &&
+        vectorY == other.vectorY &&
+        maxAmountX == other.maxAmountX &&
+        maxAmountY == other.maxAmountY &&
+        mappedChildBounds == other.mappedChildBounds;
+  }
+
+  static bool isZero(float value) {
+    constexpr float NON_ZERO_EPSILON = 0.001f;
+    return fabsf(value) <= NON_ZERO_EPSILON;
+  }
+
+  bool isNoOp() const { return isZero(vectorX) && isZero(vectorY); }
+
+  bool hasEffect() const { return !isNoOp(); }
+
+  void sanitize() {
+    // If the area is empty, or the max amount is zero, then reset back to defaults
+    if (width == 0.f || height == 0.f || isZero(maxAmountX) ||
+        isZero(maxAmountY)) {
+      *this = StretchEffect{};
+    }
+  }
+
+  float getStretchWidthMultiplier() const {
+      return CONTENT_DISTANCE_STRETCHED / (1.f + abs(vectorX));
+  }
+
+  float getStretchHeightMultiplier() const {
+      return CONTENT_DISTANCE_STRETCHED / (1.f + abs(vectorY));
+  }
+};
+
+static_assert(std::is_trivially_copyable<StretchEffect>::value,
+              "StretchEffect must be trivially copyable to be flattenable");
+
+} // namespace android
+\ No newline at end of file