libs/ui/include/ui/StretchEffect.h

/*
 * 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> {
    FloatRect area = {0, 0, 0, 0};
    float vectorX = 0;
    float vectorY = 0;
    float maxAmount = 0;

    bool operator==(const StretchEffect& other) const {
        return area == other.area && vectorX == other.vectorX && vectorY == other.vectorY &&
                maxAmount == other.maxAmount;
    }

    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 (area.isEmpty() || isZero(maxAmount)) {
            *this = StretchEffect{};
        }
    }
};

static_assert(std::is_trivially_copyable<StretchEffect>::value,
              "StretchEffect must be trivially copyable to be flattenable");

} // namespace android