SkBackingFit.cpp

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/*
 * Copyright 2023 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#include "src/gpu/SkBackingFit.h"
 
#include "include/private/base/SkMath.h"
#include "src/base/SkMathPriv.h"
 
#include <algorithm>
 
namespace skgpu {
 
SkISize GetApproxSize(SkISize size) {
    // Map 'value' to a larger multiple of 2. Values <= 'kMagicTol' will pop up to
    // the next power of 2. Those above 'kMagicTol' will only go up half the floor power of 2.
    auto adjust = [](int value) {
        constexpr int kMinApproxSize = 16;
        constexpr int kMagicTol = 1024;
 
        value = std::max(kMinApproxSize, value);
 
        if (SkIsPow2(value)) {
            return value;
        }
 
        int ceilPow2 = SkNextPow2(value);
        if (value <= kMagicTol) {
            return ceilPow2;
        }
 
        int floorPow2 = ceilPow2 >> 1;
        int mid = floorPow2 + (floorPow2 >> 1);
 
        if (value <= mid) {
            return mid;
        }
        return ceilPow2;
    };
 
    return {adjust(size.width()), adjust(size.height())};
}
 
}  // namespace skgpu