Function _sampleBilinearCommon

source/backend/cpu/compute/ImageProcessFunction.cpp:743–777

}

static void _sampleBilinearCommon(const unsigned char* source, unsigned char* dest, MNN::CV::Point* points, size_t count,
                                  size_t iw, size_t ih, size_t yStride, size_t bpp) {
    float dy   = points[1].fY;
    float dx   = points[1].fX;
    float xMax = iw - 1;
    float yMax = ih - 1;

    MNN::CV::Point curPoints;
    curPoints.fX = points[0].fX;
    curPoints.fY = points[0].fY;
    for (int i = 0; i < count; ++i) {
        float y  = __clamp(curPoints.fY, 0, yMax);
        float x  = __clamp(curPoints.fX, 0, xMax);
        int y0   = (int)y;
        int x0   = (int)x;
        int y1   = (int)ceilf(y);
        int x1   = (int)ceilf(x);
        float xF = x - (float)x0;
        float yF = y - (float)y0;

        for (int b = 0; b < bpp; ++b) {
            unsigned char c00 = source[y0 * yStride + bpp * x0 + b];
            unsigned char c01 = source[y0 * yStride + bpp * x1 + b];
            unsigned char c10 = source[y1 * yStride + bpp * x0 + b];
            unsigned char c11 = source[y1 * yStride + bpp * x1 + b];

            float v =
                (1.0f - xF) * (1.0f - yF) * c00 + xF * (1.0f - yF) * c01 + yF * (1.0 - xF) * c10 + xF * yF * (c11);
            v                 = std::min(std::max(v, 0.0f), 255.0f);
            dest[bpp * i + b] = (unsigned char)roundf(v);
        }
        curPoints.fY += dy;
        curPoints.fX += dx;
    }
}

void MNNSamplerC4Bilinear(const unsigned char* source, unsigned char* dest, MNN::CV::Point* points, size_t sta,
                          size_t count, size_t capacity, size_t iw, size_t ih, size_t yStride) {