[feisty2]

I wrote some syntactic sugar stuff for the C++ API here: https://github.com/IFeelBloated/vapo...ster/sugar.hpp
C++2a support is required (I'm 100% sure C++17 aint cuttin' it), it compiles with "-std=c++2a" for GCC10

you can use

auto MakePlane(auto Pointer, auto Width, auto Height, auto PaddingPolicy)

to access the plane in a 2-dimensional style, out-of-bound access (automatic padding) is allowed for the source plane, but not allowed for the destination plane.

I'll give you a concrete example, to write a 3x3 box blur, you would do the following:

auto srcp = reinterpret_cast<const float *>(srcp8);
auto dstp = reinterpret_cast<float *>(dstp8);

auto padded_src = reinterpret_cast<float *>(malloc((width+2) * (height+2) * sizeof(float)));
for (auto y : Range{ height })
     std::memcpy(padded_src + (y+1) * (width+2) + 1, srcp + y * width, width * sizeof(float));

// lots of code here to deal with padding for "padded_src"

auto gc_addr = padded_src;
padded_src += (width + 2) + 1;

for (auto y : Range{ height })
     for (auto x : Range{ width }) {
             auto above = padded_src - (width + 2);
             auto below = padded_src + (width + 2);
             dstp[x] = (above[x-1] + above[x] + above[x+1] + padded_src[x-1] + padded_src[x] + padded_src[x+1] + below[x-1] + below[x] + below[x+1]) / 9;
             dstp += width;
             padded_src += width + 2;
     }

free(gc_addr);

with "sugar.hpp", that huge pile of nuisance is equivalent to simply

auto srcp = MakePlane<const float>(srcp8, width, height, Repeat);
auto dstp = MakePlane<float>(dstp8, width, height, Zero);

for (auto y : Range{ height })
     for (auto x : Range{ width })
             dstp[y][x] = (srcp[y-1][x-1] + srcp[y-1][x] + srcp[y-1][x+1] + srcp[y][x-1] + srcp[y][x] + srcp[y][x+1] + srcp[y+1][x-1] + srcp[y+1][x] + srcp[y+1][x+1]) / 9;
             // possible out-of-bound access like "srcp[y-1][x-1]" is automatically handled here with the given padding policy, you got nothing to worry about

The header includes 3 pre-defined padding policies

Zero
Repeat (or simply called "pad" on this forum)
Reflect

however, you can also define your own padding policy by completing the following function and pass it to "MakePlane()"

auto PaddingFunction = [](auto Canvas, auto Width, auto Height, auto y, auto x) {
      ...
};

note that the "PaddingPolicy" argument has no effect on "dstp" as no padding is applied here.

you are welcome to leave a comment if you have any suggestions or ideas to further improve this.