plotting - How to draw grid lines on top of a plot?

I want to use ArrayPlot instead of a DensityPlot because it seems to be faster (more here) I still want axes ticks to have real values and not array index.

I came up with following code which basically centers and scales ArrayPlot according to PlotRange given to Graphics:

arrayPlot[data_, opts___] := 
  Module[{dim = Dimensions[data] // N, rls, range, imgSz, aRatio, 
    cf},

   rls = {opts}~
     Join~{PlotRange -> Transpose@{{1, 1}, dim}, 
      ImageSize -> {500, 300}, ColorFunction -> "Rainbow"};
   {range, cf} = {PlotRange, ColorFunction} /. rls;
   aRatio = 1/Divide @@ (ImageSize /. rls);
   Graphics[{Scale[#, (range.{-1, 1})*dim^-1] &@
          Translate[#, (range.{1, 1} - dim)*0.5] &@
        First@ArrayPlot[data, ColorFunction -> cf, 
          DataReversed -> True]}, Frame -> True, 
      AspectRatio -> aRatio, #] & @@ rls

   ];

It works OK and with:

dataP[m_, n_] := Table[i*Boole[j < i], {i, 1, m}, {j, 1, n}];
arrayPlot[dataP[100, 100], ImageSize -> {500, 500}, 
 ColorFunction -> "Rainbow", PlotRange -> {{-21, 23}, {-1, 1}}]

I get

If I modify a arrayPlot with GridLines -> Automatic , GridLinesStyle -> Directive[Orange, Thickness[0.05]] added to Graphics, I get gridlines behind the plot.

How can I make the grid lines appear in front of the plot? It is possible to add Mesh to ArrayPlot, but I want to avoid it since it will require synchronization of mesh with axes ticks.

Considering answer by 'rm -rf' the updated function is:

arrayPlot[data_, opts___] := 
  Module[{dim = Dimensions[data] // N, rls, range, imgSz, aRatio, 
    cf},
   rls = {opts}~
     Join~{PlotRange -> Transpose@{{1, 1}, dim}, 
      ImageSize -> {500, 300}, ColorFunction -> "Rainbow", 
      Method -> {"GridLinesInFront" -> True}};

   {range, cf} = {PlotRange, ColorFunction} /. rls;
   aRatio = 1/Divide @@ (ImageSize /. rls);
   rls = Select[rls, 
   MatchQ[#, Alternatives @@ (#[[1]] & /@ Options[Graphics]) -> _] &];
   Graphics[{Scale[#, (range.{-1, 1})*dim^-1] &@
          Translate[#, (range.{1, 1} - dim)*0.5] &@
        First@ArrayPlot[data, ColorFunction -> cf, 
          DataReversed -> True]}, Frame -> True, 
      AspectRatio -> aRatio, ##] & @@ rls
   ];


arrayPlot[dataP[100, 100], GridLines -> Automatic , 
 ColorFunction -> "BlueGreenYellow", 
 GridLinesStyle -> Directive[Orange, Thickness[0.01]], 
 ImageSize -> {500, 500}, PlotRange -> {{-28, 23}, {-1, 1}}]

Answer

Edit:

As of V11 "GridLinesInFront" was documented together with "AxesInFront", "FrameInFront" and "TransparentPolygonMesh"

---

You need to use the undocumented option

Method -> {"GridLinesInFront" -> True}

to make the grid lines appear on top of your plot. This should give you: