How to find Image Size of a control object?

Question

I want to find the ImageSize or at least dimensions of any control object irrespective of it being an image or an any other control such as Buttons,etc.

This is my code for button:

button = Button["ew", Null, ImageSize -> {100, 50}]

ImageDimensions provides size of images only and not of control objects. So, initially, I rasterized my control object using Rasterize. And then displayed the image dimensions. However the image dimensions is not exact value.

rastButton = Rasterize[button, RasterSize -> 100]  
bt = Button["ew", Null, {ImageSize -> {100, 50}}]  
rastbt = Rasterize[bt, RasterSize -> 100]  
ImageSize[rastbt]  
ImageDimensions[rastbt]  
(*  Out[272] = {100, 52} *)

bt = Button["ew", Null, {ImageSize -> {100, 1}}]
rastbt = Rasterize[bt, RasterSize -> 100]
ImageSize[rastbt]
ImageDimensions[rastbt]
(* Out[272] = {100, 17} *)

I also believe Rasterize provides error values when I call Rasterize[button][[2, 2]]. Is this a bug? Is there any workaround to estimate the size of control objects?

Ultimately, the purpose of estimating the size is to place the control object very accurately in a grid layout within specified co ordinates.

Answer 1

If you use the Option ImageSize for Rasterize then it is correct. Notice that 15 seems to be the minimum height for a button, such that the Rasterize result agrees.

   button=Button["ew",Null,ImageSize->{100,50}]
    rastButton=Rasterize[button,ImageSize->{100,50}]
    bt=Button["ew",Null,{ImageSize->{100,50}}]
    rastbt=Rasterize[bt,ImageSize->{100,50}]

    ImageDimensions[rastbt]
 (*
==> {100,50}
  *)
    bt=Button["ew",Null,{ImageSize->{100,15}}]
    rastbt=Rasterize[bt,ImageSize->{100,15}]
    ImageSize[rastbt]
    ImageDimensions[rastbt]
    (*
==> {100,15}
*)

Using ImportString and ExportString

ImageDimensions[
   ImportString[ExportString[#, "TIFF"], "TIFF"]] &@button

(* gives {100,52} *)

Appearance is the clue here:

buts = Button["xx", Null, Appearance -> #] & /@ {"DialogBox", 
   "Palette", "FramedPalette", "Frameless", 
   "Pressed", {"DialogBox", "Pressed"}}

Answer 2

It seems form the documentation that the right function for that is AbsoluteCurrentValue[]. Indeed the description: ?AbsoluteCurrentValue coincides pretty close with what is looked for. However,

pl = Plot[ Sin[t], {t, 0, 2 \[Pi]}, ImageSize -> 100];
AbsoluteCurrentValue[pl, ImageSize]

returns {350, 350} and also

pl = Plot[ Sin[t], {t, 0, 2 \[Pi]}, ImageSize -> 200];
AbsoluteCurrentValue[pl, ImageSize]

returns {350, 350}. ??