The built-in DynamicImage just click the plus sign or minus sign to rescale the image. I have to say click is a not very good operation. Could we make the custom DynamicImage which support the mouse wheel to rescale the image, and I hope it will show the pixel value when the image is large enough. I have recorded a gif for what I want.

enter image description here

It is a useful tool for debugging. But I don't know how to implement it in Mathematica

  • 1
    $\begingroup$ I don't think EventHandler has access to any mouse-wheel actions. That's the main reason this won't work. You could always do a control-mouse drag though, like Graphics3D $\endgroup$ – b3m2a1 Dec 20 '17 at 8:32
  • $\begingroup$ @b3m2a1 Or we can use click action to magnify image and ctrl+click to shrink image. $\endgroup$ – yode Dec 20 '17 at 9:10
  • $\begingroup$ Another idea is to click + drag to zoom in to the rectangle defined by the starting and stopping points. $\endgroup$ – Chip Hurst Dec 20 '17 at 16:26
  • $\begingroup$ @ChipHurst Then you have you draw a rectangle every time to zoom. $\endgroup$ – yode Dec 20 '17 at 17:26

A few simple tweaks of @Heike's answer to this question gets you most of the way there.

ImageZoom[img_Image] := 
        dim = ImageDimensions@img;
        aspect = 1.*Divide@@dim;
        If[aspect>1, xaspect = aspect];
        range = range0 = {{0,xaspect}, {0,1}};
        EventHandler[Graphics[{Inset[Image[img], {0,0}, {0,0}, aspect]},
                    PlotRange->Dynamic[range], ImageSize->500],{
            "MouseDown" :> (ref=MousePosition["GraphicsImageScaled"];
            "MouseDragged" :> Which[
                    y = MousePosition["GraphicsImageScaled"][[2]]-ref[[2]];
                    If[y>0, range=(range-ref2)*(z-y)+ref2,(*zoom in*)
                        If[y<0, range=(range-ref2)/(z+y)+ref2]];,(*zoom out*)
            "MouseClicked" :> Which[ 
                CurrentValue["ControlKey"], range={{0,xaspect},{0,1}},(*Back to start*)
                CurrentValue["ShiftKey"],(*zoom out*)
                True,(*zoom in*)

Applying the above function to an Image gives you both click-and-drag panning and zoom.

To zoom in:

  • Hold shift and drag up
  • or just click anywhere

To zoom out:

  • Hold shift and drag down
  • or just shift click anywhere

enter image description here

However, the frontend starts grinding to a halt on large images:

enter image description here

  • $\begingroup$ Good job, just don't show the pixel value. $\endgroup$ – yode Dec 21 '17 at 5:39
  • $\begingroup$ @yode I can try to add the pixel values if this basic zoom functionally if working for you $\endgroup$ – M.R. Dec 21 '17 at 5:40
  • $\begingroup$ Yes, it is a good solution.. $\endgroup$ – yode Dec 21 '17 at 5:40

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