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I want to draw a graphic $20\times20$ grid, rotate it by $\theta$ around $(0,0)$, and trim off the part on the right of the y-axis, so I came up with

ImageTrim[Rotate[GraphicsGrid[Table["", {20}, {20}], Frame -> All], Dynamic[\[Theta]], {0, 0}], {-1000, -1000}, {0, 1000}];

But it gives no output, but an error message instead

ImageTrim::imginv: Expecting an image or graphics instead of [an oblique orange square wich usually indicates something's wrong]

What should I do?

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    $\begingroup$ May I ask what is the goal at the end, I feel like your approach is not an effective one. p.s. What is that you don't understand from the error message? $\endgroup$ – Kuba Apr 26 '14 at 13:38
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Maybe you will find this useful:

grid = Translate[ First@ArrayPlot[SparseArray[{}, {20, 20}], Mesh -> All],
                  {-10, -10}];

Slider[Dynamic@θ, {0, 2 Pi}]
Graphics[ Dynamic@Rotate[grid, θ, {0, 0}], PlotRange -> {{0, Automatic}, All}]

enter image description here

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  • $\begingroup$ Thanks! But PlotRange isn't quite what I'm looking for, because I need to juxtapose two such grids in one Graphics, one on the right of the y-axis, and one on the left. Besides, I don't know why Mathematica says the return of Rotate is not Graphics $\endgroup$ – arax Apr 27 '14 at 4:22

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