Attempting to rotate a Line or Histogram meter with a TransformationMatrix rotates the graph, but results in clipping at the original boundaries of the meter.

For instance, a "wide" line or histogram meter measuring w=100 and h=20, rotated 90 degrees about its center point via TransformationMatrix=0;-1;1;0;40;60 , will only display the middle 20 pixels of the rotated line or histogram.

Similarly, a rotated "tall" line or histogram meter (measuring, say, w=20 and h=100) will only display amplitudes greater than 40% and less than 60% of the meter's original height.

Using Rainmeter version 1.2 rev 440 (64-bit)

As a feature of TransformationMatrix, it doesn't affect skin's window size. For example, if window size is 100x20, a visible region would be just 100x20 even if meter is transformed. So you need to extend a visible region using another meter as follows.

[VisibleRegion] Meter=IMAGE W=20 H=100

[TransformedMeter] Meter=LINE MeasureName= X=0 Y=0 W=100 H=20 LineWidth=2 LineColor=FF0000 TransformationMatrix=0;1;-1;0;20;0

If you need more informations about TransformationMatrix, I recommend you post a question to the Rainmeter forum since there are many supporters.