Tie visible area of a photo to a slider value
Here's one I've been trying to figure out the best way to execute. In order to explain the Law of Large Numbers to our learners, I want to use a still image of a frequency graph that goes from left to right and that shows 10000 coin flips and how the variance decreases as the number grows larger. I have a slider with 9999 steps, which seems to be the max, and understand that I could show 9999 layers based on the slider value. I have also inserted the slider variable into a text box so the learner can visually see how many flips based on where they drag the slider. But I'm not about to make 9999 images- one for each data point. I'm not even going to reduce it by a factor of ten and make 999 images. What I need is a way to take the slider's value reveal the according amount of the frequency chart- basically a moving mask based on the slider's physical position on the bar, not so much it's value. Barring that, some sort of Drag to Reveal interaction would also work.
Thanks in advance.