Math related: How do I get a different scale if the value is less than one or greater than one

This should be an easy to solve but my brain has been fried the last few days. I have a slider that zooms in and zooms out a image. I want to zoom into the pixel level and zoom out to the pixel level but I have to have the thumbnail button be centered in the slider for a scale of 1.

What I have now is,

In code: // if the scale value is 1 the image is shown at original size var scale:Number = zoomSlider.value/1000; sprite.scaleX = sprite.scaleY = scale;

I set the default value to 5000 so that the button is centered in the middle but that sets the scale to 5. What I want is when I drag left (from the initial value of 5000) it should start to scale down until it gets to the minimum scale of .10. When I drag right it should start to increase the scale to 10.

The key to this question is that I have to have the th开发者_如何学编程umbnail button centered in the middle of the slider and when centered the scale is 1.

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If you want the scale for 0 to 10,000 (since you specified center to be 5000) as above, then use

var scale:Number = zoomSlider.value/5000; 
sprite.scaleX    = sprite.scaleY = scale;

Whatever be the Scale, To keep the Scale Button centered and Image scaled to 1, set the 'scale' variable to 1/2 of the max Scale value.