how to calculate slider value from negative to positive

Question

i have a curve slider that takes in value from the height of the frame which value from -100 to 300 which i need to calculate it to equal the value of 0 to 10.

how can i calculate the negative value as what i had gotten was negative value?

my math is bad :(

     -(NSUInteger)calculatePoints:(float)pointY
{
    NSLog(@"maxOffsetValue %f minOffsetValue %fand pointY %f",maxOffsetValue,minOffsetValue, pointY);

    float value =  maxOffsetValue + minOffsetValue;
    NSLog(@"value %f",value);
    float normalValue = (pointY * 1.5) / value ;
    NSLog(@"normalValue %f",normalValue);

    return normalValue;
}
//set value from point
-(void) setValueFromPoint:(CGPoint) point
{
    [animationTimer invalidate]; 

    NSInteger value = [self calculatePoints:point.y];
    value = ((value / self.frame.size.height) * self.max);

    NSLog(@"raw value %d",value);
    value < 0 ? value = 0 : value;
    value > self.max ? value = self.max : value;
    self->_value = value;
    NSLog(@"Value %d",value);
}

@KudoCC awesome thanks it works!! if u post it as an answer, i will accept it! Cheers — Desmond, Sep 05 '14 at 07:51

score 1 · Answer 1 · edited May 23 '17 at 10:26

1

You can get your value scaled between 0 and 10 by using

(x + 100) / 40

where x is the value between -100 and 300.

Reference

edited May 23 '17 at 10:26

Community

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1

answered Sep 05 '14 at 07:05

aksh1t

5,330
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score 1 · Accepted Answer · answered Sep 05 '14 at 07:52

1

Just a short answer.

((point.y-(-100))/400) * 10

answered Sep 05 '14 at 07:52

KudoCC

6,722
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1

maybe you should enhance your short answer with some explanations – Olimpiu POP Sep 05 '14 at 08:19
@user503413 It's hard to explain a math problem to me. I don't think it is a complicated formula. – KudoCC Sep 05 '14 at 08:24

how to calculate slider value from negative to positive

2 Answers2