3个相互连接的滑块 [英] 3 interconnected sliders

问题描述

我已经绞尽脑汁解决这个问题两天了，我尝试了不同的东西，但没有一个能奏效。我正在构建一个应用程序，这是一种quizz。有三个主题包含问题。我想使用3个滑块来定义每个主题所需的问题百分比。

I've been racking my brains over this problem for two days, I've tried different things but none of them work. I'm building an app which is a kind of quizz. There are three subjects which contain questions. I would like to use 3 sliders to define the percentage of questions they want on each subject.

ex : slider one   = History
     slider two   = Maths
     slider three = Grammar

如果我选择了更多历史记录，我向上滑动历史记录滑块，其他滑块应根据3个滑块的值达到100％而减少...

If I choose to have more history, I slide the history slider up and the other sliders should decrease according to the values they have to reach 100% for the 3 sliders...

任何想法算法？当一个滑块达到零值时会发生什么？

Any idea for an algorithm ? And what happens when one slider reach a zero value ?

数学从未成为我的场景。

Maths has never been my scene.

任何帮助非常感谢。

提前致谢。

Mike

推荐答案

应该检查以下算法并进行优化。这只是我放在一起的东西，我没有测试过。

The following algorithm should be reviewed and of course optimized. It is only something that I have put together and I've not tested it.

用最大值和最小值初始化每个滑块并根据需要设置初始值，但是尊重 x + y + z = 1 。

initialize each slider with a max and minimum value and set the inital value as desired, but respecting that x + y + z = 1.

[self.slider1 setMinimumValue:0.0];
[self.slider1 setMaximumValue:1.0];
[self.slider1 setValue:0.20];

[self.slider2 setMinimumValue:0.0];
[self.slider2 setMaximumValue:1.0];
[self.slider2 setValue:0.30];

[self.slider3 setMinimumValue:0.0];
[self.slider3 setMaximumValue:1.0];
[self.slider3 setValue:0.50];

将三个滑块设置为相同的选择器：

Set the three slider to the same selector:

[self.slider1 addTarget:self action:@selector(valueChanged:) forControlEvents:UIControlEventValueChanged];
[self.slider2 addTarget:self action:@selector(valueChanged:) forControlEvents:UIControlEventValueChanged];
[self.slider3 addTarget:self action:@selector(valueChanged:) forControlEvents:UIControlEventValueChanged];

选择器应该做类似的事情：

The selector should do something like that:

- (void)valueChanged:(UISlider *)slider {
 UISlider *sliderX = nil;
 UISlider *sliderY = nil;
 UISlider *sliderZ = nil;

 if (slider == self.slider1) {
  sliderX = self.slider1;
  sliderY = self.slider2;
  sliderZ = self.slider3;
 } else if (slider == self.slider2) {
  sliderY = self.slider1;
  sliderX = self.slider2;
  sliderZ = self.slider3;
 } else {
  sliderY = self.slider1;
  sliderZ = self.slider2;
  sliderX = self.slider3;
 }

 float x = sliderX.value;
 float y = sliderY.value;
 float z = sliderZ.value;

 // x + y + z = 1 
 // Get the amout x has changed
 float oldX = 1 - y - z;
 float difference = x - oldX;

 float newY = y - difference / 2;
 float newZ = z - difference / 2;

 if (newY < 0) {
  newZ += y + newY;
  newY = 0;
 }

 if (newZ < 0) {
  newY += z + newZ;
  newZ = 0;
 }

 [sliderY setValue:newY animated:YES];
 [sliderZ setValue:newZ animated:YES];
}

如果此代码有问题，请告诉我，我可以解决它！

If there is something wrong with this code, please let me know, and I can fix it!

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