/// <summary>
/// After the slider value has changed, update the Value property to
/// hold the scaled value.
/// </summary>
private static void SetValueToTick(SliderMenuItem item, double tickValue)
{
if (item._tickValueMap.ContainsKey(tickValue))
{
item.ItemValue = item._tickValueMap[tickValue];
return;
}
double[] keys = new double[item._tickValueMap.Keys.Count];
item._tickValueMap.Keys.CopyTo(keys, 0);
int index = Array.BinarySearch <double>(keys, tickValue);
Debug.Assert(index < 0, "What? How come I didn't find the key already?");
index = ~index;
Debug.Assert(index < item.Items.Count, "How did tick value go above 1000?");
Debug.Assert(index != 0, "Insert location was before element 0.");
double lowTick = keys[index - 1];
double highTick = keys[index];
double lowValue = item._tickValueMap[lowTick];
double highValue = item._tickValueMap[highTick];
double valueScale = highValue - lowValue;
double sourceScale = highTick - lowTick;
double newValue = (tickValue - lowTick) * valueScale / sourceScale + lowValue;
item.ItemValue = newValue;
}
/// <summary>
/// Listen for change to Value property.
/// </summary>
/// <param name="obj"></param>
/// <param name="e"></param>
private static void Value_ValueChanged(DependencyObject obj,
DependencyPropertyChangedEventArgs e)
{
// find appropriate tick spot, and set slider value
SliderMenuItem item = obj as SliderMenuItem;
if (item != null)
{
SetTickToValue(item, (double)e.NewValue);
}
}
/// <summary>
/// Sets the slider thumb to the closest match after the value changes.
/// </summary>
/// <param name="item"></param>
/// <param name="newValue"></param>
private static void SetTickToValue(SliderMenuItem item, double newValue)
{
// find tick spot where
double[] ticks = new double[item._tickValueMap.Keys.Count];
item._tickValueMap.Keys.CopyTo(ticks, 0);
// Find exact match
if (item._tickValueMap.ContainsValue(newValue))
{
foreach (double tick in item._tickValueMap.Keys)
{
if (item._tickValueMap[tick] == newValue)
{
item._slider.Value = tick;
return;
}
}
}
// Find closest match
for (int i = 1; i < item._tickValueMap.Count; i++)
{
double lowTick = ticks[i - 1];
double highTick = ticks[i];
double lowValue = item._tickValueMap[lowTick];
double highValue = item._tickValueMap[highTick];
//double newValue = (double)e.NewValue;
if (newValue > lowValue &&
newValue < highValue)
{
double valueScale = highValue - lowValue;
double tickScale = highTick - lowTick;
// set slider to closest tick match
double newTick = (newValue - lowValue) / (valueScale) * tickScale + lowTick;
item._slider.Value = newTick;
}
}
}
