使用2个NumericUpDown字段来维护Dimensions纵横比

Question

I have two NumericUpDown text fields. They are used for Image Dimensions. I've done it before but I don't remember how I did it. I've looked at over 20 related questions on here but they're not really the same question. The logic and math is totally different than what I need.

Basically, numericUpDown1 is for Width and numericUpDown2 is for Height. When the numericUpDown1 value is changed (either by using arrows or typing), numericUpDown2 must auto change as well, while maintaining the correct aspect ratio.

How can I do this? I'm really lost.

Answer 1

If the aspect ratio is simply defined like this: Width/Height, you should implement both the ValueChanged events of the two NumericUpDown controls: in the event for the numericUpDown1 (for width) you should set the new height value by dividing the numericUpDown1.Value by the aspect ratio; in the other event you should multiply numericUpDown2.Value by the aspect ratio in order to get the new width.

Answer 2

• Keep the original values, as the base for the calculation. This will prevent rounding errors.
• Set a flag to indicate that you are adjusting the other control(s) from your code, and they should not react to their events. So you don't end up in an endless loop.