MonoGame.Extended/Source/MonoGame.Extended.NuclexGui/Controls/Desktop/GuiHorizontalSliderControl.cs

using Microsoft.Xna.Framework;

namespace MonoGame.Extended.NuclexGui.Controls.Desktop
{
    /// <summary>Horizontal slider that can be moved using the mouse</summary>
    public class GuiHorizontalSliderControl : GuiSliderControl
    {
        /// <summary>Obtains the region covered by the slider's thumb</summary>
        /// <returns>The region covered by the slider's thumb</returns>
        protected override RectangleF GetThumbRegion()
        {
            var bounds = GetAbsoluteBounds();

            if (ThumbLocator != null)
                return ThumbLocator.GetThumbPosition(bounds, ThumbPosition, ThumbSize);
            var thumbWidth = bounds.Width*ThumbSize;
            var thumbX = (bounds.Width - thumbWidth)*ThumbPosition;

            return new RectangleF(thumbX, 0, thumbWidth, bounds.Height);
        }

        /// <summary>Moves the thumb to the specified location</summary>
        /// <returns>Location the thumb will be moved to</returns>
        protected override void MoveThumb(float x, float y)
        {
            var bounds = GetAbsoluteBounds();

            var thumbWidth = bounds.Width*ThumbSize;
            var maxX = bounds.Width - thumbWidth;

            // Prevent divide-by-zero if the thumb fills out the whole rail
            if (maxX > 0.0f)
                ThumbPosition = MathHelper.Clamp(x/maxX, 0.0f, 1.0f);
            else
                ThumbPosition = 0.0f;

            OnMoved();
        }
    }
}