MonoGame.Samples/CardsStarterKit/1-Framework/UI/ScaleGameComponentAnimation.cs

//-----------------------------------------------------------------------------
// ScaleGameComponentAnimation.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System.Diagnostics;

namespace CardsFramework
{
    /// <summary>
    /// An animation which scales a component.
    /// </summary>
    public class ScaleGameComponentAnimation : AnimatedGameComponentAnimation
    {
        float percent = 0;
        float beginFactor;
        float factorDelta; 

        /// <summary>
        /// Initializes a new instance of the class.
        /// </summary>
        /// <param name="beginFactor">The initial scale factor.</param>
        /// <param name="endFactor">The eventual scale factor.</param>
        public ScaleGameComponentAnimation(float beginFactor, float endFactor)
        {
            this.beginFactor = beginFactor;
            factorDelta = endFactor - beginFactor;
        } 

        /// <summary>
        /// Runs the scaling animation.
        /// </summary>
        /// <param name="gameTime">Game time information.</param>
        public override void Run(GameTime gameTime)
        {
            Texture2D texture;
            if (IsStarted())
            {
                texture = Component.CurrentFrame;
                if (texture != null)
                {
                    // Calculate the completion percent of animation
                    percent += (float)(gameTime.ElapsedGameTime.TotalSeconds / 
                        Duration.TotalSeconds);                    

                    // Inflate the component with an increasing delta. The eventual
                    // delta will have the componenet scale to the specified target
                    // scaling factor.
                    Rectangle bounds = texture.Bounds;
                    bounds.X = (int)Component.CurrentPosition.X;
                    bounds.Y = (int)Component.CurrentPosition.Y;
                    float currentFactor = beginFactor + factorDelta * percent - 1;
                    bounds.Inflate((int)(bounds.Width * currentFactor), 
                        (int)(bounds.Height * currentFactor));
                    Component.CurrentDestination = bounds;
                }
            }
        }
    }
}