Add ScaleChanged event, some improvements

Author: Perksey

documentation/proposals/Proposal - Windowing 3.0.md

@@ -1121,15 +1121,20 @@ public interface ISurfaceWindow
     /// </summary>
     bool IsCloseRequested { get; set; }
 
+    /// <summary>
+    /// Raised when <see cref="IsCloseRequested" /> is set to <c>true</c>.
+    /// </summary>
+    event Action<WindowToggleEvent> CloseRequested { add; remove; }
+
     /// <summary>
     /// Gets or sets a value indicating whether the window is visible.
     /// </summary>
     bool IsVisible { get; set; }
 
     /// <summary>
-    /// Raised when <see cref="IsCloseRequested" /> is set to <c>true</c>.
+    /// Raised when <see cref="IsVisible" /> changes.
     /// </summary>
-    event Action<WindowToggleEvent> CloseRequested { add; remove; }
+    event Action<WindowToggleEvent> VisibilityChanged { add; remove; }
 
     /// <summary>
     /// Gets or sets a value indicating whether the window currently has input focus. If setting to <c>true</c>, the
@@ -1529,15 +1534,35 @@ their rendering code. It provides no configuration but provides extra informatio
 ```cs
 namespace Silk.NET.Windowing;
 
+/// <summary>
+/// Contains properties pertaining to a change in a surface's scale.
+/// </summary>
+/// <param name="Surface">The surface to which the change in scale occurred.</param>
+/// <param name="OldContent">The previous value for <see cref="ISurfaceScale.Content"/>.</param>
+/// <param name="NewContent">The new value for <see cref="ISurfaceScale.Content"/>.</param>
+/// <param name="OldDraw">The previous value for <see cref="ISurfaceScale.Draw"/>.</param>
+/// <param name="NewDraw">The new value for <see cref="ISurfaceScale.Draw"/>.</param>
+/// <param name="OldPixelDensity">The previous value for <see cref="ISurfaceScale.PixelDensity"/>.</param>
+/// <param name="NewPixelDensity">The new value for <see cref="ISurfaceScale.PixelDensity"/>.</param>
+public readonly record struct ScaleChangedEvent(
+    Surface Surface,
+    float OldContent,
+    float NewContent,
+    float OldDraw,
+    float NewDraw,
+    float OldPixelDensity,
+    float NewPixelDensity
+);
+
 /// <summary>
 /// Provides information pertaining to the surface's graphical scaling.
 /// </summary>
 /// <remarks>
-/// <see cref="ContentScale" /> is typically used to scale UI elements to the correct size for the end user.
+/// <see cref="Content" /> is typically used to scale UI elements to the correct size for the end user.
 /// <see cref="PixelDensity" /> on the other hand is used to scale the entire application to cover the entire client
 /// area in cases where the window client size is smaller than the actual drawable size (i.e. it is high density).
 /// If scaling content for legibility and scaling the application's rendering as a whole are not needed to be separated,
-/// it is recommended to use <see cref="DrawScale" />. Implementations shall always request a high density surface if
+/// it is recommended to use <see cref="Draw" />. Implementations shall always request a high density surface if
 /// given the choice, to account for the platforms where applications may not be able to opt-out of high density.
 /// </remarks> 
 public interface ISurfaceScale
@@ -1546,35 +1571,40 @@ public interface ISurfaceScale
     /// Gets the factor with which the application should scale its content to make the content more legible for the
     /// user. This has no influence on <see cref="Surface.DrawableSize" />.
     /// </summary>
-    /// <seealso cref="DrawScale" />
-    float ContentScale { get; }
+    /// <seealso cref="Draw" />
+    float Content { get; }
 
     /// <summary>
     /// Gets the suggested amplification factor when drawing in terms of <see cref="Surface.DrawableSize" />. This
     /// represents the scale from the pixel resolution to the desired content size, and is typically the multiplication
-    /// of <see cref="PixelDensity" /> and <see cref="ContentScale" />.
+    /// of <see cref="PixelDensity" /> and <see cref="Content" />.
     /// </summary>
     /// <remarks>
     /// For example, if <see cref="PixelDensity" /> is <c>2.0</c> (i.e. there are 2 pixels per screen coordinate)
     /// <i>and</i> the window manager requests that applications scale their content up by <c>2.0</c> to meet the user's
-    /// settings as per <see cref="ContentScale" />, this would be <c>4.0</c>. This is because we're scaling once to
+    /// settings as per <see cref="Content" />, this would be <c>4.0</c>. This is because we're scaling once to
     /// account for the fact that the application has twice the amount of pixels available to it for the given window
     /// size, and then scaling again so that what we are drawing appears zoomed in as per the user's request. Note that
     /// it is rarely the case that an operating system employs both dense pixels <i>and</i> content scale. macOS for
-    /// instance, instead of setting <see cref="ContentScale" />, opts to scale the resolution in the cases where the
+    /// instance, instead of setting <see cref="Content" />, opts to scale the resolution in the cases where the
     /// user wants magnified visuals instead of having the applications scale their content; whereas Windows sets
-    /// <see cref="ContentScale" /> and instead always keeps <see cref="PixelDensity" /> as <c>1.0</c>. This is down
+    /// <see cref="Content" /> and instead always keeps <see cref="PixelDensity" /> as <c>1.0</c>. This is down
     /// to philosophical differences between the window coordinate systems on platforms as to whether they prefer to
     /// deal in physical device pixels or physical content sizes.
     /// </remarks>
-    float DrawScale { get; }
+    float Draw { get; }
 
     /// <summary>
     /// Gets the ratio of pixels rendered to window size. This shall be equivalent to
     /// <see cref="Surface.DrawableSize" /> divided by <see cref="ISurfaceWindow.ClientSize" />.
     /// </summary>
-    /// <seealso cref="DrawScale" />
+    /// <seealso cref="Draw" />
     float PixelDensity { get; }
+
+    /// <summary>
+    /// An event raised when any scale factor changes.
+    /// </summary>
+    event Action<ScaleChangedEvent> Changed { add; remove; }
 }
 
 public abstract partial class Surface