pull some calculations into a new UiGeometry class

Program.cs

@@ -182,6 +182,18 @@ public class Texture : IDisposable {
   }
 }
 
+public class UiGeometry {
+  public static Vector2i MIN_WINDOW_SIZE = new Vector2i(640, 480);
+
+  public readonly Vector2i WindowSize;
+
+  public UiGeometry() : this(MIN_WINDOW_SIZE) {}
+
+  public UiGeometry(Vector2i windowSize) {
+    WindowSize = windowSize;
+  }
+}
+
 public class Game : GameWindow {
   public Game(GameWindowSettings gwSettings, NativeWindowSettings nwSettings) : base(gwSettings, nwSettings) { }
 
@@ -190,15 +202,10 @@ public class Game : GameWindow {
   static int thumbnailWidth = (int) 1.0 * thumbnailHeight * activeCamera.Resolution.X / activeCamera.Resolution.Y;
   static Texture TEXTURE_WHITE;
 
-  int windowWidth;
-  int windowHeight;
-  float[] vertices = {
-  // Position             Texture coordinates
-     0f,  0f, 0.0f, 0.0f, 0.0f,  // top left
-     2560f,  0f, 0.0f, 1.0f, 0.0f, // top right
-     2560f, 1440f, 0.0f, 1.0f, 1.0f, // bottom right
-     0f, 1440f, 0.0f, 0.0f, 1.0f, // bottom left
-  };
+  UiGeometry geometry = new UiGeometry();
+
+  // four points of (x, y, z, tex_x, tex_y)
+  float[] vertices = new float[20];
 
   uint[] indices = {
     0, 1, 3,   // first triangle
@@ -208,7 +215,7 @@ public class Game : GameWindow {
   int VertexBufferObject;
   int ElementBufferObject;
   int VertexArrayObject;
-  List<Texture> textures;
+  List<Texture> textures = new List<Texture>();
   int textureIndex = 0;
   Shader shader;
   Matrix4 projection;
@@ -275,7 +282,6 @@ public class Game : GameWindow {
 
     // Load textures from JPEGs.
     string[] files = Directory.GetFiles(@"c:\users\colin\pictures\photos\2023\06\27\");
-    textures = new List<Texture>();
     foreach (string file in files) {
       if (file.ToLower().EndsWith(".jpg")) {
         Image<Rgba32> image = Image.Load<Rgba32>(file);
@@ -298,17 +304,16 @@ public class Game : GameWindow {
     GL.BindBuffer(BufferTarget.ArrayBuffer, VertexBufferObject);
     GL.ActiveTexture(TextureUnit.Texture0);
 
-    int maxPhotoWidth = windowWidth - thumbnailWidth;
+    int maxPhotoWidth = geometry.WindowSize.X - thumbnailWidth;
 
     Texture active = textures[textureIndex];
     // TODO: handle the case where we need to letterbox vertically instead.
-    // TODO: pull these geometry calculations out into an object.
-    int photoWidth = (int) (1.0 * windowHeight / active.Height * active.Width);
+    int photoWidth = (int) (1.0 * geometry.WindowSize.Y / active.Height * active.Width);
     int letterboxWidth = (maxPhotoWidth - photoWidth) / 2;
 
-    DrawTexture(active, makeBox(letterboxWidth, 0, photoWidth, windowHeight));
+    DrawTexture(active, makeBox(letterboxWidth, 0, photoWidth, geometry.WindowSize.Y));
     for (int i = 0; i < textures.Count; i++) {
-      Box2i box = makeBox(windowWidth - thumbnailWidth, i * thumbnailHeight, thumbnailWidth, thumbnailHeight);
+      Box2i box = makeBox(geometry.WindowSize.X - thumbnailWidth, i * thumbnailHeight, thumbnailWidth, thumbnailHeight);
       DrawTexture(textures[i], box);
       if (i == textureIndex) {
         DrawBox(box, 5, Color4.Black);
@@ -341,12 +346,12 @@ public class Game : GameWindow {
   protected override void OnResize(ResizeEventArgs e) {
     base.OnResize(e);
     Console.WriteLine($"OnResize: {e.Width}x{e.Height}");
-    windowWidth = e.Width;
-    windowHeight = e.Height;
 
-    projection = Matrix4.CreateOrthographicOffCenter(0f, windowWidth, windowHeight, 0f, -1f, 1f);
+    geometry = new UiGeometry(e.Size);
+
+    projection = Matrix4.CreateOrthographicOffCenter(0f, e.Width, e.Height, 0f, -1f, 1f);
     GL.UniformMatrix4(shader.GetUniformLocation("projection"), true, ref projection);
-    GL.Viewport(0, 0, windowWidth, windowHeight);
+    GL.Viewport(0, 0, e.Width, e.Height);
   }
 
   private void SetVertices(float left, float top, float width, float height) {
@@ -402,7 +407,7 @@ static class Program {
     nwSettings.CurrentMonitor = bestMonitor.Handle;
     nwSettings.Location = new Vector2i(bestMonitor.WorkArea.Min.X + 1, bestMonitor.WorkArea.Min.Y + 31);
     nwSettings.Size = new Vector2i(bestMonitor.WorkArea.Size.X - 2, bestMonitor.WorkArea.Size.Y - 32);
-    nwSettings.MinimumSize = new Vector2i(640, 480);
+    nwSettings.MinimumSize = UiGeometry.MIN_WINDOW_SIZE;
     nwSettings.Title = "Totte";
     // FIXME: nwSettings.Icon = ...