Create a font atlaser.

Quik/Media/Font/FontAtlas.cs

@@ -0,0 +1,158 @@
+using System;
+using System.Collections.Generic;
+
+namespace Quik.Media.Font
+{
+    public struct FontAtlasGlyphInfo
+    {
+        public int Codepoint;
+        public QImage Image;
+        public QRectangle UVs;
+    }
+
+    public class FontAtlas
+    {
+        private readonly int width, height;
+        private readonly List<AtlasPage> atlases = new List<AtlasPage>();
+        private readonly Dictionary<int, FontAtlasGlyphInfo> glyphs = new Dictionary<int, FontAtlasGlyphInfo>();
+        private int index = 0;
+        private AtlasPage last = null;
+
+        public FontAtlas(int width, int height)
+        {
+            this.width = width;
+            this.height = height;
+        }
+
+        public bool GetGlyph(int codepoint, out FontAtlasGlyphInfo info)
+        {
+            return glyphs.TryGetValue(codepoint, out info);
+        }
+
+        public void PutGlyph(int codepoint, QImageLock source, out FontAtlasGlyphInfo info)
+        {
+            info = new FontAtlasGlyphInfo() { Codepoint = codepoint };
+            
+            if (last == null || last.IsFull)
+            {
+                AddPage();
+            }
+
+            last.PutGlyph(source, ref info);
+        }
+
+        private void AddPage()
+        {
+            index++;
+
+            if (index < atlases.Count)
+            {
+                last = atlases[index];
+            }
+            else
+            {
+                last = new AtlasPage(width, height);
+                atlases.Add(last);
+            }
+        }
+
+        public void Clear()
+        {
+            // Trim any pages that were not used yet.
+            for (int i = atlases.Count -1; i >= 0; i--)
+            {
+                if (atlases[i].PointerX != 0 && atlases[i].PointerY != 0)
+                {
+                    for (int j = i + 1; j < atlases.Count; j++)
+                    {
+                        atlases[j].Dispose();
+                    }
+
+                    if (i != atlases.Count - 1)
+                        atlases.RemoveRange(i+1, atlases.Count - i - 1);
+                    break;
+                }
+            }
+
+            if (atlases.Count > 0)
+            {
+                last = atlases[0];
+            }
+            else
+            {
+                last = null;
+            }
+            index = -1;
+
+            glyphs.Clear();
+        }
+
+        private class AtlasPage : IDisposable
+        {
+            public QImage Image;
+            public int PointerX, PointerY;
+            public int RowHeight;
+
+            public bool IsFull => PointerX > Image.Width || PointerY > Image.Height;
+
+            public AtlasPage(int width, int height)
+            {
+                Image = new QImageBuffer(QImageFormat.RedU8, width, height);
+                Reset();
+            }
+
+            public void PutGlyph(QImageLock src, ref FontAtlasGlyphInfo prototype)
+            {
+                if (IsFull)
+                    throw new Exception("Page is full!");
+
+                Image.LockBits2d(out QImageLock dst, QImageLockOptions.Default);
+                src.CopyTo(dst, PointerX, PointerY);
+                Image.UnlockBits();
+
+                QVec2 min = new QVec2(PointerX/Image.Width, PointerY/Image.Width);
+                QVec2 size = new QVec2(src.Width/Image.Width, src.Height/Image.Height);
+
+                prototype.Image = Image;
+                prototype.UVs = new QRectangle(min + size, min);
+
+                AdvanceColumn(src.Width, src.Height);
+            }
+
+            public void Reset()
+            {
+                RowHeight = PointerX = PointerY = 0;
+            }
+
+            public void AdvanceRow()
+            {
+                PointerX = 0;
+                PointerY += RowHeight;
+
+                RowHeight = 0;
+            }
+
+            public void AdvanceColumn(int width, int height)
+            {
+                RowHeight = Math.Max(RowHeight, height);
+                PointerX += width;
+
+                if (PointerX > Image.Width)
+                {
+                    AdvanceRow();
+                }
+            }
+
+            private bool isDisposed = false;
+            public void Dispose()
+            {
+                if (isDisposed)
+                    return;
+
+                Image?.Dispose();
+
+                isDisposed = true;
+            }
+        }
+    }
+}

Quik/Media/QImage.cs

@@ -1,5 +1,4 @@
 using System;
-
 namespace Quik.Media
 {
     public abstract class QImage : IDisposable
@@ -62,5 +61,60 @@ namespace Quik.Media
             Depth = depth;
             ImagePtr = ptr;
         }
+
+        public unsafe void CopyTo(QImageLock destination, int x, int y)
+        {
+            if (
+                Width + x > destination.Width ||
+                Height + y > destination.Height)
+            {
+                throw new Exception("Image falls outside the bounds of the destination.");
+            }
+            else if (Format != destination.Format)
+            {
+                throw new Exception("Image formats must be the same.");
+            }
+
+            int bpp = Format.BytesPerPixel();
+            for (int i = 0; i < Height; i++)
+            {
+                IntPtr srcPtr = (IntPtr)((long)ImagePtr + i * bpp);
+
+                long dstPos = x + i * destination.Width;
+                IntPtr dstPtr = (IntPtr)((long)destination.ImagePtr + dstPos * bpp);
+
+                Buffer.MemoryCopy((void*)srcPtr, (void*)dstPtr, Width * bpp, Width * bpp);
+            }
+        }
+
+        public unsafe void ExtractFrom(QImageLock destination, int x, int y, int width, int height)
+        {
+            if (
+                width != destination.Width ||
+                height != destination.Height)
+            {
+                throw new Exception("Destination is not the same size as the subregion.");
+            }
+            else if (x + width > Width || y + height > Height)
+            {
+                throw new Exception("The subregion is larger than this image.");
+            }
+            else if (Format != destination.Format)
+            {
+                throw new Exception("Image formats must be the same.");
+            }
+
+            int bpp = Format.BytesPerPixel();
+            for (int i = 0; i < height; i++)
+            {
+                long srcPos = x + y * i;
+                IntPtr srcPtr = (IntPtr)((long)ImagePtr + srcPos * bpp);
+
+                long dstPos = i * destination.Width;
+                IntPtr dstPtr = (IntPtr)((long)destination.ImagePtr + dstPos * bpp);
+
+                Buffer.MemoryCopy((void*)srcPtr, (void*)dstPtr, width * bpp, width * bpp);
+            }
+        }
     }
 }