Fix GL21 driver bug.

Quik.OpenTK/OpenTKPort.cs

@@ -78,7 +78,7 @@ namespace Quik.OpenTK
             if (!_glDriver.IsInit)
                 _glDriver.Init();
 
-            GL.Clear(GLEnum.GL_COLOR_BUFFER_BIT);
+            GL.Clear(GLEnum.GL_COLOR_BUFFER_BIT | GLEnum.GL_DEPTH_BUFFER_BIT);
             _glDriver.Draw(_vertexEngine.DrawQueue, view);
 
             _window.Context.SwapBuffers();

Quik/OpenGL/GL21Driver.cs

@@ -118,10 +118,10 @@ namespace Quik.OpenGL
             foreach (DrawCall call in queue)
             {
                 GL.Scissor(
-                    (int)MathF.Round(call.Bounds.Left),
-                    (int)MathF.Round(view.Bottom - call.Bounds.Bottom),
-                    (int)MathF.Round(call.Bounds.Right),
-                    (int)MathF.Round(view.Bottom - call.Bounds.Top));
+                    (int)MathF.Round(call.Bounds.Min.X),
+                    (int)MathF.Round(size.Y - call.Bounds.Max.Y),
+                    (int)MathF.Round(call.Bounds.Size.X),
+                    (int)MathF.Round(call.Bounds.Size.Y));
                 QMat4.Translation(out QMat4 modelMatrix, call.Bounds.Min.X, call.Bounds.Min.Y, 0);
                 QMat4 modelView = viewMatrix * modelMatrix;
                 GL.UniformMatrix4(m4Transforms, false, in modelView);

Quik/OpenGL/GLEnum.cs

@@ -21,6 +21,7 @@ namespace Quik.OpenGL
         GL_BLEND = 0x0BE2,
 
         GL_COLOR_BUFFER_BIT = 0x00004000,
+        GL_DEPTH_BUFFER_BIT = 0x00000100,
 
         GL_SRC_ALPHA = 0x0302,
         GL_ONE_MINUS_SRC_ALPHA = 0x0303,

Quik/Typography/Typesetter.cs

@@ -2,9 +2,7 @@
 using Quik.Media;
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Text;
-using System.Threading.Tasks;
 
 namespace Quik.Typography
 {
@@ -76,10 +74,38 @@ namespace Quik.Typography
             }
         }
 
-        public static void TypesetHorizontalDirect(this CommandList list, string str, QVec2 origin, float size, QFont font)
+        public static QVec2 MeasureHorizontal(ReadOnlySpan<char> str, float size, QFont font)
+        {
+            var enumerator = new LineEnumerator(str);
+
+            float width = 0.0f;
+            float height = 0.0f;
+            
+            while (enumerator.MoveNext())
+            {
+                ReadOnlySpan<char> line = enumerator.Current;
+
+                float lineHeight = 0.0f;
+
+                foreach (Rune r in line.EnumerateRunes())
+                {
+                    int codepoint = r.Value;
+                    font.Get(codepoint, size, out FontGlyph glyph);
+                    
+                    width += glyph.Metrics.Advance.X;
+                    lineHeight = Math.Max(lineHeight, glyph.Metrics.Size.Y);
+                }
+
+                height += lineHeight;
+            }
+
+            return new QVec2(width, height);
+        }
+
+        public static void TypesetHorizontalDirect(this CommandList list, ReadOnlySpan<char> str, QVec2 origin, float size, QFont font)
         {
             Dictionary<QImage, FontDrawInfo> drawInfo = new Dictionary<QImage, FontDrawInfo>();
-            var enumerator = new LineEnumerator(str.AsSpan());
+            var enumerator = new LineEnumerator(str);
            
             QVec2 pen = origin;
             while (enumerator.MoveNext())