feat: 前端界面优化 (#48)

Co-authored-by: jackfiled <xcrenchangjun@outlook.com>
Reviewed-on: PostGuard/Canon#48
Co-authored-by: Ichirinko <1621543655@qq.com>
Co-committed-by: Ichirinko <1621543655@qq.com>

Canon.Server/Services/CompilerService.cs

@@ -2,7 +2,6 @@
 using Canon.Core.LexicalParser;
 using Canon.Core.SyntaxNodes;
 using Canon.Server.Models;
-using Canon.Visualization.Services;
 using Microsoft.EntityFrameworkCore;
 
 namespace Canon.Server.Services;

Canon.Server/Services/SyntaxTreePresentationService.cs

@@ -0,0 +1,89 @@
+using Canon.Core.SyntaxNodes;
+using Canon.Server.Models;
+using SkiaSharp;
+
+namespace Canon.Server.Services;
+
+public class SyntaxTreePresentationService
+{
+    private const float Scale = 150;
+
+    public Stream Present(ProgramStruct root)
+    {
+        PresentableTreeNode presentableTreeRoot = PresentableTreeNode.Build(root);
+        ScaleTree(presentableTreeRoot);
+
+        (float height, float width) = presentableTreeRoot.CalculateImageSize();
+        using SKSurface surface = SKSurface.Create(
+            new SKImageInfo((int)(width + 2 * Scale), (int)(height * Scale)));
+
+        surface.Canvas.Clear(SKColors.White);
+
+        using Brush brush = new(surface.Canvas);
+        DrawNode(presentableTreeRoot, brush);
+
+        using SKImage image = surface.Snapshot();
+        SKData data = image.Encode();
+
+        return data.AsStream();
+    }
+
+    private void DrawNode(PresentableTreeNode node, Brush brush)
+    {
+        foreach (PresentableTreeNode child in node.Children)
+        {
+            brush.DrawLine(node.Position, child.Position);
+            DrawNode(child, brush);
+        }
+
+        brush.DrawText(node.Position, node.DisplayText);
+    }
+
+    private void ScaleTree(PresentableTreeNode root)
+    {
+        Queue<PresentableTreeNode> queue = [];
+        queue.Enqueue(root);
+        float minX = float.MaxValue;
+
+        // 第一次遍历
+        // 放大坐标并获得最左侧的节点X坐标
+        while (queue.Count != 0)
+        {
+            PresentableTreeNode node = queue.Dequeue();
+
+            node.X *= Scale;
+            node.X += Scale;
+            node.Y *= Scale;
+            node.Y += Scale;
+
+            minX = float.Min(minX, node.X);
+
+            foreach (PresentableTreeNode child in node.Children)
+            {
+                queue.Enqueue(child);
+            }
+        }
+
+        if (minX >= Scale)
+        {
+            // 判断最左侧的节点位置是否正确
+            return;
+        }
+
+        float delta = Scale - minX;
+
+        // 第二次遍历调整位置
+        queue.Enqueue(root);
+        while (queue.Count != 0)
+        {
+            PresentableTreeNode node = queue.Dequeue();
+
+            node.X += delta;
+
+            foreach (PresentableTreeNode child in node.Children)
+            {
+                queue.Enqueue(child);
+            }
+        }
+    }
+}