From 0981623c2b3a065a4a3735a996141b3c95ace37d Mon Sep 17 00:00:00 2001
From: Josh Johnson <DotJoshJohnson@users.noreply.github.com>
Date: Wed, 7 Jul 2021 06:48:57 -0400
Subject: [PATCH] Prevent Excessive Redraws (#4)

Only render the diagram if the definition changed.
This commit also adds a class for easier styling/formatting.
---
 src/MermaidJS.Blazor/MermaidDiagram.razor | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/MermaidJS.Blazor/MermaidDiagram.razor b/src/MermaidJS.Blazor/MermaidDiagram.razor
index 1853308..f83dfac 100644
--- a/src/MermaidJS.Blazor/MermaidDiagram.razor
+++ b/src/MermaidJS.Blazor/MermaidDiagram.razor
@@ -2,7 +2,7 @@
 
 @inject MermaidDiagramInterop _interop
 
-<div id="@Id"></div>
+<div id="@Id" class="mermaidjs-blazor-diagram"></div>
 @if (!string.IsNullOrWhiteSpace(errorMessage))
 {
     <p style="color:red;">@errorMessage</p>
@@ -32,6 +32,8 @@
     [Parameter]
     public EventCallback OnRender { get; set; }
 
+    string previousDefinition = string.Empty;
+
     public async ValueTask DisposeAsync()
     {
         await _interop.UnregisterComponent(this);
@@ -89,11 +91,13 @@
 
     protected override async Task OnParametersSetAsync()
     {
-        if (componentRef is null)
+        if (componentRef is null || Definition.Equals(previousDefinition))
         {
             return;
         }
 
+        previousDefinition = Definition;
+
         await BeginRender();
     }
 }
\ No newline at end of file