WIP better rendering

I think this'll take some serious attention before it even works and
saves any performance.

1 files changed, 18 insertions, 7 deletions

diff --git a/ui/Root.js b/ui/Root.js
index fd81fed..2b13203 100644
--- a/ui/Root.js
+++ b/ui/Root.js
@@ -92,7 +92,7 @@ module.exports = class Root extends DisplayElement {
   }
 
   renderTo(writable) {
-    if (this.shouldRenderTo(writable)) {
+    if (this.anyDescendantShouldRender()) {
       this.renderNowTo(writable)
     }
   }
@@ -101,27 +101,38 @@ module.exports = class Root extends DisplayElement {
     if (writable) {
       this.renderCount++
       super.renderTo(writable)
+      // Since shouldRender is false, super.renderTo won't call didRenderTo for
+      // us. We need to do that ourselves.
+      this.didRenderTo(writable)
     }
   }
 
-  shouldRenderTo(writable) {
+  anyDescendantShouldRender() {
     let render = false
     this.eachDescendant(el => {
       // If we already know we're going to render, checking the element's
       // scheduled-draw status (which involves iterating over each of its draw
       // dependency properties) is redundant.
       if (render) {
-        el.unscheduleDraw()
-      } else if (el.hasScheduledDraw()) {
-        render = true
-        el.unscheduleDraw()
+        return
       }
-      el.updateLastDrawValues()
+      render = el.hasScheduledDraw()
     })
     return render
   }
 
+  shouldRender() {
+    // We need to return false here because otherwise all children will render,
+    // since they'll see the root as an ancestor who needs to be rendered. Bad!
+    return false
+  }
+
   didRenderTo(writable) {
+    this.eachDescendant(el => {
+      el.unscheduleDraw()
+      el.updateLastDrawValues()
+    })
+
     /*
     writable.write(ansi.moveCursorRaw(1, 1))
     writable.write('Renders: ' + this.renderCount)