opt: opt ohlc size calc

src/common/utils/performance.ts

@@ -12,6 +12,8 @@
  * limitations under the License.
  */
 
+import { isFunction, isValid } from './typeChecks'
+
 export function throttle (func: (...args: any[]) => any, wait?: number): () => void {
   let previous = 0
   return function () {
@@ -22,3 +24,25 @@ export function throttle (func: (...args: any[]) => any, wait?: number): () => v
     }
   }
 }
+
+export function memoize<R1 = any, R2 = any> (func: (...args: any[]) => R1, resolver?: (...args: any[]) => R2): (...args: any[]) => R1 {
+  if (!isFunction(func) || (isValid(resolver) && !isFunction(resolver))) {
+    throw new TypeError('Expected a function')
+  }
+  const memoized = function (...args: any[]): any {
+    const key = isFunction(resolver) ? resolver.apply(this, args) : args[0]
+    const cache = memoized.cache
+
+    if (cache.has(key)) {
+      return cache.get(key)
+    }
+    const result = func.apply(this, args)
+    // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
+    memoized.cache = cache.set(key, result) || cache
+    return result
+  }
+  // eslint-disable-next-line @typescript-eslint/strict-boolean-expressions
+  memoized.cache = new (memoize.Cache || Map)()
+  return memoized
+}
+memoize.Cache = Map

src/view/CandleBarView.ts

@@ -18,6 +18,7 @@ import BarSpace from '../common/BarSpace'
 import { EventHandler } from '../common/SyntheticEvent'
 import { ActionType } from '../common/Action'
 import { CandleType, CandleBarColor, RectStyle, PolygonType } from '../common/Styles'
+import { memoize } from '../common/utils/performance'
 
 import ChartStore from '../store/ChartStore'
 
@@ -62,6 +63,10 @@ export default class CandleBarView extends ChildrenView {
     }
   }
 
+  private readonly _calcOhlcSize = memoize((gapBarSpace: number) => {
+    return Math.min(Math.max(Math.round(gapBarSpace * 0.1), 1), 3)
+  })
+
   private _drawCandleBar (
     ctx: CanvasRenderingContext2D,
     axis: Axis,
@@ -158,7 +163,7 @@ export default class CandleBarView extends ChildrenView {
         styles: { color: wickColor }
       })
     } else {
-      const size = Math.min(Math.max(Math.round(barSpace.gapBar * 0.1), 1), 3)
+      const size = this._calcOhlcSize(barSpace.gapBar)
       rects = [
         {
           name: 'rect',