From 51aace033316bf31da12d49f8d0f55f9070f026a Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Wed, 15 Nov 2017 16:31:38 -0800
Subject: [PATCH] Fix heatmap layer performance regression

---
 src/style/properties.js                      | 26 ++++---------------
 src/style/style_layer/heatmap_style_layer.js | 27 +++++++++++++++++---
 2 files changed, 29 insertions(+), 24 deletions(-)

diff --git a/src/style/properties.js b/src/style/properties.js
index a1ce3bab347..4caa6b4eac5 100644
--- a/src/style/properties.js
+++ b/src/style/properties.js
@@ -3,7 +3,6 @@
 const assert = require('assert');
 const {extend, easeCubicInOut} = require('../util/util');
 const interpolate = require('../style-spec/util/interpolate');
-const {RGBAImage} = require('../util/image');
 const {normalizePropertyExpression} = require('../style-spec/expression');
 const Color = require('../style-spec/util/color');
 
@@ -616,35 +615,20 @@ class CrossFadedProperty<T> implements Property<T, ?CrossFaded<T>> {
 }
 
 /**
- * An implementation of `Property` for `heatmap-color`, which has unique evaluation requirements.
+ * An implementation of `Property` for `heatmap-color`. Evaluation and interpolation are no-ops: the real
+ * evaluation happens in HeatmapStyleLayer.
  *
  * @private
  */
-class HeatmapColorProperty implements Property<Color, RGBAImage> {
+class HeatmapColorProperty implements Property<Color, void> {
     specification: StylePropertySpecification;
 
     constructor(specification: StylePropertySpecification) {
         this.specification = specification;
     }
 
-    possiblyEvaluate(value: PropertyValue<Color, RGBAImage>, parameters: EvaluationParameters): RGBAImage {
-        const colorRampData = new Uint8Array(256 * 4);
-        const len = colorRampData.length;
-        for (let i = 4; i < len; i += 4) {
-            const pxColor = value.expression.evaluate(extend({heatmapDensity: i / len}, parameters));
-            // the colors are being unpremultiplied because Color uses
-            // premultiplied values, and the Texture class expects unpremultiplied ones
-            colorRampData[i + 0] = Math.floor(pxColor.r * 255 / pxColor.a);
-            colorRampData[i + 1] = Math.floor(pxColor.g * 255 / pxColor.a);
-            colorRampData[i + 2] = Math.floor(pxColor.b * 255 / pxColor.a);
-            colorRampData[i + 3] = Math.floor(pxColor.a * 255);
-        }
-        return RGBAImage.create({width: 256, height: 1}, colorRampData);
-    }
-
-    interpolate(a: RGBAImage): RGBAImage {
-        return a;
-    }
+    possiblyEvaluate() {}
+    interpolate() {}
 }
 
 module.exports = {
diff --git a/src/style/style_layer/heatmap_style_layer.js b/src/style/style_layer/heatmap_style_layer.js
index 7449c2e913b..77a27bcd13b 100644
--- a/src/style/style_layer/heatmap_style_layer.js
+++ b/src/style/style_layer/heatmap_style_layer.js
@@ -31,11 +31,32 @@ class HeatmapStyleLayer extends StyleLayer {
 
     constructor(layer: LayerSpecification) {
         super(layer, properties);
+
+        // make sure color ramp texture is generated for default heatmap color too
+        this._updateColorRamp();
     }
 
-    updatePaintTransitions(options: {transition?: boolean}, transition: TransitionSpecification) {
-        super.updatePaintTransitions(options, transition);
-        this.colorRamp = this._transitioningPaint._values['heatmap-color'].possiblyEvaluate(({zoom: 0}: any));
+    setPaintProperty(name: string, value: mixed, options: {validate: boolean}) {
+        super.setPaintProperty(name, value, options);
+        if (name === 'heatmap-color') {
+            this._updateColorRamp();
+        }
+    }
+
+    _updateColorRamp() {
+        const expression = this._transitionablePaint._values['heatmap-color'].value.expression;
+        const colorRampData = new Uint8Array(256 * 4);
+        const len = colorRampData.length;
+        for (let i = 4; i < len; i += 4) {
+            const pxColor = expression.evaluate(({heatmapDensity: i / len}: any));
+            // the colors are being unpremultiplied because Color uses
+            // premultiplied values, and the Texture class expects unpremultiplied ones
+            colorRampData[i + 0] = Math.floor(pxColor.r * 255 / pxColor.a);
+            colorRampData[i + 1] = Math.floor(pxColor.g * 255 / pxColor.a);
+            colorRampData[i + 2] = Math.floor(pxColor.b * 255 / pxColor.a);
+            colorRampData[i + 3] = Math.floor(pxColor.a * 255);
+        }
+        this.colorRamp = RGBAImage.create({width: 256, height: 1}, colorRampData);
         this.colorRampTexture = null;
     }