dynamically blending colors for the heatmap

fixes #1613

5 files changed, 106 insertions, 48 deletions

diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 8a69c3cdc..032c15843 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -15,6 +15,7 @@
         "chartjs-adapter-date-fns": "2.0.0",
         "chartjs-plugin-annotation": "1.4.0",
         "chartjs-plugin-trendline": "1.0.2",
+        "color-blend": "4.0.0",
         "crypto-browserify": "3.12.0",
         "damerau-levenshtein": "1.0.8",
         "date-fns": "2.28.0",
@@ -5027,6 +5028,14 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/color-blend": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/color-blend/-/color-blend-4.0.0.tgz",
+      "integrity": "sha512-fYODTHhI/NG+B5GnzvuL3kiFrK/UnkUezWFTgEPBTY5V+kpyfAn95Vn9sJeeCX6omrCOdxnqCL3CvH+6sXtIbw==",
+      "engines": {
+        "node": ">=10.0.0"
+      }
+    },
     "node_modules/color-convert": {
       "version": "1.9.3",
       "resolved": "https://registry.npmjs.org/color-convert/-/color-convert-1.9.3.tgz",
@@ -21733,6 +21742,11 @@
         "object-visit": "^1.0.0"
       }
     },
+    "color-blend": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/color-blend/-/color-blend-4.0.0.tgz",
+      "integrity": "sha512-fYODTHhI/NG+B5GnzvuL3kiFrK/UnkUezWFTgEPBTY5V+kpyfAn95Vn9sJeeCX6omrCOdxnqCL3CvH+6sXtIbw=="
+    },
     "color-convert": {
       "version": "1.9.3",
       "resolved": "https://registry.npmjs.org/color-convert/-/color-convert-1.9.3.tgz",
diff --git a/frontend/package.json b/frontend/package.json
index 81c4aa847..d965c63d3 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -64,6 +64,7 @@
     "chartjs-adapter-date-fns": "2.0.0",
     "chartjs-plugin-annotation": "1.4.0",
     "chartjs-plugin-trendline": "1.0.2",
+    "color-blend": "4.0.0",
     "crypto-browserify": "3.12.0",
     "damerau-levenshtein": "1.0.8",
     "date-fns": "2.28.0",
diff --git a/frontend/src/styles/test.scss b/frontend/src/styles/test.scss
index e86a9d43b..5936e82af 100644
--- a/frontend/src/styles/test.scss
+++ b/frontend/src/styles/test.scss
@@ -504,22 +504,9 @@
           place-content: center center;
         }
         .box:nth-child(1) {
-          background: var(--colorful-error-color);
           border-radius: var(--roundness) 0 0 var(--roundness);
         }
-        .box:nth-child(2) {
-          background: var(--colorful-error-color);
-          filter: opacity(0.6);
-        }
-        .box:nth-child(3) {
-          background: var(--sub-color);
-        }
-        .box:nth-child(4) {
-          background: var(--main-color);
-          filter: opacity(0.6);
-        }
         .box:nth-child(5) {
-          background: var(--main-color);
           border-radius: 0 var(--roundness) var(--roundness) 0;
         }
       }
@@ -546,25 +533,8 @@
         letter.incorrect.extra {
           color: var(--error-extra-color);
         }
-        &.unreached letter {
-          filter: opacity(0.2);
-        }
-        &.heatmap0 letter {
-          color: var(--colorful-error-color);
-        }
-        &.heatmap1 letter {
-          color: var(--colorful-error-color);
-          filter: opacity(0.6);
-        }
-        &.heatmap2 letter {
-          color: var(--sub-color);
-        }
-        &.heatmap3 letter {
-          color: var(--main-color);
-          filter: opacity(0.6);
-        }
-        &.heatmap4 letter {
-          color: var(--main-color);
+        &.heatmapInherit letter {
+          color: inherit;
         }
       }
       &.rightToLeftTest {
diff --git a/frontend/src/ts/test/test-ui.ts b/frontend/src/ts/test/test-ui.ts
index 60a47d8a4..b955deddb 100644
--- a/frontend/src/ts/test/test-ui.ts
+++ b/frontend/src/ts/test/test-ui.ts
@@ -1011,7 +1011,7 @@ export function toggleResultWords(): void {
   }
 }
 
-export function applyBurstHeatmap(): void {
+export async function applyBurstHeatmap(): Promise<void> {
   if (Config.burstHeatmap) {
     $("#resultWordsHistory .heatmapLegend").removeClass("hidden");
 
@@ -1033,26 +1033,39 @@ export function applyBurstHeatmap(): void {
       adatm.push(Math.abs(median - burst));
     });
     const step = Misc.mean(adatm);
+
+    const themeColors = await ThemeColors.getAll();
+
+    const colors = [
+      themeColors.colorfulError,
+      Misc.blendTwoHexColors(themeColors.colorfulError, themeColors.text),
+      themeColors.text,
+      Misc.blendTwoHexColors(themeColors.main, themeColors.text),
+      themeColors.main,
+    ];
+
+    const unreachedColor = themeColors.sub;
+
     const steps = [
       {
         val: 0,
-        class: "heatmap0",
+        colorId: 0,
       },
       {
         val: median - step * 1.5,
-        class: "heatmap1",
+        colorId: 1,
       },
       {
         val: median - step * 0.5,
-        class: "heatmap2",
+        colorId: 2,
       },
       {
         val: median + step * 0.5,
-        class: "heatmap3",
+        colorId: 3,
       },
       {
         val: median + step * 1.5,
-        class: "heatmap4",
+        colorId: 4,
       },
     ];
 
@@ -1074,26 +1087,29 @@ export function applyBurstHeatmap(): void {
     });
 
     $("#resultWordsHistory .words .word").each((_, word) => {
-      let cls = "";
       const wordBurstAttr = $(word).attr("burst");
       if (wordBurstAttr === undefined) {
-        cls = "unreached";
+        $(word).css("color", unreachedColor);
       } else {
         const wordBurstVal = parseInt(<string>wordBurstAttr);
         steps.forEach((step) => {
-          if (wordBurstVal >= step.val) cls = step.class;
+          if (wordBurstVal >= step.val) {
+            $(word).addClass("heatmapInherit");
+            $(word).css("color", colors[step.colorId]);
+          }
         });
       }
-      $(word).addClass(cls);
+    });
+
+    $("#resultWordsHistory .heatmapLegend .boxes .box").each((index, box) => {
+      $(box).css("background", colors[index]);
     });
   } else {
     $("#resultWordsHistory .heatmapLegend").addClass("hidden");
-    $("#resultWordsHistory .words .word").removeClass("heatmap0");
-    $("#resultWordsHistory .words .word").removeClass("heatmap1");
-    $("#resultWordsHistory .words .word").removeClass("heatmap2");
-    $("#resultWordsHistory .words .word").removeClass("heatmap3");
-    $("#resultWordsHistory .words .word").removeClass("heatmap4");
-    $("#resultWordsHistory .words .word").removeClass("unreached");
+    $("#resultWordsHistory .words .word").removeClass("heatmapInherit");
+    $("#resultWordsHistory .words .word").css("color", "");
+
+    $("#resultWordsHistory .heatmapLegend .boxes .box").css("color", "");
   }
 }
 
diff --git a/frontend/src/ts/utils/misc.ts b/frontend/src/ts/utils/misc.ts
index ad8569417..7b1e2ba00 100644
--- a/frontend/src/ts/utils/misc.ts
+++ b/frontend/src/ts/utils/misc.ts
@@ -1,4 +1,5 @@
 import * as Loader from "../elements/loader";
+import { normal as normalBlend } from "color-blend";
 
 async function fetchJson<T>(url: string): Promise<T> {
   try {
@@ -235,6 +236,62 @@ export async function getContributorsList(): Promise<string[]> {
   }
 }
 
+export function blendTwoHexColors(color1: string, color2: string): string {
+  const rgb1 = hexToRgb(color1);
+  const rgb2 = hexToRgb(color2);
+
+  if (rgb1 && rgb2) {
+    const rgba1 = {
+      r: rgb1.r,
+      g: rgb1.g,
+      b: rgb1.b,
+      a: 1,
+    };
+    const rgba2 = {
+      r: rgb2.r,
+      g: rgb2.g,
+      b: rgb2.b,
+      a: 0.5,
+    };
+    const blended = normalBlend(rgba1, rgba2);
+    console.log(blended);
+    return rgbToHex(blended.r, blended.g, blended.b);
+  } else {
+    return "#000000";
+  }
+}
+
+function hexToRgb(hex: string):
+  | {
+      r: number;
+      g: number;
+      b: number;
+    }
+  | undefined {
+  if (hex.length != 4 && hex.length != 7 && !hex.startsWith("#")) {
+    return undefined;
+  }
+  let r: number;
+  let g: number;
+  let b: number;
+  if (hex.length == 4) {
+    r = ("0x" + hex[1] + hex[1]) as unknown as number;
+    g = ("0x" + hex[2] + hex[2]) as unknown as number;
+    b = ("0x" + hex[3] + hex[3]) as unknown as number;
+  } else if (hex.length == 7) {
+    r = ("0x" + hex[1] + hex[2]) as unknown as number;
+    g = ("0x" + hex[3] + hex[4]) as unknown as number;
+    b = ("0x" + hex[5] + hex[6]) as unknown as number;
+  } else {
+    return undefined;
+  }
+  return { r, g, b };
+}
+
+function rgbToHex(r: number, g: number, b: number): string {
+  return "#" + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
+}
+
 function hexToHSL(hex: string): {
   hue: number;
   sat: number;