1 files changed, 79 insertions, 11 deletions

diff --git a/src/relabi/canvas.js b/src/relabi/canvas.js
index dfbffa0..d2c55a2 100644
--- a/src/relabi/canvas.js
+++ b/src/relabi/canvas.js
@@ -17,14 +17,14 @@ export default class RelabiCanvas {
     // Speed of the wave in pixels per second
     this.speed = 1 / 5;
 
-    // Attach to the DOM
-    this.parent = parent = document.body;
-    this.canvas = document.createElement("canvas");
-    this.ctx = this.canvas.getContext("2d");
-    this.parent.appendChild(this.canvas);
+    // Position of current time on the screen, from the left
+    this.tZeroOffset = 20;
 
+    // Attach to the DOM
+    this.appendCanvas(parent);
     // Initialize array
     this.values = new Array(window.innerWidth).fill(0);
+    this.notes = [];
     this.append([]);
 
     // Clear the canvas
@@ -35,6 +35,16 @@ export default class RelabiCanvas {
   }
 
   /**
+   * Append the canvas
+   */
+  appendCanvas(parent) {
+    this.parent = parent || document.body;
+    this.canvas = this.canvas || document.createElement("canvas");
+    this.ctx = this.ctx || this.canvas.getContext("2d");
+    this.parent.appendChild(this.canvas);
+  }
+
+  /**
    * Draw the next frame
    */
   requestAnimationFrame(frame) {
@@ -63,10 +73,20 @@ export default class RelabiCanvas {
   /**
    * Append values
    */
-  append(time, values) {
+  append(time, values, notes) {
     this.lastAppendTime = time;
     this.lastAppendFrame = this.lastFrame;
-    this.values = this.values.concat(values).slice(-this.canvas.width);
+    this.values = this.values
+      .concat(values)
+      .slice(-this.canvas.width)
+      .sort((a, b) => a[0] - b[0]);
+
+    if (notes?.length) {
+      this.notes = this.notes
+        .concat(notes)
+        .slice(-50)
+        .sort((a, b) => a[0] - b[0]);
+    }
   }
 
   /**
@@ -76,6 +96,7 @@ export default class RelabiCanvas {
     this.clear();
     this.drawRelabiWave(frame);
     this.drawBounds();
+    this.drawNotes(frame);
   }
 
   /**
@@ -90,12 +111,22 @@ export default class RelabiCanvas {
       const y = getWaveHeight(bound.level, height);
 
       ctx.beginPath();
-      ctx.setLineDash([10, 5]);
+      ctx.setLineDash([4, 4]);
+      ctx.lineWidth = 1;
       ctx.strokeStyle = bound.color || "#888";
       ctx.moveTo(0, y);
       ctx.lineTo(width, y);
       ctx.stroke();
     }
+
+    // Draw the zero position
+    ctx.beginPath();
+    ctx.setLineDash([1, 1]);
+    ctx.lineWidth = 2;
+    ctx.strokeStyle = "#666";
+    ctx.moveTo(width - this.tZeroOffset, 0);
+    ctx.lineTo(width - this.tZeroOffset, height);
+    ctx.stroke();
   }
 
   /**
@@ -110,7 +141,8 @@ export default class RelabiCanvas {
 
     // Start the path
     ctx.beginPath();
-    ctx.strokeStyle = "white";
+    ctx.strokeStyle = "#dff";
+    ctx.lineWidth = 0.75;
     ctx.setLineDash([]);
 
     // This is the offset in seconds from the last frame we computed
@@ -130,13 +162,13 @@ export default class RelabiCanvas {
       // Subtracting the frame offset pulls it negative.
       const timeOffset = this.lastAppendTime + frameOffset - time;
 
-      const x = width - timeOffset * this.speed * width - 10;
+      const x = width - timeOffset * this.speed * width - this.tZeroOffset;
+      const y = getWaveHeight(value, height);
 
       if (x < 0) {
         continue;
       }
 
-      const y = getWaveHeight(value, height);
       if (index === 0) {
         ctx.moveTo(x, y);
       }
@@ -147,6 +179,42 @@ export default class RelabiCanvas {
     // Paint the line
     ctx.stroke();
   }
+
+  /**
+   * Draw the notes
+   */
+  drawNotes(frame) {
+    const { canvas, ctx } = this;
+    const { width, height } = canvas;
+
+    // This is the offset in seconds from the last frame we computed
+    const frameOffset = (frame - this.lastAppendFrame) / 1000;
+
+    // Make a path connecting all values
+    for (const note of this.notes) {
+      const [time, value, direction] = note;
+      const timeOffset = this.lastAppendTime + frameOffset - time;
+      const x = width - timeOffset * this.speed * width - this.tZeroOffset;
+      const y = getWaveHeight(value, height);
+
+      // Don't draw notes that haven't played yet
+      if (x > width - this.tZeroOffset) {
+        continue;
+      }
+
+      // Draw notes as a dot that fades out
+      const opacity = 1 - (timeOffset * this.speed * width) / 1000;
+      if (opacity < 0.001) {
+        continue;
+      }
+      ctx.beginPath();
+      ctx.arc(x - 2.5, y, 5, 0, 2 * Math.PI);
+      ctx.fillStyle = direction
+        ? `rgba(255,128,192,${opacity})`
+        : `rgba(192,255,128,${opacity})`;
+      ctx.fill();
+    }
+  }
 }
 
 /**