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Merged
Federicocervelli merged 3 commits into from
May 28, 2026
Merged

Render crosshair lines under chart content #50

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b1132a9
Render crosshair lines under chart content
Federicocervelli May 28, 2026
b880cd4
Deduplicate crosshair layer setup
Federicocervelli May 28, 2026
c2767e9
Use 1M-bin histogram preview
Federicocervelli May 28, 2026
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6 changes: 3 additions & 3 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -210,16 +210,16 @@ Generated from `dist/` after the package build.
| tooltip plugin entry | `dist/plugins/tooltip.js` | 0.1 KiB |
| crosshair plugin entry | `dist/plugins/crosshair.js` | 0.1 KiB |
| flamegraph plugin | `dist/plugins/flamegraph.js` | 20.7 KiB |
| shared Chart chunk | `dist/Chart-DstwTTQs.js` | 57.2 KiB |
| shared Chart chunk | `dist/Chart-DniudEGP.js` | 57.2 KiB |
| shared streaming data chunk | `dist/UniformRingBuffer-DVJiaja6.js` | 44.0 KiB |
| shared OhlcDataset chunk | `dist/OhlcDataset-BzaK030U.js` | 8.6 KiB |
| shared AxisController chunk | `dist/AxisController-B5zX7JBz.js` | 13.8 KiB |
| shared WebGL2Backend chunk | `dist/WebGL2Backend-DDGRc0UJ.js` | 22.0 KiB |
| shared LinkedChartsCore chunk | `dist/LinkedChartsCore-zxImWpgT.js` | 2.1 KiB |
| shared LinkedChartsCore chunk | `dist/LinkedChartsCore-BLcR3ldB.js` | 2.1 KiB |
| lazy screenshot chunk | `dist/screenshot-CljRIqNW.js` | 3.5 KiB |
| shared OverlayUtils chunk | `dist/OverlayUtils-YP9KSKL4.js` | 3.1 KiB |
| shared Tooltip chunk | `dist/Tooltip-a9NkZoPg.js` | 5.8 KiB |
| shared Crosshair chunk | `dist/Crosshair-C426MhNr.js` | 9.9 KiB |
| shared Crosshair chunk | `dist/Crosshair-Dk4xAusn.js` | 10.3 KiB |

### All public exports

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6 changes: 3 additions & 3 deletions docs/api-reference.md
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3 changes: 1 addition & 2 deletions src/ui/Chart.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -1383,9 +1383,8 @@ export class Chart implements ChartPluginContext {
this.applyAutoFitYPolicy();

try {
const [r, g, b, a] = this.resolvedTheme.backgroundColor;
this.renderer.viewport(0, 0, this.canvas.width, this.canvas.height);
this.renderer.clear(r, g, b, a);
this.renderer.clear(0, 0, 0, 0);

const viewport = this.camera.viewport;
this.currentXOrigin = viewport.xMin;
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1 change: 1 addition & 0 deletions src/ui/ChartLayout.ts
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Expand Up @@ -173,6 +173,7 @@ export class ChartLayout implements ChartLayoutElements {

this.canvas.style.position = "absolute";
this.canvas.style.inset = "0";
this.canvas.style.zIndex = "1";

@chatgpt-codex-connector chatgpt-codex-connector Bot May 28, 2026

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P2 Badge Keep inside axis labels above the canvas

When an axis is configured with position: "inside", AxisOverlay appends its tick-label divs directly to chart.plotElement without assigning a z-index, so adding zIndex = "1" to the canvas puts the WebGL canvas above those labels in the plot stacking order. In that configuration the inside tick labels are now painted underneath grid/series pixels instead of overlaying the chart as before; give the inside-axis labels a z-index above the canvas or avoid raising the canvas above existing plot overlays.

Useful? React with 👍 / 👎.

this.canvas.style.display = "block";
this.canvas.style.width = "100%";
this.canvas.style.height = "100%";
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39 changes: 28 additions & 11 deletions src/ui/Crosshair.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -159,6 +159,17 @@ function createXRangeHighlight(item: ChartPickItem, chart: Chart, strokeColor: s
return marker;
}

function createCrosshairLayer(className: string, zIndex: number): HTMLDivElement {
const layer = document.createElement("div");
layer.className = className;
layer.style.position = "absolute";
layer.style.inset = "0";
layer.style.display = "none";
layer.style.pointerEvents = "none";
layer.style.zIndex = String(zIndex);
return layer;
}

function renderDefaultLabel(
position: CrosshairPosition,
container: HTMLElement,
Expand Down Expand Up @@ -189,6 +200,8 @@ export function crosshairPlugin(options: CrosshairPluginOptions = {}): Crosshair
const rulerModifier = options.rulerModifier ?? "none";
let chartRef: ChartPluginContext | null = null;
let root: HTMLDivElement | null = null;
let lineLayer: HTMLDivElement | null = null;
let overlayLayer: HTMLDivElement | null = null;
let vertical: HTMLDivElement | null = null;
let horizontal: HTMLDivElement | null = null;
let markerLayer: HTMLDivElement | null = null;
Expand All @@ -208,7 +221,8 @@ export function crosshairPlugin(options: CrosshairPluginOptions = {}): Crosshair
const measureEndSubscribers = new Set<(measurement: RulerMeasurement) => void>();

const setVisible = (visible: boolean): void => {
if (root) root.style.display = visible ? "block" : "none";
if (lineLayer) lineLayer.style.display = visible ? "block" : "none";
if (overlayLayer) overlayLayer.style.display = visible ? "block" : "none";
};

const emitMove = (position: CrosshairPosition | null): void => {
Expand Down Expand Up @@ -271,7 +285,7 @@ export function crosshairPlugin(options: CrosshairPluginOptions = {}): Crosshair

const renderPosition = (position: CrosshairPosition | null): void => {
renderMarkers(position);
if (!position || !root || !vertical || !horizontal || !label) {
if (!position || !lineLayer || !overlayLayer || !vertical || !horizontal || !label) {
setVisible(false);
return;
}
Expand Down Expand Up @@ -354,11 +368,11 @@ export function crosshairPlugin(options: CrosshairPluginOptions = {}): Crosshair

root = document.createElement("div");
root.className = "blazeplot-crosshair";
root.style.position = "absolute";
root.style.inset = "0";
root.style.display = "none";
root.style.display = "contents";
root.style.pointerEvents = "none";
root.style.zIndex = String(options.zIndex ?? 22);

lineLayer = createCrosshairLayer("blazeplot-crosshair-lines", options.zIndex ?? 0);
overlayLayer = createCrosshairLayer("blazeplot-crosshair-overlay", options.zIndex ?? 22);

vertical = document.createElement("div");
vertical.style.position = "absolute";
Expand Down Expand Up @@ -407,11 +421,12 @@ export function crosshairPlugin(options: CrosshairPluginOptions = {}): Crosshair
if (dash) rulerLine.setAttribute("stroke-dasharray", dash);
rulerSvg.appendChild(rulerLine);

root.appendChild(vertical);
root.appendChild(horizontal);
root.appendChild(rulerSvg);
root.appendChild(markerLayer);
root.appendChild(label);
lineLayer.appendChild(vertical);
lineLayer.appendChild(horizontal);
lineLayer.appendChild(rulerSvg);
overlayLayer.appendChild(markerLayer);
overlayLayer.appendChild(label);
root.append(lineLayer, overlayLayer);
chart.plotElement.appendChild(root);

if (options.group) {
Expand Down Expand Up @@ -507,6 +522,8 @@ export function crosshairPlugin(options: CrosshairPluginOptions = {}): Crosshair
}
root?.remove();
root = null;
lineLayer = null;
overlayLayer = null;
vertical = null;
horizontal = null;
markerLayer = null;
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50 changes: 36 additions & 14 deletions website/src/site/previews-controller.ts
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
import { type ReactiveController, type ReactiveControllerHost } from "lit";
import { Chart, OhlcRingBuffer, ServerSampledDataset, StaticDataset, UniformRingBuffer, type ChartFrameStats, type ChartPickGroup, type ChartPickMode, type ChartTheme, type SeriesStore, type ViewportPolicy } from "../../../src/index.ts";
import { Chart, OhlcRingBuffer, ServerSampledDataset, StaticDataset, UniformRingBuffer, type ChartFrameStats, type ChartPickGroup, type ChartPickMode, type ChartTheme, type HistogramBin, type HistogramResult, type SeriesStore, type ViewportPolicy } from "../../../src/index.ts";
import { createLinkedCharts } from "../../../src/linked.ts";
import { annotationsPlugin } from "../../../src/plugins/annotations.ts";
import { crosshairPlugin } from "../../../src/plugins/crosshair.ts";
Expand Down Expand Up @@ -589,35 +589,57 @@ export class PreviewChartsController implements ReactiveController {
}

private mountHistogramPreview(target: HTMLElement): void {
const values = new Float64Array(18_000);
for (let index = 0; index < values.length; index++) {
const phase = index / values.length;
const cluster = index % 9;
const baseline = cluster < 5 ? 70 : cluster < 8 ? 115 : 165;
const seasonal = Math.sin(phase * Math.PI * 10) * 8 + Math.sin(index * 0.017) * 5;
const jitter = (Math.sin(index * 12.9898) * 43758.5453 % 1) * 10;
values[index] = baseline + seasonal + jitter + (index % 997 === 0 ? 85 : 0);
const binCount = 1_000_000;
const initialBins = 1_000;
const x = new Float64Array(binCount);
const y = new Float32Array(binCount);
const bins = new Array<HistogramBin>(binCount);
let total = 0;
let initialYMax = 0;
for (let index = 0; index < binCount; index++) {
const wave = 80
+ Math.sin(index * 0.00031) * 34
+ Math.sin(index * 0.017) * 18
+ Math.sin(index * 0.071) * 9;
const burst = index % 12_001 < 120 ? 70 * (1 - (index % 12_001) / 120) : 0;
const count = Math.max(1, Math.round(wave + burst + (index % 997 === 0 ? 90 : 0)));
x[index] = index + 0.5;
y[index] = count;
bins[index] = { x: index + 0.5, y: count, xStart: index, xEnd: index + 1, count, index };
total += count;
if (index < initialBins && count > initialYMax) initialYMax = count;
}
const histogram: HistogramResult = {
bins,
x,
y,
binWidth: 1,
total,
underflow: 0,
overflow: 0,
invalid: 0,
min: 0,
max: binCount,
};

const chart = new Chart(target, {
axes: { x: { position: "outside", title: "latency (ms)" }, y: { position: "outside", title: "density" } },
axes: { x: { position: "outside", title: "bin" }, y: { position: "outside", title: "count" } },
grid: true,
hover: { mode: "nearest-x", group: "none" },
plugins: [
interactionsPlugin({ wheelZoom: true, shiftDragPan: true, boxZoom: true, doubleClickReset: true }),
crosshairPlugin({ snap: "nearest-x", label: true, labelPlacement: "top-right", formatX: (value) => `${value.toFixed(0)} ms`, formatY: (value) => value.toFixed(4) }),
crosshairPlugin({ snap: "nearest-x", label: true, labelPlacement: "top-right", formatX: (value) => `bin ${Math.floor(value).toLocaleString()}`, formatY: (value) => value.toFixed(0) }),
legendPlugin({ position: "top-left" }),
],
accessibility: { label: "Histogram preview" },
});
this.previewCharts.push(chart);

chart.addHistogram({ values, binSize: 5, min: 40, max: 260, normalize: "density", name: "Latency density", downsample: "none" }, {
chart.addHistogram({ histogram, name: "1M bins" }, {
color: [0.988, 0.29, 0.02, 0.95],
baseline: 0,
});
chart.fitToData({ includeZero: true, padding: { y: 0.12 } });
chart.setViewport({ ...chart.getViewport(), xMin: 40, xMax: 260, yMin: 0 });
chart.setViewport({ xMin: 0, xMax: initialBins, yMin: 0, yMax: initialYMax * 1.12 });
chart.start();
}

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