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[fix](trx-frontend-http): reduce decoder overlay opacity in spectrum screenshots

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Decoder bar overlays (AIS, VDES, FT8, APRS, RDS) use backdrop-filter
blur for a frosted-glass look in the browser, but this can't be
replicated on canvas — resulting in opaque blocks covering the spectrum
in screenshots. Cap their background alpha to 0.35 when rendering to
the snapshot canvas.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>
This commit is contained in:
Stan Grams
2026-03-25 22:41:40 +01:00
parent d11f7b4876
commit 6eff023271
1 changed files with 13 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/trx-client/trx-frontend/trx-frontend-http/assets/web/app.js
+13 -8
View File
@@ -9600,7 +9600,7 @@ function drawRoundedRectPath(ctx, x, y, w, h, r) {
ctx.closePath();
}
function drawElementChrome(ctx, el, rootRect) {
function drawElementChrome(ctx, el, rootRect, maxAlpha = 1) {
if (!isVisibleForSnapshot(el)) return null;
const rect = el.getBoundingClientRect();
const style = getComputedStyle(el);
@@ -9613,15 +9613,17 @@ function drawElementChrome(ctx, el, rootRect) {
const borderWidth = Math.max(0, parseFloat(style.borderTopWidth) || 0);
const border = cssColorToRgba(style.borderTopColor || "rgba(0,0,0,0)");
if (bg[3] > 0.01) {
const bgAlpha = Math.min(bg[3], maxAlpha);
if (bgAlpha > 0.01) {
drawRoundedRectPath(ctx, x, y, w, h, radius);
ctx.fillStyle = `rgba(${Math.round(bg[0])}, ${Math.round(bg[1])}, ${Math.round(bg[2])}, ${bg[3]})`;
ctx.fillStyle = `rgba(${Math.round(bg[0])}, ${Math.round(bg[1])}, ${Math.round(bg[2])}, ${bgAlpha})`;
ctx.fill();
}
if (borderWidth > 0 && border[3] > 0.01) {
const borderAlpha = Math.min(border[3], maxAlpha);
if (borderWidth > 0 && borderAlpha > 0.01) {
drawRoundedRectPath(ctx, x + borderWidth * 0.5, y + borderWidth * 0.5, w - borderWidth, h - borderWidth, Math.max(0, radius - borderWidth * 0.5));
ctx.lineWidth = borderWidth;
ctx.strokeStyle = `rgba(${Math.round(border[0])}, ${Math.round(border[1])}, ${Math.round(border[2])}, ${border[3]})`;
ctx.strokeStyle = `rgba(${Math.round(border[0])}, ${Math.round(border[1])}, ${Math.round(border[2])}, ${borderAlpha})`;
ctx.stroke();
}
return { x, y, w, h, style };
@@ -9648,8 +9650,8 @@ function drawWrappedText(ctx, text, x, y, maxWidth, lineHeight, maxLines) {
}
}
function drawElementTextBlock(ctx, el, rootRect, fallbackText = null) {
const chrome = drawElementChrome(ctx, el, rootRect);
function drawElementTextBlock(ctx, el, rootRect, fallbackText = null, maxAlpha = 1) {
const chrome = drawElementChrome(ctx, el, rootRect, maxAlpha);
if (!chrome) return;
const text = (fallbackText == null ? el.innerText : fallbackText) || "";
const clean = text.replace(/\s+\n/g, "\n").replace(/\n\s+/g, "\n").trim();
@@ -9741,6 +9743,9 @@ function buildSpectrumSnapshotCanvas() {
}
// Decoder overlays over the signal view.
// Cap background alpha to avoid opaque blocks (backdrop-filter can't be
// replicated on canvas, so frosted-glass overlays would otherwise obscure
// the spectrum).
const decoderOverlayIds = [
"ais-bar-overlay",
"vdes-bar-overlay",
@@ -9751,7 +9756,7 @@ function buildSpectrumSnapshotCanvas() {
for (const id of decoderOverlayIds) {
const overlayEl = document.getElementById(id);
if (!overlayEl || !isVisibleForSnapshot(overlayEl)) continue;
drawElementTextBlock(ctx, overlayEl, rootRect);
drawElementTextBlock(ctx, overlayEl, rootRect, null, 0.35);
}
// Spectrum axis labels and bookmark chips (includes freq bar).