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Code Issues 11 Packages Projects Releases Wiki Activity

Extend canvas when required #48

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Ian Renton
2025-10-21 16:43:24 +01:00
parent be86160e9c
commit 001ec2c9b9
2 changed files with 22 additions and 5 deletions
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22
webassets/js/bands.js
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@@ -85,10 +85,8 @@ function updateBands() {
}
// Print the spots on the band. Each one is a div with the details, shifted down if necessary to prevent
// overlap, and a horizontal or diagonal line on the canvas linking it to where it properly appears on the
// band.
// overlap
bandSpotsDiv = $("<div class='band-spots'>");
bandLinesCanvas = $(`<canvas class='band-lines-canvas' width='${BAND_COLUMN_CANVAS_WIDTH_PX}' height='${BAND_COLUMN_HEIGHT_PX}'>`);
// Sort by frequency so we print higher frequencies later, and can bump them further down the track to prevent
// overlaps
spotList.sort(function(a, b) { return a.freq - b.freq; });
@@ -98,15 +96,31 @@ function updateBands() {
// Work out how far down the div to draw it
var percentDownBand = (s.freq - band.start_freq) / (band.end_freq - band.start_freq) * 0.97; // not 100% due to fudge, the first and last dashes are not exactly at the top and bottom of the div as some space is needed for text
var emDownBand = percentDownBand * BAND_COLUMN_HEIGHT_EM;
var pxDownBandFreq = (percentDownBand + 0.015) * BAND_COLUMN_HEIGHT_PX; // same fudge but add half to put the left end of the line in the right place
if (emDownBand < lastSpotEmDownBand + 1.6) {
emDownBand = lastSpotEmDownBand + 1.6; // Prevent overlap
}
lastSpotEmDownBand = emDownBand;
// Calculate how many px down the band div the label appears, and store it with the spot, so we can use it
// later for drawing the lines.
var pxDownBandLabel = (emDownBand * BAND_COLUMN_FONT_SIZE) + (0.015 * BAND_COLUMN_HEIGHT_PX);
s["pxDownBandLabel"] = pxDownBandLabel;
// Add spot div to DOM
bandSpotsDiv.append(`<div class="band-spot" style="top: ${emDownBand}em; border-top: 1px solid ${s.band_color}; border-left: 5px solid ${s.band_color}; border-bottom: 1px solid ${s.band_color}; border-right: 1px solid ${s.band_color};"><span class="band-spot-call">${s.dx_call}</span><span class="band-spot-info">${s.dx_call} ${(s.freq/1000000).toFixed(3)} ${s.mode}</span></div>`);
});
// Work out how tall the canvas should be. Normally this is matching the normal band column height, but if some
// spots have gone off the end of the band markers and stretched their div, we need to resize the canvas to
// match, otherwise we have nowhere to draw their connecting lines.
var canvasHeight = Math.max(BAND_COLUMN_HEIGHT_PX, (lastSpotEmDownBand+1.6) * BAND_COLUMN_FONT_SIZE);
// Draw horizontal or diagonal lines to join up the "real" frequency with where the spot div ended up
var bandLinesCanvas = $(`<canvas class='band-lines-canvas' width='${BAND_COLUMN_CANVAS_WIDTH_PX}px' height='${canvasHeight}px' style='height:${canvasHeight}px !important;'>`);
spotList.forEach(s => {
// Work out how far down the div to draw it
var percentDownBand = (s.freq - band.start_freq) / (band.end_freq - band.start_freq) * 0.97; // not 100% due to fudge, the first and last dashes are not exactly at the top and bottom of the div as some space is needed for text
var pxDownBandFreq = (percentDownBand + 0.015) * BAND_COLUMN_HEIGHT_PX; // same fudge but add half to put the left end of the line in the right place
var pxDownBandLabel = s["pxDownBandLabel"];
// Draw the line on the canvas
var ctx = bandLinesCanvas[0].getContext('2d');