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add support for min/max scale limits #5192

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a392b74
feat(geo): support min/max scale limits
mojoaxel Oct 5, 2020
df23838
refactor: rename min/max scale limits
mojoaxel Oct 26, 2020
388c0b0
chore: use dflt: -1 instad of null
mojoaxel Oct 26, 2020
d531576
feat: handle maxscale default in scaleExtent
mojoaxel Oct 26, 2020
b0daf38
chore: only rerender on zoom if scale changes
mojoaxel Oct 26, 2020
b46375a
chore: fix typo in min/maxscale attributes
mojoaxel Oct 26, 2020
c42cb9d
test: adopt test/plot-schema.json to new plot-schema
mojoaxel Jun 10, 2024
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15 changes: 14 additions & 1 deletion src/components/modebar/buttons.js
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Original file line number Diff line number Diff line change
Expand Up @@ -548,9 +548,22 @@ function handleGeo(gd, ev) {

if(attr === 'zoom') {
var scale = geoLayout.projection.scale;
var minscale = geoLayout.projection.minscale;
var maxscale = geoLayout.projection.maxscale;
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Now we need to handle

if(maxscale === null) maxscale = Infinity;

or

if(maxscale === -1) maxscale = Infinity;

if we decide to use -1 instead of null which is not a number.
@alexcjohnson your idea on which one is better?

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With e722947 I changed the default to -1 instead of null. Scales with less than 0 make no sense here so this should be a valid solution.

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I suppose -1 as a default is OK if we really need a "no max" value - it's better than null which behaves oddly in relayout.

But I wonder if we can't pick a decent default that's more zoomed in than is generally ever useful. I have occasionally gotten in a situation by accidentally scroll zooming so far in that everything freezes up because the SVG engine is having trouble drawing all the off-screen elements. If we cover 99% of cases and avoid this pitfall I'd say that's a reasonable tradeoff, and avoids making a coded value. Something like 10,000?

Similarly, is there a default we could use for minscale, to avoid zooming the whole map away to a point? 0.1 perhaps?

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Something like 10,000?
Similarly, is there a default we could use for minscale, to avoid zooming the whole map away to a point? 0.1 perhaps?

Makes sense!
(I'll have a look tomorrow. It's getting late her in europe 😴)


if(maxscale === -1) maxscale = Infinity;
var newScale = (val === 'in') ? 2 * scale : 0.5 * scale;

Registry.call('_guiRelayout', gd, id + '.projection.scale', newScale);
// make sure the scale is within the min/max bounds
if(newScale > maxscale) {
newScale = maxscale;
} else if(newScale < minscale) {
newScale = minscale;
}

if(newScale !== scale) {
Registry.call('_guiRelayout', gd, id + '.projection.scale', newScale);
}
}
}

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8 changes: 8 additions & 0 deletions src/plots/geo/geo.js
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Original file line number Diff line number Diff line change
Expand Up @@ -709,6 +709,14 @@ function getProjection(geoLayout) {

projection.precision(constants.precision);

// https://github.com/d3/d3-zoom/blob/master/README.md#zoom_scaleExtent
projection.scaleExtent = function() {
var minscale = projLayout.minscale;
var maxscale = projLayout.maxscale;
if(maxscale === -1) maxscale = Infinity;
return [100 * minscale, 100 * maxscale];
};

if(geoLayout._isSatellite) {
projection.tilt(projLayout.tilt).distance(projLayout.distance);
}
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20 changes: 20 additions & 0 deletions src/plots/geo/layout_attributes.js
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Expand Up @@ -177,6 +177,26 @@ var attrs = module.exports = overrideAll({
'that fits the map\'s lon and lat ranges. '
].join(' ')
},
minscale: {
valType: 'number',
min: 0,
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Shouldn't minscale have a max range of 1?

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@mojoaxel mojoaxel Oct 26, 2020 •
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I don't think so. Maybe it also make sense in some circumstances to only allow scaling between e.g. 2..3.

Then of course the initial scale should also set so one value between 2..3. This check is still missing! What would be a good place to check if scale is within the given min/max bounds and reset it otherwise? Is layout_defaults.js the right place?

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Yes, layout_defaults is the right place - note that coerce returns the set value. Also we should check that minscale <= maxscale

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Also we probably need to check when the scale is automatically determined from the contents of the map whether it's within these bounds, and push it into the range if not. I'm not quite sure where that happens, possibly multiple places in geo.js depending on the situation.

dflt: 0,
description: [
'Minimal zoom level of the map view.',
'A minscale of *0.5* (50%) corresponds to a zoom level',
'where the map has half the size of base zoom level.'
].join(' ')
},
maxscale: {
valType: 'number',
min: 0,
dflt: -1,
description: [
'Maximal zoom level of the map view.',
'A maxscale of *2* (200%) corresponds to a zoom level',
'where the map is twice as big as the base layer.'
].join(' ')
},
},
center: {
lon: {
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4 changes: 4 additions & 0 deletions src/plots/geo/layout_defaults.js
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Original file line number Diff line number Diff line change
Expand Up @@ -161,6 +161,8 @@ function handleGeoDefaults(geoLayoutIn, geoLayoutOut, coerce, opts) {
}

coerce('projection.scale');
coerce('projection.minscale');
coerce('projection.maxscale');

show = coerce('showland', !visible ? false : undefined);
if(show) coerce('landcolor');
Expand Down Expand Up @@ -205,6 +207,8 @@ function handleGeoDefaults(geoLayoutIn, geoLayoutOut, coerce, opts) {
// clear attributes that will get auto-filled later
if(fitBounds) {
delete geoLayoutOut.projection.scale;
delete geoLayoutOut.projection.minscale;
delete geoLayoutOut.projection.maxscale;

if(isScoped) {
delete geoLayoutOut.center.lon;
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1 change: 1 addition & 0 deletions src/plots/geo/zoom.js
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Expand Up @@ -32,6 +32,7 @@ module.exports = createGeoZoom;
function initZoom(geo, projection) {
return d3.behavior.zoom()
.translate(projection.translate())
.scaleExtent(projection.scaleExtent())
.scale(projection.scale());
}

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14 changes: 14 additions & 0 deletions test/plot-schema.json
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Expand Up @@ -2585,6 +2585,20 @@
"valType": "number"
},
"editType": "plot",
"maxscale": {
"description": "Maximal zoom level of the map view. A maxscale of *2* (200%) corresponds to a zoom level where the map is twice as big as the base layer.",
"dflt": -1,
"editType": "plot",
"min": 0,
"valType": "number"
},
"minscale": {
"description": "Minimal zoom level of the map view. A minscale of *0.5* (50%) corresponds to a zoom level where the map has half the size of base zoom level.",
"dflt": 0,
"editType": "plot",
"min": 0,
"valType": "number"
},
"parallels": {
"description": "For conic projection types only. Sets the parallels (tangent, secant) where the cone intersects the sphere.",
"editType": "plot",
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