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96 lines
3.1 KiB
96 lines
3.1 KiB
;(function(undefined) {
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'use strict';
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if (typeof sigma === 'undefined')
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throw 'sigma is not declared';
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// Initialize packages:
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sigma.utils.pkg('sigma.canvas.edges.labels');
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/**
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* This label renderer will just display the label on the line of the edge.
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* The label is rendered at half distance of the edge extremities, and is
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* always oriented from left to right on the top side of the line.
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*
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* @param {object} edge The edge object.
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* @param {object} source node The edge source node.
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* @param {object} target node The edge target node.
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* @param {CanvasRenderingContext2D} context The canvas context.
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* @param {configurable} settings The settings function.
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*/
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sigma.canvas.edges.labels.def =
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function(edge, source, target, context, settings) {
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if (typeof edge.label !== 'string' || source == target)
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return;
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var prefix = settings('prefix') || '',
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size = edge[prefix + 'size'] || 1;
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if (size < settings('edgeLabelThreshold'))
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return;
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if (0 === settings('edgeLabelSizePowRatio'))
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throw '"edgeLabelSizePowRatio" must not be 0.';
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var fontSize,
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x = (source[prefix + 'x'] + target[prefix + 'x']) / 2,
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y = (source[prefix + 'y'] + target[prefix + 'y']) / 2,
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dX = target[prefix + 'x'] - source[prefix + 'x'],
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dY = target[prefix + 'y'] - source[prefix + 'y'],
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sign = (source[prefix + 'x'] < target[prefix + 'x']) ? 1 : -1,
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angle = Math.atan2(dY * sign, dX * sign);
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// The font size is sublineraly proportional to the edge size, in order to
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// avoid very large labels on screen.
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// This is achieved by f(x) = x * x^(-1/ a), where 'x' is the size and 'a'
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// is the edgeLabelSizePowRatio. Notice that f(1) = 1.
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// The final form is:
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// f'(x) = b * x * x^(-1 / a), thus f'(1) = b. Application:
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// fontSize = defaultEdgeLabelSize if edgeLabelSizePowRatio = 1
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fontSize = (settings('edgeLabelSize') === 'fixed') ?
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settings('defaultEdgeLabelSize') :
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settings('defaultEdgeLabelSize') *
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size *
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Math.pow(size, -1 / settings('edgeLabelSizePowRatio'));
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context.save();
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if (edge.active) {
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context.font = [
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settings('activeFontStyle'),
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fontSize + 'px',
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settings('activeFont') || settings('font')
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].join(' ');
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context.fillStyle =
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settings('edgeActiveColor') === 'edge' ?
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(edge.active_color || settings('defaultEdgeActiveColor')) :
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settings('defaultEdgeLabelActiveColor');
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}
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else {
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context.font = [
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settings('fontStyle'),
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fontSize + 'px',
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settings('font')
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].join(' ');
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context.fillStyle =
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(settings('edgeLabelColor') === 'edge') ?
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(edge.color || settings('defaultEdgeColor')) :
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settings('defaultEdgeLabelColor');
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}
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context.textAlign = 'center';
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context.textBaseline = 'alphabetic';
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context.translate(x, y);
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context.rotate(angle);
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context.fillText(
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edge.label,
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0,
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(-size / 2) - 3
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);
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context.restore();
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};
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}).call(this);
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