Created
April 2, 2018 22:00
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/** | |
* Copyright 2018 Google Inc. All Rights Reserved. | |
* Licensed under the Apache License, Version 2.0 (the "License"); | |
* you may not use this file except in compliance with the License. | |
* You may obtain a copy of the License at | |
* http://www.apache.org/licenses/LICENSE-2.0 | |
* Unless required by applicable law or agreed to in writing, software | |
* distributed under the License is distributed on an "AS IS" BASIS, | |
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
* See the License for the specific language governing permissions and | |
* limitations under the License. | |
*/ | |
registerLayout('masonary', class { | |
static get inputProperties() { | |
return [ '--padding', '--columns' ]; | |
} | |
*intrinsicSizes() { /* TODO implement :) */ } | |
*layout(children, edges, constraints, styleMap) { | |
const inlineSize = constraints.fixedInlineSize; | |
const padding = parseInt(styleMap.get('--padding').toString()); | |
const columnValue = styleMap.get('--columns').toString(); | |
// We also accept 'auto', which will select the BEST number of columns. | |
let columns = parseInt(columnValue); | |
if (columnValue == 'auto' || !columns) { | |
columns = Math.ceil(inlineSize / 350); // MAGIC NUMBER \o/. | |
} | |
// Layout all children with simply their column size. | |
const childInlineSize = (inlineSize - ((columns + 1) * padding)) / columns; | |
const childFragments = yield children.map((child) => { | |
return child.layoutNextFragment({fixedInlineSize: childInlineSize}); | |
}); | |
let autoBlockSize = 0; | |
const columnOffsets = Array(columns).fill(0); | |
for (let childFragment of childFragments) { | |
// Select the column with the least amount of stuff in it. | |
const min = columnOffsets.reduce((acc, val, idx) => { | |
if (!acc || val < acc.val) { | |
return {idx, val}; | |
} | |
return acc; | |
}, {val: +Infinity, idx: -1}); | |
childFragment.inlineOffset = padding + (childInlineSize + padding) * min.idx; | |
childFragment.blockOffset = padding + min.val; | |
columnOffsets[min.idx] = childFragment.blockOffset + childFragment.blockSize; | |
autoBlockSize = Math.max(autoBlockSize, columnOffsets[min.idx] + padding); | |
} | |
return {autoBlockSize, childFragments}; | |
} | |
}); |
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