52 lines
1.8 KiB
JavaScript
52 lines
1.8 KiB
JavaScript
/*
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* Copyright 2019, The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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function multiplyVec2(matrix, x, y) {
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if (!matrix) return {x, y};
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// |dsdx dsdy tx| | x |
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// |dtdx dtdy ty| x | y |
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// |0 0 1 | | 1 |
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return {
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x: matrix.dsdx * x + matrix.dsdy * y + matrix.tx,
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y: matrix.dtdx * x + matrix.dtdy * y + matrix.ty,
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};
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}
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function multiplyRect(transform, rect) {
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let matrix = transform;
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if (transform && transform.matrix) {
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matrix = transform.matrix;
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}
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// |dsdx dsdy tx| | left, top |
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// matrix = |dtdx dtdy ty| rect = | |
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// |0 0 1 | | right, bottom |
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const leftTop = multiplyVec2(matrix, rect.left, rect.top);
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const rightTop = multiplyVec2(matrix, rect.right, rect.top);
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const leftBottom = multiplyVec2(matrix, rect.left, rect.bottom);
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const rightBottom = multiplyVec2(matrix, rect.right, rect.bottom);
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const outrect = {};
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outrect.left = Math.min(leftTop.x, rightTop.x, leftBottom.x, rightBottom.x);
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outrect.top = Math.min(leftTop.y, rightTop.y, leftBottom.y, rightBottom.y);
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outrect.right = Math.max(leftTop.x, rightTop.x, leftBottom.x, rightBottom.x);
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outrect.bottom = Math.max(leftTop.y, rightTop.y, leftBottom.y,
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rightBottom.y);
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return outrect;
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}
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export {multiplyRect};
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