Files
bitmappery/src/rendering/clipping.js
2021-01-18 18:08:04 +01:00

51 lines
2.4 KiB
JavaScript

/**
* The MIT License (MIT)
*
* Igor Zinken 2021 - https://www.igorski.nl
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
/**
* Prepares a clipping path corresponding to given selections outline, transformed
* appropriately to the destination coordinates. NOTE: don't forget to restore the ctx when done.
*
* @param {CanvasRenderingContext2D} ctx destination context to clip
* @param {Array<{{ x: Number, y: Number }}>} selectionPoints all coordinates within the selection
* @param {boolean} useFloodFill whether selection will be filled using .fill() (requires different clipping preparation)
* @param {Number} offsetX destination offset to shift selection by (bounds relative to viewport)
* @param {Number} offsetY destination offset to shift selection by (bounds relative to viewport)
* @param {Object=} overrideConfig optional override Object when workin in lowres preview mode
*/
export const clipContextToSelection = ( ctx, selectionPoints, useFloodFill, offsetX, offsetY, overrideConfig = null ) => {
let scale = 1;
let vpX = 0;
let vpY = 0;
if ( overrideConfig ) {
({ scale, vpX, vpY } = overrideConfig );
}
ctx.save();
ctx.beginPath();
selectionPoints.forEach(( point, index ) => {
ctx[ index === 0 ? "moveTo" : "lineTo" ]( (( point.x - offsetX ) * scale ) - vpX, (( point.y - offsetY ) * scale ) - vpY );
});
if ( !useFloodFill ) {
ctx.clip();
}
};