konva/lib/Canvas.js

HTML5 2d canvas library for interactive graphics, design editors, whiteboards, and diagrams.

import { Util } from "./Util.js";
import { SceneContext, HitContext } from "./Context.js";
import { Konva } from "./Global.js";
/**
 * Canvas Renderer constructor. It is a wrapper around native canvas element.
 * Usually you don't need to use it manually.
 * @constructor
 * @abstract
 * @memberof Konva
 * @param {Object} config
 * @param {Number} config.width
 * @param {Number} config.height
 * @param {Number} config.pixelRatio
 */
export class Canvas {
    constructor(config) {
        this.pixelRatio = 1;
        // the bitmap size, in device pixels
        this.width = 0;
        this.height = 0;
        // the size the canvas was given, in CSS pixels; the bitmap truncates it
        this._logicalWidth = 0;
        this._logicalHeight = 0;
        this.isCache = false;
        // origin of a buffer canvas in the coordinate space of the canvas it is
        // drawn back into, see Shape.drawScene
        this.x = 0;
        this.y = 0;
        const conf = config || {};
        // a Konva.pixelRatio reset to undefined or 0 means the device ratio
        const pixelRatio = conf.pixelRatio ||
            Konva.pixelRatio ||
            Konva._global.devicePixelRatio ||
            1;
        this.pixelRatio = pixelRatio;
        this._canvas = Util.createCanvasElement();
        // set inline styles
        this._canvas.style.padding = '0';
        this._canvas.style.margin = '0';
        this._canvas.style.border = '0';
        this._canvas.style.background = 'transparent';
        this._canvas.style.position = 'absolute';
        this._canvas.style.top = '0';
        this._canvas.style.left = '0';
    }
    /**
     * get canvas context
     * @method
     * @name Konva.Canvas#getContext
     * @returns {CanvasContext} context
     */
    getContext() {
        return this.context;
    }
    /**
     * get pixel ratio
     * @method
     * @name Konva.Canvas#getPixelRatio
     * @returns {Number} pixel ratio
     * @example
     * var pixelRatio = layer.getCanvas().getPixelRatio();
     */
    getPixelRatio() {
        return this.pixelRatio;
    }
    /**
     * set pixel ratio
     * KonvaJS automatically handles pixel ratio adustments in order to render crisp drawings
     *  on all devices. Most desktops, low end tablets, and low end phones, have device pixel ratios
     *  of 1.  Some high end tablets and phones, like iPhones and iPads have a device pixel ratio
     *  of 2.  Some Macbook Pros, and iMacs also have a device pixel ratio of 2.  Some high end Android devices have pixel
     *  ratios of 2 or 3.  Some browsers like Firefox allow you to configure the pixel ratio of the viewport.  Unless otherwise
     *  specificed, the pixel ratio will be defaulted to the actual device pixel ratio.  You can override the device pixel
     *  ratio for special situations, or, if you don't want the pixel ratio to be taken into account, you can set it to 1.
     * @method
     * @name Konva.Canvas#setPixelRatio
     * @param {Number} pixelRatio
     * @example
     * layer.getCanvas().setPixelRatio(3);
     */
    setPixelRatio(pixelRatio) {
        this.pixelRatio = pixelRatio;
        this.setSize(this._logicalWidth, this._logicalHeight);
    }
    setWidth(width) {
        this.setSize(width, this._logicalHeight);
    }
    setHeight(height) {
        this.setSize(this._logicalWidth, height);
    }
    getWidth() {
        return this.width;
    }
    getHeight() {
        return this.height;
    }
    // the bitmap holds whole pixels: a fractional pixel ratio truncates, and
    // a size that does not match the bitmap would resample every draw of it
    _bitmapSize(size) {
        return Math.floor((size || 0) * this.pixelRatio);
    }
    setSize(width, height) {
        // a NaN or Infinity size would silently give an empty bitmap
        if (!isFinite(width !== null && width !== void 0 ? width : 0) || !isFinite(height !== null && height !== void 0 ? height : 0)) {
            Util.error(`Canvas size must be finite numbers, got ${width}x${height}. The canvas is left empty.`);
            width = height = 0;
        }
        width = width || 0;
        height = height || 0;
        const pixelRatio = this.pixelRatio;
        const context = this.getContext()._context;
        const imageSmoothingEnabled = context.imageSmoothingEnabled;
        this._logicalWidth = width;
        this._logicalHeight = height;
        // take into account pixel ratio. Assigning a dimension reallocates the
        // bitmap and resets the whole context state, so scale once after both
        this.width = this._canvas.width = this._bitmapSize(width);
        this.height = this._canvas.height = this._bitmapSize(height);
        this._canvas.style.width = width + 'px';
        this._canvas.style.height = height + 'px';
        context.scale(pixelRatio, pixelRatio);
        context.imageSmoothingEnabled = imageSmoothingEnabled;
    }
    // setSize() re-allocates and clears the canvas even for the same size,
    // so lazily sized canvases use this to stay untouched when nothing changed
    setSizeIfChanged(width, height) {
        if (this.width !== this._bitmapSize(width) ||
            this.height !== this._bitmapSize(height)) {
            this.setSize(width, height);
        }
    }
    /**
     * to data url
     * @method
     * @name Konva.Canvas#toDataURL
     * @param {String} mimeType
     * @param {Number} quality between 0 and 1 for jpg mime types
     * @returns {String} data url string
     */
    toDataURL(mimeType, quality) {
        try {
            // If the requested encoding fails, retry with the default PNG encoding.
            return this._canvas.toDataURL(mimeType, quality);
        }
        catch (e) {
            try {
                return this._canvas.toDataURL();
            }
            catch (err) {
                Util.error('Unable to get data URL. ' +
                    err.message +
                    ' For more info read https://konvajs.org/docs/posts/Tainted_Canvas.html.');
                throw err;
            }
        }
    }
}
export class SceneCanvas extends Canvas {
    constructor(config = { width: 0, height: 0, willReadFrequently: false }) {
        super(config);
        this.context = new SceneContext(this, {
            willReadFrequently: config.willReadFrequently,
        });
        this.setSize(config.width, config.height);
    }
}
export class HitCanvas extends Canvas {
    constructor(config = { width: 0, height: 0 }) {
        super(config);
        this.hitCanvas = true;
        this.context = new HitContext(this);
        this.context.imageSmoothingEnabled = false;
        this.setSize(config.width, config.height);
    }
}