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    ./demo/canvas-001.js ./demo/canvas-002.js ./demo/canvas-003.js ./demo/canvas-004.js ./demo/canvas-005.js ./demo/canvas-006.js ./demo/canvas-007.js ./demo/canvas-008.js ./demo/canvas-009.js ./demo/canvas-010.js ./demo/canvas-011.js ./demo/canvas-012.js ./demo/canvas-013.js ./demo/canvas-014.js ./demo/canvas-015.js ./demo/canvas-016.js ./demo/canvas-017.js ./demo/canvas-018.js ./demo/canvas-019.js ./demo/canvas-020.js ./demo/canvas-021.js ./demo/canvas-022.js ./demo/canvas-023.js ./demo/canvas-024.js ./demo/canvas-025.js ./demo/canvas-026.js ./demo/canvas-027.js ./demo/canvas-028.js ./demo/canvas-029.js ./demo/canvas-030.js ./demo/canvas-031.js ./demo/canvas-032.js ./demo/canvas-033.js ./demo/canvas-034.js ./demo/canvas-035.js ./demo/canvas-036.js ./demo/canvas-037.js ./demo/canvas-038.js ./demo/canvas-039.js ./demo/canvas-040.js ./demo/canvas-041.js ./demo/canvas-042.js ./demo/canvas-043.js ./demo/canvas-044.js ./demo/canvas-045.js ./demo/canvas-046.js ./demo/canvas-047.js ./demo/component-001.js ./demo/component-002.js ./demo/component-003.js ./demo/component-004.js ./demo/component-005.js ./demo/component-006.js ./demo/component-007.js ./demo/core-001.js ./demo/dom-001.js ./demo/dom-002.js ./demo/dom-003.js ./demo/dom-004.js ./demo/dom-005.js ./demo/dom-006.js ./demo/dom-007.js ./demo/dom-008.js ./demo/dom-009.js ./demo/dom-010.js ./demo/dom-011.js ./demo/dom-012.js ./demo/dom-013.js ./demo/dom-014a.js ./demo/dom-014b.js ./demo/dom-014c.js ./demo/dom-015.js ./demo/dom-016.js ./demo/filters-001.js ./demo/filters-002.js ./demo/filters-003.js ./demo/filters-004.js ./demo/filters-005.js ./demo/filters-006.js ./demo/filters-007.js ./demo/filters-008.js ./demo/filters-009.js ./demo/filters-010.js ./demo/filters-011.js ./demo/filters-012.js ./demo/filters-013.js ./demo/filters-014.js ./demo/filters-015.js ./demo/filters-016.js ./demo/filters-017.js ./demo/filters-018.js ./demo/filters-019.js ./demo/filters-020.js ./demo/filters-501.js ./demo/filters-502.js ./demo/filters-503.js ./demo/filters-504.js ./demo/filters-505.js ./demo/particles-001.js ./demo/particles-002.js ./demo/particles-003.js ./demo/particles-004.js ./demo/particles-005.js ./demo/particles-006.js ./demo/particles-007.js ./demo/particles-008.js ./demo/particles-009.js ./demo/particles-010.js ./demo/particles-011.js ./demo/particles-012.js ./demo/particles-013.js ./demo/particles-014.js ./demo/particles-015.js ./demo/particles-016.js ./demo/temp-001.js ./demo/temp-inkscapeSvgFilters.js
  • ¶

    Demo Canvas 028

    Image magnifier; test some composite operations

  • ¶

    Run code

    import scrawl from '../source/scrawl.js'
  • ¶

    Scene setup

    scrawl.importDomImage('.angels');
    
    let canvas = scrawl.library.canvas.mycanvas;
    
    canvas.set({
    
        fit: 'cover',
        checkForResize: true,
    
    }).setBase({
    
        width: 800,
        height: 400,
    
    }).setAsCurrentCanvas();
    
    let magnifier = scrawl.makeGroup({
    
        name: 'magnifier-group',
        host: canvas.base.name,
        order: 1,
    
    });
    
    scrawl.makeGroup({
    
        name: 'background-group',
        host: canvas.base.name,
        order: 2
    });
    
    let myradius = 80;
    
    let mybackground = scrawl.makePicture({
    
        name: 'background',
        group: 'background-group',
    
        asset: 'small-angels',
    
        width: '100%',
        height: '100%',
    
        copyWidth: '100%',
        copyHeight: '100%',
    
        globalCompositeOperation: 'destination-over',
    });
    
    scrawl.makeWheel({
    
        name: 'magnifier',
        group: 'magnifier-group',
    
        order: 1,
    
        radius: 80,
    
        handleX: 'center',
        handleY: 'center',
    
        lockTo: 'mouse',
    
        method: 'fill',
    
    }).clone({
    
        name: 'magnifier-rim',
    
        order: 3,
    
        lineWidth: 5,
        strokeStyle: 'gold',
    
        method: 'draw',
    });
    
    let myMagnifierImage = scrawl.makePicture({
    
        name: 'enlarged',
        group: 'magnifier-group',
    
        order: 2,
    
        asset: 'big-angels',
    
        width: myradius * 2,
        height: myradius * 2,
    
        copyWidth: myradius * 2,
        copyHeight: myradius * 2,
    
        handleX: 'center',
        handleY: 'center',
    
        lockTo: 'mouse',
    
        globalCompositeOperation: 'source-in',
    });
    
    let checkMagnifier = function () {
    
        let display, base;
    
        return function () {
    
            if (!display) display = canvas.here;
            if (!base) base = canvas.base.here;
    
            let active = display.active;
    
            magnifier.set({
                visibility: (active) ? true : false,
            });
    
            if (active) {
    
                myMagnifierImage.set({
    
                    copyStartX: (base.x * 3) - myradius,
                    copyStartY: (base.y * 3) - myradius,
                });
            }
        };
    }();
  • ¶

    Scene animation

    Function to display frames-per-second data, and other information relevant to the demo

    let report = function () {
    
        let testTicker = Date.now(),
            testTime, testNow,
    
            displayed = canvas.here,
            hidden = canvas.base.here,
    
            testMessage = document.querySelector('#reportmessage');
    
        return function () {
    
            testNow = Date.now();
            testTime = testNow - testTicker;
            testTicker = testNow;
    
            testMessage.textContent = `Screen refresh: ${Math.ceil(testTime)}ms; fps: ${Math.floor(1000 / testTime)}
    Display canvas mouse - x: ${displayed.x}, y: ${displayed.y}
    Base canvas mouse - x: ${hidden.x}, y: ${hidden.y}`;
        };
    }();
  • ¶

    Create the Display cycle animation

    scrawl.makeRender({
        name: 'demo-animation',
        target: canvas,
    
        commence: checkMagnifier,
        afterShow: report,
    });
  • ¶

    User interaction

    scrawl.observeAndUpdate({
    
        event: ['input', 'change'],
        origin: '.control-item',
    
        target: mybackground,
    
        useNativeListener: true,
        preventDefault: true,
    
        updates: {
            composite: ['globalCompositeOperation', 'raw'],
        },
    });
    document.querySelector('#composite').value = 'destination-over';
  • ¶

    Development and testing

    console.log(scrawl.library);