jquery.flot.touchNavigate.js

/* global jQuery */

(function($) {
    'use strict';

    var options = {
        pan: {
            enableTouch: false,
            touchMode: 'manual'
        }
    };

    var ZOOM_DISTANCE_MARGIN = $.plot.uiConstants.ZOOM_DISTANCE_MARGIN;

    function init(plot) {
        plot.hooks.processOptions.push(initTouchNavigation);
    }

    function initTouchNavigation(plot, options) {
        var gestureState = {
                zoomEnable: false,
                prevDistance: null,
                prevTapTime: 0,
                prevPanPosition: { x: 0, y: 0 },
                prevTapPosition: { x: 0, y: 0 }
            },
            navigationState = {
                prevTouchedAxis: 'none',
                currentTouchedAxis: 'none',
                touchedAxis: null,
                navigationConstraint: 'unconstrained',
                initialState: null,
            },
            useManualPan = options.pan.touchMode === 'manual',
            smartPanLock = options.pan.touchMode === 'smartLock',
            useSmartPan = smartPanLock || options.pan.touchMode === 'smart',
            pan, pinch, doubleTap;

        function bindEvents(plot, eventHolder) {
            var o = plot.getOptions();

            if (o.pan.interactive) {
                eventHolder[0].addEventListener('panstart', pan.start, false);
                eventHolder[0].addEventListener('pandrag', pan.drag, false);
                eventHolder[0].addEventListener('panend', pan.end, false);
                eventHolder[0].addEventListener('pinchstart', pinch.start, false);
                eventHolder[0].addEventListener('pinchdrag', pinch.drag, false);
                eventHolder[0].addEventListener('pinchend', pinch.end, false);
                eventHolder[0].addEventListener('doubletap', doubleTap.recenterPlot, false);
            }
        }

        function shutdown(plot, eventHolder) {
            eventHolder[0].removeEventListener('panstart', pan.start);
            eventHolder[0].removeEventListener('pandrag', pan.drag);
            eventHolder[0].removeEventListener('panend', pan.end);
            eventHolder[0].removeEventListener('pinchstart', pinch.start);
            eventHolder[0].removeEventListener('pinchdrag', pinch.drag);
            eventHolder[0].removeEventListener('pinchend', pinch.end);
            eventHolder[0].removeEventListener('doubletap', doubleTap.recenterPlot);
        }

        pan = {
            start: function(e) {
                presetNavigationState(e, 'pan', gestureState);
                updateData(e, 'pan', gestureState, navigationState);

                if (useSmartPan) {
                    var point = getPoint(e, 'pan');
                    navigationState.initialState = plot.navigationState(point.x, point.y);
                }
            },

            drag: function(e) {
                presetNavigationState(e, 'pan', gestureState);

                if (useSmartPan) {
                    var point = getPoint(e, 'pan');
                    plot.smartPan({
                        x: navigationState.initialState.startPageX - point.x,
                        y: navigationState.initialState.startPageY - point.y
                    }, navigationState.initialState, navigationState.touchedAxis, false, smartPanLock);
                } else if (useManualPan) {
                    plot.pan({
                        left: -delta(e, 'pan', gestureState).x,
                        top: -delta(e, 'pan', gestureState).y,
                        axes: navigationState.touchedAxis
                    });
                    updatePrevPanPosition(e, 'pan', gestureState, navigationState);
                }
            },

            end: function(e) {
                presetNavigationState(e, 'pan', gestureState);

                if (useSmartPan) {
                    plot.smartPan.end();
                }

                if (wasPinchEvent(e, gestureState)) {
                    updateprevPanPosition(e, 'pan', gestureState, navigationState);
                }
            }
        };

        var pinchDragTimeout;
        pinch = {
            start: function(e) {
                if (pinchDragTimeout) {
                    clearTimeout(pinchDragTimeout);
                    pinchDragTimeout = null;
                }
                presetNavigationState(e, 'pinch', gestureState);
                setPrevDistance(e, gestureState);
                updateData(e, 'pinch', gestureState, navigationState);
            },

            drag: function(e) {
                if (pinchDragTimeout) {
                    return;
                }
                pinchDragTimeout = setTimeout(function() {
                    presetNavigationState(e, 'pinch', gestureState);
                    plot.pan({
                        left: -delta(e, 'pinch', gestureState).x,
                        top: -delta(e, 'pinch', gestureState).y,
                        axes: navigationState.touchedAxis
                    });
                    updatePrevPanPosition(e, 'pinch', gestureState, navigationState);

                    var dist = pinchDistance(e);

                    if (gestureState.zoomEnable || Math.abs(dist - gestureState.prevDistance) > ZOOM_DISTANCE_MARGIN) {
                        zoomPlot(plot, e, gestureState, navigationState);

                        //activate zoom mode
                        gestureState.zoomEnable = true;
                    }
                    pinchDragTimeout = null;
                }, 1000 / 60);
            },

            end: function(e) {
                if (pinchDragTimeout) {
                    clearTimeout(pinchDragTimeout);
                    pinchDragTimeout = null;
                }
                presetNavigationState(e, 'pinch', gestureState);
                gestureState.prevDistance = null;
            }
        };

        doubleTap = {
            recenterPlot: function(e) {
                if (e && e.detail && e.detail.type === 'touchmove') {
                    // do not recenter during touch moving;
                    return;
                }
                recenterPlotOnDoubleTap(plot, e, gestureState, navigationState);
            }
        };

        if (options.pan.enableTouch === true) {
            plot.hooks.bindEvents.push(bindEvents);
            plot.hooks.shutdown.push(shutdown);
        }

        function presetNavigationState(e, gesture, gestureState) {
            navigationState.touchedAxis = getAxis(plot, e, gesture, navigationState);
            if (noAxisTouched(navigationState)) {
                navigationState.navigationConstraint = 'unconstrained';
            } else {
                navigationState.navigationConstraint = 'axisConstrained';
            }
        }
    }

    $.plot.plugins.push({
        init: init,
        options: options,
        name: 'navigateTouch',
        version: '0.3'
    });

    function recenterPlotOnDoubleTap(plot, e, gestureState, navigationState) {
        checkAxesForDoubleTap(plot, e, navigationState);
        if ((navigationState.currentTouchedAxis === 'x' && navigationState.prevTouchedAxis === 'x') ||
            (navigationState.currentTouchedAxis === 'y' && navigationState.prevTouchedAxis === 'y') ||
            (navigationState.currentTouchedAxis === 'none' && navigationState.prevTouchedAxis === 'none')) {
            plot.recenter({ axes: navigationState.touchedAxis });
        }
    }

    function checkAxesForDoubleTap(plot, e, navigationState) {
        var axis = plot.getTouchedAxis(e.detail.firstTouch.x, e.detail.firstTouch.y);
        if (axis[0] !== undefined) {
            navigationState.prevTouchedAxis = axis[0].direction;
        }

        axis = plot.getTouchedAxis(e.detail.secondTouch.x, e.detail.secondTouch.y);
        if (axis[0] !== undefined) {
            navigationState.touchedAxis = axis;
            navigationState.currentTouchedAxis = axis[0].direction;
        }

        if (noAxisTouched(navigationState)) {
            navigationState.touchedAxis = null;
            navigationState.prevTouchedAxis = 'none';
            navigationState.currentTouchedAxis = 'none';
        }
    }

    function zoomPlot(plot, e, gestureState, navigationState) {
        var offset = plot.offset(),
            center = {
                left: 0,
                top: 0
            },
            zoomAmount = pinchDistance(e) / gestureState.prevDistance,
            dist = pinchDistance(e);

        center.left = getPoint(e, 'pinch').x - offset.left;
        center.top = getPoint(e, 'pinch').y - offset.top;

        // send the computed touched axis to the zoom function so that it only zooms on that one
        plot.zoom({
            center: center,
            amount: zoomAmount,
            axes: navigationState.touchedAxis
        });
        gestureState.prevDistance = dist;
    }

    function wasPinchEvent(e, gestureState) {
        return (gestureState.zoomEnable && e.detail.touches.length === 1);
    }

    function getAxis(plot, e, gesture, navigationState) {
        if (e.type === 'pinchstart') {
            var axisTouch1 = plot.getTouchedAxis(e.detail.touches[0].pageX, e.detail.touches[0].pageY);
            var axisTouch2 = plot.getTouchedAxis(e.detail.touches[1].pageX, e.detail.touches[1].pageY);

            if (axisTouch1.length === axisTouch2.length && axisTouch1.toString() === axisTouch2.toString()) {
                return axisTouch1;
            }
        } else if (e.type === 'panstart') {
            return plot.getTouchedAxis(e.detail.touches[0].pageX, e.detail.touches[0].pageY);
        } else if (e.type === 'pinchend') {
            //update axis since instead on pinch, a pan event is made
            return plot.getTouchedAxis(e.detail.touches[0].pageX, e.detail.touches[0].pageY);
        } else {
            return navigationState.touchedAxis;
        }
    }

    function noAxisTouched(navigationState) {
        return (!navigationState.touchedAxis || navigationState.touchedAxis.length === 0);
    }

    function setPrevDistance(e, gestureState) {
        gestureState.prevDistance = pinchDistance(e);
    }

    function updateData(e, gesture, gestureState, navigationState) {
        var axisDir,
            point = getPoint(e, gesture);

        switch (navigationState.navigationConstraint) {
            case 'unconstrained':
                navigationState.touchedAxis = null;
                gestureState.prevTapPosition = {
                    x: gestureState.prevPanPosition.x,
                    y: gestureState.prevPanPosition.y
                };
                gestureState.prevPanPosition = {
                    x: point.x,
                    y: point.y
                };
                break;
            case 'axisConstrained':
                axisDir = navigationState.touchedAxis[0].direction;
                navigationState.currentTouchedAxis = axisDir;
                gestureState.prevTapPosition[axisDir] = gestureState.prevPanPosition[axisDir];
                gestureState.prevPanPosition[axisDir] = point[axisDir];
                break;
            default:
                break;
        }
    }

    function distance(x1, y1, x2, y2) {
        return Math.sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2));
    }

    function pinchDistance(e) {
        var t1 = e.detail.touches[0],
            t2 = e.detail.touches[1];
        return distance(t1.pageX, t1.pageY, t2.pageX, t2.pageY);
    }

    function updatePrevPanPosition(e, gesture, gestureState, navigationState) {
        var point = getPoint(e, gesture);

        switch (navigationState.navigationConstraint) {
            case 'unconstrained':
                gestureState.prevPanPosition.x = point.x;
                gestureState.prevPanPosition.y = point.y;
                break;
            case 'axisConstrained':
                gestureState.prevPanPosition[navigationState.currentTouchedAxis] =
                point[navigationState.currentTouchedAxis];
                break;
            default:
                break;
        }
    }

    function delta(e, gesture, gestureState) {
        var point = getPoint(e, gesture);

        return {
            x: point.x - gestureState.prevPanPosition.x,
            y: point.y - gestureState.prevPanPosition.y
        }
    }

    function getPoint(e, gesture) {
        if (gesture === 'pinch') {
            return {
                x: (e.detail.touches[0].pageX + e.detail.touches[1].pageX) / 2,
                y: (e.detail.touches[0].pageY + e.detail.touches[1].pageY) / 2
            }
        } else {
            return {
                x: e.detail.touches[0].pageX,
                y: e.detail.touches[0].pageY
            }
        }
    }
})(jQuery);