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Added better swiping support for touch devices. #496

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Added better swiping support for touch devices. #496

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dbdf740
Added better swiping support for touch devices.
AndersonDunai Sep 25, 2015
43724d1
Improved swipe effect.
AndersonDunai Sep 26, 2015
184565c
Removed disabling mobile support.
AndersonDunai Sep 26, 2015
09b6bce
Added cancellation of current swipe + decreased threshold.
AndersonDunai Sep 27, 2015
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173 changes: 139 additions & 34 deletions js/impress.js
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Original file line number Diff line number Diff line change
Expand Up @@ -84,7 +84,21 @@
var toNumber = function (numeric, fallback) {
return isNaN(numeric) ? (fallback || 0) : Number(numeric);
};


var toNumberAdvanced = function (numeric) {
if (!(typeof numeric == 'string')) {
return toNumber(numeric);
}
var ratio = numeric.match(/^([\d\.]+)([wh])$/);
if (ratio == null) {
return toNumber(numeric);
} else {
var value = parseFloat(ratio[1]);
var multiplier = ratio[2] == 'w' ? window.innerWidth : window.innerHeight;
return value * multiplier;
}
};

// `byId` returns element with given `id` - you probably have guessed that ;)
var byId = function ( id ) {
return document.getElementById(id);
Expand Down Expand Up @@ -174,12 +188,7 @@

// and `classList` and `dataset` APIs
( body.classList ) &&
( body.dataset ) &&

// but some mobile devices need to be blacklisted,
// because their CSS 3D support or hardware is not
// good enough to run impress.js properly, sorry...
( ua.search(/(iphone)|(ipod)|(android)/) === -1 );
( body.dataset );

if (!impressSupported) {
// we can't be sure that `classList` is supported
Expand Down Expand Up @@ -299,9 +308,9 @@
var data = el.dataset,
step = {
translate: {
x: toNumber(data.x),
y: toNumber(data.y),
z: toNumber(data.z)
x: toNumberAdvanced(data.x),
y: toNumberAdvanced(data.y),
z: toNumberAdvanced(data.z)
},
rotate: {
x: toNumber(data.rotateX),
Expand Down Expand Up @@ -555,15 +564,131 @@

return goto(prev);
};


var interpolate = function(a, b, k) {
return a + (b - a) * k;
};

// `next` API function goes to next step (in document order)
var next = function () {
var next = steps.indexOf( activeStep ) + 1;
next = next < steps.length ? steps[ next ] : steps[ 0 ];

return goto(next);
};


// Touch handler to detect swiping left and right based on window size.
// If the difference in X change is bigger than 1/20 of the screen width,
// we simply call an appropriate API function.
var startX = 0;
var lastX = 0;
var lastDX = 0;
var threshold = window.innerWidth / 20;

document.addEventListener('touchstart', function (event) {
startX = event.touches[0].clientX;
lastX = startX;
});
document.addEventListener('touchmove', function (event) {
var x = event.touches[0].clientX;
var diff = x - startX;

lastDX = lastX - x;

lastX = x;

// currentState

var target;
if (diff < 0) {
var next = steps.indexOf(activeStep) + 1;
target = next < steps.length ? steps[next] : steps[0];
} else if (diff > 0) {
var prev = steps.indexOf(activeStep) - 1;
target = prev >= 0 ? steps[prev] : steps[steps.length - 1];
} else {
// No move
return;
}

var targetStep = stepsData['impress-' + target.id];

var k = Math.abs(diff) / window.innerWidth;

//console.log(currentState);

//console.log(activeStep.id, '->', targetStep.el.id);


var zoomin = targetStep.scale >= currentState.scale;

// if the same step is re-selected, force computing window scaling,
var targetScale = targetStep.scale * windowScale;

var interpolatedStep = {
translate: {
x: interpolate(currentState.translate.x, -targetStep.translate.x, k),
y: interpolate(currentState.translate.y, -targetStep.translate.y, k),
z: interpolate(currentState.translate.z, -targetStep.translate.z, k)
},
rotate: {
x: interpolate(currentState.rotate.x, -targetStep.rotate.x, k),
y: interpolate(currentState.rotate.y, -targetStep.rotate.y, k),
z: interpolate(currentState.rotate.z, -targetStep.rotate.z, k)
},
scale: interpolate(currentState.scale, targetScale)
};

css(root, {
// to keep the perspective look similar for different scales
// we need to 'scale' the perspective, too
transform: perspective(config.perspective / interpolatedStep.scale) + scale(interpolatedStep.scale),
transitionDuration: "0ms",
transitionDelay: "0ms"
});

css(canvas, {
transform: rotate(interpolatedStep.rotate, true) + translate(interpolatedStep.translate),
transitionDuration: "0ms",
transitionDelay: "0ms"
});
});
document.addEventListener('touchend', function (event) {
var totalDiff = lastX - startX;

if (Math.abs(totalDiff) > window.innerWidth / 5 && (totalDiff * lastDX) <= 0) {
if (totalDiff > window.innerWidth / 5 && lastDX <= 0) {
prev();
} else if (totalDiff < -window.innerWidth / 5 && lastDX >= 0) {
next();
}
} else if (Math.abs(lastDX) > threshold) {
if (lastDX < -threshold) {
prev();
} else if (lastDX > threshold) {
next();
}
} else {
// No movement - move to the same slide

css(root, {
// to keep the perspective look similar for different scales
// we need to 'scale' the perspective, too
transform: perspective(config.perspective / currentState.scale) + scale(currentState.scale),
transitionDuration: config.transitionDuration + "ms",
transitionDelay: "0ms"
});

css(canvas, {
transform: rotate(currentState.rotate, true) + translate(currentState.translate),
//transitionDuration: duration + "ms",
//transitionDelay: (zoomin ? 0 : delay) + "ms"
transitionDuration: config.transitionDuration + "ms",
transitionDelay: "0ms"
});
}
});

// Adding some useful classes to step elements.
//
// All the steps that have not been shown yet are given `future` class.
Expand Down Expand Up @@ -760,33 +885,13 @@
event.preventDefault();
}
}, false);

// touch handler to detect taps on the left and right side of the screen
// based on awesome work of @hakimel: https://github.com/hakimel/reveal.js
document.addEventListener("touchstart", function ( event ) {
if (event.touches.length === 1) {
var x = event.touches[0].clientX,
width = window.innerWidth * 0.3,
result = null;

if ( x < width ) {
result = api.prev();
} else if ( x > window.innerWidth - width ) {
result = api.next();
}

if (result) {
event.preventDefault();
}
}
}, false);


// rescale presentation when window is resized
window.addEventListener("resize", throttle(function () {
// force going to active step again, to trigger rescaling
api.goto( document.querySelector(".step.active"), 500 );
}, 250), false);

}, false);

})(document, window);
Expand Down