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TiddlyWiki5/core/modules/macros/zoomer.js

108 lines
3.5 KiB
JavaScript

/*\
title: $:/core/modules/macros/zoomer.js
type: application/javascript
module-type: macro
Zooming navigator macro
\*/
(function(){
/*jslint node: true, browser: true */
/*global $tw: false */
"use strict";
exports.info = {
name: "zoomer",
wrapperTag: "div",
params: {
},
events: ["touchstart","touchmove","touchend"]
};
exports.startZoomer = function(x,y) {
this.inZoomer = true;
this.startX = x;
this.startY = y;
$tw.utils.addClass(document.body,"in-zoomer");
};
exports.stopZoomer = function() {
var newScrollY = this.yFactor * (this.bodyHeight - this.windowHeight);
this.inZoomer = false;
window.scrollTo(0,newScrollY);
document.body.style.webkitTransform = "translateY(" + newScrollY * this.xFactor + "px) " +
"scale(" + this.scale + ") " +
"translateY(" + ((this.windowHeight / this.scale) - this.bodyHeight) * this.yFactor * this.xFactor + "px)";
$tw.utils.removeClass(document.body,"in-zoomer");
document.body.style.webkitTransform = "translateY(0) scale(1) translateY(0)";
};
/*
Zoom the body element given a touch/mouse position in screen coordinates
*/
exports.hoverZoomer = function(x,y) {
// Put the transform origin at the top in the middle
document.body.style.webkitTransformOrigin = "50% 0";
// Some shortcuts
this.bodyWidth = document.body.offsetWidth;
this.bodyHeight = document.body.offsetHeight;
this.windowWidth = window.innerWidth;
this.windowHeight = window.innerHeight;
// Compute the scale factor for fitting the entire page into the window. This is
// the scale factor we'll use when the touch is far to the left
this.minScale = this.windowHeight / this.bodyHeight;
if(this.minScale < 0.1) {
// Don't scale to less than 10% of original size
this.minScale = 0.1;
} else if(this.minScale > 1) {
// Nor should we scale up if the body is shorter than the window
this.minScale = 1;
}
// We divide the screen into two horizontal zones divided by the right edge of the body at maximum zoom (ie minimum scale)
this.splitPos = this.windowWidth/2 + (this.bodyWidth * this.minScale)/2;
// Compute the 0->1 ratio (from right to left) of the position of the touch within the right zone
this.xFactor = (this.windowWidth - x) / (this.windowWidth - this.splitPos);
if(this.xFactor > 1) {
this.xFactor = 1;
}
// And the 0->1 ratio (from top to bottom) of the position of the touch down the screen
this.yFactor = y/this.windowHeight;
// Now interpolate the scale
this.scale = (this.minScale - 1) * this.xFactor + 1;
// Apply the transform. The malarkey with .toFixed() is because otherwise we might get numbers in
// exponential notation (such as 5.1e-15) that are illegal in CSS
var preTranslateY = window.scrollY * this.xFactor,
scale = this.scale,
postTranslateY = ((this.windowHeight / this.scale) - this.bodyHeight) * this.yFactor * this.xFactor;
var transform = "translateY(" + preTranslateY.toFixed(8) + "px) " +
"scale(" + scale.toFixed(8) + ") " +
"translateY(" + postTranslateY.toFixed(8) + "px)";
document.body.style.webkitTransform = transform;
};
exports.handleEvent = function(event) {
switch(event.type) {
case "touchstart":
this.startZoomer(event.touches[0].clientX,event.touches[0].clientY);
this.hoverZoomer(event.touches[0].clientX,event.touches[0].clientY);
event.preventDefault();
return false;
case "touchmove":
this.hoverZoomer(event.touches[0].clientX,event.touches[0].clientY);
event.preventDefault();
return false;
case "touchend":
this.stopZoomer();
event.preventDefault();
return false;
}
};
exports.executeMacro = function() {
this.inZoomer = false;
return [];
};
})();