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TiddlyWiki5/archive/js/macros/zoomer.js
2012-05-05 22:49:23 +01:00

107 lines
3.8 KiB
JavaScript

/*\
title: js/macros/zoomer.js
\*/
(function(){
/*jslint node: true, browser: true */
"use strict";
var Renderer = require("../Renderer.js").Renderer,
Dependencies = require("../Dependencies.js").Dependencies,
Tiddler = require("../Tiddler.js").Tiddler,
utils = require("../Utils.js");
function startZoomer(macroNode,x,y) {
macroNode.inZoomer = true;
macroNode.startX = x;
macroNode.startY = y;
utils.addClass(document.body,"in-zoomer");
}
function stopZoomer(macroNode) {
var newScrollY = macroNode.yFactor * (macroNode.bodyHeight - macroNode.windowHeight);
macroNode.inZoomer = false;
window.scrollTo(0,newScrollY);
document.body.style.webkitTransform = "translateY(" + newScrollY * macroNode.xFactor + "px) " +
"scale(" + macroNode.scale + ") " +
"translateY(" + ((macroNode.windowHeight / macroNode.scale) - macroNode.bodyHeight) * macroNode.yFactor * macroNode.xFactor + "px)";
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
*/
function hoverZoomer(macroNode,x,y) {
// Put the transform origin at the top in the middle
document.body.style.webkitTransformOrigin = "50% 0";
// Some shortcuts
macroNode.bodyWidth = document.body.offsetWidth;
macroNode.bodyHeight = document.body.offsetHeight;
macroNode.windowWidth = window.innerWidth;
macroNode.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
macroNode.minScale = macroNode.windowHeight / macroNode.bodyHeight;
if(macroNode.minScale < 0.1) {
// Don't scale to less than 10% of original size
macroNode.minScale = 0.1;
} else if(macroNode.minScale > 1) {
// Nor should we scale up if the body is shorter than the window
macroNode.minScale = 1;
}
// We divide the screen into two horizontal zones divided by the right edge of the body at maximum zoom (ie minimum scale)
macroNode.splitPos = macroNode.windowWidth/2 + (macroNode.bodyWidth * macroNode.minScale)/2;
// Compute the 0->1 ratio (from right to left) of the position of the touch within the right zone
macroNode.xFactor = (macroNode.windowWidth - x) / (macroNode.windowWidth - macroNode.splitPos);
if(macroNode.xFactor > 1) {
macroNode.xFactor = 1;
}
// And the 0->1 ratio (from top to bottom) of the position of the touch down the screen
macroNode.yFactor = y/macroNode.windowHeight;
// Now interpolate the scale
macroNode.scale = (macroNode.minScale - 1) * macroNode.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 * macroNode.xFactor,
scale = macroNode.scale,
postTranslateY = ((macroNode.windowHeight / macroNode.scale) - macroNode.bodyHeight) * macroNode.yFactor * macroNode.xFactor;
var transform = "translateY(" + preTranslateY.toFixed(8) + "px) " +
"scale(" + scale.toFixed(8) + ") " +
"translateY(" + postTranslateY.toFixed(8) + "px)";
document.body.style.webkitTransform = transform;
}
exports.macro = {
name: "zoomer",
wrapperTag: "div",
params: {
},
events: {
touchstart: function(event) {
startZoomer(this,event.touches[0].clientX,event.touches[0].clientY);
hoverZoomer(this,event.touches[0].clientX,event.touches[0].clientY);
event.preventDefault();
return false;
},
touchmove: function(event) {
hoverZoomer(this,event.touches[0].clientX,event.touches[0].clientY);
event.preventDefault();
return false;
},
touchend: function(event) {
stopZoomer(this);
event.preventDefault();
return false;
}
},
execute: function() {
this.inZoomer = false;
return [];
}
};
})();