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function ImagePicker(dz){
var dropZone = document.getElementById(dz);
var zoom = null; // Zoom Slider
var rotate = null; // Rotate Slider
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var img = new Image();
var WIDTH = canvas.width; // Canvas width;
var HEIGHT = canvas.height; // Canvas height;
var posX = null;
var posY = null;
/**
* Control slider activation and default values.
*/
var adaptSlider = function(width, height){
rotate.disabled = false;
zoom.disabled = false;
zoom.oldValue = 100;
};
/**
* Handles dropped file and draws it into canvas.
*/
var handleFileSelect = function(evt){
evt.stopPropagation();
evt.preventDefault();
var file = evt.dataTransfer.files[0]; // FileList object.
var reader = new FileReader();
// Closure to capture the file information.
reader.onload = (function(f) {
return function(e) {
img.src = e.target.result;
img.onload = function(){
adaptSlider(this.width, this.height);
ctx.drawImage(this, 0, 0, this.width, this.height);
};
};
})(file);
// Read in the image file as a data URL.
reader.readAsDataURL(file);
};
/**
* Handles dropped file when it is not on the drop zone
*/
var handleDragOver = function(evt){
evt.stopPropagation();
evt.preventDefault();
evt.dataTransfer.dropEffect = 'copy'; // Explicitly show this is a copy.
};
/**
* Handles image zoom.
*/
var onZoom = function(evt){
/*
* I want to rescale image from its own center if it is smaller that canvas. not from the left-top corner.
* Doesn't work.
*/
if(img.width * zoom.value / 100 < WIDTH || img.height * zoom.value / 100 < HEIGHT){
/*ctx.scale(zoom.value / 100, zoom.value / 100);
var decalWidth = - ((img.width * zoom.value / 100));
var decalHeight = - ((img.height * zoom.value / 100));
console.log(decalWidth, decalHeight);
ctx.translate(WIDTH - decalWidth, HEIGHT - decalHeight);
ctx.drawImage(img, 0, 0 , img.width, img.height);*/
} else { // Default béhavior.
ctx.clearRect ( 0 ,0 , WIDTH , HEIGHT );
ctx.save();
ctx.scale(zoom.value / 100, zoom.value / 100);
ctx.drawImage(img, 0, 0, img.width, img.height);
ctx.restore();
}
};
/**
* Handles image rotation.
*/
var onRotate = function(evt){
ctx.clearRect ( 0 ,0 , WIDTH , HEIGHT );
ctx.save();
/*
* Quel valeur dois-je utiliser pour que le point d'origine correspond au centre de mon image même si le canvas à été redimensionné?
* Quel valeur doi-je ensuite utilisé comme coordonnée de l'image?
*/
ctx.translate(img.width * (zoom.value/100) /2, img.height * (zoom.value/100) /2);
ctx.rotate(rotate.value*Math.PI/180);
ctx.drawImage(img, -1 * (img.width * (zoom.value/100) /2), -1 * (img.height * (zoom.value/100) /2), img.width, img.height );
ctx.restore();
};
/**
* Handles image move.
*/
var onMouseMove = function(evt){
var newPosX = evt.pageX;
var newPosY = evt.pageY;
ctx.clearRect ( 0 ,0 , WIDTH , HEIGHT );
//ctx.drawImage(img, newPosX - posX , newPosY - posY , img.width, img.height );
if(newPosX > posX && newPosY > posY)
ctx.drawImage(img, newPosX - posX , newPosY - posY , img.width, img.height );
else if(newPosX < posX && newPosY < posY)
ctx.drawImage(img, newPosX - posX , newPosY - posY , img.width, img.height );
else if(newPosX > posX && newPosY < posY)
ctx.drawImage(img, newPosX - posX , newPosY - posY , img.width, img.height );
else if(newPosX < posX && newPosY > posY)
ctx.drawImage(img, newPosX - posX , newPosY - posY , img.width, img.height );
};
var handlePictureMove = function(evt){
posX = evt.pageX;
posY = evt.pageY;
canvas.addEventListener('mousemove', onMouseMove, false);
canvas.addEventListener('mouseup', function(evt){
canvas.removeEventListener('mousemove', onMouseMove, false);
}, false);
};
/**
* Set the slider that control zoom.
*/
this.setZoom = function(elem){
zoom = elem;
zoom.addEventListener('input', onZoom, false);
zoom.addEventListener('change', onZoom, false);
};
/**
* Set the slider that control rotation.
*/
this.setRotate = function(elem){
rotate = elem;
rotate.addEventListener('input', onRotate, false);
rotate.addEventListener('change', onRotate, false);
};
dropZone.addEventListener('dragover', handleDragOver, false);
dropZone.addEventListener('drop', handleFileSelect, false);
canvas.addEventListener('mousedown', handlePictureMove, false);
}; |
Edition photo dans un canvas
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