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draw.js
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draw.js
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// Constructor for Shape objects to hold data for all drawn objects.
// For now they will just be defined as rectangles.
function Shape(x, y, w, h, fill, type, text) {
// This is a very simple and unsafe constructor. All we're doing is checking if the values exist.
// "x || 0" just means "if there is a value for x, use that. Otherwise use 0."
// But we aren't checking anything else! We could put "Lalala" for the value of x
this.x = x || 0;
this.y = y || 0;
this.w = w || 1;
this.h = h || 1;
this.fill = fill || '#AAAAAA';
this.type = type || 'node';
this.text = text;
}
// Draws this shape to a given context
Shape.prototype.draw = function(ctx) {
ctx.fillStyle = this.fill;
ctx.fillRect(this.x, this.y, this.w, this.h);
ctx.fillStyle = 'white';
tx = this.x + (this.w/4);
ty = this.y + (this.h/2);
ctx.fillText(this.text, tx, ty);
//ctx.strokeText(this.text, tx, ty);
}
// Determine if a point is inside the shape's bounds
Shape.prototype.contains = function(mx, my) {
// All we have to do is make sure the Mouse X,Y fall in the area between
// the shape's X and (X + Height) and its Y and (Y + Height)
return (this.x <= mx) && (this.x + this.w >= mx) &&
(this.y <= my) && (this.y + this.h >= my);
}
Pict.prototype.contains = function(mx, my) {
// All we have to do is make sure the Mouse X,Y fall in the area between
// the shape's X and (X + Height) and its Y and (Y + Height)
return (this.x <= mx) && (this.x + this.w >= mx) &&
(this.y <= my) && (this.y + this.h >= my);
}
function Pict(img, dx, dy, w, h, type, text) {
this.img = new Image();
this.img.src = img;
this.x = dx;
this.y = dy;
this.w = w;
this.h = h;
this.type = type;
this.text = text;
}
function Line(start, end) {
this.start = start
this.end = end
}
function CanvasState(canvas) {
// **** First some setup! ****
this.canvas = canvas;
this.width = canvas.width;
this.height = canvas.height;
this.ctx = canvas.getContext('2d');
// This complicates things a little but but fixes mouse co-ordinate problems
// when there's a border or padding. See getMouse for more detail
var stylePaddingLeft, stylePaddingTop, styleBorderLeft, styleBorderTop;
if (document.defaultView && document.defaultView.getComputedStyle) {
this.stylePaddingLeft = parseInt(document.defaultView.getComputedStyle(canvas, null)['paddingLeft'], 10) || 0;
this.stylePaddingTop = parseInt(document.defaultView.getComputedStyle(canvas, null)['paddingTop'], 10) || 0;
this.styleBorderLeft = parseInt(document.defaultView.getComputedStyle(canvas, null)['borderLeftWidth'], 10) || 0;
this.styleBorderTop = parseInt(document.defaultView.getComputedStyle(canvas, null)['borderTopWidth'], 10) || 0;
}
// Some pages have fixed-position bars (like the stumbleupon bar) at the top or left of the page
// They will mess up mouse coordinates and this fixes that
var html = document.body.parentNode;
this.htmlTop = html.offsetTop;
this.htmlLeft = html.offsetLeft;
// **** Keep track of state! ****
this.valid = false; // when set to false, the canvas will redraw everything
this.shapes = []; // the collection of things to be drawn
this.images = [];
this.lines = [];
this.dragging = false; // Keep track of when we are dragging
// the current selected object. In the future we could turn this into an array for multiple selection
this.selection = null;
this.dblclick = null;
this.dragoffx = 0; // See mousedown and mousemove events for explanation
this.dragoffy = 0;
// **** Then events! ****
// This is an example of a closure!
// Right here "this" means the CanvasState. But we are making events on the Canvas itself,
// and when the events are fired on the canvas the variable "this" is going to mean the canvas!
// Since we still want to use this particular CanvasState in the events we have to save a reference to it.
// This is our reference!
var myState = this;
//fixes a problem where double clicking causes text to get selected on the canvas
canvas.addEventListener('selectstart', function(e) { e.preventDefault(); return false; }, false);
// Up, down, and move are for dragging
canvas.addEventListener('mousedown', function(e) {
var mouse = myState.getMouse(e);
var mx = mouse.x;
var my = mouse.y;
var images = myState.images;
var l = images.length;
for (var i = l-1; i >= 0; i--) {
if (images[i].contains(mx, my)) {
var mySel = images[i];
// Keep track of where in the object we clicked
// so we can move it smoothly (see mousemove)
myState.dragoffx = mx - mySel.x;
myState.dragoffy = my - mySel.y;
myState.dragging = true;
myState.selection = mySel;
myState.valid = false;
return;
}
}
// havent returned means we have failed to select anything.
// If there was an object selected, we deselect it
if (myState.selection) {
myState.selection = null;
myState.valid = false; // Need to clear the old selection border
}
}, true);
canvas.addEventListener('mousemove', function(e) {
if (myState.dragging){
var mouse = myState.getMouse(e);
// We don't want to drag the object by its top-left corner, we want to drag it
// from where we clicked. Thats why we saved the offset and use it here
myState.selection.x = mouse.x - myState.dragoffx;
myState.selection.y = mouse.y - myState.dragoffy;
myState.valid = false; // Something's dragging so we must redraw
}
}, true);
canvas.addEventListener('mouseup', function(e) {
myState.dragging = false;
}, true);
// double click for making new shapes
canvas.addEventListener('dblclick', function(e) {
var mouse = myState.getMouse(e);
var mx = mouse.x;
var my = mouse.y;
var images = myState.images;
var l = images.length;
for (var i = l-1; i >= 0; i--) {
if (images[i].contains(mx, my)) {
var mySel = images[i];
if (myState.dblclick != null) {
if (myState.dblclick != mySel) {
// One has to be a node and another a network
var types = [];
types.push(myState.dblclick.type);
types.push(mySel.type);
var net_found = 0;
var node_found = 0;
for(var nn = 0; nn < types.length; nn++) {
if (types[nn] == 'node'){
node_found = 1;
}
if (types[nn] == 'network'){
net_found = 1;
}
}
if (net_found == 0 || node_found == 0) {
// Clear selection
myState.dblclick = null;
return;
}
// Check if the selections are already connected
var lines = myState.lines;
var connected = null;
for (var ln=0; ln < lines.length; ln++) {
if (lines[ln].start == myState.dblclick &&
lines[ln].end == mySel) {
connected = lines[ln];
}
if (lines[ln].start == mySel &&
lines[ln].end == myState.dblclick) {
connected = lines[ln];
}
}
if (connected) {
// Remove connection
var newlines = new Array();
for (var ln=0; ln < lines.length; ln++) {
if (lines[ln] != connected) {
newlines.push(lines[ln]);
}
}
myState.lines = newlines;
lines = newlines;
myState.valid = false;
myState.draw();
myState.dblclick = null;
return;
}
// Check if the node is already connected to another network
var node = null;
if (myState.dblclick.type == 'node') {
node = myState.dblclick;
} else {
node = mySel;
}
newlines = new Array();
for (var ln=0; ln < lines.length; ln++) {
if (lines[ln].start == node || lines[ln].end == node) {
// Do not store this line
} else {
newlines.push(lines[ln]);
}
}
myState.lines = newlines;
// Draw line between elements
myState.addLine(new Line(myState.dblclick, images[i]));
// Clear selection
myState.dblclick = null;
return;
} else {
// Clear selection
myState.dblclick = null;
return;
}
}
myState.dblclick = mySel;
myState.valid = false;
return;
}
}
}, true);
// **** Options! ****
this.selectionColor = '#CC0000';
this.dblclickColor = '#07ED45';
this.dblclickWidth = 4;
this.selectionWidth = 2;
this.interval = 30;
setInterval(function() { myState.draw(); }, myState.interval);
}
CanvasState.prototype.addShape = function(shape) {
this.shapes.push(shape);
this.valid = false;
}
CanvasState.prototype.addLine = function(line) {
this.lines.push(line);
this.valid = false;
}
CanvasState.prototype.clear = function() {
this.ctx.clearRect(0, 0, this.width, this.height);
}
CanvasState.prototype.addImage = function(image) {
this.images.push(image)
this.valid = false;
}
// While draw is called as often as the INTERVAL variable demands,
// It only ever does something if the canvas gets invalidated by our code
CanvasState.prototype.draw = function() {
// if our state is invalid, redraw and validate!
if (!this.valid) {
var ctx = this.ctx;
var shapes = this.shapes;
this.clear();
// ** Add stuff you want drawn in the background all the time here **
// draw all shapes
var l = shapes.length;
for (var i = 0; i < l; i++) {
var shape = shapes[i];
// We can skip the drawing of elements that have moved off the screen:
if (shape.x > this.width || shape.y > this.height ||
shape.x + shape.w < 0 || shape.y + shape.h < 0) continue;
shapes[i].draw(ctx);
}
// Draw all images
var im = this.images.length;
for (var i=0; i < im; i++) {
var image = this.images[i];
ctx.drawImage(image.img, image.x, image.y, image.w, image.h);
ctx.font = "12px helvetica";
ctx.fillStyle = 'black';
ctx.fillText(image.text, image.x, image.y);
}
// draw selection
// right now this is just a stroke along the edge of the selected Shape
if (this.selection != null) {
ctx.strokeStyle = this.selectionColor;
ctx.lineWidth = this.selectionWidth;
var mySel = this.selection;
ctx.strokeRect(mySel.x,mySel.y,mySel.w,mySel.h);
}
if (this.dblclick != null) {
ctx.strokeStyle = this.dblclickColor;
ctx.lineWidth = this.dblclickWidth;
var mySel = this.dblclick;
ctx.strokeRect(mySel.x,mySel.y,mySel.w,mySel.h);
}
// ** Add stuff you want drawn on top all the time here **
// Draw lines
var ln = this.lines.length;
for (var i = 0; i < ln; i++) {
var line = this.lines[i];
// Get start element position
var start_x = line.start.x
var start_y = line.start.y
// Get end element position
var end_x = line.end.x
var end_y = line.end.y
cp_x = null;
cp_y = null;
// Check position of points relative to each other
if (start_x > end_x) {
// Left edge of start and right edge of end
start_y = line.start.y + (line.start.h/2);
end_x = line.end.x + line.end.w;
end_y = line.end.y + (line.end.h/2);
cp_x = start_x + ((start_x - end_x)/2);
} else {
// Right edge of start and left edge of end
start_y = line.start.y + (line.start.h/2);
start_x = line.start.x + line.start.w;
end_y = line.end.y + (line.end.h/2);
cp_x = end_x + ((end_x - start_x)/2);
}
// Calculate control points between lines
cp_y = (end_y + start_y)/2;
ctx.beginPath();
ctx.moveTo(start_x, start_y);
ctx.lineTo(end_x, end_y);
ctx.closePath();
//ctx.quadraticCurveTo(cp_x, cp_y, end_x, end_y);
ctx.lineWidth = 3;
ctx.strokeStyle = "red"; // line color
ctx.lineCap = "round";
ctx.stroke();
}
this.valid = true;
}
}
// Creates an object with x and y defined, set to the mouse position relative to the state's canvas
// If you wanna be super-correct this can be tricky, we have to worry about padding and borders
CanvasState.prototype.getMouse = function(e) {
var element = this.canvas, offsetX = 0, offsetY = 0, mx, my;
// Compute the total offset
if (element.offsetParent !== undefined) {
do {
offsetX += element.offsetLeft;
offsetY += element.offsetTop;
} while ((element = element.offsetParent));
}
// Add padding and border style widths to offset
// Also add the <html> offsets in case there's a position:fixed bar
offsetX += this.stylePaddingLeft + this.styleBorderLeft + this.htmlLeft;
offsetY += this.stylePaddingTop + this.styleBorderTop + this.htmlTop;
mx = e.pageX - offsetX;
my = e.pageY - offsetY;
// We return a simple javascript object (a hash) with x and y defined
return {x: mx, y: my};
}
// If you dont want to use <body onLoad='init()'>
// You could uncomment this init() reference and place the script reference inside the body tag
//init();
function init() {
var s = new CanvasState(document.getElementById('box'));
s.addShape(new Shape(40,40,50,50)); // The default is gray
s.addShape(new Shape(60,140,40,60, 'lightskyblue'));
// Lets make some partially transparent
s.addShape(new Shape(80,150,60,30, 'rgba(127, 255, 212, .5)'));
s.addShape(new Shape(125,80,30,80, 'rgba(245, 222, 179, .7)'));
}
// Now go make something amazing!