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233 lines (193 loc) · 8.71 KB
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var QuickPlot = function(canvas){
//Canvas properties
this.canvas;
this.canvasContext;
this.canvasWidth;
this.canvasHeight;
//Graph properties
this.canvasBackgroundColor;
this.functionColor;
this.graphDomain; //Domain/range from far left to far right of the canvas
this.graphRange;
this.drawAxis;
//Function properties
this.functionLambda;
this.functionDomain; //What domain/range to graph the function on
this.functionRange;
//METHODS-----------------------------------------------------------
//void notifyCanvasSizeUpdate(redraw)
//Refreshes canvas width and height and scales graph accordingly.
//Redraws after internal resizing if redraw=true
this.notifyCanvasSizeUpdate = function(redraw){
this.canvasWidth = this.canvas.width;
this.canvasHeight = this.canvas.height;
if(redraw){
this.drawGraph();
}
}
//SETTERS
//void setDrawAxis(enabled) enables drawing the axis if passed true.
//NOTE: Does not update canvas.
this.setDrawAxis = function(enabled){
this.drawAxis = enabled;
}
//void setBackgroundColor(color) sets the background color for the canvas.
//Note: Does not update canvas
//E.g. setBackgroundColor("#FFFFFF");
this.setBackgroundColor = function(color){
this.canvasBackgroundColor = color;
}
//void setFunctionColor(color) sets the function plot color.
//Note: Does not update canvas.
//E.g. setFunctionColor("#e3e300");
this.setFunctionColor = function(color){
this.functionColor = color;
}
//void setGraphDomain(from, to) sets the graph domain.
//E.g. setGraphDomain(-2.5, 2.5) would make the very left of the graph x=-2.5 and
// the very right of the graph x=2.5
this.setGraphDomain = function(from, to){
this.graphDomain = {"from": from,
"to": to};
if(this.functionDomain == undefined){
this.functionDomain = this.graphDomain;
}
}
//void setGraphRange(from, to) sets the graph range.
//E.g. setGraphRange(-3, 0) would make the very top of the graph y=0 and
// the very bottom of the graph y=-3
this.setGraphRange = function(from, to){
this.graphRange = {"from": from,
"to": to};
if(this.functionRange == undefined){
this.functionRange = this.graphRange;
}
}
//void setFunction(functionLambda) sets the function to be plotted to functionLambda
//NOTE: setFunction does not update the canvas
//NOTE: functionLambda must have one parameter and must output a floating point number.
this.setFunction = function(functionLambda){
this.functionLambda = functionLambda;
}
//void setFunctionDomain(from, to) sets the domain the function should be plotted on.
//NOTE: This domain is bounded by the canvas domain.
this.setFunctionDomain = function(from, to){
this.functionDomain = {"from": from,
"to": to};
}
//void setFunctionRange(from, to) sets the range the function should be plotted on.
//NOTE: This range is bounded by the canvss range.
this.setFunctionRange = function(from, to){
this.functionRange = {"from": from,
"to": to};
}
//GETTERS
//Boolean getDrawAxis() returns whether or not axis is currently being drawn.
this.getDrawAxis = function(){
return this.drawAxis;
}
//Object getBackgroundColor() returns the current canvas background color.
this.getBackgroundColor = function(){
return this.canvasBackgroundColor;
}
//Object getFunctionColor() returns the current function color.
this.getFunctionColor = function(){
return this.functionColor;
}
//Object getGraphDomain() returns the current graph domain object.
this.getGraphDomain = function(){
return this.graphDomain;
}
//Object getGraphRange() returns the current graph range object.
this.getGraphRange = function(){
return this.graphRange;
}
//Object getFunctionDomain() returns the current function domain object.
this.getFunctionDomain = function(){
return this.functionDomain;
}
//Object getFunctionRange() returns the current function range object.
this.getFunctionRange = function(){
return this.functionRange;
}
//Function getFunctionLambda() returns the current function lambda.
this.getFunctionLambda = function(){
return this.functionLambda;
}
//boolean drawGraph() draws the graph according to properties set using setters.
//NOTE: Returns false and prints an error if draw fails. Otherwise returns true.
this.drawGraph = function(){
//Check for valid properties
var errorFlag = false;
if(this.canvas == undefined || this.canvasContext == undefined){
errorFlag = true;
console.error("QuickPlot Error: Canvas not defined");
}
if(this.canvasWidth <=0 || this.canvasHeight <= 0){
errorFlag = true;
console.error("QuickPlot Error: Canvas dimension error.");
}
if(this.functionLambda == undefined || this.functionLambda == undefined){
errorFlag = true;
console.error("QuickPlot Error: Function not defined.");
}
if(this.graphDomain == undefined || this.graphRange == undefined){
errorFlag = true;
console.error("QuickPlot Error: Graph domain or range not set.");
}
if(this.graphDomain.to - this.graphDomain.from <= 0){
errorFlag = true;
console.error("QuickPlot Error: Graph domain error.");
}
if(errorFlag){
return false;
}
//Properties are valid, we can draw the graph now.
//First, draw the background.
this.canvasContext.fillStyle = (this.canvasBackgroundColor == undefined) ? "#FFFFFF" : this.canvasBackgroundColor;
this.canvasContext.fillRect(0, 0, this.canvasWidth, this.canvasHeight);
//Now draw the axis:
if(this.drawAxis){
var xAxis = (-1 * this.graphDomain.from) * (this.canvasWidth)/(this.graphDomain.to - this.graphDomain.from);
var yAxis = (-1 * this.graphRange.from) * (this.canvasHeight)/(this.graphRange.to - this.graphRange.from);
//Change to black color for axis
this.canvasContext.fillStyle = "#000000";
this.canvasContext.fillRect(xAxis, 0, 1, this.canvasHeight);
this.canvasContext.fillRect(0, (this.canvasHeight - yAxis), this.canvasWidth, 1);
//We flip the y because y=0 is at the top of the canvas
}
//Finally, the function
this.canvasContext.fillStyle = (this.functionColor == undefined) ? "#AA0000" : this.functionColor;
//We cache previous y2 values because they're the same as y1 on the next iteration.
var cacheY1 = null;
var cacheY1Pixel = null;
for(var i = 0; i<=this.canvasWidth; i++){
var x = ((i) * ((this.graphDomain.to - this.graphDomain.from) / this.canvasWidth)) + this.graphDomain.from;
if(x < this.functionDomain.from || x > this.functionDomain.to)
continue;
var y1 = (cacheY1 == null) ? this.functionLambda(x) : cacheY1;
var y2 = this.functionLambda(x+((this.graphDomain.to - this.graphDomain.from) / this.canvasWidth));
var y1Pixel = (cacheY1Pixel == null) ? ((y1 - this.graphRange.from) * (this.canvasHeight) / (this.graphRange.to - this.graphRange.from)) : cacheY1Pixel;
var y2Pixel = ((y2 - this.graphRange.from) * (this.canvasHeight) / (this.graphRange.to - this.graphRange.from));
var point = Math.max(y1Pixel, y2Pixel);
var height = Math.abs(y1Pixel-y2Pixel)+1;
this.canvasContext.fillRect(i, this.canvasHeight - point, 1, height);
cacheY1 = y2;
cacheY1Pixel = y2Pixel;
}
}
//Initialization function - gets called on instantiation
this.init = function(){
if(canvas.nodeName.toLowerCase() != "canvas"){
console.log(canvas.nodeName.toLowerCase());
console.error("Invalid canvas passed to QuickPlot");
return 1;
}
this.canvas = canvas;
this.canvasContext = canvas.getContext("2d");
this.canvasWidth = canvas.width;
this.canvasHeight = canvas.height;
this.drawAxis = true;
}
this.init(canvas);
}