179 lines
No EOL
5.9 KiB
JavaScript
179 lines
No EOL
5.9 KiB
JavaScript
function Graph(config) {
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// user defined properties
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this.minX = config.minX;
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this.minY = config.minY;
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this.maxX = config.maxX;
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this.maxY = config.maxY;
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this.unitsPerTick = config.unitsPerTick;
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this.centerY = config.centerY; /*center x and y is the "origin" of the graph relative to canvas location*/
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this.centerX = config.centerX;
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// constants
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this.canvas = document.getElementById('myCanvas');
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this.tickSize = 20;
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// relationships
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this.context = this.canvas.getContext('2d');
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this.rangeX = this.maxX - this.minX;
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this.rangeY = this.maxY - this.minY;
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this.unitX = this.canvas.width / this.rangeX;
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this.unitY = this.canvas.height / this.rangeY;
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this.iteration = (this.maxX - this.minX) / 1000;
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this.scaleX = this.canvas.width / this.rangeX;
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this.scaleY = this.canvas.height / this.rangeY;
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this.XmaxUnit;
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this.XminUnit;
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// draw x and y axis
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this.drawXAxis();
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this.drawYAxis();
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this.drawGrid();
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}
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Graph.prototype.drawXAxis = function () {
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var context = this.context;
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context.save();
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context.beginPath();
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context.moveTo(0, this.centerY);
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context.lineTo(this.canvas.width, this.centerY);
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context.strokeStyle = 'green';
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context.lineWidth = 2;
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context.stroke();
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context.restore();
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};
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Graph.prototype.drawYAxis = function () {
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var context = this.context;
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context.save();
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context.beginPath();
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context.moveTo(this.centerX, 0);
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context.lineTo(this.centerX, this.canvas.height);
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context.strokeStyle = 'green';
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context.lineWidth = 2;
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context.stroke();
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context.restore();
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};
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Graph.prototype.drawGrid = function () {
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var context = this.context;
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context.save();
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context.beginPath();
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context.strokeStyle = '#8c8c8c';
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context.fillStyle = '#000000';
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context.lineWidth = 2;
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// Sets up x coordinate tick marks
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var xPosIncrement = this.unitsPerTick * this.unitX;
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var xPos, unit;
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context.font = '12pt Ubuntu';
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context.textAlign = 'left';
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context.textBaseline = 'top';
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// draws vertical lines before x = 0
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xPos = this.centerX - xPosIncrement;
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unit = -1 * this.unitsPerTick;
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while (xPos > 0) {
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context.moveTo(xPos, this.centerY - this.tickSize / 2);
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context.lineTo(xPos, this.canvas.height);
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context.lineTo(xPos, -this.canvas.height);
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context.stroke();
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context.fillText(unit, xPos, this.centerY + this.tickSize / 2 + 3);
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unit -= this.unitsPerTick;
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xPos = Math.round(xPos - xPosIncrement);
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this.XminUnit = unit;
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}
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if (this.XminUnit === undefined) {
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this.XminUnit = -1;
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}
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// draws vertical lines after x = 0
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xPos = this.centerX + xPosIncrement;
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unit = this.unitsPerTick;
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while (xPos < this.canvas.width) {
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context.moveTo(xPos, this.centerY - this.tickSize / 2);
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context.lineTo(xPos, this.canvas.height);
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context.lineTo(xPos, -this.canvas.height);
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context.stroke();
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context.fillText(unit, xPos, this.centerY + this.tickSize / 2 + 3);
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unit += this.unitsPerTick;
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xPos = Math.round(xPos + xPosIncrement);
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this.XmaxUnit = unit;
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}
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// Sets up Y coordinate tick marks
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var yPosIncrement = this.unitsPerTick * this.unitY;
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var yPos, unit;
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context.font = '12pt Ubuntu';
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context.textAlign = 'right';
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context.textBaseline = 'bottom';
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// draws horizontal lines after y = 0
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yPos = this.centerY - yPosIncrement;
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unit = this.unitsPerTick;
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while (yPos > 0) {
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context.moveTo(this.centerX - this.tickSize / 2, yPos);
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context.lineTo(this.canvas.width, yPos);
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context.lineTo(-this.canvas.width, yPos);
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context.stroke();
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context.fillText(unit, this.centerX - this.tickSize / 2 - 3, yPos);
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unit += this.unitsPerTick;
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yPos = Math.round(yPos - yPosIncrement);
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}
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// draws horizontal lines before y = 0
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yPos = this.centerY + yPosIncrement;
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unit = -1 * this.unitsPerTick;
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while (yPos < this.canvas.height) {
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context.moveTo(this.centerX - this.tickSize / 2, yPos);
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context.lineTo(this.canvas.width, yPos);
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context.lineTo(-this.canvas.width, yPos);
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context.stroke();
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context.fillText(unit, this.centerX - this.tickSize / 2 - 3, yPos);
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unit -= this.unitsPerTick;
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yPos = Math.round(yPos + yPosIncrement);
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}
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context.restore();
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};
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Graph.prototype.drawEquation = function (equation) {
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var context = this.context;
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context.save();
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this.transformContext();
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context.beginPath();
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context.moveTo(this.XminUnit, equation(this.XminUnit));
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for (var x = this.XminUnit + this.iteration; x <= this.XmaxUnit; x += this.iteration) {
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context.lineTo(x, equation(x));
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}
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context.restore();
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context.lineJoin = 'round';
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context.lineWidth = 1;
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context.strokeStyle = 'red';
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context.stroke();
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context.restore();
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};
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Graph.prototype.drawPoint = function (goalx, goaly) {
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var context = this.context;
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context.save();
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this.transformContext();
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context.beginPath();
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var c = document.getElementById("myCanvas");
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var img = document.getElementById("balloon");
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context.drawImage(img, goalx - 0.32, goaly - 0.48, 0.64, 0.96);
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context.stroke();
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context.restore();
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};
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//sets context to origin
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Graph.prototype.transformContext = function () {
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var context = this.context;
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this.context.translate(this.centerX, this.centerY);
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context.scale(this.scaleX, -this.scaleY);
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};
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Graph.prototype.reset = function () {
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var context = this.context;
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context.save();
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context.fillStyle = 'white';
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context.fillRect(0, 0, myCanvas.width, myCanvas.height);
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this.drawXAxis();
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this.drawYAxis();
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this.drawGrid();
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context.restore();
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}; |