LogarithmPlotter/qml/LogGraphCanvas.qml

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/**
* Logarithm Graph Creator - Create graphs with logarithm scales.
* Copyright (C) 2020 Ad5001
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
import QtQuick 2.12
import "js/objects.js" as Objects
import "js/utils.js" as Utils
import "js/mathlib.js" as MathLib
Canvas {
id: canvas
anchors.top: separator.bottom
anchors.left: parent.left
height: parent.height - 90
width: parent.width
property double xmin: 0
property double ymax: 0
property int xzoom: 10
property int yzoom: 10
property string xaxisstep: "4"
property string yaxisstep: "4"
property string xlabel: ""
property string ylabel: ""
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property int maxgradx: 8
property bool logscalex: false
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property bool showxgrad: false
property bool showygrad: false
property var yaxisstepExpr: (new MathLib.Expression(`x*(${yaxisstep})`))
property double yaxisstep1: yaxisstepExpr.execute(1)
property int drawMaxY: Math.ceil(Math.max(Math.abs(ymax), Math.abs(px2y(canvasSize.height)))/yaxisstep1)
property var xaxisstepExpr: (new MathLib.Expression(`x*(${xaxisstep})`))
property double xaxisstep1: xaxisstepExpr.execute(1)
property int drawMaxX: Math.ceil(Math.max(Math.abs(xmin), Math.abs(px2x(canvasSize.width)))/xaxisstep1)
onPaint: {
//console.log('Redrawing')
var ctx = getContext("2d");
reset(ctx)
drawGrille(ctx)
drawAxises(ctx)
for(var objType in Objects.currentObjects) {
for(var obj of Objects.currentObjects[objType]){
ctx.strokeStyle = obj.color
ctx.fillStyle = obj.color
if(obj.visible) obj.draw(canvas, ctx)
}
}
drawLabels(ctx)
}
function reset(ctx){
// Reset
ctx.fillStyle = "#FFFFFF"
ctx.strokeStyle = "#000000"
ctx.font = "12px sans-serif"
ctx.fillRect(0,0,width,height)
}
// Drawing the log based graph
function drawGrille(ctx) {
ctx.strokeStyle = "#C0C0C0"
if(logscalex) {
for(var xpow = -maxgradx; xpow <= maxgradx; xpow++) {
for(var xmulti = 1; xmulti < 10; xmulti++) {
drawXLine(ctx, Math.pow(10, xpow)*xmulti)
}
}
} else {
for(var x = 0; x < drawMaxX; x+=1) {
drawXLine(ctx, x*xaxisstep1)
drawXLine(ctx, -x*xaxisstep1)
}
}
for(var y = 0; y < drawMaxY; y+=1) {
drawYLine(ctx, y*yaxisstep1)
drawYLine(ctx, -y*yaxisstep1)
}
}
function drawAxises(ctx) {
ctx.strokeStyle = "#000000"
var axisypos = logscalex ? 1 : 0
drawXLine(ctx, axisypos)
drawYLine(ctx, 0)
var axisypx = x2px(axisypos) // X coordinate of Y axis
var axisxpx = y2px(0) // Y coordinate of X axis
// Drawing arrows
drawLine(ctx, axisypx, 0, axisypx-10, 10)
drawLine(ctx, axisypx, 0, axisypx+10, 10)
drawLine(ctx, canvasSize.width, axisxpx, canvasSize.width-10, axisxpx-10)
drawLine(ctx, canvasSize.width, axisxpx, canvasSize.width-10, axisxpx+10)
}
function drawLabels(ctx) {
var axisypx = x2px(logscalex ? 1 : 0) // X coordinate of Y axis
var axisxpx = y2px(0) // Y coordinate of X axis
// Labels
ctx.fillStyle = "#000000"
ctx.font = "16px sans-serif"
ctx.fillText(ylabel, axisypx+5, 24)
var textSize = ctx.measureText(xlabel).width
ctx.fillText(xlabel, canvasSize.width-14-textSize, axisxpx-5)
// Axis graduation labels
ctx.font = "12px sans-serif"
var txtMinus = ctx.measureText('-').width
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if(showxgrad) {
if(logscalex) {
for(var xpow = -maxgradx; xpow <= maxgradx; xpow+=1) {
var textSize = ctx.measureText("10"+Utils.textsup(xpow)).width
if(xpow != 0)
drawVisibleText(ctx, "10"+Utils.textsup(xpow), x2px(Math.pow(10,xpow))-textSize/2, axisxpx+16+(6*(y==0)))
}
} else {
for(var x = 1; x < drawMaxX; x += 1) {
var drawX = x*xaxisstep1
var txtX = xaxisstepExpr.simplify(x)
var textSize = measureText(ctx, txtX, 6).height
drawVisibleText(ctx, txtX, x2px(drawX)-4, axisxpx+6+textSize)
drawVisibleText(ctx, '-'+txtX, x2px(-drawX)-4, axisxpx+6+textSize)
}
}
}
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if(showygrad) {
for(var y = 0; y < drawMaxY; y += 1) {
var drawY = y*yaxisstep1
var txtY = yaxisstepExpr.simplify(y)
var textSize = ctx.measureText(txtY).width
drawVisibleText(ctx, txtY, axisypx-6-textSize, y2px(drawY)+4+(10*(y==0)))
if(y != 0)
drawVisibleText(ctx, '-'+txtY, axisypx-6-textSize-txtMinus, y2px(-drawY)+4)
}
}
ctx.fillStyle = "#FFFFFF"
}
function drawXLine(ctx, x) {
if(visible(x, ymax)) {
drawLine(ctx, x2px(x), 0, x2px(x), canvasSize.height)
}
}
function drawYLine(ctx, y) {
if(visible(xmin, y)) {
drawLine(ctx, 0, y2px(y), canvasSize.width, y2px(y))
}
}
function drawVisibleText(ctx, text, x, y, lineHeight = 14) {
if(x > 0 && x < canvasSize.width && y > 0 && y < canvasSize.height) {
text.toString().split("\n").forEach(function(txt, i){
ctx.fillText(txt, x, y+(lineHeight*i))
})
}
}
// Method to calculate multi-line string dimensions
function measureText(ctx, text, lineHeight=14) {
var theight = 0
var twidth = 0
text.split("\n").forEach(function(txt, i){
theight += lineHeight
if(ctx.measureText(txt).width > twidth) twidth = ctx.measureText(txt).width
})
return {'width': twidth, 'height': theight}
}
// Converts x coordinate to it's relative position on the
function x2px(x) {
if(logscalex) {
var logxmin = Math.log(xmin)
return (Math.log(x)-logxmin)*xzoom
} else return (x - xmin)*xzoom
}
// Converts y coordinate to it's relative position on the
// Y is NOT ln based.
function y2px(y) {
return (ymax-y)*yzoom
}
// Reverse functions
function px2x(px) {
if(logscalex) {
return Math.exp(px/xzoom+Math.log(xmin))
} else return (px/xzoom+xmin)
}
function px2y(px) {
return -(px/yzoom-ymax)
}
// Checks whether a point is visible or not.
function visible(x, y) {
return (x2px(x) >= 0 && x2px(x) <= canvasSize.width) && (y2px(y) >= 0 && y2px(y) <= canvasSize.height)
}
// Draws a line from a (x1, y1) to (x2, y2)
function drawLine(ctx, x1, y1, x2, y2) {
ctx.beginPath();
ctx.moveTo(x1, y1);
ctx.lineTo(x2, y2);
ctx.stroke();
}
function drawDashedLine(ctx, x1, y1, x2, y2, dashPxSize = 10) {
var distance = Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))
var progPerc = dashPxSize/distance
ctx.beginPath();
ctx.moveTo(x1, y1);
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for(var i = 0; i < 1; i += progPerc) {
ctx.lineTo(x1-(x1-x2)*i, y1-(y1-y2)*i)
ctx.moveTo(x1-(x1-x2)*(i+progPerc/2), y1-(y1-y2)*(i+progPerc/2))
}
ctx.stroke();
}
}