In questo codice il risultato di calcolo per ogni pixel viene salvato in un array imgData che poi
trasferito in un colpo sul Canvas. In questo modo il tempo di calcolo e' divenuto inferiore ad un terzo di quello della precedente prova
/*
* Copyright (C) 2020 Luca Innocenit
*
* 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; version 3.
*
* ubuntu-calculator-app 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 <http://www.gnu.org/licenses/>.
*/
import QtQuick 2.7
import Ubuntu.Components 1.3
//import QtQuick.Controls 2.2
import QtQuick.Layouts 1.3
import Qt.labs.settings 1.0
import QtQuick.Window 2.2
MainView {
id: root
objectName: 'mainView'
applicationName: 'qtcpp.com.luca.innocenti'
automaticOrientation: true
visible: true
width: Screen.width
height: Screen.width
Canvas {
id: mycanvas
anchors.centerIn: parent
width: Screen.width
height: Screen.width
onPaint: {
console.log("width "+ width.toString())
console.log("height "+ height.toString())
var ctx = getContext("2d");
ctx.fillStyle = Qt.rgba(0, 0, 0, 1);
ctx.fillRect(0, 0, width, height);
var imgData = ctx.createImageData(height, width);
////////
var re_min = -2.0;
var im_min = -1.2;
var re_max = 0.7;
var im_max = 1.2;
var iterazioni = 50;
var r;
var a,b;
var x,y,x_new,y_new;
var test;
var re_factor = (re_max-re_min);
var im_factor = (im_max-im_min);
var indice = 0;
for (var i=0;i<width;i++)
{
for (var j=0;j<height;j++)
{
a = re_min+(j*re_factor/height);
b = im_min+(i*im_factor/width);
x = 0;
y = 0;
test = 0;
imgData.data[indice+3]= 255;
//console.log(indice)
for (var k=0;k<iterazioni;k++)
{
x_new = (x*x)-(y*y)+a;
y_new = (2*x*y)+b;
if (((x_new*x_new)+(y_new*y_new))>4)
{
if (k%2)
{
// colora il punto
imgData.data[indice]=255;
imgData.data[indice+1]=255;
imgData.data[indice+2]=255;
}
break;
}
x = x_new;
y = y_new;
}
indice = indice + 4;
}
}
///////
console.log("terminato")
ctx.drawImage(imgData, 0, 0);
}
}
}
