tonalisa/qml/FFTDisplay.qml

//    tonalisa - software to look at overtone-structures
//    Copyright (C) 2016  Dominik Schmidt-Philipp
//
//    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 <http://www.gnu.org/licenses/>.
//
import QtQuick 2.0

Item {
    id:root
    width:512; height:300

    property string file: activeAudioFile.path
    property real sampleRate: activeAudioFile.sampleRate
    property int fftSize: activeAudioFile.npts
    property var fftData: activeAudioFile.spectrum
    property var grid: [[100,300,500,1000,2000,5000,10000]]
    property var pixelData: []
    property real leftHz: 0
    property real rightHz: 10000

    property real max:0
    property real min:0
    
    function binToHertz(bin) {
	return bin * sampleRate / fftSize
    }
    function hertzToBin(hertz) {
	return Math.floor(hertz * fftSize / sampleRate)
    }
    function binToX(bin) {
	return width * (binToHertz(bin)-leftHz)/(rightHz-leftHz)
    }
    onFftDataChanged: {
        display.requestPaint()
    }
    onLeftHzChanged: {
        display.requestPaint()
    }
    onRightHzChanged: {
        display.requestPaint()
    }
    Canvas {
        id: display
        anchors.fill: parent
        function scale(val){
            return -Math.log(val/sampleRate)  * 8
        }
        onPaint: {
            var ctx = getContext("2d")

            ctx.fillStyle = Qt.rgba(255,255,255,1);
            ctx.fillRect(0,0,width,height);

            ctx.beginPath()
            var i = hertzToBin(leftHz)
            ctx.moveTo(binToX(i),scale(fftData[i]))

            while ( i<hertzToBin( rightHz )) {
                i++

                ctx.lineTo(binToX(i),scale(fftData[i]))
            }
            ctx.strokeStyle = "#000000";
            ctx.stroke()
        }
        MouseArea {
            anchors.fill: parent
            onPressed: {
                fftvalue.text = "val= " + fftData[mouse.x];
            }
        }
    }
}