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Qt: use non-linear scale for zoom slider

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This commit is contained in:
Brad Parker 2018-05-03 23:58:15 -04:00
parent e372bb5320
commit fc3251b6a9
1 changed files with 33 additions and 4 deletions
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37
ui/drivers/qt/ui_qt_window.cpp
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@ -54,6 +54,7 @@ extern "C" {
#include <encodings/utf.h>
#include <file/file_path.h>
#include <file/archive_file.h>
#include <math.h>
}
#define TIMER_MSEC 1000 /* periodic timer for gathering statistics */
@ -85,6 +86,24 @@ enum CoreSelection
CORE_SELECTION_LOAD_CORE
};
static double lerp(double x, double y, double a, double b, double d) {
return a + (b - a) * ((double)(d - x) / (double)(y - x));
}
/* https://stackoverflow.com/questions/7246622/how-to-create-a-slider-with-a-non-linear-scale */
static double expScale(double inputValue, double midValue, double maxValue)
{
double returnValue = 0;
double M = maxValue / midValue;
double C = log(pow(M - 1, 2));
double B = maxValue / (exp(C) - 1);
double A = -1 * B;
returnValue = A + B * exp(C * inputValue);
return returnValue;
}
#ifdef HAVE_LIBRETRODB
static void scan_finished_handler(void *task_data, void *user_data, const char *err)
{
@ -513,12 +532,15 @@ MainWindow::MainWindow(QWidget *parent) :
QToolButton *searchResetButton = NULL;
QWidget *zoomWidget = new QWidget();
QHBoxLayout *zoomLayout = new QHBoxLayout();
QLabel *zoomLabel = new QLabel("Zoom:", zoomWidget);
int i = 0;
zoomLabel->setObjectName("zoomLabel");
m_zoomSlider = new QSlider(Qt::Horizontal, zoomWidget);
m_zoomSlider->setMinimum(20);
m_zoomSlider->setMaximum(200);
m_zoomSlider->setMinimum(0);
m_zoomSlider->setMaximum(100);
m_zoomSlider->setValue(50);
m_lastZoomSliderValue = m_zoomSlider->value();
@ -539,7 +561,7 @@ MainWindow::MainWindow(QWidget *parent) :
zoomWidget->setLayout(zoomLayout);
zoomLayout->addSpacerItem(new QSpacerItem(0, 0, QSizePolicy::Expanding, QSizePolicy::Preferred));
zoomLayout->addWidget(new QLabel("Zoom:"));
zoomLayout->addWidget(zoomLabel);
zoomLayout->addWidget(m_zoomSlider);
m_gridWidget->layout()->addWidget(zoomWidget);
@ -717,7 +739,14 @@ void MainWindow::onZoomValueChanged(int value)
{
foreach(GridItem *item, m_gridItems)
{
item->widget->setFixedSize(QSize(value * 5.12f, value * 5.12f));
int newSize = 0;
if (value < 50)
newSize = expScale(lerp(0, 49, 25, 49, value) / 50.0, 102, 256);
else
newSize = expScale(value / 100.0, 256, 1024);
item->widget->setFixedSize(QSize(newSize, newSize));
}
m_lastZoomSliderValue = value;