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Imageviewer: zoom in and out using fixed set of common-sense zoom values

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Previously scale factor for zoom in/out was calculated as

$(currentScaleFactor)^1.2

This results in weird zoom levels such as 83.3% or 144%. Replace this
approach with using pre-defined set of 'normal' zoom level values
such as {25%, 50%, .. 100%, 150%, 200% .. }, similar to what most
graphic editors do

To find the nearest greater or lesser fixed zoom level for any given
floating point scale factor I borrowed some code from qmldesigner/
timelinewidget

I didn't know what to do with zooming using mouse wheel so I left the
old code in place

Change-Id: Id037ef99f89cce5e8dcd58bb9ad0e6f3c8536f36
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
This commit is contained in:
Katarina Behrens
2022-01-27 14:58:00 +01:00
parent 95627ce10f
commit dbfd226e85
1 changed files with 33 additions and 13 deletions
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46
src/plugins/imageviewer/imageview.cpp
View File

@@ -57,10 +57,31 @@
namespace ImageViewer {
namespace Constants {
const qreal DEFAULT_SCALE_FACTOR = 1.2;
const qreal zoomLevels[] = { 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 4.0, 8.0 };
}
namespace Internal {
static qreal nextLevel(qreal currentLevel)
{
auto iter = std::find_if(std::begin(Constants::zoomLevels), std::end(Constants::zoomLevels), [&](qreal val) {
return val > currentLevel;
});
if (iter != std::end(Constants::zoomLevels))
return *iter;
return currentLevel;
}
static qreal previousLevel(qreal currentLevel)
{
auto iter = std::find_if(std::rbegin(Constants::zoomLevels), std::rend(Constants::zoomLevels), [&](qreal val) {
return val < currentLevel;
});
if (iter != std::rend(Constants::zoomLevels))
return *iter;
return currentLevel;
}
ImageView::ImageView(ImageViewerFile *file)
: m_file(file)
{
@@ -245,16 +266,7 @@ void ImageView::setViewOutline(bool enable)
void ImageView::doScale(qreal factor)
{
qreal currentScale = transform().m11();
qreal newScale = currentScale * factor;
qreal actualFactor = factor;
// cap to 0.001 - 1000
if (newScale > 1000)
actualFactor = 1000./currentScale;
else if (newScale < 0.001)
actualFactor = 0.001/currentScale;
scale(actualFactor, actualFactor);
scale(factor, factor);
emitScaleFactor();
if (auto pixmapItem = dynamic_cast<QGraphicsPixmapItem *>(m_imageItem))
pixmapItem->setTransformationMode(
@@ -264,18 +276,26 @@ void ImageView::doScale(qreal factor)
void ImageView::wheelEvent(QWheelEvent *event)
{
qreal factor = qPow(Constants::DEFAULT_SCALE_FACTOR, event->angleDelta().y() / 240.0);
doScale(factor);
qreal currentScale = transform().m11();
qreal newScale = currentScale * factor;
// cap to 0.001 - 1000
qreal actualFactor = qBound(0.001, factor, 1000.0);
doScale(actualFactor);
event->accept();
}
void ImageView::zoomIn()
{
doScale(Constants::DEFAULT_SCALE_FACTOR);
qreal nextZoomLevel = nextLevel(transform().m11());
resetTransform();
doScale(nextZoomLevel);
}
void ImageView::zoomOut()
{
doScale(1. / Constants::DEFAULT_SCALE_FACTOR);
qreal previousZoomLevel = previousLevel(transform().m11());
resetTransform();
doScale(previousZoomLevel);
}
void ImageView::resetToOriginalSize()