rework updating the image in the preview viewer

src/ksaneimagebuilder.cpp

@@ -65,7 +65,6 @@ void KSaneImageBuilder::start(const SANE_Parameters &params)
         m_image->setDotsPerMeterY(dpm);
     }
     m_image->fill(0xFFFFFFFF);
-    m_imageResized = false;
 }
 
 void KSaneImageBuilder::beginFrame(const SANE_Parameters &params)
@@ -252,20 +251,10 @@ bool KSaneImageBuilder::copyToImage(const SANE_Byte readData[], int read_bytes)
     return false;
 }
 
-bool KSaneImageBuilder::imageResized()
-{
-    if (m_imageResized) {
-        m_imageResized = false;
-        return true;
-    }
-    return false;
-}
-
 void KSaneImageBuilder::renewImage()
 {
     // resize the image
     *m_image = m_image->copy(0, 0, m_image->width(), m_image->height() + m_image->width());
-    m_imageResized = true;
 }
 
 void KSaneImageBuilder::incrementPixelData()

src/ksaneimagebuilder.h

@@ -30,7 +30,6 @@ public:
     void start(const SANE_Parameters &params);
     void beginFrame(const SANE_Parameters &params);
     bool copyToImage(const SANE_Byte readData[], int read_bytes);
-    bool imageResized();
     void setDPI(int dpi);
 
 private:
@@ -46,9 +45,8 @@ private:
 
     QImage *m_image;
     int *m_dpi;
-
-    bool m_imageResized = false;
 };
+
 }
 
 #endif // KSANE_IMAGE_BUILDER_H

src/ksanescanthread.cpp

@@ -79,13 +79,10 @@ void KSaneScanThread::run()
 {
     m_dataSize = 0;
     m_readStatus = ReadOngoing;
-    m_saneStartDone = false;
 
     // Start the scanning with sane_start
     m_saneStatus = sane_start(m_saneHandle);
 
-    m_saneStartDone = true;
-
     if (m_readStatus == ReadCancel) {
         return;
     }
@@ -121,6 +118,8 @@ void KSaneScanThread::run()
     m_frameRead = 0;
     m_frame_t_count = 0;
 
+    Q_EMIT scanProgressUpdated(0);
+
     while (m_readStatus == ReadOngoing) {
         readData();
     }
@@ -141,7 +140,9 @@ void KSaneScanThread::updateScanProgress()
         bytesRead = m_frameRead;
     }
 
-    Q_EMIT scanProgressUpdated(static_cast<int>((static_cast<float>(bytesRead) * 100.0) / m_dataSize));
+    if (bytesRead > 0) {
+        Q_EMIT scanProgressUpdated(static_cast<int>((static_cast<float>(bytesRead) * 100.0) / m_dataSize));
+    }
 }
 
 void KSaneScanThread::finishProgress()
@@ -240,14 +241,4 @@ void KSaneScanThread::copyToScanData(int readBytes)
     }
 }
 
-bool KSaneScanThread::saneStartDone()
-{
-    return m_saneStartDone;
-}
-
-bool KSaneScanThread::imageResized()
-{
-    return m_imageBuilder.imageResized();
-}
-
 }  // NameSpace KSaneIface

src/ksanescanthread.h

@@ -47,9 +47,6 @@ public:
     void setImageResolution(const QVariant &newValue);
     void cancelScan();
 
-    bool saneStartDone();
-    bool imageResized();
-
     ReadStatus frameStatus();
     SANE_Status saneStatus();
     
@@ -77,7 +74,6 @@ private:
     SANE_Parameters m_params;
     SANE_Status     m_saneStatus = SANE_STATUS_GOOD;
     ReadStatus      m_readStatus = ReadReady;
-    bool            m_saneStartDone = false;
     bool            m_invertColors = false;
     KSaneImageBuilder m_imageBuilder;
     QImage          m_image;

src/ksaneviewer.cpp

@@ -56,6 +56,9 @@ struct KSaneViewer::Private {
     bool multiSelectionEnabled = true;
 
     int wheelDelta = 0;
+
+    int currentImageWidth;
+    int currentImageHeight;
 };
 
 KSaneViewer::KSaneViewer(QImage *img, QWidget *parent) : QGraphicsView(parent), d(new Private)
@@ -69,14 +72,18 @@ KSaneViewer::KSaneViewer(QImage *img, QWidget *parent) : QGraphicsView(parent),
     // Init the scene
     d->scene = new QGraphicsScene(this);
     const auto dpr = img->devicePixelRatio();
-    d->scene->setSceneRect(0, 0, img->width() / dpr, img->height() / dpr);
+
+    d->currentImageWidth = img->width();
+    d->currentImageHeight = img->height();
+
+    d->scene->setSceneRect(0, 0, d->currentImageWidth / dpr, d->currentImageHeight / dpr);
     setScene(d->scene);
 
     d->selection = new SelectionItem(QRectF());
     d->selection->setZValue(10);
     d->selection->setSaved(false);
-    d->selection->setMaxRight(img->width());
-    d->selection->setMaxBottom(img->height());
+    d->selection->setMaxRight(d->currentImageWidth);
+    d->selection->setMaxBottom(d->currentImageHeight);
     d->selection->setRect(d->scene->sceneRect());
     d->selection->setVisible(false);
 
@@ -140,6 +147,18 @@ KSaneViewer::~KSaneViewer()
     delete d;
 }
 
+// ------------------------------------------------------------------------
+int KSaneViewer::currentImageHeight() const
+{
+    return d->currentImageHeight;
+}
+
+// ------------------------------------------------------------------------
+int KSaneViewer::currentImageWidth() const
+{
+    return d->currentImageWidth;
+}
+
 // ------------------------------------------------------------------------
 void KSaneViewer::setQImage(QImage *img)
 {
@@ -154,9 +173,13 @@ void KSaneViewer::setQImage(QImage *img)
     resetTransform();
 
     const auto dpr = img->devicePixelRatio();
-    d->scene->setSceneRect(0, 0, img->width() / dpr, img->height() / dpr);
-    d->selection->setMaxRight(img->width());
-    d->selection->setMaxBottom(img->height());
+
+    d->currentImageWidth = img->width();
+    d->currentImageHeight = img->height();
+
+    d->scene->setSceneRect(0, 0, d->currentImageWidth / dpr, d->currentImageHeight / dpr);
+    d->selection->setMaxRight(d->currentImageWidth);
+    d->selection->setMaxBottom(d->currentImageHeight);
 
     d->selection->setDevicePixelRatio(dpr);
     d->hideTop->setDevicePixelRatio(dpr);

src/ksaneviewer.h

@@ -33,6 +33,9 @@ public:
 
     QSize sizeHint() const override;
 
+    int currentImageHeight() const;
+    int currentImageWidth() const;
+
 public Q_SLOTS:
 
     void setTLX(float ratio);

src/ksanewidget_p.cpp

@@ -1351,23 +1351,22 @@ void KSaneWidgetPrivate::invertPreview()
 void KSaneWidgetPrivate::updateProgress(int progress)
 {
     if (m_isPreview) {
-        if (m_scanThread->saneStartDone()) {
-            if (!m_progressBar->isVisible() || m_scanThread->imageResized()) {
-                m_warmingUp->hide();
-                m_activityFrame->show();
-                // the image size might have changed
-                m_scanThread->lockScanImage();
-                m_previewViewer->setQImage(m_scanThread->scanImage());
-                m_previewViewer->zoom2Fit();
-                m_scanThread->unlockScanImage();
-            } else {
-                m_scanThread->lockScanImage();
-                m_previewViewer->updateImage();
-                m_scanThread->unlockScanImage();
-            }
+        if (!m_progressBar->isVisible() || m_scanThread->scanImage()->height() != m_previewViewer->currentImageHeight()
+            || m_scanThread->scanImage()->width() != m_previewViewer->currentImageWidth() ) {
+            m_warmingUp->hide();
+            m_activityFrame->show();
+            // the image size might have changed
+            m_scanThread->lockScanImage();
+            m_previewViewer->setQImage(m_scanThread->scanImage());
+            m_previewViewer->zoom2Fit();
+            m_scanThread->unlockScanImage();
+        } else {
+            m_scanThread->lockScanImage();
+            m_previewViewer->updateImage();
+            m_scanThread->unlockScanImage();
         }
     } else {
-        if (!m_progressBar->isVisible() && (m_scanThread->saneStartDone())) {
+        if (!m_progressBar->isVisible()) {
             m_warmingUp->hide();
             m_activityFrame->show();
         }