Merge pull request #622 from jdpurcell/issue552

Workaround for slow font loading on Windows

src/mainwindow.cpp

@@ -318,7 +318,8 @@ void MainWindow::fileChanged()
     populateOpenWithTimer->start();
     disableActions();
 
-    refreshProperties();
+    if (info->isVisible())
+        refreshProperties();
     buildWindowTitle();
 }
 

src/qvinfodialog.cpp

@@ -2,6 +2,7 @@
 #include "ui_qvinfodialog.h"
 #include <QDateTime>
 #include <QMimeDatabase>
+#include <QTimer>
 
 static int getGcd (int a, int b) {
     return (b == 0) ? a : getGcd(b, a%b);
@@ -31,8 +32,20 @@ void QVInfoDialog::setInfo(const QFileInfo &value, const int &value2, const int
     width = value2;
     height = value3;
     frameCount = value4;
-    updateInfo();
-    window()->adjustSize();
+
+    // If the dialog is visible, it means we've just navigated to a new image. Instead of running
+    // updateInfo immediately, add it to the event queue. This is a workaround for a (Windows-specific?)
+    // delay when calling adjustSize on the window if the font contains certain characters (e.g. Chinese)
+    // the first time that happens for a given font. At least on Windows, by making the work happen later
+    // in the event loop, it allows the main window to repaint first, giving the appearance of better
+    // responsiveness. If the dialog is not visible, however, it means we're preparing to display for an
+    // image already opened. In this case there is no urgency to repaint the main window, and we need to
+    // process the updates here synchronously to avoid the caller showing the dialog before it's ready
+    // (i.e. to avoid showing outdated info or placeholder text).
+    if (isVisible())
+        QTimer::singleShot(0, this, &QVInfoDialog::updateInfo);
+    else
+        updateInfo();
 }
 
 void QVInfoDialog::updateInfo()
@@ -63,4 +76,5 @@ void QVInfoDialog::updateInfo()
         ui->framesLabel2->hide();
         ui->framesLabel->hide();
     }
+    window()->adjustSize();
 }