Add preview for videos

Grab 4 frames from a video and display them in the Viewer. First frame
is @00:01:00, last at length - 1 minute, and the other two are in
between: length / 4 * 2 and 3 (hardcoded).

1 files changed, 56 insertions, 0 deletions

diff --git a/helper.cpp b/helper.cpp
index db113ec..a895ec4 100644
--- a/helper.cpp
+++ b/helper.cpp
@@ -4,6 +4,11 @@
 #include <QByteArray>
 #include <QSettings>
 #include <QProcess>
+#include <QJsonObject>
+#include <QTemporaryFile>
+#include <QProcess>
+#include <QFontMetrics>
+#include <QPainter>
 
 #include "helper.h"
 
@@ -66,6 +71,57 @@ namespace Helper {
         return QJsonDocument::fromJson(ffData);
     }
 
+    const QPixmap preview(const QString &file){
+        QJsonDocument jDoc = ffpmegData(file);
+        QJsonObject jObj = jDoc.object();
+        QJsonValue durationV = jObj["format"].toObject()["duration"];
+        int seconds = durationV.toVariant().toDouble();
+        int interval = seconds / 4;
+        QImage img1 = snapshot(file, 60);
+        QImage img2 = snapshot(file, interval * 2);
+        QImage img3 = snapshot(file, interval * 3);
+        QImage img4 = snapshot(file, seconds - 60);
+        QImage retval(640 * 2 + 10, img1.height() * 2 + 10, QImage::Format_ARGB32);
+        //retval.fill(Qt::red);
+        QPainter p(&retval);
+        p.drawImage(0, 0, img1);
+        p.drawImage(650, 0, img2);
+        p.drawImage(0, img1.height() + 10, img3);
+        p.drawImage(650, img1.height() + 10, img4);
+        return QPixmap::fromImage(retval);
+    }
+
+    const QImage snapshot(const QString &file, int offset){
+        const int fixedWith = 640;
+        QSettings s;
+        QString ffmpeg = s.value("ext/ffmpeg").toString();
+        QTemporaryFile tempFile;
+        tempFile.open();
+        QStringList ffmpegArgs = QStringList() << "-y" << "-ss" << QString::number(offset) << "-i" << file << "-f" << "image2" << "-vframes" << "1" << tempFile.fileName();
+        QProcess ffproc;
+        ffproc.start(ffmpeg, ffmpegArgs);
+        if(!ffproc.waitForStarted()){
+            return QImage();
+        }
+        if(ffproc.state() == QProcess::Running){
+            ffproc.waitForFinished();
+        }
+        QImage retval(tempFile.fileName());
+        retval = retval.scaledToWidth(fixedWith);
+        Duration dur(offset);
+        QFont font("Monospace", 10);
+        QFontMetrics fm(font);
+        int width = fm.width(dur.toString());
+        int height = fm.height();
+        QPainter p(&retval);
+        p.setBrush(QBrush(QColor(255, 255, 255, 70)));
+        QRect durationRect(fixedWith / 2 - width / 2 - 4, retval.height() - height - 8, width + 4, height + 4);
+        p.drawRect(durationRect);
+        p.setPen(Qt::black);
+        p.drawText(durationRect, Qt::AlignCenter, dur.toString());
+        return retval;
+    }
+
     Duration::Duration() : mHours(0), mMinutes(0), mSeconds(0) {}
 
     Duration::Duration(qint64 seconds){