Store images compressed as pngs. Don't scan images for equality.

2 files changed, 24 insertions, 35 deletions

diff --git a/src/eventqueue.cpp b/src/eventqueue.cpp
index 76c68f7..a1af3e4 100644
--- a/src/eventqueue.cpp
+++ b/src/eventqueue.cpp
@@ -2,19 +2,6 @@
 #include "webclient.h"
 #include <QImage>
 
-bool imagesEqual(const QImage &a, const QImage &b, QRect rect)
-{
-    if (a.size() != b.size())
-        return false;
-
-    for (int y = rect.top(); y < rect.bottom(); ++y)
-        for (int x = rect.left(); x < rect.right(); ++x)
-            if (a.pixel(x,y) != b.pixel(x,y))
-                return false;
-
-    return true;
-}
-
 void encodeText(QString &text)
 {
     // encode "breakout" characters
@@ -121,34 +108,34 @@ void EventQueue::handleImageRequest(json_object* jsonRequest, HttpResponse *resp
     const quintptr id = json_object_get_int(idObject);
     DEBUG << "id" << this << id << images.value(id).size();
 
-    QByteArray block;
-    QBuffer buffer(&block);
-    buffer.open(QIODevice::WriteOnly);
-    QImageWriter writer(&buffer, "png");
-    writer.write(images.value(id));
+    // Save server memory and CPU time by storing images in the png
+    // format after the first serve. The browser could request
+    // the image again, for example if the user hits refresh.
+    QByteArray pngImage;
+    QImage uncompressedImage = images.value(id);
+    if (uncompressedImage.isNull()== false) {
+        images.remove(id);
+
+        QBuffer buffer(&pngImage);
+        buffer.open(QIODevice::WriteOnly);
+        QImageWriter writer(&buffer, "png");
+        writer.write(uncompressedImage);
+
+        compressedImages.insert(id, pngImage);
+    }
+
+    if (pngImage.isEmpty()) {
+        pngImage = compressedImages.value(id);
+    }
 
-    response->setBody(block);
+    response->setBody(pngImage);
     response->setContentType("image/png");
 }
 
 void EventQueue::addUpdateEvent(quintptr id, const QImage &image, QRect updateRect)
 {
-      DEBUG << "addUpdateEvent" << this << id << image.size();
-
-    if (images.contains(id) == false) {
-        DEBUG << "new image for" << id;
-        images.insert(id, image);
-    } else {
-        if (imagesEqual(image, images.value(id), updateRect)) {
-          DEBUG << "discard update" << id;
-            return;
-        } else {
-        //  image.save("images/" + widget->objectName() + ".png");
-            images.insert(id, image);
-            DEBUG << "accept update" << id;
-        }
-    }
-
+    DEBUG << "addUpdateEvent" << this << id << image.size();
+    images.insert(id, image);
     addEvent(id, EventEntry::Update);
 }
 
diff --git a/src/eventqueue.h b/src/eventqueue.h
index 3f418b8..7085a32 100644
--- a/src/eventqueue.h
+++ b/src/eventqueue.h
@@ -53,6 +53,8 @@ public:
     Session *m_session; 
     QQueue<EventEntry> events;
     QHash<quintptr, QImage> images;
+    QHash<quintptr, QByteArray> compressedImages;
+
     QHash<quintptr, QRect> geometries;
 };