Avoid removing imgbuf and decoding the whole image again for reloads.

Using the same testing files as the previous patch,
the results are:

.---------------------------------------------.
|imgbufs     | No patch | Patch #1 | Patch #2 |
|----------------------------------------------
|1imgA.html  |   2/1    |   1/1    |    1/0   |
|2imgSA.html |   3/2    |   1/2    |    1/0   |
|3imgSA.html |   4/3    |   1/3    |    1/0   |
|----------------------------------------------
|2imgA.html  |   4/2    |   2/2    |    2/0   |
|3imgA.html  |   6/3    |   3/3    |    3/0   |
'---------------------------------------------'

n1/n2 means:
  n1 imgbufs were created for first load (empty cache)
  n2 imgbufs were created for reload (cached image)

Notes:
 * Rendering is much faster. Easy to notice with Back operation.
 * Between four to five times on www.welt.de.
 * Corner cases can be more than ten times. Usually, it *feels* faster.

4 files changed, 33 insertions, 21 deletions

diff --git a/dw/image.cc b/dw/image.cc
index 5df6b93e..e71c8f2f 100644
--- a/dw/image.cc
+++ b/dw/image.cc
@@ -425,9 +425,6 @@ void Image::setBuffer (core::Imgbuf *buffer, bool resize)
 {
    core::Imgbuf *oldBuf = this->buffer;
 
-   if (resize)
-      queueResize (0, true);
-
    if (wasAllocated () && needsResize () &&
       getContentWidth () > 0 && getContentHeight () > 0) {
       // Don't create a new buffer for the transition from alt text to img,
@@ -438,6 +435,7 @@ void Image::setBuffer (core::Imgbuf *buffer, bool resize)
       this->buffer = buffer;
       buffer->ref ();
    }
+   queueResize (0, true);
 
    DBG_OBJ_ASSOC_CHILD (this->buffer);
 
diff --git a/dw/widget.cc b/dw/widget.cc
index 82677cc8..e6c2aa76 100644
--- a/dw/widget.cc
+++ b/dw/widget.cc
@@ -164,6 +164,10 @@ void Widget::queueDrawArea (int x, int y, int width, int height)
                  x, y, width, height);
    DBG_OBJ_MSG_START ();
 
+   _MSG("Widget::queueDrawArea alloc(%d %d %d %d) wid(%d %d %d %d)\n",
+       allocation.x, allocation.y,
+       allocation.width, allocation.ascent + allocation.descent,
+       x, y, width, height);
    if (layout)
       layout->queueDraw (x + allocation.x, y + allocation.y, width, height);
 
diff --git a/src/cache.c b/src/cache.c
index 04c8d356..6a7d2748 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -1258,7 +1258,6 @@ static CacheEntry_t *Cache_process_queue(CacheEntry_t *entry)
 
    /* Trigger cleanup when there are no cache clients */
    if (dList_length(ClientQueue) == 0) {
-      _MSG("  a_Dicache_cleanup()\n");
       a_Dicache_cleanup();
    }
 
diff --git a/src/dicache.c b/src/dicache.c
index b63e9d3b..2704da50 100644
--- a/src/dicache.c
+++ b/src/dicache.c
@@ -182,8 +182,8 @@ static void Dicache_remove(const DilloUrl *Url, int version)
    }
 
    if (entry) {
-      _MSG("Dicache_remove Decoder=%p DecoderData=%p\n",
-          entry->Decoder, entry->DecoderData);
+      _MSG("Dicache_remove Imgbuf=%p Decoder=%p DecoderData=%p\n",
+          entry->v_imgbuf, entry->Decoder, entry->DecoderData);
       /* Eliminate this dicache entry */
       dFree(entry->cmap);
       a_Bitvec_free(entry->BitVec);
@@ -218,9 +218,13 @@ void a_Dicache_unref(const DilloUrl *Url, int version)
 
    _MSG("a_Dicache_unref\n");
    if ((entry = a_Dicache_get_entry(Url, version))) {
-      if (--entry->RefCount == 0) {
+      _MSG(" a_Dicache_unref: RefCount=%d\n", entry->RefCount);
+      _MSG(" a_Dicache_unref: ImgbufLastRef=%d\n",
+          entry->v_imgbuf ? a_Imgbuf_last_reference(entry->v_imgbuf) : -1);
+      if (entry->RefCount > 0) --entry->RefCount;
+      if (entry->v_imgbuf == NULL ||
+          (entry->RefCount == 0 && a_Imgbuf_last_reference(entry->v_imgbuf)))
          Dicache_remove(Url, version);
-      }
    }
 }
 
@@ -370,6 +374,9 @@ void a_Dicache_close(DilloUrl *url, int version, CacheClient_t *Client)
 
    /* a_Dicache_unref() may free DicEntry */
    _MSG("a_Dicache_close RefCount=%d\n", DicEntry->RefCount - 1);
+   _MSG("a_Dicache_close DIC_Close=%d State=%d\n", DIC_Close, DicEntry->State);
+   _MSG(" a_Dicache_close imgbuf=%p Decoder=%p DecoderData=%p\n",
+        DicEntry->v_imgbuf, DicEntry->Decoder, DicEntry->DecoderData);
 
    if (DicEntry->State < DIC_Close) {
       DicEntry->State = DIC_Close;
@@ -412,24 +419,27 @@ static void *Dicache_image(int ImgType, const char *MimeType, void *Ptr,
 
    DicEntry = a_Dicache_get_entry(web->url, DIC_Last);
    if (!DicEntry) {
-      /* Let's create an entry for this image... */
+      /* Create an entry for this image... */
       DicEntry = Dicache_add_entry(web->url);
-      DicEntry->DecoderData =
-         (ImgType == DIC_Png) ?
-            a_Png_new(web->Image, DicEntry->url, DicEntry->version) :
-         (ImgType == DIC_Gif) ?
-            a_Gif_new(web->Image, DicEntry->url, DicEntry->version) :
-         (ImgType == DIC_Jpeg) ?
-            a_Jpeg_new(web->Image, DicEntry->url, DicEntry->version) :
-            NULL;
+      /* Attach a decoder */
+      if (ImgType == DIC_Jpeg) {
+         DicEntry->Decoder = (CA_Callback_t)a_Jpeg_callback;
+         DicEntry->DecoderData =
+            a_Jpeg_new(web->Image, DicEntry->url, DicEntry->version);
+      } else if (ImgType == DIC_Gif) {
+         DicEntry->Decoder = (CA_Callback_t)a_Gif_callback;
+         DicEntry->DecoderData =
+            a_Gif_new(web->Image, DicEntry->url, DicEntry->version);
+      } else if (ImgType == DIC_Png) {
+         DicEntry->Decoder = (CA_Callback_t)a_Png_callback;
+         DicEntry->DecoderData =
+            a_Png_new(web->Image, DicEntry->url, DicEntry->version);
+      }
    } else {
       /* Repeated image */
       a_Dicache_ref(DicEntry->url, DicEntry->version);
    }
-   DicEntry->Decoder = (ImgType == DIC_Png)  ? (CA_Callback_t)a_Png_callback :
-                       (ImgType == DIC_Gif)  ? (CA_Callback_t)a_Gif_callback :
-                       (ImgType == DIC_Jpeg) ? (CA_Callback_t)a_Jpeg_callback:
-                                               NULL;
+
    *Data = DicEntry->DecoderData;
    *Call = (CA_Callback_t) a_Dicache_callback;
 
@@ -548,6 +558,7 @@ void a_Dicache_cleanup(void)
          if (entry->v_imgbuf &&
              a_Imgbuf_last_reference(entry->v_imgbuf)) {
             /* free this unused entry */
+            _MSG("a_Dicache_cleanup: removing entry...\n");
             if (entry->next) {
                Dicache_remove(node->url, entry->version);
             } else {