X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/b23bc769d3d1943ca2b02ca90701d86b00880af9..af58844636f51ca9c9350c66de3baf427d3e8646:/src/common/stream.cpp

diff --git a/src/common/stream.cpp b/src/common/stream.cpp
index c612f4835b..357499b047 100644
--- a/src/common/stream.cpp
+++ b/src/common/stream.cpp
@@ -75,24 +75,24 @@ void wxStreamBuffer::Init()
     m_fixed = true;
 }
 
-wxStreamBuffer::wxStreamBuffer(BufMode mode)
+void wxStreamBuffer::InitWithStream(wxStreamBase& stream, BufMode mode)
 {
     Init();
 
-    m_stream = NULL;
+    m_stream = &stream;
     m_mode = mode;
 
-    m_flushable = false;
+    m_flushable = true;
 }
 
-wxStreamBuffer::wxStreamBuffer(wxStreamBase& stream, BufMode mode)
+wxStreamBuffer::wxStreamBuffer(BufMode mode)
 {
     Init();
 
-    m_stream = &stream;
+    m_stream = NULL;
     m_mode = mode;
 
-    m_flushable = true;
+    m_flushable = false;
 }
 
 wxStreamBuffer::wxStreamBuffer(const wxStreamBuffer& buffer)
@@ -916,13 +916,48 @@ wxFileOffset wxInputStream::SeekI(wxFileOffset pos, wxSeekMode mode)
 {
     // RR: This code is duplicated in wxBufferedInputStream. This is
     // not really a good design, but buffered stream are different
-    // from all other in that they handle two stream-related objects,
+    // from all others in that they handle two stream-related objects:
     // the stream buffer and parent stream.
 
     // I don't know whether it should be put as well in wxFileInputStream::OnSysSeek
     if (m_lasterror==wxSTREAM_EOF)
         m_lasterror=wxSTREAM_NO_ERROR;
 
+    // avoid unnecessary seek operations (optimization)
+    wxFileOffset currentPos = TellI(), size = GetLength();
+    if ((mode == wxFromStart && currentPos == pos) ||
+        (mode == wxFromCurrent && pos == 0) ||
+        (mode == wxFromEnd && size != wxInvalidOffset && currentPos == size-pos))
+        return currentPos;
+
+    if (!IsSeekable() && mode == wxFromCurrent && pos > 0)
+    {
+        // rather than seeking, we can just read data and discard it;
+        // this allows to forward-seek also non-seekable streams!
+        char buf[BUF_TEMP_SIZE];
+        size_t bytes_read;
+
+        // read chunks of BUF_TEMP_SIZE bytes until we reach the new position
+        for ( ; pos >= BUF_TEMP_SIZE; pos -= bytes_read)
+        {
+            bytes_read = Read(buf, WXSIZEOF(buf)).LastRead();
+            if ( m_lasterror != wxSTREAM_NO_ERROR )
+                return wxInvalidOffset;
+            
+            wxASSERT(bytes_read == WXSIZEOF(buf));
+        }
+        
+        // read the last 'pos' bytes
+        bytes_read = Read(buf, (size_t)pos).LastRead();
+        if ( m_lasterror != wxSTREAM_NO_ERROR )
+            return wxInvalidOffset;
+        
+        wxASSERT(bytes_read == (size_t)pos);
+        
+        // we should now have seeked to the right position...
+        return TellI();
+    }
+
     /* RR: A call to SeekI() will automatically invalidate any previous
        call to Ungetch(), otherwise it would be possible to SeekI() to
        one position, unread some bytes there, SeekI() to another position
@@ -1204,21 +1239,33 @@ void wxFilterClassFactory::Remove()
 // wxBufferedInputStream
 // ----------------------------------------------------------------------------
 
-wxBufferedInputStream::wxBufferedInputStream(wxInputStream& s,
+namespace
+{
+
+// helper function used for initializing the buffer used by
+// wxBufferedInput/OutputStream: it simply returns the provided buffer if it's
+// not NULL or creates a buffer of the given size otherwise
+template <typename T>
+wxStreamBuffer *
+CreateBufferIfNeeded(T& stream, wxStreamBuffer *buffer, size_t bufsize = 1024)
+{
+    return buffer ? buffer : new wxStreamBuffer(bufsize, stream);
+}
+
+} // anonymous namespace
+
+wxBufferedInputStream::wxBufferedInputStream(wxInputStream& stream,
                                              wxStreamBuffer *buffer)
-                     : wxFilterInputStream(s)
+                     : wxFilterInputStream(stream)
 {
-    if ( buffer )
-    {
-        // use the buffer provided by the user
-        m_i_streambuf = buffer;
-    }
-    else // create a default buffer
-    {
-        m_i_streambuf = new wxStreamBuffer(*this, wxStreamBuffer::read);
+    m_i_streambuf = CreateBufferIfNeeded(*this, buffer);
+}
 
-        m_i_streambuf->SetBufferIO(1024);
-    }
+wxBufferedInputStream::wxBufferedInputStream(wxInputStream& stream,
+                                             size_t bufsize)
+                     : wxFilterInputStream(stream)
+{
+    m_i_streambuf = CreateBufferIfNeeded(*this, NULL, bufsize);
 }
 
 wxBufferedInputStream::~wxBufferedInputStream()
@@ -1248,12 +1295,15 @@ wxInputStream& wxBufferedInputStream::Read(void *buf, size_t size)
         size -= m_lastcount;
         buf = (char *)buf + m_lastcount;
 
-        // the call to wxStreamBuffer::Read() below will reset our m_lastcount,
-        // so save it
+        // the call to wxStreamBuffer::Read() below may reset our m_lastcount
+        // (but it also may not do it if the buffer is associated to another
+        // existing stream and wasn't created by us), so save it
         size_t countOld = m_lastcount;
 
-        m_i_streambuf->Read(buf, size);
+        // the new count of the bytes read is the count of bytes read this time
+        m_lastcount = m_i_streambuf->Read(buf, size);
 
+        // plus those we had read before
         m_lastcount += countOld;
     }
 
@@ -1317,20 +1367,18 @@ void wxBufferedInputStream::SetInputStreamBuffer(wxStreamBuffer *buffer)
 // wxBufferedOutputStream
 // ----------------------------------------------------------------------------
 
-wxBufferedOutputStream::wxBufferedOutputStream(wxOutputStream& s,
+wxBufferedOutputStream::wxBufferedOutputStream(wxOutputStream& stream,
                                                wxStreamBuffer *buffer)
-                      : wxFilterOutputStream(s)
+                      : wxFilterOutputStream(stream)
 {
-    if ( buffer )
-    {
-        m_o_streambuf = buffer;
-    }
-    else // create a default one
-    {
-        m_o_streambuf = new wxStreamBuffer(*this, wxStreamBuffer::write);
+    m_o_streambuf = CreateBufferIfNeeded(*this, buffer);
+}
 
-        m_o_streambuf->SetBufferIO(1024);
-    }
+wxBufferedOutputStream::wxBufferedOutputStream(wxOutputStream& stream,
+                                               size_t bufsize)
+                      : wxFilterOutputStream(stream)
+{
+    m_o_streambuf = CreateBufferIfNeeded(*this, NULL, bufsize);
 }
 
 wxBufferedOutputStream::~wxBufferedOutputStream()