+/////////////////////////////////////////////////////////////////////////////
+// Name: gifdecod.cpp
+// Purpose: wxGIFDecoder, GIF reader for wxImage and wxAnimation
+// Author: Guillermo Rodriguez Garcia <guille@iies.es>
+// Version: 3.01
+// Last rev: 1999/08/14
+// Copyright: (c) Guillermo Rodriguez Garcia
+// Licence: wxWindows licence
+/////////////////////////////////////////////////////////////////////////////
+
+#ifdef __GNUG__
+#pragma implementation "gifdecod.h"
+#endif
+
+// For compilers that support precompilation, includes "wx.h".
+#include "wx/wxprec.h"
+
+#ifdef __BORLANDC__
+# pragma hdrstop
+#endif
+
+#ifndef WX_PRECOMP
+# include "wx/setup.h"
+#endif
+
+#if wxUSE_STREAMS
+
+#include <stdlib.h>
+#include <string.h>
+#include "wx/defs.h"
+#include "wx/gifdecod.h"
+
+
+//---------------------------------------------------------------------------
+// wxGIFDecoder constructor and destructor
+//---------------------------------------------------------------------------
+
+wxGIFDecoder::wxGIFDecoder(wxInputStream *s, bool anim)
+{
+ m_f = s;
+ m_anim = anim;
+
+ m_background = -1;
+ m_screenw = 0;
+ m_screenh = 0;
+
+ m_pimage = NULL;
+ m_pfirst = NULL;
+ m_plast = NULL;
+ m_image = 0;
+ m_nimages = 0;
+}
+
+wxGIFDecoder::~wxGIFDecoder()
+{
+ Destroy();
+}
+
+void wxGIFDecoder::Destroy()
+{
+ IMAGEN *pimg, *paux;
+
+ pimg = m_pfirst;
+
+ while (pimg != NULL)
+ {
+ paux = pimg->next;
+ free(pimg->p);
+ free(pimg->pal);
+ free(pimg);
+ pimg = paux;
+ }
+}
+
+
+//---------------------------------------------------------------------------
+// Convert this image to a wxImage object
+//---------------------------------------------------------------------------
+
+// This function was designed by Vaclav Slavik
+
+bool wxGIFDecoder::ConvertToImage(wxImage *image) const
+{
+ unsigned char *src, *dst, *pal;
+ unsigned long i;
+ int transparent;
+
+ /* create the image */
+ image->Create(GetWidth(), GetHeight());
+
+ if (!image->Ok())
+ return FALSE;
+
+ pal = GetPalette();
+ src = GetData();
+ dst = image->GetData();
+ transparent = GetTransparentColour();
+
+ /* set transparent colour mask */
+ if (transparent != -1)
+ {
+ for (i = 0; i < 256; i++)
+ {
+ if ((pal[3 * i + 0] == 255) &&
+ (pal[3 * i + 1] == 0) &&
+ (pal[3 * i + 2] == 255))
+ {
+ pal[3 * i + 2] = 254;
+ }
+ }
+
+ pal[3 * transparent + 0] = 255,
+ pal[3 * transparent + 1] = 0,
+ pal[3 * transparent + 2] = 255;
+
+ image->SetMaskColour(255, 0, 255);
+ }
+ else
+ image->SetMask(FALSE);
+
+ /* copy image data */
+ for (i = 0; i < (GetWidth() * GetHeight()); i++, src++)
+ {
+ *(dst++) = pal[3 * (*src) + 0];
+ *(dst++) = pal[3 * (*src) + 1];
+ *(dst++) = pal[3 * (*src) + 2];
+ }
+
+ return TRUE;
+}
+
+
+//---------------------------------------------------------------------------
+// Data accessors
+//---------------------------------------------------------------------------
+
+// Get data for current frame
+
+int wxGIFDecoder::GetFrameIndex() const { return m_image; }
+unsigned char* wxGIFDecoder::GetData() const { return (m_pimage->p); }
+unsigned char* wxGIFDecoder::GetPalette() const { return (m_pimage->pal); }
+unsigned int wxGIFDecoder::GetWidth() const { return (m_pimage->w); }
+unsigned int wxGIFDecoder::GetHeight() const { return (m_pimage->h); }
+unsigned int wxGIFDecoder::GetTop() const { return (m_pimage->top); }
+unsigned int wxGIFDecoder::GetLeft() const { return (m_pimage->left); }
+int wxGIFDecoder::GetTransparentColour() const { return (m_pimage->transparent); }
+int wxGIFDecoder::GetDisposalMethod() const { return (m_pimage->disposal); }
+long wxGIFDecoder::GetDelay() const { return (m_pimage->delay); }
+
+// Get global data
+
+unsigned int wxGIFDecoder::GetLogicalScreenWidth() const { return m_screenw; }
+unsigned int wxGIFDecoder::GetLogicalScreenHeight() const { return m_screenh; }
+int wxGIFDecoder::GetBackgroundColour() const { return m_background; }
+int wxGIFDecoder::GetNumberOfFrames() const { return m_nimages; }
+bool wxGIFDecoder::IsAnimation() const { return (m_nimages > 1); }
+
+
+//---------------------------------------------------------------------------
+// Functions to move through the animation
+//---------------------------------------------------------------------------
+
+bool wxGIFDecoder::GoFirstFrame()
+{
+ if (!IsAnimation())
+ return FALSE;
+
+ m_image = 1;
+ m_pimage = m_pfirst;
+ return TRUE;
+}
+
+bool wxGIFDecoder::GoLastFrame()
+{
+ if (!IsAnimation())
+ return FALSE;
+
+ m_image = m_nimages;
+ m_pimage = m_plast;
+ return TRUE;
+}
+
+bool wxGIFDecoder::GoNextFrame(bool cyclic)
+{
+ if (!IsAnimation())
+ return FALSE;
+
+ if ((m_image < m_nimages) || (cyclic))
+ {
+ m_pimage = m_pimage->next;
+ m_image++;
+
+ if (!m_pimage)
+ {
+ m_image = 1;
+ m_pimage = m_pfirst;
+ }
+
+ return TRUE;
+ }
+ else
+ return FALSE;
+}
+
+bool wxGIFDecoder::GoPrevFrame(bool cyclic)
+{
+ if (!IsAnimation())
+ return FALSE;
+
+ if ((m_image > 1) || (cyclic))
+ {
+ m_pimage = m_pimage->prev;
+ m_image--;
+
+ if (!m_pimage)
+ {
+ m_image = m_nimages;
+ m_pimage = m_plast;
+ }
+
+ return TRUE;
+ }
+ else
+ return FALSE;
+}
+
+bool wxGIFDecoder::GoFrame(int which)
+{
+ int i;
+
+ if (!IsAnimation())
+ return FALSE;
+
+ if ((which >= 1) && (which <= m_nimages))
+ {
+ m_pimage = m_pfirst;
+
+ for (i = 1; i < which; i++)
+ m_pimage = m_pimage->next;
+
+ return TRUE;
+ }
+ else
+ return FALSE;
+}
+
+
+//---------------------------------------------------------------------------
+// GIF reading and decoding
+//---------------------------------------------------------------------------
+
+// getcode:
+// Reads the next code from the file stream, with size 'bits'
+//
+int wxGIFDecoder::getcode(int bits, int ab_fin)
+{
+ unsigned int mask; /* bit mask */
+ unsigned int code; /* code (result) */
+
+
+ /* get remaining bits from last byte read */
+ mask = (1 << bits) - 1;
+ code = (m_lastbyte >> (8 - m_restbits)) & mask;
+
+ /* keep reading new bytes while needed */
+ while (bits > m_restbits)
+ {
+ /* if no bytes left in this block, read the next block */
+ if (m_restbyte == 0)
+ {
+ m_restbyte = (unsigned char)m_f->GetC();
+
+ /* Some encoders are a bit broken: instead of issuing
+ * an end-of-image symbol (ab_fin) they come up with
+ * a zero-length subblock!! We catch this here so
+ * that the decoder sees an ab_fin code.
+ */
+ if (m_restbyte == 0)
+ {
+ code = ab_fin;
+ break;
+ }
+ }
+
+ /* read next byte and isolate the bits we need */
+ m_lastbyte = (unsigned char)m_f->GetC();
+ mask = (1 << (bits - m_restbits)) - 1;
+ code = code + ((m_lastbyte & mask) << m_restbits);
+ m_restbyte--;
+
+ /* adjust total number of bits extracted from the buffer */
+ m_restbits = m_restbits + 8;
+ }
+
+ /* find number of bits remaining for next code */
+ m_restbits = (m_restbits - bits);
+
+ return code;
+}
+
+
+// dgif:
+// GIF decoding function. The initial code size (aka root size)
+// is 'bits'. Supports interlaced images (interl == 1).
+//
+int wxGIFDecoder::dgif(IMAGEN *img, int interl, int bits)
+{
+ int ab_prefix[4096]; /* alphabet (prefixes) */
+ int ab_tail[4096]; /* alphabet (tails) */
+ int stack[4096]; /* decompression stack */
+
+ int ab_clr; /* clear code */
+ int ab_fin; /* end of info code */
+ int ab_bits; /* actual symbol width, in bits */
+ int ab_free; /* first free position in alphabet */
+ int ab_max; /* last possible character in alphabet */
+ int pass; /* pass number in interlaced images */
+ int pos; /* index into decompresion stack */
+ unsigned int x, y; /* position in image buffer */
+
+ int code, readcode, lastcode, abcabca;
+
+ /* these won't change */
+ ab_clr = (1 << bits);
+ ab_fin = (1 << bits) + 1;
+
+ /* these will change through the decompression proccess */
+ ab_bits = bits + 1;
+ ab_free = (1 << bits) + 2;
+ ab_max = (1 << ab_bits) - 1;
+ lastcode = -1;
+ abcabca = -1;
+ pass = 1;
+ pos = x = y = 0;
+
+ /* reset static globals */
+ m_restbits = 0;
+ m_restbyte = 0;
+ m_lastbyte = 0;
+
+ do
+ {
+ /* get next code */
+ readcode = code = getcode(ab_bits, ab_fin);
+
+ /* end of image? */
+ if (code == ab_fin) break;
+
+ /* reset alphabet? */
+ if (code == ab_clr)
+ {
+ /* reset main variables */
+ ab_bits = bits + 1;
+ ab_free = (1 << bits) + 2;
+ ab_max = (1 << ab_bits) - 1;
+ lastcode = -1;
+ abcabca = -1;
+
+ /* skip to next code */
+ continue;
+ }
+
+ /* unknown code: special case (like in ABCABCA) */
+ if (code >= ab_free)
+ {
+ code = lastcode; /* take last string */
+ stack[pos++] = abcabca; /* add first character */
+ }
+
+ /* build the string for this code in the stack */
+ while (code > ab_clr)
+ {
+ stack[pos++] = ab_tail[code];
+ code = ab_prefix[code];
+ }
+ stack[pos] = code; /* push last code into the stack */
+ abcabca = code; /* save for special case */
+
+ /* make new entry in alphabet (only if NOT just cleared) */
+ if (lastcode != -1)
+ {
+ ab_prefix[ab_free] = lastcode;
+ ab_tail[ab_free] = code;
+ ab_free++;
+
+ if ((ab_free > ab_max) && (ab_bits < 12))
+ {
+ ab_bits++;
+ ab_max = (1 << ab_bits) - 1;
+ }
+ }
+
+ /* dump stack data to the buffer */
+ while (pos >= 0)
+ {
+ (img->p)[x + (y * (img->w))] = (char)stack[pos--];
+
+ if (++x >= (img->w))
+ {
+ x = 0;
+
+ if (interl)
+ {
+ /* support for interlaced images */
+ switch (pass)
+ {
+ case 1: y += 8; break;
+ case 2: y += 8; break;
+ case 3: y += 4; break;
+ case 4: y += 2; break;
+ }
+ if (y >= (img->h))
+ {
+ switch (++pass)
+ {
+ case 2: y = 4; break;
+ case 3: y = 2; break;
+ case 4: y = 1; break;
+ }
+ }
+ }
+ else
+ {
+ /* non-interlaced */
+ y++;
+ }
+ }
+ }
+
+ pos = 0;
+ lastcode = readcode;
+ }
+ while (code != ab_fin);
+
+ return 0;
+}
+
+
+// ReadGIF:
+// Reads and decodes one or more GIF images, depending on whether
+// animated GIF support is enabled. Can read GIFs with any bit
+// size (color depth), but the output images are always expanded
+// to 8 bits per pixel. Also, the image palettes always contain
+// 256 colors, although some of them may be unused. Returns E_OK
+// (== 0) on success, or an error code if something fails. Error
+// codes are E_ARCHIVO, E_FORMATO, E_MEMORIA (see header file).
+//
+int wxGIFDecoder::ReadGIF()
+{
+ int ncolors, bits, interl, transparent, disposal, i;
+ long size;
+ long delay;
+ unsigned char type;
+ unsigned char pal[768];
+ unsigned char buf[16];
+ IMAGEN **ppimg, *pimg, *pprev;
+
+
+ /* check GIF signature and animated GIF support (ver. >= 89a) */
+ m_f->Read(buf, 6);
+
+ if (memcmp(buf, "GIF", 3) != 0)
+ return E_FORMATO;
+
+ if (memcmp(buf + 3, "89a", 3) < 0)
+ m_anim = FALSE;
+
+ /* read logical screen descriptor block (LSDB) */
+ m_f->Read(buf, 7);
+ m_screenw = buf[0] + 256 * buf[1];
+ m_screenh = buf[2] + 256 * buf[3];
+
+ /* load global color map if available */
+ if ((buf[4] & 0x80) == 0x80)
+ {
+ m_background = buf[5];
+
+ ncolors = 2 << (buf[4] & 0x07);
+ m_f->Read(pal, 3 * ncolors);
+ }
+
+ /* transparent colour, disposal method and delay default to unused */
+ transparent = -1;
+ disposal = -1;
+ delay = -1;
+
+ /* read images */
+ ppimg = &m_pfirst;
+ pprev = NULL;
+ pimg = NULL;
+
+ while (1)
+ {
+ type = (unsigned char)m_f->GetC();
+
+ /* end of data? */
+ if (type == 0x3B)
+ break;
+
+ /* extension block? */
+ if (type == 0x21)
+ {
+ if (((unsigned char)m_f->GetC()) == 0xF9)
+ /* graphics control extension, parse it */
+ {
+ m_f->Read(buf, 6);
+
+ /* read delay and convert from 1/100 of a second to ms */
+ delay = 10 * (buf[2] + 256 * buf[3]);
+
+ /* read transparent colour index, if used */
+ if (buf[1] & 0x01)
+ transparent = buf[4];
+
+ /* read disposal method */
+ disposal = (buf[1] & 0x1C) - 1;
+ }
+ else
+ /* other extension, skip */
+ {
+ while ((i = (unsigned char)m_f->GetC()) != 0)
+ {
+ /* This line should not be neccessary!
+ * Some images are not loaded correctly
+ * without it. A bug in wxStream?
+ */
+ // m_f->SeekI(m_f->TellI(), wxFromStart);
+ m_f->SeekI(i, wxFromCurrent);
+ }
+ }
+ }
+
+ /* image descriptor block? */
+ if (type == 0x2C)
+ {
+ /* allocate memory for IMAGEN struct */
+ pimg = (*ppimg) = (IMAGEN *) malloc(sizeof(IMAGEN));
+
+ if (pimg == NULL)
+ {
+ Destroy();
+ return E_MEMORIA;
+ }
+
+ /* fill in the data */
+ m_f->Read(buf, 9);
+ pimg->left = buf[4] + 256 * buf[5];
+ pimg->top = buf[4] + 256 * buf[5];
+ pimg->w = buf[4] + 256 * buf[5];
+ pimg->h = buf[6] + 256 * buf[7];
+ interl = ((buf[8] & 0x40)? 1 : 0);
+ size = pimg->w * pimg->h;
+
+ pimg->transparent = transparent;
+ pimg->disposal = disposal;
+ pimg->delay = delay;
+ pimg->next = NULL;
+ pimg->prev = pprev;
+ pprev = pimg;
+ ppimg = &pimg->next;
+
+ /* allocate memory for image and palette */
+ pimg->p = (unsigned char *) malloc(size);
+ pimg->pal = (unsigned char *) malloc(768);
+
+ if ((!pimg->p) || (!pimg->pal))
+ {
+ Destroy();
+ return E_MEMORIA;
+ }
+
+ /* load local color map if available, else use global map */
+ if ((buf[8] & 0x80) == 0x80)
+ {
+ ncolors = 2 << (buf[8] & 0x07);
+ m_f->Read(pimg->pal, 3 * ncolors);
+ }
+ else
+ memcpy(pimg->pal, pal, 768);
+
+ /* get initial code size from first byte in raster data */
+ bits = (unsigned char)m_f->GetC();
+
+ /* decode image */
+ dgif(pimg, interl, bits);
+
+ m_nimages++;
+ }
+
+ /* if we have one image and no animated GIF support, exit */
+ if (m_nimages == 1 && !m_anim)
+ break;
+ }
+
+ /* finish successfully :-) */
+ if (m_nimages != 0)
+ {
+ m_image = 1;
+ m_plast = pimg;
+ m_pimage = m_pfirst;
+ }
+
+ return E_OK;
+}
+
+#endif // wxUSE_STREAM
projects / wxWidgets.git / commitdiff
