loader_jpeg.cpp

konqueror3 embedded版本, KDE环境下的当家浏览器的嵌入式版本源码包.

    // filling buffer with the new data
    memcpy(jsrc.buffer + jsrc.valid_buffer_len, buffer, consumed);
    jsrc.valid_buffer_len += consumed;

    if(jsrc.skip_input_bytes)
    {
#ifdef BUFFER_DEBUG
        qDebug("doing skipping");
        qDebug("valid_buffer_len %d", jsrc.valid_buffer_len);
        qDebug("skip_input_bytes %d", jsrc.skip_input_bytes);
#endif
        int skipbytes = kMin((size_t) jsrc.valid_buffer_len, jsrc.skip_input_bytes);

        if(skipbytes < jsrc.valid_buffer_len)
            memmove(jsrc.buffer, jsrc.buffer+skipbytes, jsrc.valid_buffer_len - skipbytes);

        jsrc.valid_buffer_len -= skipbytes;
        jsrc.skip_input_bytes -= skipbytes;

        // still more bytes to skip
        if(jsrc.skip_input_bytes) {
            if(consumed <= 0) qDebug("ERROR!!!");
            return consumed;
        }

    }

    cinfo.src->next_input_byte = (JOCTET *) jsrc.buffer;
    cinfo.src->bytes_in_buffer = (size_t) jsrc.valid_buffer_len;

#ifdef BUFFER_DEBUG
    qDebug("buffer contains %d bytes", jsrc.valid_buffer_len);
#endif

    if(state == Init)
    {
        if(jpeg_read_header(&cinfo, true) != JPEG_SUSPENDED) {
            // do some simple memory requirements limitations
            // as long as we use that stupid Qt stuff
            int s = cinfo.image_width * cinfo.image_height;
            if ( s > 16384 * 12388 )
                cinfo.scale_denom = 8;
            else if ( s > 8192 * 6144 )
                cinfo.scale_denom = 4;
            else if ( s > 4096 * 3072 )
                cinfo.scale_denom = 2;

            if ( consumer )
                consumer->setSize(cinfo.image_width/cinfo.scale_denom,
                                  cinfo.image_height/cinfo.scale_denom);

            state = startDecompress;
        }
    }

    if(state == startDecompress)
    {
        jsrc.do_progressive = jpeg_has_multiple_scans( &cinfo );

#ifdef JPEG_DEBUG
        qDebug( "**** DOPROGRESSIVE: %d",  jsrc.do_progressive );
#endif
        if ( jsrc.do_progressive )
            cinfo.buffered_image = true;
        else
            cinfo.buffered_image = false;

        // setup image sizes
        jpeg_calc_output_dimensions( &cinfo );

        if ( cinfo.jpeg_color_space == JCS_YCbCr )
            cinfo.out_color_space = JCS_RGB;

        cinfo.do_fancy_upsampling = true;
        cinfo.do_block_smoothing = false;
        cinfo.quantize_colors = false;

        // false: IO suspension
        if(jpeg_start_decompress(&cinfo)) {
            if ( cinfo.output_components == 3 || cinfo.output_components == 4) {
                image.create( cinfo.output_width, cinfo.output_height, 32 );
            } else if ( cinfo.output_components == 1 ) {
                image.create( cinfo.output_width, cinfo.output_height, 8, 256 );
                for (int i=0; i<256; i++)
                    image.setColor(i, qRgb(i,i,i));
            }

#ifdef JPEG_DEBUG
            qDebug("will create a picture %d/%d in size", cinfo.output_width, cinfo.output_height);
#endif

#ifdef JPEG_DEBUG
            qDebug("ok, going to decompressStarted");
#endif

            jsrc.decoder_timestamp.start();
            state = jsrc.do_progressive ? decompressStarted : doOutputScan;
        }
    }

again:

    if(state == decompressStarted) {
        state =  (!jsrc.final_pass && jsrc.decoder_timestamp.elapsed() < max_consumingtime)
                ? consumeInput : prepareOutputScan;
    }

    if(state == consumeInput)
    {
        int retval;

        do {
            retval = jpeg_consume_input(&cinfo);
        } while (retval != JPEG_SUSPENDED && retval != JPEG_REACHED_EOI
                 && (retval != JPEG_REACHED_SOS || jsrc.decoder_timestamp.elapsed() < max_consumingtime));

        if(jsrc.decoder_timestamp.elapsed() >= max_consumingtime ||
           jsrc.final_pass ||
           retval == JPEG_REACHED_EOI || retval == JPEG_REACHED_SOS)
            state = prepareOutputScan;
    }

    if(state == prepareOutputScan)
    {
        if ( jpeg_start_output(&cinfo, cinfo.input_scan_number) )
            state = doOutputScan;
    }

    if(state == doOutputScan)
    {
        if(image.isNull() || jsrc.decoding_done)
        {
#ifdef JPEG_DEBUG
            qDebug("complete in doOutputscan, eating..");
#endif
            return consumed;
        }
        uchar** lines = image.jumpTable();
        int oldoutput_scanline = cinfo.output_scanline;

        while(cinfo.output_scanline < cinfo.output_height &&
              jpeg_read_scanlines(&cinfo, lines+cinfo.output_scanline, cinfo.output_height))
            ; // here happens all the magic of decoding

        int completed_scanlines = cinfo.output_scanline - oldoutput_scanline;
#ifdef JPEG_DEBUG
        qDebug("completed now %d scanlines", completed_scanlines);
#endif

        if ( cinfo.output_components == 3 ) {
	    // Expand 24->32 bpp.
	    for (int j=oldoutput_scanline; j<oldoutput_scanline+completed_scanlines; j++) {
		uchar *in = image.scanLine(j) + cinfo.output_width * 3;
		QRgb *out = (QRgb*)image.scanLine(j);

		for (uint i=cinfo.output_width; i--; ) {
		    in-=3;
		    out[i] = qRgb(in[0], in[1], in[2]);
		}
	    }
	}

        if(consumer && completed_scanlines)
        {
            QRect r(0, oldoutput_scanline, cinfo.output_width, completed_scanlines);
#ifdef JPEG_DEBUG
            qDebug("changing %d/%d %d/%d", r.x(), r.y(), r.width(), r.height());
#endif
            jsrc.change_rect |= r;

            if ( jsrc.decoder_timestamp.elapsed() >= max_consumingtime ) {
                if( !jsrc.old_change_rect.isEmpty()) {
                    consumer->changed(jsrc.old_change_rect);
                    jsrc.old_change_rect = QRect();
                }
                consumer->changed(jsrc.change_rect);
                jsrc.change_rect = QRect();
                jsrc.decoder_timestamp.restart();
            }
        }

        if(cinfo.output_scanline >= cinfo.output_height)
        {
            if ( jsrc.do_progressive ) {
                jpeg_finish_output(&cinfo);
                jsrc.final_pass = jpeg_input_complete(&cinfo);
                jsrc.decoding_done = jsrc.final_pass && cinfo.input_scan_number == cinfo.output_scan_number;
                if ( !jsrc.decoding_done ) {
                    jsrc.old_change_rect |= jsrc.change_rect;
                    jsrc.change_rect =  QRect();
                }
            }
            else
                jsrc.decoding_done = true;

#ifdef JPEG_DEBUG
            qDebug("one pass is completed, final_pass = %d, dec_done: %d, complete: %d",
                   jsrc.final_pass, jsrc.decoding_done, jpeg_input_complete(&cinfo));
#endif
            if(!jsrc.decoding_done)
            {
#ifdef JPEG_DEBUG
                qDebug("starting another one, input_scan_number is %d/%d", cinfo.input_scan_number,
                       cinfo.output_scan_number);
#endif
                jsrc.decoder_timestamp.restart();
                state = decompressStarted;
                // don't return until necessary!
                goto again;
            }
        }

        if(state == doOutputScan && jsrc.decoding_done) {
#ifdef JPEG_DEBUG
            qDebug("input is complete, cleaning up, returning..");
#endif
            if ( consumer && !jsrc.change_rect.isEmpty() )
                consumer->changed( jsrc.change_rect );

            if(consumer)
                consumer->end();

            jsrc.ateof = true;

            (void) jpeg_finish_decompress(&cinfo);
            (void) jpeg_destroy_decompress(&cinfo);

            state = readDone;

            return 0;
        }
    }

#ifdef BUFFER_DEBUG
    qDebug("valid_buffer_len is now %d", jsrc.valid_buffer_len);
    qDebug("bytes_in_buffer is now %d", jsrc.bytes_in_buffer);
    qDebug("consumed %d bytes", consumed);
#endif
    if(jsrc.bytes_in_buffer && jsrc.buffer != jsrc.next_input_byte)
        memmove(jsrc.buffer, jsrc.next_input_byte, jsrc.bytes_in_buffer);
    jsrc.valid_buffer_len = jsrc.bytes_in_buffer;
    return consumed;
}

// -----------------------------------------------------------------------------
// This is the factory that teaches Qt about progressive JPEG's

QImageFormat* khtml::KJPEGFormatType::decoderFor(const unsigned char* buffer, int length)
{
    if(length < 3) return 0;

    if(buffer[0] == 0377 &&
       buffer[1] == 0330 &&
       buffer[2] == 0377)
         return new KJPEGFormat;

    return 0;
}

const char* khtml::KJPEGFormatType::formatName() const
{
    return "JPEG";
}

#else
#ifdef __GNUC__
#warning You don't seem to have libJPEG. jpeg support in khtml won't work
#endif
#endif // HAVE_LIBJPEG

// -----------------------------------------------------------------------------