private void ProcessComponentImpl(
JpegDecoderCore decoder,
int i,
ref ComponentScan currentComponentScan,
ref int totalHv,
ref Component currentComponent)
{
// Section B.2.3 states that "the value of Cs_j shall be different from
// the values of Cs_1 through Cs_(j-1)". Since we have previously
// verified that a frame's component identifiers (C_i values in section
// B.2.2) are unique, it suffices to check that the implicit indexes
// into comp are unique.
for (int j = 0; j < i; j++)
{
if (currentComponentScan.ComponentIndex == this.pointers.ComponentScan[j].ComponentIndex)
{
throw new ImageFormatException("Repeated component selector");
}
}
totalHv += currentComponent.HorizontalFactor * currentComponent.VerticalFactor;
currentComponentScan.DcTableSelector = (byte)(decoder.Temp[2 + (2 * i)] >> 4);
if (currentComponentScan.DcTableSelector > HuffmanTree.MaxTh)
{
throw new ImageFormatException("Bad DC table selector value");
}
currentComponentScan.AcTableSelector = (byte)(decoder.Temp[2 + (2 * i)] & 0x0f);
if (currentComponentScan.AcTableSelector > HuffmanTree.MaxTh)
{
throw new ImageFormatException("Bad AC table selector value");
}
}
private void InitComponentScan(JpegDecoderCore decoder, int i, ref ComponentScan currentComponentScan, ref int totalHv)
{
// Component selector.
int cs = decoder.Temp[1 + (2 * i)];
int compIndex = -1;
for (int j = 0; j < decoder.ComponentCount; j++)
{
// Component compv = ;
if (cs == decoder.ComponentArray[j].Identifier)
{
compIndex = j;
}
}
if (compIndex < 0)
{
throw new ImageFormatException("Unknown component selector");
}
currentComponentScan.ComponentIndex = (byte)compIndex;
this.ProcessComponentImpl(decoder, i, ref currentComponentScan, ref totalHv, ref decoder.ComponentArray[compIndex]);
}