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Bugfixing of transparency

This commit is contained in:
Jakub Melka 2021-01-25 20:27:19 +01:00
parent 77255cc56a
commit 8c210176b8
2 changed files with 44 additions and 6 deletions
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49
Pdf4QtLib/sources/pdftransparencyrenderer.cpp
View File

@ -137,6 +137,7 @@ void PDFFloatBitmap::blend(const PDFFloatBitmap& source,
bool alphaIsShape,
PDFColorComponent constantAlpha,
BlendMode mode,
bool knockoutGroup,
uint32_t activeColorChannels,
OverprintMode overprintMode)
{
@ -263,20 +264,33 @@ void PDFFloatBitmap::blend(const PDFFloatBitmap& source,
const PDFColorComponent f_s_i = f_j_i * f_m_i * f_k_i;
const PDFColorComponent alpha_j_i = sourceColor[opacityChannel];
const PDFColorComponent alpha_s_i = alpha_j_i * (f_m_i * q_m_i) * (f_k_i * q_k_i);
const PDFColorComponent alpha_g_b = backdropColor[opacityChannel];
const PDFColorComponent alpha_0 = initialBackdropColor[opacityChannel];
const PDFColorComponent f_g_i_1 = targetColor[shapeChannel];
// Old alpha (alpha_g_i_1) is stored in target (immediate) buffer
const PDFColorComponent alpha_g_i_1 = targetColor[opacityChannel];
const PDFColorComponent alpha_b = backdropColor[opacityChannel];
// alpha_g_0 == 0.0f according to the specification, otherwise select alpha_g_i_1 from target color
const PDFColorComponent alpha_g_b = knockoutGroup ? 0.0f : alpha_g_i_1;
// alpha_0 is taken from initial backdrop color buffer
const PDFColorComponent alpha_0 = initialBackdropColor[opacityChannel];
// f_g_i_1 is stored in target (immediate) buffer
const PDFColorComponent f_g_i_1 = targetColor[shapeChannel];
// Formulas taken from
const PDFColorComponent f_g_i = PDFBlendFunction::blend_Union(f_g_i_1, f_s_i);
const PDFColorComponent alpha_g_i = (1.0f - f_s_i) * alpha_g_i_1 + (f_s_i - alpha_s_i) * alpha_g_b + alpha_s_i;
const PDFColorComponent alpha_i_1 = PDFBlendFunction::blend_Union(alpha_0, alpha_g_i_1);
const PDFColorComponent alpha_i = PDFBlendFunction::blend_Union(alpha_0, alpha_g_i);
// alpha_b is either alpha_0 (for knockout group) or alpha_i_1
const PDFColorComponent alpha_b = knockoutGroup ? alpha_0 : alpha_i_1;
if (qFuzzyIsNull(alpha_g_i))
{
// If alpha_i is zero, then color is undefined
// If alpha_i is zero, then color is undefined, just fill shape/opacity
targetColor[shapeChannel] = f_g_i;
targetColor[opacityChannel] = alpha_g_i;
continue;
}
@ -606,6 +620,24 @@ void PDFTransparencyRenderer::performBeginTransparencyGroup(ProcessOrder order,
// Make initial backdrop transparent
data.initialBackdrop.makeTransparent();
}
else if (!isTransparencyGroupKnockout())
{
// We have stored alpha_g_i in immediate buffer. We must mix it with alpha_0 to get alpha_i
const PDFFloatBitmapWithColorSpace* initialBackdrop = getInitialBackdrop();
const uint8_t opacityChannelIndex = initialBackdrop->getPixelFormat().getOpacityChannelIndex();
const size_t width = data.initialBackdrop.getWidth();
const size_t height = data.initialBackdrop.getHeight();
for (size_t x = 0; x < width; ++x)
{
for (size_t y = 0; y < height; ++y)
{
PDFConstColorBuffer oldPixel = initialBackdrop->getPixel(x, y);
PDFColorBuffer newPixel = data.initialBackdrop.getPixel(x, y);
newPixel[opacityChannelIndex] = PDFBlendFunction::blend_Union(oldPixel[opacityChannelIndex], newPixel[opacityChannelIndex]);
}
}
}
// Prepare soft mask
data.softMask = PDFFloatBitmap(oldBackdrop->getWidth(), oldBackdrop->getHeight(), PDFPixelFormat::createOpacityMask());
@ -615,6 +647,11 @@ void PDFTransparencyRenderer::performBeginTransparencyGroup(ProcessOrder order,
data.initialBackdrop.convertToColorSpace(getCMS(), data.renderingIntent, data.blendColorSpace, this);
data.immediateBackdrop = data.initialBackdrop;
// Jakub Melka: According to 11.4.8 of PDF 2.0 specification, we must
// initialize f_g_0 and alpha_g_0 to zero. We store f_g_0 and alpha_g_0
// in the immediate backdrop, so we will make it transparent.
data.immediateBackdrop.makeTransparent();
m_transparencyGroupDataStack.emplace_back(qMove(data));
}
}
@ -635,7 +672,7 @@ void PDFTransparencyRenderer::performEndTransparencyGroup(ProcessOrder order, co
sourceData.immediateBackdrop.convertToColorSpace(getCMS(), targetData.renderingIntent, targetData.blendColorSpace, this);
PDFFloatBitmap::blend(sourceData.immediateBackdrop, targetData.immediateBackdrop, *getBackdrop(), *getInitialBackdrop(), sourceData.softMask,
sourceData.alphaIsShape, sourceData.alphaFill, BlendMode::Normal, 0xFFFF, PDFFloatBitmap::OverprintMode::NoOveprint);
sourceData.alphaIsShape, sourceData.alphaFill, BlendMode::Normal, targetData.group.knockout, 0xFFFF, PDFFloatBitmap::OverprintMode::NoOveprint);
}
}

1
Pdf4QtLib/sources/pdftransparencyrenderer.h
View File

@ -198,6 +198,7 @@ public:
bool alphaIsShape,
PDFColorComponent constantAlpha,
BlendMode mode,
bool knockoutGroup,
uint32_t activeColorChannels,
OverprintMode overprintMode);