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Implemented stencil masks.
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@dmester
dmester committed Jul 17, 2021
1 parent d581829 commit c19ef18
Showing 1 changed file with 58 additions and 58 deletions.
116 changes: 58 additions & 58 deletions src/PdfToSvg/Drawing/SvgRenderer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -433,35 +433,14 @@ private void gs_GraphicsStateFromDictionary(PdfName dictName)

#region XObject operators

private static ColorSpace CreateImageMaskColorSpace(RgbColor strokeColor)
{
// PDF spec 1.7, Table 89
// Unmasked pixels should be rendered using the stroking color

static byte FloatToByte(float floatValue)
{
return (byte)MathUtils.Clamp(unchecked((int)(floatValue * 255f)), 0, 255);
}

var colorLookup = new byte[]
{
/* 0 */ FloatToByte(strokeColor.Red), FloatToByte(strokeColor.Green), FloatToByte(strokeColor.Blue),
/* 1 */ 255, 255, 255
};

return new IndexedColorSpace(new DeviceRgbColorSpace(), colorLookup);
}

private string? GetSvgImageId(PdfDictionary imageObject, out int width, out int height)
private string? GetSvgImageId(PdfDictionary imageObject)
{
if (imageObject.Stream != null &&
imageObject.TryGetName(Names.Subtype, out var subtype) && subtype == Names.Image &&
imageObject.TryGetInteger(Names.Width, out width) &&
imageObject.TryGetInteger(Names.Height, out height))
imageObject.TryGetInteger(Names.Width, out var width) &&
imageObject.TryGetInteger(Names.Height, out var height))
{
// graphicsState may be accessed below
var strokeColor = imageObject.GetValueOrDefault(Names.ImageMask, false) ? graphicsState.StrokeColor : default;

var interpolate = imageObject.GetValueOrDefault(Names.Interpolate, false);
if (!interpolate)
{
Expand All @@ -475,7 +454,7 @@ static byte FloatToByte(float floatValue)
}
}

var imageLookupKey = Tuple.Create(new ReferenceEquatableBox(imageObject), strokeColor, interpolate);
var imageLookupKey = Tuple.Create(new ReferenceEquatableBox(imageObject), interpolate);

// graphicsState must not be accessed below this line

Expand All @@ -488,16 +467,20 @@ static byte FloatToByte(float floatValue)

if (imageObject.GetValueOrDefault(Names.ImageMask, false))
{
colorSpace = CreateImageMaskColorSpace(strokeColor);
colorSpace = new IndexedColorSpace(new DeviceRgbColorSpace(), new byte[]
{
/* 0 */ 255, 255, 255,
/* 1 */ 0, 0, 0,
});
}
else
{
colorSpace = GetColorSpace(imageObject[Names.ColorSpace]);
}

if (colorSpace is UnsupportedColorSpace)
{
return null;
if (colorSpace is UnsupportedColorSpace)
{
return null;
}
}

var image = ImageFactory.Create(imageObject, colorSpace);
Expand Down Expand Up @@ -535,8 +518,6 @@ static byte FloatToByte(float floatValue)
return imageId;
}

width = 0;
height = 0;
return null;
}

Expand Down Expand Up @@ -600,7 +581,7 @@ private void RenderImage(PdfDictionary xobject)
imageAttributes.Add(new XAttribute("opacity", SvgConversion.FormatCoordinate(graphicsState.FillAlpha)));
}

var imageId = GetSvgImageId(xobject, out var imageWidth, out var imageHeight);
var imageId = GetSvgImageId(xobject);
if (imageId == null)
{
// Missing image
Expand Down Expand Up @@ -631,46 +612,65 @@ private void RenderImage(PdfDictionary xobject)
return;
}

// Mask
if (xobject.TryGetDictionary(Names.SMask, out var smask))
var isStencilMask = xobject.GetValueOrDefault(Names.ImageMask, false);

// Decide mask
PdfDictionary? maskImage;

if (isStencilMask)
{
maskImage = xobject;
}
else if (xobject.TryGetDictionary(Names.SMask, out var smask))
{
maskImage = smask;
}
else if (xobject.TryGetDictionary(Names.Mask, out var stencilMask))
{
maskImage = stencilMask;
}
else
{
maskImage = null;
}

// Create mask definition
if (maskImage != null)
{
var maskImageId = GetSvgImageId(smask, out var maskWidth, out var maskHeight);
var maskImageId = GetSvgImageId(maskImage);
if (maskImageId != null)
{
var maskId = StableID.Generate("m",
maskImageId + ";" +
imageWidth.ToString(CultureInfo.InvariantCulture) + ";" +
imageHeight.ToString(CultureInfo.InvariantCulture));
var maskId = StableID.Generate("m", maskImageId);

if (defIds.Add(maskId))
{
var use = new XElement(
ns + "use",
new XAttribute("href", "#" + maskImageId));

if (imageWidth != maskWidth || imageHeight != maskHeight)
{
var scaleX = (double)imageWidth / maskWidth;
var scaleY = (double)imageHeight / maskHeight;

use.Add(new XAttribute("transform", "scale(" +
SvgConversion.FormatCoordinate(scaleX) + " " +
SvgConversion.FormatCoordinate(scaleY) + ")"));
}

defs.Add(new XElement(
ns + "mask",
new XAttribute("id", maskId),
use));
new XElement(
ns + "use",
new XAttribute("href", "#" + maskImageId))));
}

imageAttributes.Add(new XAttribute("mask", "url(#" + maskId + ")"));
}
}

AppendClipped(new XElement(ns + "g", imageAttributes,
new XElement(ns + "use", new XAttribute("href", "#" + imageId))
));
// Output
if (isStencilMask)
{
AppendClipped(new XElement(ns + "g", imageAttributes,
new XElement(ns + "path",
new XAttribute("d", "M0 0V1H1V-1z"),
new XAttribute("fill", SvgConversion.FormatColor(graphicsState.FillColor)))
));
}
else
{
AppendClipped(new XElement(ns + "g", imageAttributes,
new XElement(ns + "use", new XAttribute("href", "#" + imageId))
));
}
}

[Operation("Do")]
Expand Down

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