alpha constant on tiling pattern

Submitted by nov..@..il.com

Assigned to poppler-bugs

Link to original bug (#101417)

Description

Created attachment 131943 test case

In the attached test case, the main content stream

1. sets the nonstroking colour to a tiling pattern
2. sets the nonstroking alpha constant to 0.5
3. fills a rectangle.

The tiling pattern itself sets the nonstroking alpha constant to 0.75, then paints a blue pattern cell.

I thought that the pattern cell should be rendered with alpha 0.75, then when it is used to fill the rectangle, the alpha constant 0.5 also has an effect. So the final image would be a blue rectangle with alpha 0.75 * 0.5. This is the behaviour exhibited by Acrobat, xpdf, poppler/test/gtk-test, and poppler/qt4/demos/poppler_qt4viewer

However, the output with evince and poppler-glib-demo is a blue rectangle with alpha 0.75, where the alpha constant set in the main content stream has no effect on the filling of the rectangle.

Sorry if this is not a bug, or if it is filed in the wrong place.

Attachment 131943, "test case":
alpha-tiling-pattern.pdf