| Summary: |
Do cairo_mask on a rgba source produces wrong result |
| Product: |
cairo
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Reporter: |
david_wu |
| Component: |
image backend | Assignee: |
Carl Worth <cworth> |
| Status: |
RESOLVED
FIXED
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QA Contact: |
cairo-bugs mailing list <cairo-bugs> |
| Severity: |
normal
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| Priority: |
medium
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| Version: |
1.6.0 | |
|
| Hardware: |
x86 (IA32) | |
|
| OS: |
Linux (All) | |
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| Whiteboard: |
|
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i915 platform:
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i915 features:
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| Attachments: |
testing sample code
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Created attachment 18451 [details] testing sample code The following sequence produces wrong masked color: cairo_t* cr = cairo_create(target); cairo_set_source_surface(cr, source, 0, 0); cairo_paint_with_alpha(cr, alpha); cairo_set_source_rgba(cr, 1.0, 1.0, 1.0, alpha); cairo_mask_surface(cr, mask, 0, 0); where target, source, and mask are image surfaces, and alpha is an arbitrary value other than 1.0. For example, when data is as follows: uchar sourceWhite[] = { 0xff,0xff,0xff,0xff,0xff,0xff,0xff,0xff }; uchar maskA8[] = { 0x00,0xff,0x00,0x00 }; double alpha = 0.5; we will get this result in target surface: 80808080404040C0 while the expected should be: 80808080C0C0C0C0. Please see the attached for a sample code. (compile command was: g++ -Wall -ffast-math -g `pkg-config --cflags --libs cairo` cairo_mask.cpp g++ version: g++ (GCC) 4.2.3 (Ubuntu 4.2.3-2ubuntu7))