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Starred by 6 users
Status: Verified
Owner:
Closed: Apr 2012
Cc:
Components:
EstimatedDays: ----
NextAction: ----
OS: ----
Pri: 2
Type: Bug

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Canvas 2D line drawing bug with GPU acceleration
Reported by clayyo...@gmail.com, Mar 31 2012 Back to list
OS Version: Mac OSX 10.7.3
Exact GPU vendor/model: Mac Pro 2007
URLs (if applicable): http://cycomics.com/test/chromebugtest.html
Other browsers tested: Firefox, Safari
Add OK or FAIL after other browsers where you have tested this issue:
     Safari 5: OK
     Firefox 4.x: OK
     IE 7/8/9: Not tested

What steps will reproduce the problem?
1. go to my test page: http://cycomics.com/test/chromebugtest.html where there is some javascript code that draws a bunch of line segments at about 1500x800 pixels
2. You probably have to scroll over to the bottom right to see the blue line.

What is the expected result?
The line should be a straight-ish, and about 1/2 inch tall, with no offshoots.

What happens instead?
Some line segments create offshoots along a diagonal axis.

Please provide any additional information. Attach a screenshot if
possible.

I'm making a canvas drawing app, and it seems to happen more frequently when drawing from down to up, slowly, with a small line width (1-2 px). Also the greater the x/y coordinates, the bigger the offshoot artifacts are. I can reproduce on a macbook pro with a different video card, and I tried is in Windows XP in parallels, but wasn't getting the bug (I'm pretty sure that it's because GPU acceleration is turned off when running in parallels) This is a new bug since the release of Chrome 18 with GPU accelerated 2D canvas.

Here's a screenshot of how it affects the drawing app I'm making
http://i.imgur.com/dTHqN.png

Please copy the contents of about:gpu (chrome://gpu/) below

Graphics Feature Status
Canvas: Hardware accelerated
HTML Rendering: Hardware accelerated
3D CSS: Hardware accelerated
WebGL: Hardware accelerated
WebGL multisampling: Hardware accelerated
Version Information
Data exported	Sat Mar 31 2012 11:48:32 GMT-0400 (EDT)
Chrome version	18.0.1025.142 (Official Build 129054)
Operating system	Mac OS X 10.7.3
Software rendering list version	1.25
ANGLE revision	988
2D graphics backend	Skia
Performance Information
Graphics	0.0
Gaming	0.0
Overall	0.0
Driver Information
Initialization time	39
Vendor Id	0x10de
Device Id	0x0602
Optimus	false
Driver vendor	
Driver version	7.18.11
Driver date	
Pixel shader version	1.20
Vertex shader version	1.20
GL version	2.1
GL_VENDOR	NVIDIA Corporation
GL_RENDERER	NVIDIA GeForce 8800 GT OpenGL Engine
GL_VERSION	2.1 NVIDIA-7.18.11
GL_EXTENSIONS	GL_ARB_color_buffer_float GL_ARB_depth_buffer_float GL_ARB_depth_clamp GL_ARB_depth_texture GL_ARB_draw_buffers GL_ARB_draw_elements_base_vertex GL_ARB_draw_instanced GL_ARB_fragment_program GL_ARB_fragment_program_shadow GL_ARB_fragment_shader GL_ARB_framebuffer_object GL_ARB_framebuffer_sRGB GL_ARB_half_float_pixel GL_ARB_half_float_vertex GL_ARB_imaging GL_ARB_instanced_arrays GL_ARB_multisample GL_ARB_multitexture GL_ARB_occlusion_query GL_ARB_pixel_buffer_object GL_ARB_point_parameters GL_ARB_point_sprite GL_ARB_provoking_vertex GL_ARB_shader_objects GL_ARB_shader_texture_lod GL_ARB_shading_language_100 GL_ARB_shadow GL_ARB_sync GL_ARB_texture_border_clamp GL_ARB_texture_compression GL_ARB_texture_compression_rgtc GL_ARB_texture_cube_map GL_ARB_texture_env_add GL_ARB_texture_env_combine GL_ARB_texture_env_crossbar GL_ARB_texture_env_dot3 GL_ARB_texture_float GL_ARB_texture_mirrored_repeat GL_ARB_texture_non_power_of_two GL_ARB_texture_rectangle GL_ARB_texture_rg GL_ARB_transpose_matrix GL_ARB_vertex_array_bgra GL_ARB_vertex_blend GL_ARB_vertex_buffer_object GL_ARB_vertex_program GL_ARB_vertex_shader GL_ARB_window_pos GL_EXT_abgr GL_EXT_bgra GL_EXT_bindable_uniform GL_EXT_blend_color GL_EXT_blend_equation_separate GL_EXT_blend_func_separate GL_EXT_blend_minmax GL_EXT_blend_subtract GL_EXT_clip_volume_hint GL_EXT_compiled_vertex_array GL_EXT_depth_bounds_test GL_EXT_draw_buffers2 GL_EXT_draw_range_elements GL_EXT_fog_coord GL_EXT_framebuffer_blit GL_EXT_framebuffer_multisample GL_EXT_framebuffer_object GL_EXT_framebuffer_sRGB GL_EXT_geometry_shader4 GL_EXT_gpu_program_parameters GL_EXT_gpu_shader4 GL_EXT_multi_draw_arrays GL_EXT_packed_depth_stencil GL_EXT_packed_float GL_EXT_provoking_vertex GL_EXT_rescale_normal GL_EXT_secondary_color GL_EXT_shadow_funcs GL_EXT_stencil_two_side GL_EXT_stencil_wrap GL_EXT_texture_array GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_s3tc GL_EXT_texture_env_add GL_EXT_texture_filter_anisotropic GL_EXT_texture_integer GL_EXT_texture_lod_bias GL_EXT_texture_mirror_clamp GL_EXT_texture_rectangle GL_EXT_texture_shared_exponent GL_EXT_texture_sRGB GL_EXT_texture_sRGB_decode GL_EXT_timer_query GL_EXT_transform_feedback GL_EXT_vertex_array_bgra GL_APPLE_aux_depth_stencil GL_APPLE_client_storage GL_APPLE_element_array GL_APPLE_fence GL_APPLE_float_pixels GL_APPLE_flush_buffer_range GL_APPLE_flush_render GL_APPLE_object_purgeable GL_APPLE_packed_pixels GL_APPLE_pixel_buffer GL_APPLE_rgb_422 GL_APPLE_row_bytes GL_APPLE_specular_vector GL_APPLE_texture_range GL_APPLE_transform_hint GL_APPLE_vertex_array_object GL_APPLE_vertex_array_range GL_APPLE_vertex_point_size GL_APPLE_vertex_program_evaluators GL_APPLE_ycbcr_422 GL_ATI_separate_stencil GL_ATI_texture_env_combine3 GL_ATI_texture_float GL_ATI_texture_mirror_once GL_IBM_rasterpos_clip GL_NV_blend_square GL_NV_conditional_render GL_NV_depth_clamp GL_NV_fog_distance GL_NV_fragment_program_option GL_NV_fragment_program2 GL_NV_light_max_exponent GL_NV_multisample_filter_hint GL_NV_point_sprite GL_NV_texgen_reflection GL_NV_vertex_program2_option GL_NV_vertex_program3 GL_SGIS_generate_mipmap GL_SGIS_texture_edge_clamp GL_SGIS_texture_lod
Log Messages
[72905:-1389911360:766244358465641:INFO:gpu_child_thread.cc(110)] : gpu_info_collector::CollectGraphicsInfo complete. success = 1
 
Cc: twiz@chromium.org reed@chromium.org bsalomon@chromium.org senorblanco@chromium.org tomhud...@chromium.org junov@chromium.org
Owner: bsalo...@google.com
I'm not seeing the bug on my windows machines. I'll try on the Macs I have.

Note that GPU canvas is not supported on XP so we wouldn't expect to see it there.
issue121285screenshots.png
206 KB View Download
Labels: -Area-Undefined Feature-GPU-Canvas2D
Status: Started
I see the issue on a MacPro with an HD 5770. However, I don't see it in the canary so it seems this bug is already fixed. I'll try to bisect to find out what the fix was.
Issue121285 20.0.1089.0 screenshot.png
3.4 KB View Download
Issue121285 18.0.1025.142 screenshot.png
3.5 KB View Download
Cc: karen@chromium.org
Labels: Merge-Requested Mstone-18

I found the fix. There was an issue where a point on the interior of a path wasn't calculated with high enough precision when the path was small but the coords were large. This was fixed in this skia change: http://code.google.com/p/skia/source/detail?r=3241. The fix is quite safe and I'd feel comfortable merging it to M18. I don't know if this is a serious enough regression to warrant back-porting so I'm CC'ing Karen for feedback.
Comment 6 by kareng@google.com, Apr 2 2012
Labels: -Merge-Requested Merge-Approved
Labels: -Merge-Approved Merge-Merged
http://code.google.com/p/skia/source/detail?r=3574
Status: Fixed
I verified that it is fixed in 18.0.1025.148.
bsalomon@ I was trying to verify this issue in Mac 10.7., Launching the test page http://cycomics.com/test/chromebugtest.html gives me a blank page . But in Win 7 i am finding a line as in comment #3.
Could u provide me the reproducible steps.

Chrome://gpu
Graphics Feature Status
Canvas: Hardware accelerated
HTML Rendering: Hardware accelerated
3D CSS: Hardware accelerated
WebGL: Hardware accelerated
WebGL multisampling: Hardware accelerated
Version Information
Data exported	Wed Apr 04 2012 11:00:31 GMT-0700 (PDT)
Chrome version	18.0.1025.142 (Official Build 129054)
Operating system	Mac OS X 10.7.3
Software rendering list version	1.25
ANGLE revision	988
2D graphics backend	Skia
Performance Information
Graphics	0.0
Gaming	0.0
Overall	0.0
Driver Information
Initialization time	114
Vendor Id	0x10de
Device Id	0x0863
Optimus	false
Driver vendor	
Driver version	7.18.11
Driver date	
Pixel shader version	1.20
Vertex shader version	1.20
GL version	2.1
GL_VENDOR	NVIDIA Corporation
GL_RENDERER	NVIDIA GeForce 9400M OpenGL Engine
GL_VERSION	2.1 NVIDIA-7.18.11

ligimole@, you're still on 1025.142; check 1025.148 for the claimed fix.
Initially I tried with 1025.151 , It rendered me a blank page , so wanted to see the real issue & tried with 1025.142 , then also it rendered me a blank page.
You may have to scroll pretty far down and to the right to see the rendered shape. Ther e is a large canvas that is likely bigger than your window.
Status: Verified
@bsalomon , Thanks for the update . I was able to reproduce the the real issue in 18.0.1025.142 . This appears to be fixed in 18.0.1025.51. Hence marking as verified.
OS : Mac 10.7.3 , Linux Ubuntu 10.04, Win 7
Comment 14 by ant...@gmail.com, Apr 12 2012
On Mac with Chrome 18.0, flash player not working
@antwal, this bug isn't about Flash -- if you're having Flash issues please open another bug and provide as much detail as possible.
Project Member Comment 16 by bugdroid1@chromium.org, Oct 13 2012
Labels: Restrict-AddIssueComment-Commit
This issue has been closed for some time. No one will pay attention to new comments.
If you are seeing this bug or have new data, please click New Issue to start a new bug.
Project Member Comment 17 by bugdroid1@chromium.org, Mar 10 2013
Labels: -Feature-GPU -Feature-GPU-Canvas2D -Mstone-18 Cr-Internals-GPU Cr-Internals-GPU-Canvas2D M-18
Project Member Comment 18 by bugdroid1@chromium.org, Mar 13 2013
Labels: -Restrict-AddIssueComment-Commit Restrict-AddIssueComment-EditIssue
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