IncrementalTextLayout doesn't align correctly using anchor_x='center' in certain cases

[GoogleCodeExporter]

What steps will reproduce the problem?

I've tried all of this on python 2.6 with both pyglet 1.1.4 official
release and pyglet current SVN version (2434), both fails equally

1) run attached script, the layouts should be aligned, but they are not!
2) type some text.. you will see how the first aligned layout gets out of
alignment as the size of text exceeds the layout width..

it feels like the layout is being aligned by the whole text width, and not
by the layout width.

another secondary issue: if you don't set the "anchor_x" on every text
update, it doesn't work properly, but maybe this is how it's supposed to
work... it feels odd, comment the "anchor_x" line at "add_string" method to
see what I mean.

here's the pyglet.info, if it matters:

C:\Python26>python -m pyglet.info
Python
------------------------------------------------------------------------------
sys.version: 2.6.2 (r262:71605, Apr 14 2009, 22:40:02) [MSC v.1500 32 bit
(Intel)]
sys.platform: win32
os.getcwd(): C:\Python26

pyglet
------------------------------------------------------------------------------
pyglet.version: 1.2dev
pyglet.__file__: C:\Python26\lib\site-packages\pyglet\__init__.pyc
pyglet.options['debug_trace_depth'] = 1
pyglet.options['xlib_fullscreen_override_redirect'] = False
pyglet.options['font'] = ('gdiplus', 'win32')
pyglet.options['xsync'] = True
pyglet.options['debug_trace_flush'] = True
pyglet.options['debug_win32'] = False
pyglet.options['debug_gl_trace'] = False
pyglet.options['debug_x11'] = False
pyglet.options['shadow_window'] = True
pyglet.options['debug_font'] = False
pyglet.options['debug_media'] = False
pyglet.options['debug_trace'] = False
pyglet.options['debug_lib'] = False
pyglet.options['graphics_vbo'] = True
pyglet.options['vsync'] = None
pyglet.options['debug_trace_args'] = False
pyglet.options['debug_gl'] = True
pyglet.options['debug_graphics_batch'] = False
pyglet.options['audio'] = ('directsound', 'pulse', 'openal', 'silent')
pyglet.options['debug_texture'] = False
pyglet.options['debug_gl_trace_args'] = False

pyglet.window
------------------------------------------------------------------------------
platform: <pyglet.window.Platform object at 0x00B61730>
display: <pyglet.canvas.win32.Win32Display object at 0x00FDF550>
screens[0]: Win32Screen(x=0, y=0, width=1680, height=1050)
config['double_buffer'] = 1
config['stereo'] = 0
config['buffer_size'] = 32
config['aux_buffers'] = 4
config['sample_buffers'] = 0
config['samples'] = 0
config['red_size'] = 8
config['green_size'] = 8
config['blue_size'] = 8
config['alpha_size'] = 0
config['depth_size'] = 24
config['stencil_size'] = 0
config['accum_red_size'] = 16
config['accum_green_size'] = 16
config['accum_blue_size'] = 16
config['accum_alpha_size'] = 16
config['major_version'] = None
config['minor_version'] = None
config['forward_compatible'] = None
config['debug'] = None
context: Win32ARBContext()

window.context._info
------------------------------------------------------------------------------
gl_info.get_version(): 3.2.0
gl_info.get_vendor(): NVIDIA Corporation
gl_info.get_renderer(): GeForce GTX 280/PCI/SSE2
gl_info.get_extensions():
   GL_ARB_color_buffer_float
   GL_ARB_compatibility
   GL_ARB_copy_buffer
   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_coord_conventions
   GL_ARB_fragment_program
   GL_ARB_fragment_program_shadow
   GL_ARB_fragment_shader
   GL_ARB_framebuffer_object
   GL_ARB_framebuffer_sRGB
   GL_ARB_geometry_shader4
   GL_ARB_half_float_pixel
   GL_ARB_half_float_vertex
   GL_ARB_imaging
   GL_ARB_map_buffer_range
   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_seamless_cube_map
   GL_ARB_shader_objects
   GL_ARB_shading_language_100
   GL_ARB_shadow
   GL_ARB_sync
   GL_ARB_texture_border_clamp
   GL_ARB_texture_buffer_object
   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_multisample
   GL_ARB_texture_non_power_of_two
   GL_ARB_texture_rectangle
   GL_ARB_texture_rg
   GL_ARB_transpose_matrix
   GL_ARB_uniform_buffer_object
   GL_ARB_vertex_array_bgra
   GL_ARB_vertex_array_object
   GL_ARB_vertex_buffer_object
   GL_ARB_vertex_program
   GL_ARB_vertex_shader
   GL_ARB_window_pos
   GL_ATI_draw_buffers
   GL_ATI_texture_float
   GL_ATI_texture_mirror_once
   GL_EXTX_framebuffer_mixed_formats
   GL_EXT_Cg_shader
   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_compiled_vertex_array
   GL_EXT_depth_bounds_test
   GL_EXT_direct_state_access
   GL_EXT_draw_buffers2
   GL_EXT_draw_instanced
   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_packed_pixels
   GL_EXT_pixel_buffer_object
   GL_EXT_point_parameters
   GL_EXT_provoking_vertex
   GL_EXT_rescale_normal
   GL_EXT_secondary_color
   GL_EXT_separate_shader_objects
   GL_EXT_separate_specular_color
   GL_EXT_shadow_funcs
   GL_EXT_stencil_two_side
   GL_EXT_stencil_wrap
   GL_EXT_texture3D
   GL_EXT_texture_array
   GL_EXT_texture_buffer_object
   GL_EXT_texture_compression_latc
   GL_EXT_texture_compression_rgtc
   GL_EXT_texture_compression_s3tc
   GL_EXT_texture_cube_map
   GL_EXT_texture_edge_clamp
   GL_EXT_texture_env_add
   GL_EXT_texture_env_combine
   GL_EXT_texture_env_dot3
   GL_EXT_texture_filter_anisotropic
   GL_EXT_texture_integer
   GL_EXT_texture_lod
   GL_EXT_texture_lod_bias
   GL_EXT_texture_mirror_clamp
   GL_EXT_texture_object
   GL_EXT_texture_sRGB
   GL_EXT_texture_shared_exponent
   GL_EXT_texture_swizzle
   GL_EXT_timer_query
   GL_EXT_vertex_array
   GL_EXT_vertex_array_bgra
   GL_IBM_rasterpos_clip
   GL_IBM_texture_mirrored_repeat
   GL_KTX_buffer_region
   GL_NVX_conditional_render
   GL_NV_blend_square
   GL_NV_conditional_render
   GL_NV_copy_depth_to_color
   GL_NV_copy_image
   GL_NV_depth_buffer_float
   GL_NV_depth_clamp
   GL_NV_explicit_multisample
   GL_NV_fence
   GL_NV_float_buffer
   GL_NV_fog_distance
   GL_NV_fragment_program
   GL_NV_fragment_program2
   GL_NV_fragment_program_option
   GL_NV_framebuffer_multisample_coverage
   GL_NV_geometry_shader4
   GL_NV_gpu_program4
   GL_NV_half_float
   GL_NV_light_max_exponent
   GL_NV_multisample_coverage
   GL_NV_multisample_filter_hint
   GL_NV_occlusion_query
   GL_NV_packed_depth_stencil
   GL_NV_parameter_buffer_object
   GL_NV_parameter_buffer_object2
   GL_NV_pixel_data_range
   GL_NV_point_sprite
   GL_NV_primitive_restart
   GL_NV_register_combiners
   GL_NV_register_combiners2
   GL_NV_shader_buffer_load
   GL_NV_texgen_reflection
   GL_NV_texture_barrier
   GL_NV_texture_compression_vtc
   GL_NV_texture_env_combine4
   GL_NV_texture_expand_normal
   GL_NV_texture_rectangle
   GL_NV_texture_shader
   GL_NV_texture_shader2
   GL_NV_texture_shader3
   GL_NV_transform_feedback
   GL_NV_transform_feedback2
   GL_NV_vertex_array_range
   GL_NV_vertex_array_range2
   GL_NV_vertex_buffer_unified_memory
   GL_NV_vertex_program
   GL_NV_vertex_program1_1
   GL_NV_vertex_program2
   GL_NV_vertex_program2_option
   GL_NV_vertex_program3
   GL_S3_s3tc
   GL_SGIS_generate_mipmap
   GL_SGIS_texture_lod
   GL_SGIX_depth_texture
   GL_SGIX_shadow
   GL_SUN_slice_accum
   GL_WIN_swap_hint
   WGL_EXT_swap_control

pyglet.gl.glu_info
------------------------------------------------------------------------------
glu_info.get_version(): 1.2.2.0 Microsoft Corporation
glu_info.get_extensions():
   GL_EXT_bgra

pyglet.gl.glx_info
------------------------------------------------------------------------------
GLX not available.

pyglet.media
------------------------------------------------------------------------------
audio driver: <pyglet.media.drivers.directsound.DirectSoundDriver object at
0x00B6C370>

pyglet.media.avbin
------------------------------------------------------------------------------
Library: <CDLL 'avbin', handle 6e440000 at 10a2ab0>
AVbin version: 5
FFmpeg revision: 13661

pyglet.media.drivers.openal
------------------------------------------------------------------------------
Library: <CDLL 'openal32', handle 10000000 at 10b3990>
Version: (1, 1)
Extensions:
   ALC_ENUMERATE_ALL_EXT ALC_ENUMERATION_EXT ALC_EXT_CAPTURE ALC_EXT_EFX

pyglet.input.wintab
------------------------------------------------------------------------------
WinTab: Wintab Digitizer Services 1.39 (Spec 1.3)

Any additional info (platform/language/hardware) that may be relevant?
windows xp sp3, english

Original issue reported on code.google.com by averstra...@gmail.com on 20 Jan 2010 at 1:16

Attachments:

• alignment_error.py

[GoogleCodeExporter]

here's a hint:

if you override the "_get_left" method on IncrementalTextLayout 

replacing:

        elif self._anchor_x == 'center':
            return self._x - width // 2

with this:

        elif self._anchor_x == 'center':
            return self._x - min(self.width, self.content_width) // 2

it fixes this issue... as I'm not sure if this breaks something else.. I've 
made this
changes on a separate class, extending the original IncrementalTextLayout.

see the attached file... it's exactly like the original, but using this "fix".
it works as expected.. the only problem I see is one or two pixels offset.. but 
I can
deal with that. ;)

hope it helps to fix the issue.

oh, I also removed the "begin_update" "end_update" on the attached sample, as I 
see
it was not needed and created even more glitches.

Original comment by averstra...@gmail.com on 20 Jan 2010 at 11:52

Attachments:

• alignment_error_fixed.py