Bug 126067

Created attachment 15737 [details]
Image showing how Konqueror fails to display a wide image in a wide window after scrolling.

Created attachment 15738 [details]
Testcase used to create the screenshot.

Created attachment 15748 [details]
 showing a displaced segment in the lines image

Occurs here too, when stretching (in a few steps) the Konqueror window to a bit
wider than twice the screen -- which is 1024, so a width of about 2200 pixels. 
It only occurs in the Embeddable Image Viewer, not in Kuickshow, and only when
sliding left and right somewhat quickly, not when doing it very slowly.

As my default Konqueror background is not white but beige, the little image shows that the mistaken segment is displaced both horizontally and a bit vertically.

You folks don't have X backing store on by any chance, do you?

xdpyinfo says:
name of display:    :0.0
version number:    11.0
vendor string:    The X.Org Foundation
vendor release number:    70000000
X.Org version: 7.0.0
maximum request size:  16777212 bytes
motion buffer size:  256
bitmap unit, bit order, padding:    32, LSBFirst, 32
image byte order:    LSBFirst
number of supported pixmap formats:    7
supported pixmap formats:
    depth 1, bits_per_pixel 1, scanline_pad 32
    depth 4, bits_per_pixel 8, scanline_pad 32
    depth 8, bits_per_pixel 8, scanline_pad 32
    depth 15, bits_per_pixel 16, scanline_pad 32
    depth 16, bits_per_pixel 16, scanline_pad 32
    depth 24, bits_per_pixel 32, scanline_pad 32
    depth 32, bits_per_pixel 32, scanline_pad 32
keycode range:    minimum 8, maximum 255
focus:  window 0x1e00007, revert to PointerRoot
number of extensions:    29
    BIG-REQUESTS
    DAMAGE
    DPMS
    Extended-Visual-Information
    GLX
    LBX
    MIT-SCREEN-SAVER
    MIT-SHM
    MIT-SUNDRY-NONSTANDARD
    RANDR
    RENDER
    SECURITY
    SGI-GLX
    SHAPE
    SYNC
    TOG-CUP
    X-Resource
    XC-APPGROUP
    XC-MISC
    XFIXES
    XFree86-Bigfont
    XFree86-DGA
    XFree86-DRI
    XFree86-Misc
    XFree86-VidModeExtension
    XInputExtension
    XKEYBOARD
    XTEST
    XVideo
default screen number:    0
number of screens:    1

screen #0:
  print screen:    no
  dimensions:    1920x1200 pixels (332x210 millimeters)
  resolution:    147x145 dots per inch
  depths (7):    24, 1, 4, 8, 15, 16, 32
  root window id:    0x4c
  depth of root window:    24 planes
  number of colormaps:    minimum 1, maximum 1
  default colormap:    0x20
  default number of colormap cells:    256
  preallocated pixels:    black 0, white 16777215
  options:    backing-store NO, save-unders NO
  largest cursor:    64x64
  current input event mask:    0xfa4031
    KeyPressMask             EnterWindowMask          LeaveWindowMask          
    KeymapStateMask          StructureNotifyMask      SubstructureNotifyMask   
    SubstructureRedirectMask FocusChangeMask          PropertyChangeMask       
    ColormapChangeMask       
  number of visuals:    16
  default visual id:  0x23
  visual:
    visual id:    0x23
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x24
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x25
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x26
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x27
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x28
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x29
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x2a
    class:    TrueColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x2b
    class:    DirectColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x2c
    class:    DirectColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x2d
    class:    DirectColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x2e
    class:    DirectColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x2f
    class:    DirectColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x30
    class:    DirectColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x31
    class:    DirectColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits
  visual:
    visual id:    0x32
    class:    DirectColor
    depth:    24 planes
    available colormap entries:    256 per subfield
    red, green, blue masks:    0xff0000, 0xff00, 0xff
    significant bits in color specification:    8 bits

Created attachment 15958 [details]
HTML testpage showing that the bug also happens without images

Further testing has revealed that this bug is not specific to image viewing.
Wide web pages without images are also garbled when scrolled horizontally.

Created attachment 15959 [details]
Image showing the bug on a web page without images

This is a screenshot of the HTLM testcase that was just attached. Note how the
alphabetic order is destroyed.

> dimensions:    1920x1200 pixels 

1. Does it occur with lower resolutions.
2. what video card/driver are you using.
3. does it still occur with Option "NoAccel" in xorg.

At comment #9: It does not occur here at 800x600: I can see the misdraw happen, but it always gets quickly corrected.  The "NoAccel" option makes no difference -- well, everything's slower, but the problem remains (at 1024x768).  I'm using a via Unichrome KM400 video chip and the Openchrome driver.

> I can see the misdraw happen, but it always gets quickly corrected.
>
Yeah it's not misdrawing you can see happening but the way that window scroll works. The current contents are blitted to their new position first, then the a re-draw occurs for the newly visible section afterwards.

> I'm using a via Unichrome KM400 video chip and the Openchrome driver.
>
I guessed that much from you. :) Can the original reporter comment.

1. It happens with 1600x1200 but not with 1152x968 or 1024x768.
2. Mobility Radeon 9600/radeon.
3. [will test later today]

3. Option "NoAccel" makes no difference except that everything is so slow that I can barely scroll anything at all. The bug is still reproducible.

Cannot reproduce on KDE 3.5.9 and 4 (trunk r804500).
Tested with an nvidia card (with nvidia closed source drivers) on a resolution of 1600x1200 and 1024x768.

Did you have recently had this bug? If not we should close this report.

Thanks a lot! :-)

I can not currently reproduce this with KDE 3.5.8.

Verified: cannot reproduce this either on KDE-3.5.9 -- at 1024x768 on a VIA chip.