Re: wrong pixel extents retrieved from PangoLayout of arabic text

[Behdad Esfahbod <behdad behdad org>]

Your code works just fine for me.  Have no idea how it may behave that way for
you.  Looks like the line-breaking algorithm is somehow failing.  That's
extremely suspect.  I don't have much else to add.

behdad

On 13-04-19 07:32 AM, Parth Kanungo wrote:
> Hello,
>
> I am facing an issue related to the pixel extents of PangoLayout.
> Here is what I have done.
>
>
> I am rendering Arabic Text.
>
>          gunichar2 text[] = {  0x0644, 0x0627, 0x0020, 0x064A, 0x0648, 0x062C,
> 0x062F, 0x0020, 0x0645, 0x0644, 0x0641, 0x0020, 0x0641, 0x064A, 0x062F,
> 0x064A, 0x0648, 0x0020, 0x0645, 0x062A, 0x0627, 0x062D, 0x0020, 0x062D,
> 0x0627, 0x0644, 0x064A, 0x064B, 0x0627, 0x002E, 0 };
>
> char* inputStr = g_utf16_to_utf8(text, 28, &itemsRead, &itemsWritten, &error);
> pango_layout_set_text(layout, (const char*)inputStr, -1);
>
> I have set the height, width and other parameters of PangoLayout.
>
> pango_layout_set_height(layout,100*PANGO_SCALE);
> pango_layout_set_width(layout,215*PANGO_SCALE);
> pango_layout_set_alignment(layout, PANGO_ALIGN_CENTER);
> pango_layout_set_wrap(layout, PANGO_WRAP_CHAR);
>
> On output, it appeared to me as if the left-most portion of the text was
> getting clipped. Hence, I printed the pixel-extents of the PangoLayout.   
> (Output image:  https://sites.google.com/site/fontengine/issue)
>
>
> This is what I got:
>
> logical_rect:
> x: -6
> y:  0
> w:  227
> h:  72
>
> ink_rect
> x: -5
> y:  8
> w: 226
> h:  64
>
> I don't understand how can I get a negitive x OR, a width greater than the
> width that I have manually set on PangoLayout
> Moreover, I found that this issue occurs only in case of arabic text. 
>
> Is this a known bug? OR, have I done some mistake here?
>
> My source code (test.cpp) has been shared here:
>  https://sites.google.com/site/fontengine/issue/
> <https://sites.google.com/site/fontengine/issue>
>
> Thanks a lot.
>
> -- 
> Parth 

-- 
behdad
http://behdad.org/