Re: resolution and zoom issues

From: Martin Sevior (msevior@mccubbin.ph.unimelb.edu.au)
Date: Tue Apr 30 2002 - 10:16:32 EDT

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    On Tue, 30 Apr 2002, Tomas Frydrych wrote:

    >
    > Currently we assume a square pixel and use same resolution for
    > both x and y axes. Should we change this? (FreeType uses two
    > separate resolutions.)

    I don't see the need for this.

    >
    > Also, there is a potential problem with zoom. If I understand it
    > correctly, when we zoom text, we simply request a proportionally
    > bigger font from the system.

    Yes, that's right.

    > Unfortunately, IIRC, the width of
    > glyphs does not necesarily scale linearly with height, but rather
    > often the ratio is adjusted (by the font designer) to look best at
    > different sizes. I have observed on windows that the difference
    > between the ratios at different point sizes can be quite dramatic,
    > resulting in non-wysiwig behaviour.

    Ahh that's what causes this. The number of lines per page stays the same
    (since we always use the same font for vertical layout) but if you
    specify left-aligned text the width of the line relative to the left and
    right margin changes at different zooms.

    > One way to get around this
    > would be to change the resolution and keep the same point size of
    > the font when we request it from the system; I think with FreeType
    > this would be fairly straight forward.
    >

    Would this mean we would not always choose the best font though? Generally
    fonts at large point size look nicer. I guess it depends how good freetype
    is at scaling the glyphs.

    Otherwise this is a nice solution. We might finally fix that annoying
    non-WYSIWYG bug.

    Cheers

    Martin



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