Michal Suchanek wrote:
> On 11 February 2010 11:19, Michal Suchanek <hramr...@centrum.cz> wrote:
>
>> 2010/2/11 Vladimir 'φ-coder/phcoder' Serbinenko <phco...@gmail.com>:
>>
>>> Michal Suchanek wrote:
>>>
>>>> Hello
>>>>
>>>> Sending a preliminary framebuffer rotation patch.
>>>>
>>>> You can use videotest to see 4 tiles rotated from the same bitmap data.
>>>>
>>>>
>>>>
>>> +char leaf_data[] = { 0x00, 0x0f, 0xe0, 0x00,
>>> + 0x00, 0x7f, 0xfc, 0x00,
>>> + 0x01, 0xff, 0xff, 0x00,
>>> + 0x03, 0xff, 0xff, 0x80,
>>> This is a blob. Could it be generated automatically at build time?
>>>
>> How less of a blob it would be if it was included as a bitmap?
>>
>> This is just a shape used for the video tests.
>>
>> There are some X tools for working with bitmaps/pixmaps which could
>> generate this from a viewable file but they are usually not available
>> on Windows and other non-X platforms AFAIK.
>>
>>
>>> +
>>> + sans = grub_font_get ("Helvetica Bold 14");
>>> Please use free font rather than Helvetica
>>>
>> I am pretty sure I did not choose the fonts, they must have been there
>> before I started with modifications to the tests.
>>
>>
>>> Could you split addition of videotests from the rest of the patch?
>>> - unsigned int x;
>>> - unsigned int y;
>>> - unsigned int width;
>>> - unsigned int height;
>>> + int x;
>>> + int y;
>>> + int width;
>>> + int height;
>>> Why do you need negative values?
>>>
>> I don't need the negative values everywhere but this change was to
>> align the typing so that casts are not required.
>>
>>
>>> +/* Supported operations are simple and easy to understand.
>>> + * MIRROR | swap image across (around) the vertical axis
>>> + * FLIP - swap image across the horizontal axis - upside down
>>> + * SWAP / swap image across the x=y axis - swap the x and y coordinates
>>> It's just a D_8 group. Could you add a comment to functions what they do
>>> in group theoretical sense? It would make the code easier to follow and
>>>
>> Obviously it is a group, any set of transforms closed on composition is.
>>
>> And according to Wikipedia it's actually called D4.
>>
>>
>>> compute transformations for mathematicians. Perhaps another
>>> representation of D_8 would result in more efficient code?
>>>
>> If you have clearer explanation or more efficient code please share.
>>
>>
>
> Let me elaborate a bit more on this one.
>
> The provided explanation should make it possible for anybody who
> understands plain English to also understand the operations used and
> how they interact should they know group theory in English, any other
> language, or not at all.
>
Perhaps one could add an example of how it moves vertices of a square?
E.g for vertical flip:1---2 2----1 | | --> | | 4---3 3----4 > I guess mentioning the English mathematical terms where applicable and > where I can figure them out should not that much of a problem, as well > as checking that the transform functions are sufficiently described. > > Feel free to ask any questions. -- Regards Vladimir 'φ-coder/phcoder' Serbinenko
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