Re: [ft] How to draw FT_Bitmap to the ARGB image?

[Wojciech Mamrak]

Unless you decide to save the transparent view of the gui to a file so
that it can later be composited over something, you are free to use
subpixel-antialiasing, using the formulae from my first message.

> I am writing a GUI library

So we are kind of a blood brothers :-)

2015-11-05 15:00 GMT+01:00 John Found <address@hidden>:
> On Thu, 5 Nov 2015 13:05:43 +0100
> Wojciech Mamrak <address@hidden> wrote:
>
>> > In a result I made it first to convert the RGB glyph to grayscale and
>> > then to blend it to the background. This way, the transparency is always 
>> > OK.
>>
>> You can return grayscale bitmaps from FT directly, without the
>> conversion on your side.
>> The transparency will be OK but remember to use the alpha channel
>> blending formula this time :)
>
> I am writing a GUI library and the user later will choose how FT fonts to be 
> rendered.
> So, I need to provide support for all possible formats.
>
> For the grayscale rendered glyphs, I am using the value as a "intensity", 
> multiplying
> by it every component of the the drawing color:
>
> Crgb = Crgb * Gray and then making the standard alpha blending of so computed 
> color and
> the background. Everything seems to work fine...
>
> Now I am using the same algorithm for LCD rendered glyphs, only computing the 
> gray value
> by a little bit weird equation: Gray = (R + 2*G + B)/4 and the result is also 
> pretty good.
>
>>
>> > But the big question is "Do I need subpixel antialiased fonts so badly?" :)
>>
>> This question holds if you intend to compose and display some images
>> on the screen (which is always opaque). Then it depends on font size,
>> font itself, targeted device (e.g. resolution, pixel layout), etc. If
>> you intend to save images with transparency, the only versatile option
>> is grayscale antialiased text. Generating SVG images, which are
>> composed "at runtime", assuming rendering engine supports
>> subpixel-antialiased text, is another option.
>>
>
> It depends greatly on the use cases of the library.
>
> But as long as it is not finished yet, I can say only that it is intended to
> be used for GUI creation on x86 computers, working under different OSes.
>
>
> --
> http://fresh.flatassembler.net
> http://asm32.info
> John Found <address@hidden>