Implement font outline.

[andy840119]

The safety way is to calculate outline texture, not in render.
See how this demo works.
.
Edit :
oops this demo seems cannot use because it's slow and not perfect.

[andy840119]

Or this demo.
Only see OpenGL Demo because other project is written for other framework.

[andy840119]

Or using image sharp to draw text?
SixLabors/ImageSharp#407
See the example here, might install SixLabors.Fonts(in prelease).

[andy840119]

Sample code has been created.
Need to calculate the time it spend.

Edit:
ImageSharp cost too much time 😢

[andy840119]

http://geoffprewett.com/blog/software/opengl-outline/
Maybe it's better add .fs file and deal with outline effect.

[andy840119]

Or trying https://gist.github.com/xoppa/33589b7d5805205f8f08
.
Note :
can search openGL texture outline GLSL to get more relative info.
And this sample is just for testing.

[andy840119]

Writing GLSL in vscode :
https://www.youtube.com/watch?v=WNcczXF4hSY
.
Install Shader languages support for vscode and glsl canvas in vscode.

[andy840119]

Run this project and check is it workable with text.
Run this project and try to change texture, change outline size and color first.
.
Edit :

Not working perfect 😢

[andy840119]

Running this code :

new SpriteText
{
    Text = "Outlined Text",
    Font = new FontUsage(size: 72),
}.WithEffect(new OutlineEffect
{
    BlurSigma = new Vector2(3f),
    Strength = 100f,
    Colour = Color4.Blue,
    PadExtent = true,
}),

Can have this effect :

.
Maybe create IEffect like KaraokeSolidOutlineEffect and try to loading them like :

Child = InitializeEffect?.invoke(x => {
   //...
});

Then like
karaokeText.InitializeEffect = (x) => {
x.WithEffect(KaraokeSolidOutlineEffect){
// Parameter
}
}
in DrawableLyric

[andy840119]

Also need to test about accept multi outline effect at the same time?

[andy840119]

Implemented in #43 using shader.
Finally.