Add Drop Shadow on Texts

[Jay Van Diyk]

Hi,

How do I add shadow on texts?? I can successfully draw the text, but I would like to have a little drop shadow effect on it.

Any thoughts?

thanks.

[bungeman]

Look in Skia's gm/blurs.cpp for an example (there's a comment '//drawText' with the relevant code). At a low level, you want to install a SkBlurMaskFilter on the paint to draw blurred text, then draw the non-blurred text on top. Alternatively, you could install a SkBlurDrawLooper on the paint, see gm/shadows.cpp for an example. The SkBlurDrawLooper takes care of the the low level details for you.

[Mike Reed]

... SkLayerDrawLoopers is more general, and gets a *lot* more attention (it is used by chrome/android). Consider SkBlurDrawLooper DEPRECATED...

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[Jay Van Diyk]

Thank you. Will give it a try! :)

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[tuệ việt trí]

Hi, I encountered a problem as you! you can help me! thank you!

Vào 12:33:02 UTC+7 Chủ Nhật, ngày 28 tháng 7 năm 2013, Jay Van Diyk đã viết:

[Jim Van Verth]

You can do this with an SkLayerDrawLooper. If you look at gm/drawlooper.cpp, you'll see an example of how to set one up. Essentially you use a builder to build up paint information for each layer, then assign the resulting looper to the SkPaint. When you draw the text, it will render it with each layer's information in turn. So one layer would be the regular text, and the other would be the shadow.

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[Mike Reed]

True enough, but know that there is nothing special about layerdrawlooper, and in the very long run we may remove it. All that it does is to make several draw calls in a row, which you can do directly, where each draw modifies the paint and/or the canvas.

[Hal Canary]

    const char text[] = "Skia";

    const SkScalar radius = 1.0f;

    const SkScalar xDrop = 2.0f;

    const SkScalar yDrop = 2.0f;

    const SkScalar x = 4.0f;

    const SkScalar y = 26.0f;

    const SkScalar textSize = 24.0f;

    const uint8_t blurAlpha = 127;

    canvas->drawColor(SK_ColorWHITE);

    SkPaint paint;

    paint.setAntiAlias(true);

    paint.setTextSize(textSize);

    SkPaint blur(paint);

    blur.setAlpha(blurAlpha);

    blur.setMaskFilter(SkBlurMaskFilter::Make(

        kNormal_SkBlurStyle, 

        SkBlurMaskFilter::ConvertRadiusToSigma(radius), 0));

    canvas->drawText(text, strlen(text), x + xDrop, y + yDrop, blur);

    canvas->drawText(text, strlen(text), x, y, paint);

[Mike Reed]

Do we have named-fiddles yet for our FAQ?

[Hal Canary]

https://fiddle.skia.org/c/@text_shadow