49 lines
1.5 KiB
Markdown
49 lines
1.5 KiB
Markdown
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Tips & FAQ
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==========
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Tips and Tricks
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---------------
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### Bitmap Subsetting
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Taking a subset of a bitmap is effectively free - no pixels are copied or
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memory is allocated. This allows Skia to offer an API that typically operates
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on entire bitmaps; clients who want to operate on a subset of a bitmap can use
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the following pattern, here being used to magnify a portion of an image with
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drawBitmapNine():
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SkBitmap subset;
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bitmap.extractSubset(&subset, rect);
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canvas->drawBitmapNine(subset, ...);
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FAQ
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---
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### Does Skia support HW acceleration?
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There are two ways Skia can take advantage of HW.
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1. Subclass SkCanvas
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Since all drawing calls go through SkCanvas, those calls can be redirected to
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a different graphics API. SkGLCanvas has been written to direct its drawing
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calls to OpenGL. See src/gl/
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2. Custom bottleneck routines
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There are sets of bottleneck routines inside the blits of Skia that can be
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replace on a platform in order to take advantage of specific CPU features. One
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such example is the NEON SIMD instructions on ARM v7 devices. See src/opts/
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### Does Skia support Font hinting?
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Skia has a built-in font cache, but it does not know how to actual render font
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files like TrueType? into its cache. For that it relies on the platform to
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supply an instance of SkScalerContext?. This is Skia's abstract interface for
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communicating with a font scaler engine. In src/ports you can see support
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files for FreeType?, Mac OS X, and Windows GDI font engines. Other font
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engines can easily be supported in a like manner.
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