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