97 lines
2.5 KiB
Lua
97 lines
2.5 KiB
Lua
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Skia Update
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Skia : Overview
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- portable 2D graphics engine
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- src: geometry, images, text
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- dst : raster, gpu, pdf, displaylist, *user-defined
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- attr: shaders, filters, antialiasing, blending, *user-defined
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Skia : Clients
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- Blink : direct and via GraphicsContext
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- Chrome : ui/gfx and compositor
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- Android framework
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- third parties : e.g. Mozilla
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- code.google.com/p/skia
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Skia : Porting
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- C++ and some SIMD assembly
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- Fonts : CoreText, FreeType, GDI, DirectWrite, *user-define
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- Threads : wrappers for native apis
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- Memory : wrappers for [new, malloc, discardable]
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Skia : API
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- SkCanvas
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-- save, saveLayer, restore
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-- translate, scale, rotate, concat
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-- clipRect, clipPath
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- SkPaint
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-- color, stroking, antialiasing, filtering
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-- typeface, textSize, text-flags
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-- effects: shader, color-filter, image-filter, mask-filter, xfermode
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<blockstyle = code>
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void onDraw(SkCanvas* canvas) {
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SkPaint paint;
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paint.setFoo(...);
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canvas->drawRect(..., paint);
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paint.setBar(...);
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canvas->drawOval(..., paint);
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}
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<blockstyle = code>
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void onDraw(SkCanvas* canvas) {
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canvas->drawRect(..., fPaint0);
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canvas->drawOval(..., fPaint1);
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}
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Skia In Blink : GraphicsContext
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- Similar
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-- rects, paths, images, text
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-- matrices, clips
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- Different
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-- save/restore affect matrix+clip PLUS all paint settings
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-- both fill and stroke settings are specified
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-- hence: fillRect(), strokeRect(), drawRect()
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<blockstyle = code>
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void onDraw(GraphicsContext* gc) {
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gc->save();
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gc->setFoo(...);
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gc->fillRect(...);
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gc->setBar(...);
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gc->fillOval(...);
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gc->restore();
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}
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Skia In Blink : more than GraphicsContext
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- Simple wrappers
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-- FloatRect -- SkRect
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-- Path -- SkPath
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- Font.h + 21 others
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-- SkTypeface + flags
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- Image.h + 25 others
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-- SkBitmap, SkImage
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Skia In Blink : Fonts
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- Assist with code-sharing between platforms
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- Runtime switch between GDI and DirectWrite
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- Add SkFontMgr for selection
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- Push LCD decision-making out of Blink
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Skia In Blink : Record-Time-Rasterization
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- Direct rendering during “Paint” pass
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-- Image scaling, filters
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-- SVG patterns, masks
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- Problematic in modern Blink
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-- CTM not always known/knowable
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-- Rendering backend not always known (gpu or cpu)
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-- Rasterization takes (too much) time
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Skia In Blink : RTR response
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- SkImageFilter w/ CPU and GPU implementations
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- SkPaint::FilterLevel : none, low, medium (mipmaps), high
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- SkPicture for caching SVG
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- SkPicture + saveLayer() for masks
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-- PathOps for resolving complex paths
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- SkPictureShader for device-independent patterns
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