unraveling custom drawing

Transcript

1. Desvendando Custom Drawing Matheus C. Candido Android @ Concrete speakerdeck.com/mcassiano
2. pixabay/somraya
3. val default = Paint() val smoother = Paint(FLAG_ANTI_ALIAS) val copy = Paint(smoother)
4. FLAG_ANTI_ALIAS
5. stroke width paint.strokeWidth = 4f paint.strokeWidth = 6f paint.strokeWidth = 8f todos os valores são em pixels!
6. style Paint.Style.STROKE Paint.Style.FILL_AND_STROKE Paint.Style.FILL
7. join (ligações) Paint.Join.MITER Paint.Join.ROUND Paint.Join.BEVEL
8. cap (pontas) Source: Microsoft Xamarin Docs
9. pixabay/coyot
10. formas
11. formas canvas.drawRect( rectBounds, paint )
12. rectBounds???
13. formas canvas.drawRoundRect( rectFBounds, radiusX, radiusY, paint )
14. formas canvas.drawArc( rectFBounds, startAngle, sweepAngle, useCenter, paint )
15. formas canvas.drawCircle( centerX, centerY, radius, paint )
16. paths
17. transformações canvas.save() // faça alguma transformação canvas.restore()
18. transformações val count = canvas.save() // faça alguma transformação canvas.restoreToCount(count)
19. translate canvas.translate(deltaX, deltaY)
20. rotate canvas.rotate(degrees) canvas.rotate(degrees, pivotX, pivotY)
21. scale canvas.scale(scaleX, scaleY) canvas.scale(scaleX, scaleY, pivotX, pivotY)
22. skew canvas.skew(skewX, skewY)
23. clipping (recortes)
24. clipping (recortes) clipOutPath clipOutRect
25. clipping (recortes) clipRect clipPath
26. bitmaps
27. bitmaps drawables
28. bitmaps drawables Levels example: https://ryanharter.com/blog/2015/04/03/custom-drawables/
29. bitmaps drawables custom views
30. bitmaps drawables custom views item decorators
31. performance • evite alocações no onDraw • faça clip nas regiões que não for desenhar • use as ferramentas de profiling para verificar overdraw e debugar quebra de frames
32. acessibilidade AccessibilityNodeProvider ExploreByTouchHelper
33. acessibilidade getVirtualViewAt(x: Float, y: Float) getVisibleVirtualViews(virtualViewIds: MutableList<Int>) onPerformActionForVirtualView( virtualViewId: Int, action: Int, arguments: Bundle? ) onPopulateNodeForVirtualView( virtualViewId: Int, node: AccessibilityNodeInfoCompat )
34. acessibilidade ????
35. virtual view data class VirtualView( var id: Int = View.NO_ID, var contentDescription: CharSequence, val rect: Rect = Rect() )
36. node provider override fun getVirtualViewAt( x: Float, y: Float ): Int { val view = virtualViews.find{ it.rect.contains(x, y) } return view?.id ?: HOST_ID }
37. node provider override fun onPopulateNodeForVirtualView( virtualViewId: Int, node: AccessibilityNodeInfoCompat ) { val view = virtualViews.find { it.id == virtualViewId } view?.let { node.setBoundsInParent(it.rect) node.contentDescription = it.contentDescription } }
38. exemplos
39. backgrounds (itemdecoration) Exemplo: https://github.com/ajarl/item-decoration-sample/blob/master/ app/src/main/java/com/example/itemdecorationsample/ItemDecoration.kt
40. backgrounds (itemdecoration) Exemplo: https://github.com/ajarl/item-decoration-sample/blob/master/ app/src/main/java/com/example/itemdecorationsample/ItemDecoration.kt
41. backgrounds (itemdecoration) Exemplo: https://github.com/ajarl/item-decoration-sample/blob/master/ app/src/main/java/com/example/itemdecorationsample/ItemDecoration.kt
42. histograma Exemplo: https://github.com/mcassiano/custom-drawing
43. mcassiano