Google I/O 2011, Android Accelerated Rendering
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May. 12, 2011•0 likes•9,097 views
Google I/O 2011, Android Accelerated Rendering
May. 12, 2011•0 likes•9,097 views
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Google I/O 2011, Android Accelerated Rendering
- 2. Android Rendering Romain Guy @romainguy Chet Haase @chethaase May 11, 2011 Feedback goo.gl/wI57L Hashtags #io2011, #Android
- 3. Android Accelerated Rendering Romain Guy @romainguy Chet Haase @chethaase May 11, 2011 Feedback goo.gl/wI57L Hashtags #io2011, #Android
- 4. Hardware OpenGL
- 6. Why now?
- 8. memcpy (MiB/s) Pixel count 1100 825 550 275 0 G1 Droid N1 NS XOOM
- 9. UI on the GPU
- 10. on the GPU UI
- 11. Software rendering
- 12. Hardware rendering
- 13. Drawing a list
- 14. Drawing a list
- 15. Drawing a button
- 16. Drawing a button
- 17. Drawing a path
- 18. Drawing a path
- 19. Drawing a path
- 20. attribute vec4 position; attribute vec2 texCoords; uniform mat4 transform; uniform mat4 screenSpace; varying vec2 outTexCoords; varying vec2 linear; void main(void) { outTexCoords = texCoords; linear = vec2((screenSpace * position).x, 0.5); gl_Position = transform * position; } Text+gradient vertex shader
- 21. precision mediump float; varying vec2 outTexCoords; varying vec2 linear; uniform sampler2D sampler; uniform sampler2D gradientSampler; void main(void) { lowp vec4 color; vec4 gradient = texture2D(gradientSampler, linear); color = gradient * texture2D(sampler, outTexCoords).a; gl_FragColor = color; } Text+gradient fragment shader
- 22. ?
- 23. android:hardwareAccelerated="true"
- 24. Hardware acceleration control
- 25. 1 <application android:hardwareAccelerated="true"> 2 <activity ... /> 3 <activity android:hardwareAccelerated="false" /> 4 </application>
- 26. getWindow().setFlags( WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED, WindowManager.LayoutParams.FLAG_HARDWARE_ACCELERATED);
- 27. view.setLayerType(View.LAYER_TYPE_SOFTWARE, null);
- 28. View.isHardwareAccelerated(); Canvas.isHardwareAccelerated(); GPU aware code
- 29. Caveats
- 30. Canvas clipPath clipRegion drawPicture drawPoints drawPosText drawTextOnPath drawVertices Paint setLinearText setMaskFilter setRasterizer Unsupported operations
- 31. 3D transforms, XOR, Diff, Canvas clipRect ReverseDiff ignored drawBitmapMesh Colors array ignored drawLines No anti-aliasing setDrawFilter Ignored Paint setDither Ignored setFilterBitmap Filtering always on setShadowLayer Works with text only Limitations
- 32. ComposeShader Cannot contain another ComposeShader Cannot contain two shaders of the same type Limitations
- 33. view.setLayerType(View.LAYER_TYPE_SOFTWARE, null); Workaround
- 34. New drawing model
- 35. ViewRoot ViewGroup View View Old model
- 36. ViewRoot ViewGroup View View invalidate() Old model
- 37. ViewRoot ViewGroup View View invalidate() Old model
- 38. ViewRoot ViewGroup invalidate() View View invalidate() Old model
- 39. ViewRoot ViewGroup invalidate() View View invalidate() Old model
- 40. ViewRoot invalidate() ViewGroup invalidate() View View invalidate() Old model
- 41. ViewRoot invalidate() ViewGroup invalidate() View View invalidate() Old model
- 42. ViewRoot ViewGroup View View Old model
- 43. ViewRoot draw() ViewGroup View View Old model
- 44. ViewRoot draw() ViewGroup View View Old model
- 45. ViewRoot draw() ViewGroup draw() View View Old model
- 46. ViewRoot draw() ViewGroup draw() View View Old model
- 47. • No logic! • List of drawing commands • Cached when a View changes DisplayList
- 48. Save 3 DrawPatch Save 3 ClipRect 20.00, 4.00, 99.00, 44.00, 1 Translate 20.00, 12.00 DrawText 9, 18, 9, 0.00, 19.00, 0x17e898 Restore RestoreToCount 0 DisplayList to draw a Button
- 49. ViewRoot ViewGroup DisplayList View A View B DisplayList B DisplayList A New model
- 50. ViewRoot ViewGroup DisplayList View A View B DisplayList B DisplayList A invalidate() New model
- 51. ViewRoot ViewGroup DisplayList View A View B DisplayList B DisplayList A mark dirty invalidate() New model
- 52. ViewRoot ViewGroup DisplayList View A View B DisplayList B DisplayList A mark dirty invalidate() New model
- 53. ViewRoot ViewGroup DisplayList invalidate() View A View B DisplayList B DisplayList A mark dirty invalidate() New model
- 54. ViewRoot invalidate() ViewGroup DisplayList invalidate() View A View B DisplayList B DisplayList A mark dirty invalidate() New model
- 55. rebuild ViewRoot ViewGroup DisplayList View A View B DisplayList B DisplayList A New model
- 56. rebuild ViewRoot ViewGroup rebuild DisplayList View A View B DisplayList B DisplayList A New model
- 57. ViewRoot ViewGroup DisplayList View A View B DisplayList B DisplayList A New model
- 58. draw() ViewRoot ViewGroup DisplayList View A View B DisplayList B DisplayList A New model
- 63. 1 background.draw(); 2 panel.draw(); 3 selector.draw(); 4 wifi.draw(); 5 turnOnWifi.draw(); 6 checkBox.draw(); Old model
- 64. 1 selector.draw(); 2 drawDisplayLists(); New model
- 65. Old model New model View.invalidate() Intersects a dirty View When does View.draw() run?
- 66. ViewRoot ViewGroup View View Old model
- 67. ViewRoot ViewGroup invalidate() View View Old model
- 68. ViewRoot ViewGroup invalidate() View View Old model
- 69. ViewRoot invalidate() ViewGroup invalidate() View View Old model
- 70. ViewRoot invalidate() ViewGroup invalidate() View View Old model
- 71. ViewRoot ViewGroup View View Old model
- 72. ViewRoot draw() ViewGroup View View Old model
- 73. ViewRoot draw() ViewGroup View View Old model
- 74. ViewRoot draw() ViewGroup draw() View View Old model
- 75. ViewRoot draw() ViewGroup draw() draw() View View Old model
- 76. ViewRoot ViewGroup DisplayList View A View B DisplayList B DisplayList A New model
- 77. ViewRoot invalidate() ViewGroup DisplayList View A View B DisplayList B DisplayList A New model
- 78. ViewRoot invalidate() ViewGroup DisplayList mark dirty View A View B DisplayList B DisplayList A New model
- 79. ViewRoot invalidate() ViewGroup DisplayList mark dirty View A View B DisplayList B DisplayList A New model
- 80. ViewRoot invalidate() invalidate() ViewGroup DisplayList View A View B DisplayList B DisplayList A New model
- 81. ViewRoot draw() invalidate() ViewGroup DisplayList View A View B DisplayList B DisplayList A New model
- 82. ViewRoot invalidate() ViewGroup DisplayList rebuild View A View B DisplayList B DisplayList A New model
- 83. ViewRoot invalidate() ViewGroup DisplayList rebuild View A View B DisplayList B DisplayList A New model
- 84. View.setLayerType(int type, Paint p)
- 85. Button draw() DisplayList Display Save DrawPatch ClipRect Translate DrawText Restore
- 86. Button draw() draw() DisplayList Layer Display Save DrawPatch ClipRect Translate DrawText Restore
- 87. view.setLayerType(View.LAYER_TYPE_NONE, null) 3 types of layers
- 88. view.setLayerType(View.LAYER_TYPE_SOFTWARE, null) Software layer
- 89. view.setLayerType(View.LAYER_TYPE_HARDWARE, null) Hardware layer
- 90. 1. Performance Hardware layers
- 91. Drawing a ListView Hardware layer DisplayList Software Time in ms 0.009 2.1 10.3 Measured when drawing a ListView with Android 3.0 on a Motorola XOOM
- 92. 2. Visual effects Hardware and software layers
- 94. ColorMatrix m = new ColorMatrix(); m.setSaturation(0.0f); Paint p = new Paint(); p.setColorFilter(new ColorMatrixColorFilter(m)); page.setLayerType(LAYER_TYPE_HARDWARE, p);
- 95. 3. Compatibility Software layers
- 96. 4. Animations Hardware and software layers
- 97. Opacity Position Size Orientation Origin alpha x scaleX rotation pivotX y scaleY rotationX pivotY translationX rotationY translationY Layers-friendly properties
- 98. ViewRoot ViewGroup DisplayList View A View B Layer B DisplayList A Layers-friendly properties
- 99. ViewRoot ViewGroup DisplayList View A View B Layer B DisplayList A setRotationY(45) Layers-friendly properties
- 100. ViewRoot ViewGroup DisplayList invalidate() View A View B Layer B DisplayList A setRotationY(45) Layers-friendly properties
- 101. ViewRoot mark dirty ViewGroup DisplayList invalidate() View A View B Layer B DisplayList A setRotationY(45) Layers-friendly properties
- 102. ViewRoot mark dirty ViewGroup DisplayList invalidate() View A View B Layer B DisplayList A setRotationY(45) Layers-friendly properties
- 103. Save 3 DrawDisplayList A DrawLayer B Restore Parent DisplayList
- 104. viewB.setRotationY(45) Save 3 DrawDisplayList A DrawLayer B Restore Parent DisplayList
- 105. viewB.setRotationY(45) Save 3 Save 3 DrawDisplayList A DrawDisplayList A DrawLayer B Rotate 0.0, 45.0, 0.0 Restore DrawLayer B Restore Parent DisplayList
- 106. view.setLayerType(View.LAYER_TYPE_HARDWARE, null); ObjectAnimator.ofFloat(view, "rotationY", 180).start(); Animating a complex View efficiently
- 107. view.setLayerType(View.LAYER_TYPE_HARDWARE, null); ObjectAnimator animator = ObjectAnimator.ofFloat( view, "rotationY", 180); animator.addListener(new AnimatorListenerAdapter() { @Override public void onAnimationEnd(Animator animation) { view.setLayerType(View.LAYER_TYPE_NONE, null); } }); animator.start();
- 108. Tips & tricks
- 109. 1. Don’t use too many views Keep your hierarchy flat
- 110. 2. Be careful of setAlpha() Without hardware layers, it costs 2x the fill-rate
- 111. 3. Reuse rendering objects Don’t create new Paints, Bitmaps, etc. in draw()
- 112. 4. Don’t modify Bitmaps often Every change causes a texture upload
- 113. 5. Don’t modify Paths often Every change causes a new rasterization
- 114. 6. Avoid overdraw GPUs are fill-rate limited
- 115. 7. Profile DDMS and traceview are your friends
- 116. Android blog d.android.com Romain’s blog curious-creature.org Chet’s blog graphics-geek.blogspot.com
- 117. Feedback http://goo.gl/wI57L Hashtags #io2011, #Android
- 118. Q&A Feedback http://goo.gl/wI57L Hashtags #io2011, #Android
Editor's Notes
- \n
- \n
- \n
- Since Android 1.0: hardware OpenGL ES 1.x and 2.x support\nWindows composition\nGames\nRich media (live wallpapers)\n
- But the UI remains in software\n
- Aren&#x2019;t we done?\nFaster CPUs, multi-cores, etc.\n
- New, richer experiences\nMore smoother animations\nMore and more pixels (tablets, hdpi screens)\n
- Software cannot keep up\nGraph from 2008 to 2011\nYellow bar increase at the same rate or faster rate\n
- Android 3.0 has many new features\nFavorite new UI toolkit feature: GPU support\nAll 2D ops run with OpenGL on the GPU\nAll standard apps run on the GPU\n
- Android 3.0 has many new features\nFavorite new UI toolkit feature: GPU support\nAll 2D ops run with OpenGL on the GPU\nAll standard apps run on the GPU\n
- Android 3.0 has many new features\nFavorite new UI toolkit feature: GPU support\nAll 2D ops run with OpenGL on the GPU\nAll standard apps run on the GPU\n
- Android 3.0 has many new features\nFavorite new UI toolkit feature: GPU support\nAll 2D ops run with OpenGL on the GPU\nAll standard apps run on the GPU\n
- Android 3.0 has many new features\nFavorite new UI toolkit feature: GPU support\nAll 2D ops run with OpenGL on the GPU\nAll standard apps run on the GPU\n
- How does it work?\nHere&#x2019;s the software rendering pipeline (pre-3.0 or apps without h/w in 3.0+)\n
- The new hw accelerated pipeline translates Canvas calls to OpenGL\nOpenGL primitives are rasterized by the GPU\n
- We have points, lines, triangles and textures\nEach draw call is a combo of those\nHere is a ListView, you can notice the fades at top/bottom\n
- A simple button, 9patches are great in OpenGL\nResult is a simple mesh + texture\n
- A path is rendered using a combination of geometry (quad) and an alpha texture\nColor is applied in the fragment shader\nText is drawn in a similar way\n
- A path is rendered using a combination of geometry (quad) and an alpha texture\nColor is applied in the fragment shader\nText is drawn in a similar way\n
- A path is rendered using a combination of geometry (quad) and an alpha texture\nColor is applied in the fragment shader\nText is drawn in a similar way\n
- A path is rendered using a combination of geometry (quad) and an alpha texture\nColor is applied in the fragment shader\nText is drawn in a similar way\n
- A path is rendered using a combination of geometry (quad) and an alpha texture\nColor is applied in the fragment shader\nText is drawn in a similar way\n
- A path is rendered using a combination of geometry (quad) and an alpha texture\nColor is applied in the fragment shader\nText is drawn in a similar way\n
- A path is rendered using a combination of geometry (quad) and an alpha texture\nColor is applied in the fragment shader\nText is drawn in a similar way\n
- Here&#x2019;s an example of the vertex shader used to draw text filled with a gradient\nShaders are generated at runtime by the pipeline\nSeveral millions of shaders can be thus generated\n
- Drawing text with a gradient requires 2 textures:\n- an alpha texture for text\n- the gradient texture\n
- To enable 2D h/w acceleration, put this in AndroidManifest.xml\nThat&#x2019;s all you need to do\n
- To enable 2D h/w acceleration, put this in AndroidManifest.xml\nThat&#x2019;s all you need to do\n
- Hardware acceleration can be enabled/disabled at several levels\nLet&#x2019;s see how it can be done at each level\n
- Here, enabled for the app, disabled for an activity\n
- It can also be enabled for a specific window\n(for instance in Activity.onCreate())\n
- H/w acceleration can be disabled per View\nWe&#x2019;ll talk more about layers later\n
- If you write custom views, checking the hw accel. status might be important\nCanvas.isHardwareAccelerated() is the preferred method\nView.isHA() && !Canvas.isHA() is possible (e.g. bitmap cache)\n
- Because of the nature of the 2D API and what GL can do, not everything will work\nSome features are missing, some are limited\nAll standard views/drawables will work\n
- Some ops will be supported in future releases (drawPoints for instance)\nIf these ops are needed, draw in a Bitmap, or use a software layer\n
- Some limitations will be lifted in future releases (AA lines for instance)\n
- ComposeShaders are very useful\nCurrent constraints\n
- An easy workaround is to use a software layer\nYou can also use a Bitmap, or Canvas.isHardwareAccelerated()\n
- The new rendering pipeline changes the way rendering works\nIt&#x2019;s still an immediate mode\nBut with a special kind of caching\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- In the old model, invalidate()ing a View meant redrawing each parent\nThis executes a lot of Java code\nBut the logic remains the same for the parents!\nExpensive!\n
- DisplayList are simplified lists of drawing commands\nOne DisplayList per View, cached when a View changes\nTo redraw a View, we just re-issue its DisplayList\n
- Here is an example of a DisplayList: this draws a button\nSeveral 100s of lines of Java code are required to produce this\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- A DisplayList can reference other DisplayLists\nNote that only one DisplayList is rebuilt, nothing else is touched!\nMuch less code is executed\nDrawing a display list = native code only\n\n
- Let&#x2019;s examine what happens when enabling WiFi in Settings\nWe&#x2019;re going to tap the Wi-Fi list item and look at what happens in both models\n\n
- Let&#x2019;s examine what happens when enabling WiFi in Settings\nWe&#x2019;re going to tap the Wi-Fi list item and look at what happens in both models\n\n
- Let&#x2019;s examine what happens when enabling WiFi in Settings\nWe&#x2019;re going to tap the Wi-Fi list item and look at what happens in both models\n\n
- Let&#x2019;s examine what happens when enabling WiFi in Settings\nWe&#x2019;re going to tap the Wi-Fi list item and look at what happens in both models\n\n
- Let&#x2019;s examine what happens when enabling WiFi in Settings\nWe&#x2019;re going to tap the Wi-Fi list item and look at what happens in both models\n\n
- When the selector turns blue, here are all the views that need to redraw\nEach View executes all of its Java drawing logic\nLot of code!\n
- With the new model, only one piece of Java code is executed\nDrawing display lists is done in native\nOnly a series of draw calls, no logic whatsoever\n
- If you change a View, call invalidate() on it\nDO NOT rely on calling invalidate() on a parent or sibling\nIt may have worked before, it won&#x2019;t anymore\nIt was incorrect before, but worked anyway\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the old model, invalidate()ing a View meant redrawing intersecting Views (children for instance)\nNotice how both leaves are drawn even though they are not dirty\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- In the new model, invalidating a parent redraws that parent only\nNote how the children are not redrawn\n\n
- We briefly mentioned layers earlier, for compatibility\nBut layers can do much more, they are very useful and efficient\nThe option Paint can be used to control compositing\n
- Even with display lists, drawing is expensive\nA display list can have many operations\nAnimating a View requires to rerun these operations on every frame\nAnimating complex Views can be more efficient\n
- With a layer (or offscreen cache/bitmap), drawing happens once (or when the view invalidates)\nOnly the layer is drawn on screen, it&#x2019;s just a texture\nIt&#x2019;s *very* efficient, especially for the GPU\nAnd layers have other advantages too\n
- The type of layer LAYER_TYPE_NONE disables caching\nDefault value, View is not backed by an off-screen buffer\n
- The View is rendered into a Bitmap, just like setDrawingCacheEnabled(true)\nForces software rendering, good for compatibility\nExpensive to refresh a software layer (sw rendering + texture upload)\nUse only if necessary! (costs Dalvik heap memory!!!!)\n\n
- The View is rendered into an FBO, using OpenGL/HW acceleration\nReally fast, costs only GPU memory\nOptimized for blending\n
- Hardware layers render View into a hardware texture\nDrawing code runs only when View.invalidate() is called\nSome animations are applied directly onto the layer\n
- Perf comparison of \nDrawing a hardware layer is much faster, recommended when animating a complex View\nBut layers cost memory and refreshing a layer costs 2x the fillrate\n
- Use the optional Paint to apply visual treatments:\nopacity, color filter, blending modes etc.\nYou can tint a view, make it grayscale, etc.\n
- Launcher modified to display the icons in gray\nThe pages of icons are backed by hardware layers\nVery easy to do\n
- Here is the code used in the previous screenshot\nJust sets a ColorFilter on the paint used by the hardware layer\nEasy!\n
- Forces a View to render in software\nWorkaround for hw limitations or GL pipeline limitations\n
- Related to performance, but worth talking about in detail\nSome View properties affect layers directly, which make them very cheap\n
- When changing one of these properties, the View does not invalidate\nThe layer is not redrawn, instead the parent&#x2019;s DisplayList is updated\nThis is a very efficient way to animate Views\nThese properties are also DisplayLists friendly\n
- When setting one of these properties, the parent is invalidated, and the parent&#x2019;s DisplayList is dirtied\nRebuilding the parent&#x2019;s display list is usually very cheap, since it refers to DisplayLists/Layers\n
- When setting one of these properties, the parent is invalidated, and the parent&#x2019;s DisplayList is dirtied\nRebuilding the parent&#x2019;s display list is usually very cheap, since it refers to DisplayLists/Layers\n
- When setting one of these properties, the parent is invalidated, and the parent&#x2019;s DisplayList is dirtied\nRebuilding the parent&#x2019;s display list is usually very cheap, since it refers to DisplayLists/Layers\n
- When setting one of these properties, the parent is invalidated, and the parent&#x2019;s DisplayList is dirtied\nRebuilding the parent&#x2019;s display list is usually very cheap, since it refers to DisplayLists/Layers\n
- When setting one of these properties, the parent is invalidated, and the parent&#x2019;s DisplayList is dirtied\nRebuilding the parent&#x2019;s display list is usually very cheap, since it refers to DisplayLists/Layers\n
- When setting one of these properties, the parent is invalidated, and the parent&#x2019;s DisplayList is dirtied\nRebuilding the parent&#x2019;s display list is usually very cheap, since it refers to DisplayLists/Layers\n
- Here is a simplified version of the parent&#x2019;s display list\nDoes NOT execute() viewB.draw()\n
- Here is a simplified version of the parent&#x2019;s display list\nDoes NOT execute() viewB.draw()\n
- Here is a simplified version of the parent&#x2019;s display list\nDoes NOT execute() viewB.draw()\n
- If you want to animated a complex View (a ListView for instance), use layers\nThis is an example of a 3D rotation optimized with layers\nBut layers are costly to maintain (memory, refresh/fillrate)\n
- Keep layers only for the duration of the animation\nEasy to do with an AnimatorListener\nSaves time and space\n
- The new rendering pipeline changes the way rendering works\nIt&#x2019;s still an immediate mode\nBut with a special kind of caching\n
- The more views you have, the longer is takes to draw\nViewGroups in particular are very costly\nKeep your hierarchy flat\n
- Changing the alpha of a View costs 2x the fillrate, if you are not using layers\nAvoid it on large views (half the size of the screen) or make sure you use hardware layers\n
- Do NOT create Paints, Bitmaps, Shaders, etc. in draw methods\nCreating new ones is costly and will defeat internal caches and optimizations\nIt also avoids unnecessary GCs\n
- Changing a Bitmap, even one pixel, is expensive\nIt will cause a texture upload, which is a copy to GPU memory\nAvoid doing it if you can\n
- Paths are rendered using texture\nChanging a path causes the generation of an offscreen bitmap, software rasterization and texture upload\n
- On current hardware, no more than 2.5x times the entire screen\nRemove obscured views (useless background bitmap for instance)\n
- Profile profile profile\nWe&#x2019;ve spent weeks profiling our code to optimize it on tablets\nNasty surprises sometimes (new bitmaps created on every frame, etc.)\nAlways profile your code before blaming someone else!\n
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