Efficient Graphics with Qt
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This document discusses techniques for efficient and beautiful graphics in Qt applications. It covers topics like 2D graphics with QPainter, transformations with QTransform, pixel manipulation in QImage, common effects like blurring and colorizing, using physics engines, and optimizing for performance by avoiding slow operations and ensuring code is cache friendly. The goal is to provide ideas and tricks to enhance the visual quality of Qt and KDE applications.
Efficient Graphics with Qt
- 1. E cient Graphics with Qt ARIYA HIDAYAT ENGINEERING DIRECTOR, SENCHA 1
- 2. whoami 2
- 3. ? 3
- 4. about... Patterns on beauty 2-D low-level QPainter Graphics View Widget tricks 4
- 5. and NOT about Qt Quick (QML) Scene Graph 5
- 6. Objectives Ideas & tricks to beautify your Qt & KDE apps 6
- 7. 7
- 8. 8
- 9. 9
- 10. Graphics Performance Gunnar Sletta’s blog posts on Qt Labs http://labs.qt.nokia.com/author/gunnar/ 10
- 11. Premature Optimization... 11
- 12. Blazing Fast. How? 12
- 13. Avoid Slow Operations 13
- 14. Don’t Assume. Measure! Valgrind Shark 14
- 15. Transformation 15
- 16. QTransform 16
- 18. Composing Screenshots 18
- 19. Fancy! http://screenie.googlecode.com 19
- 20. Flow E ect http://pictureflow.googlecode.com 20
- 23. Pixel Manipulation 23
- 24. Accessing Pixels in QImage QRgb QImage::pixel (int x, int y) void QImage::setPixel (int x, int y, uint rgb ) 24
- 25. Faster Pixel Access bits() scanLine(y) 25
- 26. Careful with Implicit Sharing uchar * QImage::bits () const uchar * QImage::bits () 26
- 29. Image Formats ARGB32 ARGB32_Premultiplied A: 128 A: 128 R: 175 R: 088 G: 212 G: 106 B: 240 B: 120 29
- 30. Faster Alpha Blending R=R A +R A s s d d R=R +R A s d d 30
- 31. Cache Friendly 31
- 32. Let There Be Colors 32-bit 16-bit 32
- 33. Special F/X 33
- 34. With great power must come great responsibility. 34
- 35. Grayscale 35
- 36. Composition Modes 36
- 37. Tint / Colorize http://labs.qt.nokia.com/2008/11/10/colorize-an-image-via-painter-composition/ 37
- 38. RGB, HSL, HSV 38
- 42. Genie http://labs.qt.nokia.com/2008/12/15/genie-fx/ 42
- 44. Physics 44
- 50. Minimize Path Operations collision detection 50
- 51. Approximation Qt::IntersectItemShape Qt::IntersectBoundingRect 51
- 52. Widgets & Applications 52
- 53. Graphics System yourapp -graphicssystem raster native Automatic raster Pure software rasterizer x11 Use X11 + its extensions opengl Use OpenGL (ES) 2 53
- 54. Widget Attributes Qt::WA_StaticContents paint events only for the newly visible part Qt::WA_OpaquePaintEvent paints all its pixels when it receives a paint event Qt::WA_NoSystemBackground the background is not automatically repainted 54
- 55. More Widget Attributes Qt::WA_PaintOnScreen draw directly onto the screen might cause flickering!! Qt::WA_NativeWindow this widget is native (to the window system) Qt::WA_DontCreateNativeAncestors the widget's ancestors are kept non-native 55
- 56. Antialiasing 56
- 57. Thumbnail Preview 57
- 59. Fast vs Smooth 59
- 60. Smooth vs Cheat 60
- 61. Conclusions 61
- 62. Patterns of Beauty Tranformations Special E ects Pixel manipulations Physics 62
- 63. THANK YOU! ariya @ kde.org ariya.blogspot.com ariyahidayat 63