skia.lua 1.8 KB

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  1. -- Experimental helpers for skia --
  2. function string.startsWith(String,Start)
  3. return string.sub(String,1,string.len(Start))==Start
  4. end
  5. function string.endsWith(String,End)
  6. return End=='' or string.sub(String,-string.len(End))==End
  7. end
  8. Sk = {}
  9. function Sk.isFinite(x)
  10. return x * 0 == 0
  11. end
  12. -------------------------------------------------------------------------------
  13. Sk.Rect = { left = 0, top = 0, right = 0, bottom = 0 }
  14. Sk.Rect.__index = Sk.Rect
  15. function Sk.Rect.new(l, t, r, b)
  16. local rect
  17. if r then
  18. -- 4 arguments
  19. rect = { left = l, top = t, right = r, bottom = b }
  20. elseif l then
  21. -- 2 arguments
  22. rect = { right = l, bottom = t }
  23. else
  24. -- 0 arguments
  25. rect = {}
  26. end
  27. setmetatable(rect, Sk.Rect)
  28. return rect;
  29. end
  30. function Sk.Rect:width()
  31. return self.right - self.left
  32. end
  33. function Sk.Rect:height()
  34. return self.bottom - self.top
  35. end
  36. function Sk.Rect:isEmpty()
  37. return self:width() <= 0 or self:height() <= 0
  38. end
  39. function Sk.Rect:isFinite()
  40. local value = self.left * 0
  41. value = value * self.top
  42. value = value * self.right
  43. value = value * self.bottom
  44. return 0 == value
  45. end
  46. function Sk.Rect:setEmpty()
  47. self.left = 0
  48. self.top = 0
  49. self.right = 0
  50. self.bottom = 0
  51. end
  52. function Sk.Rect:set(l, t, r, b)
  53. self.left = l
  54. self.top = t
  55. self.right = r
  56. self.bottom = b
  57. end
  58. function Sk.Rect:offset(dx, dy)
  59. dy = dy or dx
  60. self.left = self.left + dx
  61. self.top = self.top + dy
  62. self.right = self.right + dx
  63. self.bottom = self.bottom + dy
  64. end
  65. function Sk.Rect:inset(dx, dy)
  66. dy = dy or dx
  67. self.left = self.left + dx
  68. self.top = self.top + dy
  69. self.right = self.right - dx
  70. self.bottom = self.bottom - dy
  71. end
  72. -------------------------------------------------------------------------------