Some additional function variations for 2D Drawing Lib

[Demivec]

The 2D drawing library has a Circle() and Ellipse() function that only allow parameters for radius. I think they should be more complete and allow the radius to be determined by a bounding box like so:

Code: Select all

Circle(x, y, Radius [, Color]) ;current implementation
Circle(x, y, x2, y2 [, Color]) ;requested variation.
Ellipse(x, y, RadiusX, RadiusY [, Color])  
Ellipse(x, y, x2, y2 [, Color]) ;requested variation

Line() has the variation LineXY() that does this in a similar way by computing the height and width of a line from the coordinates.

Unlike Line(), Circle() is limited in this respect because it cannot draw a fractional radius. This means that if the radius is an integer, only circles of even diameters can be drawn. This leaves out half of all circles. If the bounding coordinates were able to be specified instead this would be handled by the function easier.

Here's a demonstration for the visually minded that shows this graphically using API to draw the circles in the manner I'm desiring. The top drawing is done with PB's Circle() and draws circles of integer radii from 0 to 100. The bottom drawing is done with API and draws circles in boxes to generate circles of diameters from 0 to 200 (the same as the other method). The API method shows the overlapping circles cover the in-between radii that PB's method doesn't.

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OpenWindow(0,0,0,221,421,"Circle method",#PB_Window_SystemMenu)

hdc.l = StartDrawing(WindowOutput(0))
  FillArea(50,50,-1,$0000A0)
  
  ;draw grid
  For i.l = 0 To 420 Step 10
    LineXY(0,i,220,i,$0000FF)
    LineXY(i,0,i,420,$0000FF)
  Next i
  
  DrawingMode(#PB_2DDrawing_Outlined)
  ;using radius and PB Circle
  For i = 0 To 100
    Circle(110,110,i,RGB(i << 1,i << 1,i << 1))
  Next i
  
  ;using diameter and API Ellipse
  hNewPen.l = CreatePen_(#PS_SOLID,0,0)
  hOldPen.l = SelectObject_(hdc, hNewPen)
  hOldBrush = SelectObject_(hdc, #Null)

  For i = 0 To 200
    hPrevPen.l = hNewPen
    hNewPen.l = CreatePen_(#PS_SOLID,0,RGB(i,i,i))
    SelectObject_(hdc,hNewPen)
    DeleteObject_(hPrevPen)
    tl.l = 110 - Round(i / 2,#pb_round_down)
    br.l = 110 + Round(i / 2,#pb_round_up)
    Ellipse_(hdc,tl,tl + 200,br,br + 200)
  Next i

  SelectObject_(hdc, hOldPen)
  DeleteObject_(hNewPen)
  SelectObject_(hdc, hOldBrush)
 StopDrawing()

Repeat
  event.l = WindowEvent()
Until event = #PB_Event_CloseWindow