get at point color

[mestnyi]

can you confirm that this is a bug in windows?

Code: Select all

If OpenWindow(0, 0, 0, 200, 200, "2DDrawing Example DPI", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
    If CreateImage(0, 200, 200, 24, $FFFFFF) And StartDrawing(ImageOutput(0))
        
      ; Draw the same figure at different locations by moving the drawing origin
      For x = 0 To 120 Step 40
        For y = 0 To 120 Step 60
          
          SetOrigin(x, y)
          
          color = Point(x, y) 
          
          Debug color
          
          Box(0, 0, 30, 30, $FF0000)
          Circle(15, 15, 10, $00FF00)
          
          
          Circle(15, 15, 5, color)
          
        Next y
      Next x   
         
      StopDrawing() 
      ImageGadget(0, 0, 0, 200, 200, ImageID(0))      
    EndIf
    
    Repeat
      Event = WaitWindowEvent()
    Until Event = #PB_Event_CloseWindow
  EndIf

[infratec]

If you use SetOrigin() you move the offset.
If you use the original x y, you get out of the image.

Use

Code: Select all

Debug Str(x) + "/" + Str(y)

to see the cordinates.
If you get 120 for y you are at 240 in reality, which is out of the image.

[Bisonte]

the help says for POINT() :

For performance reasons there are no bounds checks performed on these coordinates, the specified coordinates must be inside the current drawing area. OutputWidth() and OutputHeight() can be used to verify that. This command is also not affected by calls to ClipOutput().

So there is no check if the coordinates are exist... and if not... error. I said no bug, because the help also said : This command is also not affected by calls to ClipOutput() so I think all is ok.
It makes no sense in your example to write Point(x, y) more 0, 0 or another fixed point, because you are already use a SetOrigin and there you not need the whole Output...

[mestnyi]

in this example I expected the inner circle to be colored blue, what do you think?

Code: Select all

If OpenWindow(0, 0, 0, 200, 200, "2DDrawing Example DPI", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
  If CreateImage(0, 200, 200, 24, $FFFFFF) And StartDrawing(ImageOutput(0))
    x = 50
    y = 50
    size = 30
    
    Box(x, y, size, size, $FF0000)
    Circle(x+15, y+15, 10, $00FF00)
                
    color = Point(x+size, y+size) 
    
    Debug color
    
    Circle(x+15, y+15, 5, color)
    
    
    StopDrawing() 
    ImageGadget(0, 0, 0, 200, 200, ImageID(0))      
  EndIf
  
  Repeat
    Event = WaitWindowEvent()
  Until Event = #PB_Event_CloseWindow
EndIf

[jacdelad]

Point gets a pixel outside your rectangle, because the box ends at X+size-1 (the first of your 30 pixels is on X, then 29 remaining). A box with width 1 draws a single pixel at x,y. Width 2 draws 2 pixel next to each other (x and X+1). The last pixel is always X+width-1. And of course same with y.

[mestnyi]

Point gets a pixel outside your rectangle, because the box ends at X+size-1 (the first of your 30 pixels is on X, then 29 remaining). A box with width 1 draws a single pixel at x,y. Width 2 draws 2 pixel next to each other (x and X+1). The last pixel is always X+width-1. And of course same with y.

why box draw X+size-1?

[jacdelad]

I said the box ends at X+size-1. The last pixel is there. You get the colour of X+size...but never drew there.

As an example:

Code: Select all

Box(0,0,1,1)

draws a box containing just a single pixel at 0,0. You try to get the pixel at 1,1, aka X+size.

[Mijikai]

A Macro to help debug color:

Code: Select all

Macro DebugColorTriplet(_v_)
  Debug RSet(Hex(_v_,#PB_Long),6,"0")
EndMacro

DebugColorTriplet(65280)