g.Pixel error?

General
1

Hi,
I’m just taking baby steps with Xojo (I’ve got a design and filemaker background). I picked up the book “I wish I knew how to program the canvas control” and I’ve gotten to example 1-6 which is just a simple canvas with the paint event and the following code:

'Draw a green filled rectangle
g.ForeColor = RGB(10, 240, 10) 'Green
g.FillRect(49, 49, 100, 100) 'Filled Rectangle

'Colour the centre pixel red
g.Pixel(99, 99) = RGB(240, 10, 10)

'Get the pixel values outside and inside the Rectangle
MsgBox "The colour inside the rectangle is: " + CStr(g.Pixel(60,60)) + chr(13) +"The colour outside the Rectangle is: " + CStr(g.Pixel(20,20))

This crashes on the last line, something to do with the g.Pixel(60,60), any idea why?

Thanks!
Glen

2

This item has been DEPRECATED since version 2016r1 and should no longer be used.
Please use RGBSurface as a replacement.

3

What is the error message?

4

UnsupportedOperationException
Exception Message: Graphics.Pixel can only be used with a Picture’s graphics object.

and it has to do with READING the pixel… not WRITING it

dim c as color=g.pixel(60,60)

gives the same error

5

Yes, that’s the error. Anyone know how to use RGBSurface to get it?

thanks!

6

g here (in the paint event) can be considered a temporary graphic.
You can send to it, but you cant read from it.

If you want to know what pixels are what, you are better off creating a picture
Drawing to the picture’s rgbsurface
Reading from the picture’s rgbsurface

and in the Paint event where you have this g, just g.drawpicture thepicture, 0,0 to display your picture

7

[quote=381218:@Glen Newbury]Yes, that’s the error. Anyone know how to use RGBSurface to get it?

thanks![/quote]

myColor = thepicture.RGBSurface.pixel(x,y)

http://documentation.xojo.com/index.php/RGBSurface

In practice, replace picture.graphics by picture.rgbsurface.

8

Thanks Jeff and Michel, I’ll try it later today. I was trying it last night using that link and getting pretty frustrated, two steps forward, one back. :slight_smile:

9

Once you allow one thing to frustrate you ,everything seems insurmountable.