How can I reliably set the backroundimage of a picturebox to be a random color? - powershell

Question

I have a fairly simple color randomization snippet that I am using so I can accurately see the bounds of an image matrix I am making on screen. Problem is that I can not get it to work 100% of the time.
$listingImage = [System.Windows.Forms.PictureBox]::new()
...
# Temp color code to help with visual
$listingImage.BackColor = ([System.Drawing.Color](Get-Random -Minimum 1 -Maximum 999999))
The rest of the code follows in the question but that is the heart of what I am trying to do. I have seen it working several times but repeated executions show what seem like, empty, blank or otherwise invisible picture boxes. If I hard code a colour like $listingImage.BackColor = [System.Drawing.Color]::DarkCyan I can see that working fine every time. I want different colours though so I can see how to boxes are lining up with each other.
The code you can use for testing is as follows:
Add-Type -AssemblyName System.Windows.Forms
$imageContainerSize = [Drawing.Size]::new(100,100) # Width, Height
$numberOfImages = [pscustomobject]#{
Horizontal = 5
Vertical = 4
}
$formOverallSize = [Drawing.Size]::new(
$imageContainerSize.Width * $numberOfImages.Horizontal,
$imageContainerSize.Height * $numberOfImages.Vertical
)
$listingImageForm = New-Object System.Windows.Forms.Form
$listingImageForm.Text = $listing.URL
$listingImageForm.Size = $formOverallSize
$listingImageForm.FormBorderStyle = [System.Windows.Forms.FormBorderStyle]::FixedSingle
$listingImageForm.StartPosition = [System.Windows.Forms.FormStartPosition]::CenterScreen
$imageMatrixXOffset = 0
$imageMatrixYOffset = 0
# Load the image place holder image.
$placeholderImagePath = "m:\scripts\test.png"
# $placeholderImage = [system.drawing.image]::FromStream([IO.MemoryStream]::new([System.IO.File]::ReadAllBytes($placeholderImagePath)))
# Create an image matrix from the images provided in a listing group
for ($verticalImageIndex = 0; $verticalImageIndex -lt $numberOfImages.Vertical; $verticalImageIndex++){
for ($horizonalImageIndex = 0; $horizonalImageIndex -lt $numberOfImages.Horizontal; $horizonalImageIndex++){
$listingImage = [System.Windows.Forms.PictureBox]::new()
$listingImage.Size = $imageContainerSize
$listingImage.BorderStyle = [System.Windows.Forms.BorderStyle]::None
$listingImage.SizeMode = [System.Windows.Forms.PictureBoxSizeMode]::CenterImage
$listingImage.Location = [System.Drawing.Point]::new($horizonalImageIndex * $listingImage.Size.Width + $imageMatrixXOffset,
$verticalImageIndex * $listingImage.Size.Height + $imageMatrixYOffset )
# Temp color code to help with visual
$listingImage.BackColor = ([System.Drawing.Color](Get-Random -Minimum 1 -Maximum 999999))
# Place the image based
# $listingImage.Image = $placeholderImage
$listingImage.Tag = "h:$horizonalImageIndex v:$verticalImageIndex"
# Download the image as a memory stream to bypass saving the file
$listingImageForm.Controls.Add($listingImage)
}
}
# Adjust the size of the form to account for the title bar and the width of the form.
$formBorderWidth = ($listingImageForm.Width - $listingImageForm.ClientSize.Width) / 2
$formTitleBarHeight = $listingImageForm.Height – $listingImageForm.ClientSize.Height – 2 * $formBorderWidth
# Adjust for based on previosly calculated values
$listingImageForm.Size.Height = $listingImageForm.Size.Height + $formTitleBarHeight + ($formBorderWidth * 2)
$listingImageForm.Size.Width = $listingImageForm.Size.Width + ($formBorderWidth * 2)
$listingImageForm.Add_Shown({$listingImageForm.Activate()})
[void]$listingImageForm.ShowDialog()
"Form Height : $($listingImageForm.Size.Height)"
"Form Width : $($listingImageForm.Size.Width)"
"Image Height: $($imageContainerSize.Height)"
"Image Width : $($imageContainerSize.Width)"
$listingImageForm.Dispose()
Why is my randomization not working correctly? I really don't think it is the randomization itself since I can run

Answer 1

The problem is with the randomization upperbound.
[System.Drawing.Color](Get-Random -Minimum 1 -Maximum 999999)
So this will only generate values of a maximum 999999. The number will never get high enough to change the alpha channel / opacity value of the 'random' colour. If you kept trying that code in the command line you will see the A value is always zero.
([System.Drawing.Color](Get-Random -Minimum 1 -Maximum 999999))
R : 10
G : 177
B : 51
A : 0
IsKnownColor : False
IsEmpty : False
IsNamedColor : False
IsSystemColor : False
Name : ab133
A larger testing set to prove the point.
1..1000 | ForEach-Object {
([system.Drawing.Color](Get-Random -Minimum 1 -Maximum 999999))} |
Group-Object -Property A -NoElement
Count Name
----- ----
1000 0
This is why it did not appear to work as the opacity was always zero. I suspect it was periodically working as you might have been changing the randomization code between tests and not correlating the changes.
RGBA Values can be represented as int32 integers values. Setting your randomization to use that as your upper bound will prove more fruitful.
[System.Drawing.Color](Get-Random ([int32]::MaxValue))
Yes, it is possible you could randomize all 0 alpha again but for simple testing that should work just fine.
Click image to embiggen
Or, as Ansgar Wiechers mentions in comments, this might be a friendlier solution to the issue
[Drawing.Color]::FromArgb((Random 256),(Random 256),(Random 256),(Random 256))