Load image based on query return

McDian · **Joined:** Fri Sep 14, 2007 5:00 pm **Posts:** 408

I am trying to get a Canvas object to display an image based on a name that is returned from a query.

Right now this code is located in popHelpTopic.Text

// Variable declarations...
Dim recSet As RecordSet = mthGetHelpTopic(popHelpTopic.Text)

// Function(s)...
txtHelpDetail.Text = recSet.IdxField(3).StringValue
lblRelated01.Caption = recSet.IdxField(4).StringValue
lblRelated02.Caption = recSet.IdxField(5).StringValue
lblRelated03.Caption = recSet.IdxField(6).StringValue
lblRelated04.Caption = recSet.IdxField(7).StringValue
lblRelated05.Caption = recSet.IdxField(8).StringValue
lblRelated06.Caption = recSet.IdxField(9).StringValue

mthLoadPopHelp

Properties:
Private pic As Picture

And this code is located in cnvImage.Paint

// Variable declarations...
Dim recSet As RecordSet = mthGetHelpTopic(popHelpTopic.Text)
Dim fldMeter As FolderItem
Dim picHelpImg As Picture
Dim maxWidth, maxHeight As Integer
Dim factor As Double

// Function(s)...
maxWidth = cnvImage.Width
maxHeight = cnvImage.Height

fldMeter = GetFolderItem("Pics/Help Images/").Child(recSet.IdxField(10).StringValue)

If(fldMeter) <> Nil Then
  picHelpImg = fldMeter.OpenAsPicture
End If

factor = Min(maxWidth / picHelpImg.Width, maxHeight / picHelpImg.Height)
factor = Min(factor, 1.0) ' If it's too small then do not scale the image...

If(pic) <> Nil Then
  '    pic = NewPicture(picHelpImg.Width * factor, picHelpImg.Height * factor, 32)
  '    pic.Graphics.DrawPicture picHelpImg, 0, 0, pic.Width, pic.Height, 0, 0, picHelpImg.Width, picHelpImg.Height
  
  g.DrawPicture pic, 0, 0
End If

cnvImage.Refresh
'cnvImage.Backdrop = fldMeter.OpenAsPicture

How this works is or is supposed to work is the user selects an item from a PopUp Menu which will call a Query. A recordset is returned and that is used to populate various elements. The last field in the query contains a name for an image.

I have a canvas object defined (it's called cnvImage) and based on the name in the query I want to display the appropriate image. I found a spot in the help manual (you can see I have been using it to try and get the results I want) and have had no luck getting the image to paint.

I am stumped and really don't know how to get around this one.

One issue that is coming up now is with the factor segment:

factor = Min(maxWidth / picHelpImg.Width, maxHeight / picHelpImg.Height)
factor = Min(factor, 1.0) ' If it's too small then do not scale the image...

I am getting a Nil Object Exception, from what I can tell in debug is that picHelpImg is the Nil object, but I am not sure why or how to correct it.

jefftullin · **Posted:** Mon Apr 05, 2010 3:44 pm

is recset nil?

what is the value of recSet.IdxField(10).StringValue at the point you use it to get a folder item?

"Pics/Help Images/" will not exist at debug time, if you expect it to be local to your application.

try creating the pics folder on your desktop.
Then use

fldMeter = Specialfolder.desktop.child("Pics").child("Help Images").Child(recSet.IdxField(10).StringValue)

McDian · **Joined:** Fri Sep 14, 2007 5:00 pm **Posts:** 408

recSet is not Nil

recSet.IdxField(10).StringValue = "MeterDetail01.jpg"

I have the Pics/Help Images folders contained in the CurrentWorkingDirectory.

So I changed the code a bit to this

fldMeter = SpecialFolder.CurrentWorkingDirectory.Child("Pics").Child("Help Images").Child(recSet.IdxField(10).StringValue)

When the application errors out the message at the bottom of the IDE window is NilObjectException.

The Variables have the following:

Globals
factor = 0.
fldMeter = Nil
g = Graphics [random chars]
maxHeight = 416
maxWidth = 801
me = Canvas [random chars]
picHelpImg = Nil
recSet = RecordSet [random chars]
self = frmHelp.frmHelp [random chars]

McDian · **Joined:** Fri Sep 14, 2007 5:00 pm **Posts:** 408

Okay some progress has been made...

// Variable declarations...
Dim recSet As RecordSet = mthGetHelpTopic(popHelpTopic.Text)
Dim fldMeter As FolderItem
Dim picHelpImg As Picture
Dim maxWidth, maxHeight As Integer
Dim factor As Double

// Function(s)...
maxWidth = cnvImage.Width
maxHeight = cnvImage.Height

fldMeter = GetFolderItem("Pics/Help Images/").Child(recSet.IdxField(10).StringValue)

If(fldMeter) <> Nil Then
  picHelpImg = fldMeter.OpenAsPicture
End If

factor = Min(maxWidth / picHelpImg.Width, maxHeight / picHelpImg.Height)
factor = Min(factor, 1.0) ' If it's too small then do not scale the image...

If(picHelpImg) <> Nil Then
  pic = NewPicture(picHelpImg.Width * factor, picHelpImg.Height * factor, 32)
  pic.Graphics.DrawPicture picHelpImg, 0, 0, pic.Width, pic.Height, 0, 0, picHelpImg.Width, picHelpImg.Height
  
  g.DrawPicture pic, 0, 0
  
End If

mthLoadPopHelp

Exit

This is working... sort of again. There seems to be an issue with how I have this designed.

I have a TabPanel with two tabs.

TabPanel.Name = pnlHelp
Panel 1 has an EditField.Name = txtHelpDetail
Panel 2 has the Canvas.Name = cnvImage

When I click on Panel two the image now appears. But if I try to go back to Panel 1 the NilObjectException gets thrown again.

timhare · **Posted:** Mon Apr 05, 2010 6:16 pm

Quote:

factor = Min(maxWidth / picHelpImg.Width, maxHeight / picHelpImg.Height)

Put this line (and the one following it) inside your "if picHelpImg <> nil" test.

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Load image based on query return