FIX: Scale and Line Methods Work Differently on Printer Object

The Scale and Line methods are used to display a line on a form in a Visual Basic project. When the same arguments for the Scale and Line methods are used with the Printer object, the lines on the printed page are different from those displayed on the form. The expected behavior is that the line printed on the page will match the line displayed on the form.

The Printer.Scale method does not properly handle the case where the value of one of the XY coordinates in the second point is less than the value of corresponding coordinate in the first point.

For example, the following statement would behave incorrectly because the value of the second Y coordinate is less than that of the first one.

Remove the call to the Scale method and replace it by setting the ScaleLeft, ScaleTop, ScaleWidth, and ScaleHeight properties as shown in the sample in the MORE INFORMATION section.

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why  (http://support.microsoft.com/kb/194022/EN-US/ )

194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed  (http://support.microsoft.com/kb/194295/EN-US/ )

This section illustrates how to create a Visual Basic project that demonstrates this behavior. It assumes you are familiar with using the methods of the Printer and Form objects.

Steps to Reproduce Behavior

1. Start a new Standard EXE project in Visual Basic. Form1 is created by default.
2. Add three CommandButton controls to Form1.
3. Copy the following code to the General Declaration section of Form1:

      Option Explicit
   
      Private Sub Command1_Click()
         Scale (0, 5)-(10, 0)
         Line (0, 4)-(10, 3)
      End Sub
   
      Private Sub Command2_Click()
         Printer.Scale (0, 5)-(10, 0)
         Printer.Line (0, 4)-(10, 3)
         Printer.EndDoc
      End Sub
   
      Private Sub Command3_Click()
         Printer.ScaleLeft = 0
         Printer.ScaleTop = 5
         Printer.ScaleWidth = 10
         Printer.ScaleHeight = -5
         Printer.Line (0, 4)-(10, 3)
         Printer.EndDoc
      End Sub
   						

4. Run the project. Click Command1 to draw a line on Form1 then click Command2 to print a line.
   
   RESULT: The endpoint of the line on the right side of the printed page is higher than the starting point. On Form1 the endpoint is lower. The expected behavior is that the line on the printed page should match the line that appears on Form1.
5. Click Command3 and compare the printed output to the screen image. The output now matches correctly.