ID Number: Q79604
1.00
WINDOWS
Summary:
The DrawWidth property controls line thickness for the graphics methods
Circle, Line, and PSet. You can only set DrawWidth in units of pixels.
Pixel size and density vary among video and printer devices.
This article describes how to set DrawWidth to the number of pixels to
correspond with measurements in units other than pixels.
This information applies to the Visual Basic programming system
version 1.0 for Windows.
More Information:
The following steps describe how to calculate DrawWidth from units
other than pixels, referred to as "target units."
1. Determine the form (or printer) width in target units by setting
the ScaleMode property to one of the values listed below and then
retrieving the ScaleWidth property.
ScaleMode Settings
------------------
0 -- user-defined
1 -- twips
2 -- points
4 -- characters
5 -- inches
6 -- millimeters
7 -- centimeters
For example:
Form1.ScaleMode = 7 ' centimeters
cm = Form1.ScaleWidth
2. Determine the form (or printer) width in pixels by setting the
ScaleMode property to 3 (PIXELS in CONSTANT.TXT) and then
retrieving the ScaleWidth property.
For example:
Form1.ScaleMode = 3
pixel = Form1.ScaleWidth
3. Calculate the ratio of pixels per target unit by dividing the form
(or printer) width in target units by the form (or printer) width
in pixels.
For example:
pixel_per_cm = pixel / cm
4. Set DrawWidth to the number of target units multiplied by the ratio
of pixels per target unit.
For example:
Form1.DrawWidth = 5 * pixel_per_cm ' 5cm thick lines
The following code example demonstrates how to calculate the DrawWidth
property in inches, for a form and the printer:
'*** In the global module: ***
' ScaleMode (form, picture box, Printer)
Global Const TWIPS = 1
Global Const POINTS = 2 ' 20 twips
Global Const PIXELS = 3
Global Const CHARACTERS = 4 ' x: 120 twips, y: 240 twips
Global Const INCHES = 5 ' 1440 twips
Global Const MILLIMETERS = 6 ' 5669 twips
Global Const CENTIMETERS = 7 ' 566.9 twips
' *** In the form: ***
Sub Form_Click ()
Dim ptr_inch As Integer ' printer width in inches
Dim ptr_pixel As Long ' printer width in pixels
Dim ptr_dpi As Single ' printer dots (pixels) per inch
Dim scn_inch As Integer ' screen width in inches
Dim scn_pixel As Long ' screen width in pixels
Dim scn_dpi As Single ' screen dots (pixels) per inch
' Determine printer pixels-per-inch ratio
save% = Printer.ScaleMode
Printer.ScaleMode = INCHES: ptr_inch = Printer.ScaleWidth
Printer.ScaleMode = PIXELS: ptr_pixel= Printer.ScaleWidth
Printer.ScaleMode = save%
ptr_dpi = ptr_pixel / ptr_inch
' Determine form (screen) pixels-per-inch ratio
save% = Form1.ScaleMode
Form1.ScaleMode = INCHES: scn_inch = Form1.ScaleWidth
Form1.ScaleMode = PIXELS: scn_pixel = Form1.ScaleWidth
Form1.ScaleMode = save%
scn_dpi = scn_pixel / scn_inch
' Set printer and form DrawWidth to 0.25 inches
' and draw a 0.25 inch thick line
Printer.DrawWidth = .25 * ptr_dpi
Form1.DrawWidth = .25 * scn_dpi
Printer.Line (0, 0)-(Form1.ScaleWidth, Form1.ScaleHeight)
Form1.Line (0, 0)-(Form1.ScaleWidth, Form1.ScaleHeight)
' Set printer.DrawWidth to match screen pixel size
' and draw a 5 screen-pixel thick line
Form1.DrawWidth = 5
Printer.DrawWidth = Form1.DrawWidth * ptr_dpi / scn_dpi
Form1.Line (0, Form1.ScaleHeight)-(Form1.ScaleWidth, 0)
Printer.Line (0, Form1.ScaleHeight)-(Form1.ScaleWidth, 0)
Printer.EndDoc
End Sub
When run, the above sample program will cause two lines in the form of
an X to be printed to the form and printer simultaneously. The width
of the thicker diagonal line should be 0.25 inches wide on the printed
page. The other diagonal line represents a line five pixels wide.
Additional reference words: 1.00