How to create PDF file from Visual Basic
: example "Hello, PDF!"
This page contatins step-by-step tutorial aimed to teach you how to createPDFfile from Visual Basic application using PDF Creator Pilot library.
1)InstallPDF Creator Pilotlibrary on your computer and runVisual Basic.
You will see New Project Wizard:
2)SelectStandard EXEproject type and clickOpento create new project.
Visual Basic will generate new projectProject1and will automatically open the main form of the generated project:
3)Now we should place a button that will launchl PDF generation function. To place the button just clickCommandButtonon the controls toolbar on the left:
Now press your right mouse button and then drag the mouse so you will set the rectangle for a new control and release the mouse button to create the control. It will look like this:
4)Visual Basic will create new button control on theForm1. Double-click on the control to letVisual Basiccreate the click handler function in the project code: Visual Basicwill create new function which will be launched every time when user clicks the button:
5)Now you have to write the code that will generate PDF file using PDF Creator Pilot .
To generate PDF document you have to do the following:
1.connect to the PDF Creator Pilot library;
2.set the filename for PDF document;
3.draw "Hello, PDF!" message on the PDF page;
4.disconnect from the library.
Here is the source code:
Private Sub Command1_Click()
’ connect to library
SetPDF = CreateObject("PDFCreatorPilot.piPDFDocument")
’ initialize PDF Engine
PDF.StartEngine "demo@demo", "demo"
’ set PDF ouput filename
PDF.FileName = "HelloPDF_VB.pdf"
PDF.AutoLaunch = True’ auto-open generated pdf document
’ start document generation
PDF.BeginDoc
’ draw "HELLO, PDF" message on the current PDF page
PDF.PDFPAGE_BeginText
PDF.PDFPAGE_SetActiveFont "Verdana", True, False, False, False, 14, 0
PDF.PDFPAGE_TextOut 10, 20, 0, "HELLO, PDF!"
PDF.PDFPAGE_EndText
’ finalize document generation
PDF.EndDoc
’ disconnect from library
SetPDF = Nothing
End Sub
This function will generate PDF document and save it as "HelloPDF_VB.PDF"file in the application’s folder.
Hint:
You can simply copy the source code from the snippet above and then paste it in theVisual Basiccode editor as it’s shown on the
screenshot below:
6)PressF5to run the application (you can also use "Run" | "Start" menu command).
Visual Basic will run the application and you will see its main form:
7)Click "Command1" button and application will generate"HelloPDF_VB.PDF"file.
If you have any PDF viewer (for example,Adobe Acrobat Reader) installed on your computer then the library will launch it to open
the generated PDF document:
You can find the source code of this example in the"\Examples\VB\"sub-folder.
Organising your first project
The first step is to create a project template within VB, to organise and store your work. This will consist of a menu structure with headings that will let you access the many exercises and examples you complete.
Activity 1
· Open VisualBasic 6.0
· Use the file menu to open a new project with a blank form.
· Use the properties window to set
– Main.frm as the form name.
– My programs as the caption.
– BackColor to White.
– BorderStyle to Fixed Single.
– WindowState to Maximised.
· Find the Menu icon and click on it to select it. Enter the following menu headings:
Quit
Introduction with indented subheadings of Example1 , Example2
Click OK after each menu caption and name are typed.
· Click on Quit menu heading and enter the following code. This procedure is used to exit from running the project display and return to the design screens.
Private Sub Quit_Click()
Unload me
End
End Sub
· Use the <F5> function key to run the application to verify that the Menu structure is correct and that the Quit procedure is free from error.
· Use the File menu to save your work as Main.frm and (your intitials)Project1.vbp
· Use the file menu to open a new blank form (or the properties window)
· Set the following form properties:
form name as Welcome caption to Example1 BackColor to White BorderStyle to Fixed Single
WindowState to Maximised
· Click on the Example 1 main menu heading and enter the following code:
Private Sub Example1_Click()
Welcome.Show
End Sub
· Save your work and run <F5> to ensure that it is free of errors.
· Add two labels, an image and a command button to create a welcome screen. To do this Select label icon from the toolbox. Click towards the centre-top of your form and position and resize your label as required. With the label selected, use the properties window to Change the caption to WELCOME TO VISUAL BASIC
Choose a bright back colour
Set the font (Arial, underline, alignment centred, size 24 point, forecolour blue)
Repeat to add the Enjoy label.
Use the image icon on your toolbox to add the image to your form. Use the
properties window of the image to select a picture. Use the command Button icon to add the button. Change its caption to RETURN. Then double-click the button and add the following line of code after the Command1_Click() procedure.
– Unload Welcome
· Use the file menu to save your work and use <F5> to run the application.
· DON’T FORGET TO SAVE (AND BACK UP TO FLOPPY) ALL YOUR WORK.
Event handlers and scroll bars Some definitions to learn
· An object is a thing anything that appears on the screen. An object has a set of properties. Each property of the object has a value.
e.g. Label.Caption = “Welcome to Visual Basic” where
Label is an object
Caption is a property of label
“Welcome to Visual Basic” is a value of the Caption property.
· Events are things that happen on the screen. Event handlers transfer data to procedures that complete the task. The results of these procedures are returned back to other screen objects, e.g. onChange onClick
· A procedure is a group of statements designed to perform a specific task. A
procedure attached to an object, such as a button, is a command used to make something happen, e.g.
Public Sub Command2_Click()
Text1.Text = “This is a procedure.”
End Sub
Add new form to menu
As each new example and exercise solution is to be added to your project you will need to:
· add a new form
· set the form properties using the properties window
· click on the main menu icon with the main form displayed to show the menu
designer
· add a new menu heading
· click on the menu heading to show the procedure code
· to the procedure code, add the statement
FormXX.Show
where FormXX is the new form name.
Activity 2
1. Open a new form and change its name to ColourChanger. Place the following objects on this form.
A heading label2 (Caption = Colour Changer)
3 horizontal scroll bars (Set the max value property of all three to 255)
3 other labels (2red, 3Green, 4Blue) a command button to quit the form (Caption = Return) another small label5 under the button with its visible property set to false.
2. Double click each scroll bar and add the following code to its _onChange() event. Use cut and paste to make the task easier.
Label1.BackColor = RGB(HScroll1.Value, HScroll2.Value, HScroll3.Value)
Label5.BackColor = RGB(HScroll1.Value, HScroll2.Value, HScroll3.Value)
Label1.ForeColor = RGB(255 - HScroll1.Value, 255 - HScroll2.Value, 255 -
HScroll3.Value)
Label5.ForeColor = RGB(255 - HScroll1.Value, 255 - HScroll2.Value, 255 -
HScroll3.Value)
Label5.Visible = True
Label5.Caption = “WOW!”
Label2.BackColor = RGB(HScroll1.Value, 0, 0)
Label3.BackColor = RGB(0, HScroll2.Value, 0)
Label4.BackColor = RGB)0, 0, HScroll3.Value)
3. Double click the return button and add the following code to its _onClick() event
Unload Me
4. Use the Project Explorer window to return to your main form and double click
example 2 in your menu to add the appropriate code.
5. Use <F5> function key to test your project. Save and backup.
Sweeping Images
When we created embossed and engraved images in the previous two topics, we were careful to set up our embossing or engraving loop so that when setting a pixel, we did not make use of other pixels that we had already
set in the same loop.
The reason for that is that we only wanted to plot the difference between adjacent pixels that is, the difference between two pixels only to create embossed or engraved images. If we had not restricted our operation to two pixels we had not already worked on, and instead worked on pixels we had already set earlier, we could end up propagating a pixel’s color values among several other pixels. That is, one pixel’s setting could affect many other pixels.
In fact, there are times when you want to have that happen—for example, you might want to make an image appear as though it is sweeping from upper-left to lower-right, giving the illusion of motion. In that case, you’d copy pixels with the ones to the upper-left over and over, progressively blending them together to create the effect, where it looks as though the text has a fading trail of color behind it.
we move from lower-right to upper-left, averaging each pixel with the one to the lower-right:
For x = intUpperBoundX – 1 To 1 Step –1
For y = intUpperBoundY – 1 To 1 Step –1
bytRed = Abs((Pixels(x + 1, y + 1) And &HFF) + (Pixels(x, y)_
And &HFF)) / 2
bytGreen = Abs(((Pixels(x + 1, y + 1) And &HFF00) / &H100)_
Mod &H100 + ((Pixels(x, y) And &HFF00) / &H100) Mod_
&H100) / 2
bytBlue = Abs(((Pixels(x + 1, y + 1) And &HFF0000) / &H10000) _
Mod &H100 + ((Pixels(x, y) And &HFF0000) / &H10000) Mod_
&H100) / 2
Pixels(x, y) = RGB(bytRed, bytGreen, bytBlue)
Next y
Next x
That’s all it takes—now we copy the image into the second picture box, picture2. (To be able to work pixel by pixel, make sure you set each picture box’s ScaleMode property to vbPixel (3).) By combining successive pixels
as we do in this example, we create the sweeping effect. Now we’re creating complex images using image handling techniques.
Blurring Images
The Aesthetic Design Department is calling again. If you’re going to add image effects to your program, SuperDuperGraphicsPro, why not let the user blur images? You can blur images by averaging pixels. To see how this works, we load the pixels from a picture box, Picture1, and blur them, then display the result in another picture box, Picture2. To be able to work pixel by pixel, set each picture box’s ScaleMode property to vbPixel (3). As with the code in the previous few topics in this chapter, we load the pixels from Picture1 into an array named Pixels. To blur the pixels, you average them together; here, we just average each pixel with the next pixel to the right , but you can set up any blurring region you like (such as all eight pixels that surround the current pixel). This is the way our blurring process looks in code:
For x = 1 To intUpperBoundX – 1
For y = 1 To intUpperBoundY
bytRed = Abs((Pixels(x + 1, y) And &HFF) + (Pixels(x, y) _
And &HFF)) / 2
bytGreen = Abs(((Pixels(x + 1, y) And &HFF00) / &H100) Mod _
&H100 + ((Pixels(x, y) And &HFF00) / &H100) Mod &H100) / 2
bytBlue = Abs(((Pixels(x + 1, y) And &HFF0000) / &H10000) _
Mod &H100 + ((Pixels(x, y) And &HFF0000) / &H10000)_
Mod &H100) / 2
Pixels(x, y) = RGB(bytRed, bytGreen, bytBlue)
Next y
Next x
Creating Grayscale Images
We’ve seen how to work with images bit by bit in the previous topic. We’ll augment that in this topic, where we see how to convert color images to grayscale images. We do this by reading an image into a pixel array, then by converting each of those pixels to gray and writing the pixel array out to a new image. Let’s see how this works. We’ll convert the image in a picture box, Picture1, to grayscale, and display it in a new picture box, Picture2, when the user clicks a command button, Command1. To be able to work pixel by pixel, set each picture box’s ScaleMode property to vbPixel (3).
First, we set up storage space for the image in an array named Pixels, declared in the form’s (General) section:
Const intUpperBoundX = 300
Const intUpperBoundY = 300
Dim Pixels(1 To intUpperBoundX, 1 To intUpperBoundY) As Long
When the user clicks the command button, we store the image in Picture1 into the array Pixels:
Private Sub Command1_Click()
Dim x, y As Integer
For x = 1 To intUpperBoundX
For y = 1 To intUpperBoundY
Pixels(x, y) = Picture1.Point(x, y)
Next y
Next x
Now we’re free to work with the image’s pixels in a new loop (to be efficient, this new loop should be incorporated into the first loop where we read the pixels in, but here we’ll use a new loop to make the image-handling process clear). In that new loop, we first separate out the color values (red, green, and
blue) for each pixel. To create a grayscale image, you average those color values and then use the resulting average as the red, green, and blue color values in the new image. The Point method returns a Long integer holding the red, green, and blue color values (which range from 0 to 255) in hexadecimal: &HBBGGRR. That means we can separate out the red, green, and blue color
values, storing them as the bytes bytRed, bytGreen, and bytBlue this way:
Private Sub Command1_Click()
Dim x, y As Integer
Dim bytRed, bytGreen, bytBlue As Integer
For x = 1 To intUpperBoundX
For y = 1 To intUpperBoundY
Pixels(x, y) = Picture1.Point(x, y)
Next y
Next x
For x = 1 To intUpperBoundX
For y = 1 To intUpperBoundY
bytRed = Pixels(x, y) And &HFF
bytGreen = ((Pixels(x, y) And &HFF00) / &H100) Mod &H100
bytBlue = ((Pixels(x, y) And &HFF0000) / &H10000) Mod &H100
…
To convert each pixel to grayscale, we just average its color values. Finally, we display the new image in a second picture box, Picture2:
Private Sub Command1_Click()
Dim x, y As Integer
Dim bytRed, bytGreen, bytBlue, bytAverage As Integer
…
For x = 1 To intUpperBoundX
For y = 1 To intUpperBoundY
bytRed = Pixels(x, y) And &HFF
bytGreen = ((Pixels(x, y) And &HFF00) / &H100) Mod &H100
bytBlue = ((Pixels(x, y) And &HFF0000) / &H10000) Mod &H100
bytAverage = (bytRed + bytGreen + bytBlue) / 3
Pixels(x, y) = RGB(bytAverage, bytAverage, bytAverage)
Next y
Next x
For x = 1 To intUpperBoundX
For y = 1 To intUpperBoundY
Picture2.PSet (x, y), Pixels(x, y)
Next y
Next x
End Sub
Lightening Images
The Testing Department is calling. Some of the users of your super Duper Graphics Pro program are saying the images in that program are too dark—can you let them lighten them? Hmm, you think ,how does that work? You can lighten images by adding the same positive number to each color value (red, green, and blue) of each pixel. Let’s see how this works in an example. Here, we’ll take the image in a picture box, Picture1, and add a value specified by the user to each color value when the user clicks a command button, Command1, displaying the result in a second picture box, Picture2. To be able to work pixel by pixel, set each picture box’s ScaleMode property to vbPixel (3). We’ll also have a text box, Text1, that will hold the value the user wants to add to each color value to lighten it. We start by setting up the storage we’ll need for the image:
Const intUpperBoundX = 200
Const intUpperBoundY = 200
Dim Pixels(1 To intUpperBoundX, 1 To intUpperBoundY) As Long
Next, we place the value the user wants added to each color value in a new variable named intAddOn when the user clicks the command button:
Private Sub Command1_Click()
Dim intAddOn As Integer
intAddOn = Val(Text1.Text)
Now we read the image in Picture1 into the array named Pixels:
Private Sub Command1_Click()
Dim x, y, intAddOn As Integer
intAddOn = Val(Text1.Text)
For x = 1 To intUpperBoundX
For y = 1 To intUpperBoundY
Pixels(x, y) = Picture1.Point(x, y)
Next y
Next x
Next, we get the red, green, and blue color values for each pixel and add the value in intAddOn to those color values, making sure they don’t go higher than 255 (of course, you can also darken images by subtracting values here, although you should make sure the resulting color values don’t go below 0):
Private Sub Command1_Click()
Dim x, y, intAddOn As Integer
Dim bytRed, bytGreen, bytBlue As Integer
…
For x = 1 To intUpperBoundX
For y = 1 To intUpperBoundY
bytRed = Pixels(x, y) And &HFF
bytGreen = ((Pixels(x, y) And &HFF00) / &H100) Mod &H100
bytBlue = ((Pixels(x, y) And &HFF0000) / &H10000) Mod &H100
bytRed = bytRed + intAddOn
If bytRed > 255 Then bytRed = 255
bytGreen = bytGreen + intAddOn
If bytGreen > 255 Then bytGreen = 255
bytBlue = bytBlue + intAddOn
If bytBlue > 255 Then bytBlue = 255
Pixels(x, y) = RGB(bytRed, bytGreen, bytBlue)
Next y
Next x
End Sub
Finally, we just copy the new pixels to the second picture box, Picture2:
Private Sub Command1_Click()
Dim x, y, intAddOn As Integer
…
For x = 1 To intUpperBoundX
For y = 1 To intUpperBoundY
Picture2.PSet (x, y), Pixels(x, y)
Next y
Next x
End Sub
