Thursday, 31 December 2009

Change Label Width Dynamically

Ok so in the last exercise we clicked the button on the form, this then:

1) Calculated the form size at that moment
2) Set the label size to be in the form with equal distance between the start and end of the label with repsect to the form edges.
3) Wrapped the text to fit.

Now the limitation was that if you moved the form's width with your mouse the label width would stay the same and so you wouldn't see the ends of the wrapped text as you decreased the form width.

1) To make this a dynamic setting take the code from the button click event and copy it to a text editor (Word, Notepad etc).
2) Delete the code
3) Go to the code window and in the top left drop down menu pick (frm1 events)
4) In the right hand drop down pick the resize event
5) In the event handler for the resize event paste the code you copied from the button click event.
6) Take out (cut) the line where you populate the label and paste it into the button click event.
7) Save and run the application

So your click event should only have this code in it:

lbl1.Text = "I am populating the label with some text now.... and I am typing more text here to increase the width of the string beyond the width of the screen. This is to show how the label can be wrapped so that it does not print off the screen."

Your resize event should have this code in it:

Can you see in the very last line of code that a new drawing size is being created and put in the lbl1.maximumsize property? The variable value we used in the original formwidth variable will change as we change the form width

When you run it you should be able to decrease the width of the form and the label text will now shrink or increase to fit, the text line breaks will increase or decrease depending on the width of the form. It will get to a point where, if you are decreasing the width of the form to such as extent, the height of the form, which is fixed, will not be able to expand to contain all the text and it will be pushed out the bottom of the form.

Label Being Decreased to Small Width (Note the label text wrapping to fit). Any smaller than this width and the text will start to be pushed off the bottom of the form.

Label Being Increased to Large Width(Note the label text increasing to fit):

What usually happens is a form will have many controls on it and the designer will want to contain the amount the user can decrease the width. We could stipulate a minimum size for the width so that it never went below this. Height will usually be static.

Wrapping Text in a Label

Previously I showed you how to dynamically increase a form's width to take into account a control size being increased - such as the label - to hold a longer string of text. We discussed that this had a limitation that if the string font was very large (unlikely) or the string was very long then the string would write off the page if the length of the control (label stretching with long string in it) and the distance from the label to the left of the form was longer than the PC screen itself.

A solution to this is to tell the code to wrap the text in the label if it gets to the end of the screen maximum [determined] size and still needs to write out more of the string. What you can also do is set a size limit for the label and have it wrap when it gets to that size. This is the more likely option that would be used so lets do that.

Please note any old code will be commented out and a space left between it and new code I am writing. If you see code commented out just ignore it and concentrate on the work being done at present.

So what assumptions can be made?

1) The form will not get any bigger than the physical screen size
2) We can limit the size of the label width and then wrap to accommodate more text.
3) The operation will still be triggered by the button click event for now.
4) We may make a routine that can be called from the click event to calculate the length of text etc in further tutorials

So let us do the following:

  • Set an arbritary maximum size for the width of the label
  • Set the code up so that it wraps the text if the length of text string dictates it.
  • Set label property 'AutoSize' to True
1) Let us first comment out the code we have from previous exercises to leave us with just the string of text (in button click event) being put into the label as follows:

lbl1.Text = "I am populating the label with some text now.... and I am typing more text here to increase the width of the string beyond the width of the screen. This is to show how the label can be wrapped so that it does not print off the screen."

Note: I have put in extra text so that the text is much longer than the current form size.

The current form is:

Size = 526, 300

And it will be kept at that for now.

2) Go to the design window for the form. Pull the label over to the left under the button so that both left sides of the button and label are aligned. You will see a blue reference line when they are in line. See screenshot for example:

3) When you run the application then click the button it will calculate the form size at that time and create a label that will fit into it with equal space either side. The code to do this is in the screenshot below:

Please note that some of the code is commented out and some of the previous code I was able to reuse for this exercise. All the code is in the button click event. This will only work for the click event but it lets you see a simple way of wrapping the text in the label to fit a predetermined size i.e. the fixed form size. Remember the text you have to put into the label as above. Here it is again:

lbl1.Text = "I am populating the label with some text now.... and I am typing more text here to increase the width of the string beyond the width of the screen. This is to show how the label can be wrapped so that it does not print off the screen."

Putting this code in the button click event is only for illustration purposes so you can associate what happens through clicking a button. In reality this code would be part of a routine called at maybe different intervals throughout the operation of the code.

For instance if someone was resizing the form then the width would have to be continually recalculated and the label width recalcualted to fit in the moving formsize. Just try resizing the form width now and see what happens to the text.

So check out the next posting if you want to see how to have the label automatically resize as you increase and decrease the width of the form. It's much easier than you think. The hint is you do not need to write any more code, just add a new event handler and do some tweaking.

Wednesday, 30 December 2009

Remeber Your Comments

When you are coding remember to put in comments to explain what your code is doing. This fulfills the following:

1) Anyone else reading your code can get a quick plain English overview of what is happening without the need to study the code.

2) It helps you to document what you have done and by doing this you might notice a mistake you have in the logic of your code through explaining it in plain English

As you can see I have added a list of explanations as to what the code is doing in the screenshot below. The comments are the lines in green:

Remember to put the comments in the appropriate place, don't just list them all at the top of the class. Put comments about a click event in the click event and so on.

Increase Form Size Automatically to Fit Text

You might have a situation with a form where you need to automatically expand it to fit in an expanding label or other controls that vary in size. Sometimes large text strings are put in a wrapping (onto another line below) label but nevertheless this is an interesting bit of work to try as the fundamentals of it can be put too good use in other tasks.

The learning objective here is to learn how to calculate the new size of the form and then apply it. So for instance if I increased the font size in my label it would print of the edge of the form because it is not big enough to fit in the existing form size.

1) So with the previous example lets create a new font size for the message we have put into the label by doing this in the button click event before assigning the text to the label:

lbl1.Font = New Font(Font.FontFamily, 30)

So you are declaring a new font object and assigning it the value of 30. The current value will be whatver the setting is in the properties of the label in the design editor; in this case it is 8.25.

As you can see in the screen shot I have inserted the new line of code before we put in the text to the label.

Run this to see for yourself that the text runs right off the side of the form.

2) Create three variables to:

  • Hold the width of the label once it has been populated with text
  • Hold the X position of the label. This will tell you how far the left side of the label is from the left edge of the form.
  • Hold the new form width required. This will be the addition (+) of the two previous variables.

So in your code, just after the event handler code for the button click event declare the new variables as follows:

Dim labelWidth As Integer
Dim LblLocationX As Integer
Dim newFormWidth As Integer

Don't worry about the names too much as long as they tell you what the variable's purpose is. They should be declared as integers because all the values we will be dealing with are integers, and the value being input to the 3rd variable wil also be an integer because it will be the addition of the two first variables.

So as you can see in the screenshot below the variables are now defined. You will get a green squiggly line under the variables and if you hold your mouse to the line it will tell you this is an unused local variable. Do not worry however as you are going to be using then in a minute. This is not anything to worry about.

3) Put the label width in to the variable labelWidth as follows:

labelWidth = lbl1.Width

4) Put the X coordinate label location in the labelLocationX variable as follows:

LblLocationX = lbl1.Location.X

5) Add the two variables (+) you have just populated with values and put the sum of these values into the variable newFormWidth as follows:

newFormWidth = LblLocationX + labelWidth

Just to remind you what you are doing here is you are taking the measurement from the left of the form to the start of the label, you are then taking the label width (when it has the text in it) and then adding these two values. This will give you the new required width of your form to accommodate the large font that has written of the page.

Technically speaking the left side of the form is fixed and all controls on the form will reference from the left side of the form. If the form has to resize then the measurement from the left of the control (label or textbox for instance) to the left of the form can be used as a fixed reference to calculate the new form size required with respect to the increased size of the control you need to accommodate.

6) As you are in the form class, to refer to the form, and to set its width to the new size you type the following:

Me.Width = newFormWidth

7) Save your changes and run the form. You will see the form jump to a size just neat enough to accommodate the new longer label size when you hit the button.

The good thing here is if you move the label a bit further away from the left side where it originally was it will always recalculate and resize your form according to the position of the label. There is however one slight limitation - can you spot it? Answers at the bottom of the page.

Here is a screenshot of the finished product:

Before label expands:

You can see the label expands here to accommodate the increased length of the label:

So did you figure out the limitation? If you increase the text font ot such a large size that the length of the string is physically bigger than the computer's screen width then it will write off the page. As far as I know there is no simple way to make the form bigger than the screen, I think it is a Windows limitation rather than VB itself. However I will look into this and post a topic if I find out how it is done.

Generally speaking you wouldn't generally find text that big on a form. But if the text string is going to be long then it is probably better to wrap the text in the label. I will post a quick thread on how to do this soon.

Populate Label With Text

So lets populate this label with some text. We know it is going to be clear for us to put in a value as the label is cleared when the form loads. What we need to do is to use the existing btn1 click event and put some code in there. We will use the code as before but with one difference, can you spot it?

lbl1.Text = "I am populating the label with some text now...."

So lets go and put this into the button click event. You can see the new code in the click event and the resulting form at runtime, after we click the button, in the shot below:

A Note on Clearing Labels

When you start to build bigger applications you will maybe be populating a label or other controls multiple times with different values. Each time you finish the operation you will want to clear the form.

Generally what most coders do (What I have learned from looking at experienced coders coding) is that you will maybe create a sub to handle this clearing event. So to clear one form with three text fields and 2 labels you might call this:

'Do something
'End of operation
clearFields() << Call clear routine here

And the bit of code for this routine would look something like:

Private Sub clearFields()

txt1.text = ""
txt2.text = ""
txt3.text = ""
lbl1.text = ""
lbl2.text = ""

End Sub

For simplicity assume this code to be in the form class code.

Tuesday, 29 December 2009

Using form Load Event

In the last post I discussed how you can manipulate a label so that the default text in it is cleared at runtime, in anticipation of using the label for displaying some real messages. Remember we want to try and leave default text in the label so we can see it at design time.

I specified that my preferred option was to clear the text at the form load event. To do this follow the next steps:

1) Copy and paste the small bit of code from the button click event

Note: Anything after a (') is a comment and is not code.

i.e. this: lbl1.Text = "" ' You are making sure the text in the label is empty

2) Go to the code window
3) From the left hand drop down list pick the form events as in the shot below:

4) From the right hand list pick the load event shown Below:

5) Once you pick the load event the event handler will pre-populate the code window with a new event handler as below.

6) put your line of code in the new event handler so that it looks like this:

7) Then run the application again. You will see the label has already been cleared when the form appears.

this is how to clear the label at runtime. it will still show its default text when you open it at design time.

Note: Don't worry about the empty button click event handler it won't do anything when you run the code.

Show Text in a Label

If you want to show text in a label on the form, activated via a button, then you need to add the following to the form:


To do this follow these instructions:

1) Open your project
2) Have the form design selected
3) From the toolbox click on the label icon

4) Hold mouse button down and drag the label to the form
5) Place the label wherever you want the text to start and expand to the right
6) Do the same for a button, drag it onto the form
7) You can place it above or below the label if you want, it is not too critical at this time where it is, as long as it is not in line with label's potential length of text you are going to display.
8) As you done with the form click the label and make sure you see the default name of the label in the property drop down list (Label1)
9) Go to the properties list and change the name to lbl1. This is not necessary but it helps to shorten the name you have to type in code to refer to the label, and it is a quite well used naming convention for a label.

Then set the button properties:

1) Click on the button in the form
2) Go to the properties
3) Change Name property to btn1
4) Change the Text property to "Populate Label"
5) Save your changes
6) Depending on the amount of text in the button text property you might need to expand the button width. this is easy as all you need to do is highlight the button and drag one of the highlight points to the side.

Then alter the Runtime Code:

1) In the form design right click on the form and select View Code

You will see the following code window:

In this window you will see two drop down boxes at the top of this window. The left drop down shows the class form and associated controls, the right drop down shows the events of that control.

2) From this drop down list pick the btn1 item.
3) From the right hand list you can pick the associated event for this control. from the right list pick Click event. When you do this you will see a bit of code being put into the main code window called private sub btn1_Click(with system variables).
4) Between private sub and End Sub type your code. See shot below:

5) The first thing you want to do when you click the button is make sure the label does not have any default text floating about in it. To clear the label1 (lbl1) type this piece of code in where instructed:

lbl1.Text = "" ' You are making sure the text in the label is empty

Note: As you type the (.) i.e. lbl1. you will get a list of suggestions as you type, in this case pick Text. See screenshot showing suggested text and code:

Intellisense code suggestions:

6) Save the changes

7) Now to do a quick unit test. Run the form using the debug > Start debuging option from the menu.

You will see the form come up as below. Click the button and you will see the label text being cleared.

This is really to demonstrate that you should include this line of code anytime you are populating a label in case you are using different messages in it and there is text left in it from a previous operation. Once the button is cleared you will see this:

Or instead if I put this in the code:

lbl1.Text = "Label Cleared...."

you will see:

there are a few option open to you depending on your circumstances:

a) Clear the label text when the form loads
b) Clear it between operations
c) Clear it manually so it is always empty

Option C is probably the most convenient but remember when you remove the text the label will minimize and you will not see it on the form design and it is very hard to find if you want to move it about on the form design. You can probably now think how this operation can be utilised in other circumstances too. these uses will all make more sense when you start coding more. Just now it seems a bit over the top what you can do with the properties. My own preference is option A.

You can put text back into it manually through the properties list to temporarily find it.

Creating a Directory for the Project

Once you have created the new project you can select 'File' > 'Save All' in the IDE. This will create a directory listing for your new project. This will create a complete directory with project folders for this project.

All your code and classes and all other files pertaining to this project can be stored here.

Working With Our New Project

From the last post we had created a new project called MyBlogExample. Lets use that to demonstrate some simple tasks that we can perform on our new form. Firstly the shot below shows what you would see after you created the new project and then hit ok as in the steps we went through:

Note: Click on the screen shot to see bigger version but click back on your browser when finished with the larger version to get back here otherwise you will close the blog completely.

After creating new project and selecting ok:

The first thing to do is to name the form and give it a heading. Something I must emphasise is when you are working in a design environment such as this and you want to change the properties of a button or a textbox or a form you must select the item you want to change the properties of. It is not the first time I have went changing properties of a button only to find I am changing the form properties.

Ideally do the changes you think you need to the control as you create the controls on the form. On the right hand side of the page you will see a frame split into two called the solution explorer and then a properties section roughly half way down the frame. You can expand this properties frame up and out if you want to see more.

Again double check the name of the control by checking the name in the text box below where it says properties so if you are working on the form it should say form1 You can see this highlighted in the screenshot that it says form1 then the class reference ''.

So lets name the form and give it an appropriate heading:

1) Click once on the form to make sure it is highlighted

2) Check it says 'Form1 System.Windows.Forms.Form' in the drop down box just below where it says 'Properties'. In general ignore this bit (System.Windows.Forms.Form) you just need to see the main name at the start i.e. Form1.

3) In properties (right hand side of IDE ujst below where it says 'Properties') you will see an icon/button with a down arrow and an A > Z identifier. If you click on this it will sort all the properties into alphabetical order.

4) Then at the top of all the properties you will see a (Name) property with a value of 'Form1'. This is the system name you will give the form. Note the property names on the left are just the names and the actual values are on the right hand side of the properties list. You might like to note that although the properties will be listed in A > Z order the 'Name' property is right near the top (in the 'A' section) because this is usually what is changed first by designers.

So if you intend to call this form in code you will say Form1.Call.doThis because the name is 'form1'

It is up to you what you call the form but a good naming convention for forms is frm1, frm2 etc or you can call it something specific if it is going to do something like get customer details you could call it:


So for now lets call it frm1

5) In the properties change the value in the right hand column from 'Form1' to 'frm1'. This property can be seen highlighted in the shot below.

Now change it to 'frm1':

6) Once you have done this you can change the form's 'Text' value, that is the text you see at the top left of the form and it is what a user would read to understand what the form's purpose is. So if this form was to get customer details you would set the text to 'Get Customer Details'. So lets call the form 'Blog Examples'.

Find the Text Value in the Properties:

Change it to 'Blog Examples'

Now you might notice that when you change the value in the properties value that it still says 'form1' in the design window form. To have this change you will need to click out of the properties box and you will then see the property at the top of the form change to what you set it to.

Now that is the main bits of the form design and property settings you need to concern yourself with when creating a simple Windows application. Of course these properties can be set in code as well but that will be covered as and when needed.

Creating a new Project

I would advise you to save the project with an appropriate name immediately as renaming the project half-way through can cause no end of problems and confusion. If you are just playing about with code and little projects the name is not essential, you can just call it myPractice or something.

When you pick a new project in VB.NET you will see the screen as below:

If you want to create a simple form design then you will pick the Windows Application Icon. You will see that I have clicked on this icon once in the shot below. When you have done this rename the name of the application in the text box below to something more appropriate:

Appropriate Windows Application Icon Selected:

Project name Highlighted:

New Project Name:

So we have called the project something more appropriate (MyBlogExample). This takes care of the naming side of things. We do not need to worry about naming the project after we have done some work to it.

Now all we need to do is hit ok and we will have a new project.

Using Controls in VB Design Studio

The controls (Buttons, Labels etc) in the Visual Studio Integrated Development Environment (IDE) are the items you can see on the toolbox at the left side of the IDE screen. If you do not see this in your development environment then go to View > and select 'Toolbox' from the drop down menu.

You will also not see these tools if you are in the code window of the form or control. If you flick back to the form design layout window - using the tabs above the windows - you are working on you will see the tools being repopulated. You can see the toolbox frame on the left but no tools on it because we are in the code window of the form, but the next shot shows that we are back in the design window for the form and the tools are repopulated:

Note: Click on the screen shot to see bigger version but click back on your browser when finished with the larger version to get back here otherwise you will close the blog completely.

No tools in box because we are in the code window:

Tools now repopulated because we are back in the design window for the form:

Introduction From Your Blog Host


My name is Andrew. Since graduating in computer science 2 years ago I have been working in different areas of technology including Oracle, Business Objects and reporting tools. I also have some experience in Microsoft Technology and currently hold MCP qualifications. In my current role I am working with VB6 and I also have experience working in other non-development technical support areas and have exposure to SQL Server database and networking principles as well.

On a personal level I do work in VB.NET 2005 Visual Studio building small applications and I use a local 10g Oracle Express Edition Database as a data source for my VB projects. This allows me to keep my skills and knowledge up to scratch and to always learn new ways of doing things and learn from my mistakes. I decided that it would be helpful to others to start a small blog to share my experiences of coding so that you can learn quicker and become more productive and experienced in a shorter time using these types of development tools. I am not going to go through structured subjects like in a book from the basics through pre-determined learning objectives, but I will endevour to share and explain as much as I can about the things I am doing, things that I think will help you, especially if you are a relative newbie to VB6 or .NET.

Hope you enjoy it anyway and any questions you might have about my posts or anything you need to know then do please ask.