<< Continues from the previous
We’ll now give users the option to add their own images to the
picture box, instead of the one we chose. To do that, you need to display an
Open File dialogue box when the user clicks your View > View Images
Dialogue boxes in C# can be added with the aid of an inbuilt object. Have a
look in the Toolbox on the left hand side of Visual C#. There should be a category
All the dialogue boxes you are familiar with in Windows are on the list above.
The one highlighted is the one we want – OpenFileDialog. Double click
this item, and you’ll see a new item appear at the bottom of Visual C#, next
to your menuStrip1 object:
Nothing will appear on your form, however, because the Dialog controls are
are hidden from view. The one in the image above has a default Name of openFileDialog1.
This is a bit long, so have a look at the Properties Window on the right. Change
the Name to openFD:
The control at the bottom of Visual C# should have changed, as well:
With the control selected, have another look at the Properties Window. You’ll
see that there are Properties for Filter, FileName, InitialDirectory
and Title. We’ll change these with code. But one important point to bear
in mind about the Open File Dialogue box is this: They don’t actually open files!
What the Open File Dialogue box does, and the same is true for the other Dialog
controls, is to allow you to select a file for opening. You have to write separate
code to open anything. The only thing you’re really doing here is to get at
a file name.
We want the dialogue box to appear when the View > View Images menu
is clicked. So double click this item on your View menu. A code stub
To see the Open Dialogue box, add this line to your code, in between the curly
So you type the Name of your control, and then a dot. After the dot, select
ShowDialog from the IntelliSense list. As its name suggest, this shows
you the dialogue box.
Run your programme and try it out. You should see something like the following
appear when you click your View > View Images menu item:
Because we haven’t yet set any Properties, a default location is displayed,
which is the Documents folder in Windows. The File name has the default openFileDialog1.
You can change all these, though.
We can set a Title, first. The default Title is the word Open. Add this line
to your code, before the first line:
openFD.Title = “Insert an Image”;
This time, we’re using the Title Property, and setting it to the text
“Insert an Image”. You can, of course, type anything you like here.
When you run your programme and click the menu item, the new Title will look
Another thing you can change is that Look in area. The default location is
the Debug folder from your project. You can reset it with the InitialDirectory
property. Add the following line to your code, before the other two lines:
openFD.InitialDirectory = “C:”;
We’re setting the default folder to be C. This would assume that the user had
a hard drive called C. If you want to set the Initial Directory to the “My
Documents” folder of any computer, try this after the equals sign, instead
This will get the folder path to the My Document folder (Personal folder),
which is also known as the Documents folder in Windows. You need to do it this
way because different users will have different user names, and there’s no way
for you to tell beforehand.
But run your programme and try it out. The location at the top should have
For the File name area, you can use the FileName Property. Add this
line to your code (add it before the final line):
openFD.FileName = “”;
Here, we’re setting the File Name to a blank string. Run your programme and
you’ll find that the File name area on your dialogue box will be blank,
and the cursor will be flashing away. Select any file you like, and the file
name will appear in the box.
The next thing to do is to set up some Files of type. This is for the drop
down list you see at the bottom, just under File name. Here’s what we want to
So we want the user to be able to select JPEG images, GIF images, and Bitmap
images. When you set the files of type, you are restricting the type of files
that the user can open. This is done with the Filter Property. After all, you
don’t want your users trying to insert text files into a picture box!
The filter property makes use of the pipe character ( | ). The pipe character
can be found above the backslash on a UK keyboard. Add this code, just before
the last line:
openFD.Filter = “JPEG|*.jpg”;
Notice what comes after the equals sign:
Your filters need to go between quote marks. But the JPEG part, before the
pipe character, is what you want to display in the drop down list. You can have
anything you like here, “JPEG Images” instead of just “JPEG”,
for example. After the pipe character, you need an asterisk symbol * followed
by a dot. The asterisk symbol means “any file name”. After the dot,
you type the file extension that you want to filter for.
Run you code and try it out. You should see this in the “Files of type”
list on the right of the text box:
Now change your code to this:
openFD.Filter = “JPEG Images|*.jpg”;
The “Files of type” list will then look like this:
Using just one filter means that no other file types will display. To add other
file types you just need to use the pipe character again. Let’s add GIF images,
as well. Change your code to this:
openFD.Filter = “JPEG Images|*.jpg|GIF Images|*.gif”;
As you can see, the line is a bit messy! The new part is in blue, though. Notice
that you separate one file type from another with a pipe character. But you
also need a pipe to separate the text for the drop down list from the actual
file type. To add Bitmap images, the code would be this:
openFD.Filter = “JPEG Images|*.jpg|GIF Images|*.gif|BITMAPS|*.bmp”;
In the line above, the three file types have been displayed using different
colours, so that you can see them better.
Here’s a few more image types, and their file extensions:
TIFF Images: *.tif or *.tiff
PNG Images: *.png
PICT Images: *pct or *.pict
There are, of course, lots of others. In the image below, we’ve set up the
list to search for JPEG, GIF, and BITMAP images:
To display files of any type, use an asterisk symbol in place of the file extension.
openFD.Filter = “JPEG Images|*.jpg|All Files|*.*”;
However, we still haven’t inserted a new image. To place a selected image into
the picture box, you have to get the file name that the user selected. You can
add a string variable to your code for this:
string Chosen_File = “”;
You then access the FileName property of openFD. Like this:
Chosen_File = openFD.FileName;
The file name will then be in the variable we’ve called Chosen_File.
To place a new image into the picture box you have on the form, you need the
To place your chosen file into the Image property, you need this:
pictureBox1.Image = Image.FromFile(Chosen_File);
So after the equals sign, you can use the Image object. This has a method
called FromFile( ). In between the round brackets of this method, you
type the name of the image file. For us, this image file is stored in our Chosen_File
Add the new lines to your code and your coding window should look something
like ours below (we’ve cut down on a few filters):
Run your programme and test it out. Select an image to open. You should find
that your new image replaces the old one in your picture box.
However, there is a problem with the code. Instead of clicking Open,
Because the Cancel button was clicked, there is no image name in the variable
Chosen_File. So the programme “bugs out” on you. You need to handle
this in your code.
To check if the cancel button was clicked, you can use this:
if (openFD.ShowDialog() = = DialogResult.Cancel)
So there is inbuilt object called DialogResult. You check if this has
a value of Cancel. Adding an else statement gives us this code:
Change your code so that it looks like ours above. When you run your programme
now, it shouldn’t crash when you click the Cancel button.
You can also have this for you IF Statement, instead of the one above:
if (openFD.ShowDialog() != DialogResult.Cancel)
Chosen_File = openFD.FileName;
pictureBox1.Image = Image.FromFile(Chosen_File);
We’ve used the NOT symbol, here ( ! ). So we’re checking if DialogResult does
NOT equal Cancel.
In the next part, you’ll see how to use the Open File Dialogue box to insert
a text file into your text boxes.
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