Learn Visual Basic 6.0

4. More Exploration of the Visual Basic Toolbox

Example 4-2: Image Viewer

One possible solution to the Image Viewer Application:


1. Place a drive list box, directory list box, file list box, four label boxes, a line (use the line tool) and a command button on the form. We also want to add an image box, but make it look like it's in some kind of frame. Build this display area in these steps: draw a 'large shape', draw another shape within this first shape that is the size of the image display area, and lastly, draw an image box right on top of this last shape. Since the two shapes and image box are in the same display layer, the image box is on top of the second shape which is on top of the first shape, providing the desired effect of a kind of picture frame. The form should look like this:
   
   
   
   
   
   Note the second shape is directly beneath the image box.
   
   
2. Set properties of the form and each object.
   
   

   Form1:	BorderStyle	1-Fixed Single
   	Caption	Image Viewer
   	Name	frmImage
   Drive1:	Name	drvImage
   Dir1:	Name	dirImage
   File1:	Name	filImage
   	Pattern	*.bmp;*.ico;*.wmf;*gif;*jpg [type this line with no spaces]
   Label1:	Caption	[Blank]
   	BackColor	Yellow
   	BorderStyle	1-Fixed Single
   	Name	lblImage
   Label2:	Caption	Files:
   Label3:	Caption	Directories:
   Label4:	Caption	Drives:
   Command1:	Caption	&Show Image
   	Default	True
   	Name	cmdShow
   Command2:	Cancel	True
   	Caption	E&xit
   	Name	cmdExit
   Line1:	BorderWidth	3
   Shape1:	BackColor	Cyan
   	BackStyle	1-Opaque
   	FillColor	Blue
   	FillStyle	4-Upward Diagonal
   	Shape	4-Rounded Rectangle
   Shape2:	BackColor	White
   	BackStyle	1-Opaque
   Image1:	BorderStyle	1-Fixed Single
   	Name	imgImage
   	Stretch	True

   
   
3. Attach the following code to the drvImage_Change procedure.
   
   Private Sub drvImage_Change()
   'If drive changes, update directory
   dirImage.Path = drvImage.Drive
   End Sub
   
   When a new drive is selected, this code forces the directory list box to display directories on that drive.
   
   
4. Attach this code to the dirImage_Change procedure.
   
   Private Sub dirImage_Change()
   'If directory changes, update file path
   filImage.Path = dirImage.Path
   End Sub
   
   Likewise, when a new directory is chosen, we want to see the files on that directory.
   
   
5. Attach this code to the cmdShow_Click event.
   
   Private Sub cmdShow_Click()
   'Put image file name together and
   'load image into image box
   Dim ImageName As String
   'Check to see if at root directory
   If Right(filImage.Path, 1) = "\" Then
   ImageName = filImage.Path + filImage.filename
   Else
   ImageName = filImage.Path + "\" + filImage.filename
   End If
   lblImage.Caption = ImageName
   imgImage.Picture = LoadPicture(ImageName)
   End Sub
   
   This code forms the file name (ImageName) by concatenating the directory path with the file name. It then displays the complete name and loads the picture into the image box.
   
   
6. Copy the code from the cmdShow_Click procedure and paste it into the filImage_DblClick procedure. The code is identical because we want to display the image either by double-clicking on the filename or clicking the command button once a file is selected. Those of you who know how to call routines in Visual Basic should note that this duplication of code is unnecessary - we could simply have the filImage_DblClick procedure call the cmdShow_Click procedure. We�ll learn more about this next class.
   
   
7. Attach this code to the cmdExit_Click procedure.
   
   Private Sub cmdExit_Click()
   End
   End Sub
   
   
8. Save your project. Run and try the application. Find bitmaps, icons, and metafiles. Notice how the image box Stretch property affects the different graphics file types. Here�s how the form should look when displaying one example metafile:
   
   
   

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