Creating and Using Resources in Visual Basic 6

Creating and Using Resources in Visual Basic 6 After Visual Basic students learn all about loops and conditional statements and subroutines and so forth, one of the next things that they often ask about is, How do I add a bitmap, a wav file, a custom cursor or some other special effect? One answer is resource files. When you add a file using Visual Studio resource files, theyre integrated directly into your Visual Basic project for maximum execution speed and minimum hassle packaging and deploying your application. Resource files are available in both VB 6 and VB.NET, but the way theyre used, like everything else, is quite a bit different between the two systems. Keep in mind that this isnt the only way to use files in a VB project, but it has real advantages. For example, you could include a bitmap in a PictureBox control or use the mciSendString Win32 API. MCI is a prefix that usually indicates a Multimedia Command String.   Creating a Resource File in VB 6 You can see the resources in a project in both VB 6 and VB.NET in the Project Explorer window (Solution Explorer in VB.NET - they had to make it just a little bit different). A new project wont have any since resources arent a default tool in VB 6. So lets add a simple resource to a project and see how that is done. Step one is to start VB 6 by selecting a Standard EXE project on the New tab in the startup dialog. Now select the Add-Ins option on the menu bar, and then the Add-In Manager... This will open the Add-In Manager dialog window. Scroll down the list and find VB 6 Resource Editor. You can just double-click it or you can put a check mark in the Loaded/Unloaded box to add this tool to your VB 6 environment. If you think youre going to use the Resource Editor a lot, then you can also place a check mark in the box Load on Startup and you wont have to go through this step again in the future. Click OK and the Resources Editor pops open. Youre ready to start adding resources to your project! Go to the menu bar and select Project then Add New Resource File or just right-click in the Resource Editor and select Open from the context menu that pops up. A window will open, prompting you for the name and location of a resource file. The default location will probably not be what you want, so navigate to your project folder and enter the name of your new resource file into the File name box. In this article, Ill use the name AboutVB.RES for this file. Youll have to confirm the creation of the file in a verification window, and the a AboutVB.RES file will be created and filled into the Resource Editor. VB6 Supports VB6 supports the following: A string table editor(Edit String Tables...)Custom cursors - CUR files(Add Cursor...)Custom icons - ICO files(Add Icon...)Custom bitmaps - BMP files(Add Bitmap...)Programmer defined resources(Add Custom Resource...) VB 6 provides a simple editor for strings but you have to have a file created in another tool for all of the other choices. For example, you could create a BMP file using the simple Windows Paint program. Each resource in the resource file is identified to VB 6 by an  Id  and a name in the Resource Editor. To make a resource available to your program, you add them in the Resource Editor and then use the Id and the resource Type to point to them in your program. Lets add four icons to the resource file and use them in the program. When you add a resource, the actual file itself is copied into your project. Visual Studio 6 provides a whole collection of icons in the folder... C:\Program Files\Microsoft Visual Studio\Common\Graphics\Icons To go with tradition, well select the Greek philosopher Aristotles four elements - Earth, Water, Air, and Fire - from the Elements subdirectory. When you add them, the Id is assigned by Visual Studio (101, 102, 103, and 104) automatically. To use the icons in a program, we use a VB 6 Load Resource function. There are several of these functions to choose from: LoadResPicture(index, format)  for bitmaps, icons, and cursors Use the VB predefined constants  vbResBitmap  for bitmaps,  vbResIcon  for icons, and  vbResCursor  for cursors for the format parameter. This function returns a picture that you can use directly.  LoadResData  (explained below) returns a string containing the actual bits in the file. Well see how to use that after we demonstrate icons. LoadResString(index)  for stringsLoadResData(index, format)  for anything up to 64K As noted earlier, this function returns a string with the actual bits in the resource. These are the values that can be used for format parameter here: 1 Cursor resource2 Bitmap resource3 Icon resource4 Menu resource5 Dialog box6 String resource7 Font directory resource8 Font resource9 Accelerator table10 User-defined resource12 Group cursor14 Group icon Since we have four icons in our AboutVB.RES resource file, lets use  LoadResPicture(index, format)  to assign these to the Picture property of a CommandButton in VB 6. I created an application with four  OptionButton  components labeled Earth, Water, Air and Fire and four Click events - one for each option. Then I added a  CommandButton  and changed the Style property to 1 – Graphical. This is necessary to be able to add a custom icon to the CommandButton. The code for each OptionButton (and the Form Load event - to initialize it) looks like this (with the Id and Caption changed accordingly for the other OptionButton Click events): Private Sub Option1_Click()   Ã‚  Ã‚  Command1.Picture _   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  LoadResPicture(101, vbResIcon)   Ã‚  Ã‚  Command1.Caption _   Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Earth End Sub Custom Resources The big deal with custom resources is that you normally have to provide a way to process them in your program code. As Microsoft states it, this usually requires the use of Windows API calls. Thats what well do. The example well use is a fast way to load an array with a series of constant values. Remember that the resource file is included into your project, so if the values that you need to load change, youll have to use a more traditional approach such as a sequential file that you open and read. The Windows API well use is the  CopyMemory  API. CopyMemory copies block of memory to a different block of memory without regard to the data type that is stored there. This technique is well known to VB 6ers as an ultra fast way to copy data inside a program. This program is a bit more involved because first we have to create the a resource file containing a series of long values. I simply assigned values to an array: Dim longs(10) As Longlongs(1) 123456longs(2) 654321 ... and so forth. Then the values can be written to a file called  MyLongs.longs  using the VB 6 Put statement. Dim hFile As Long hFile FreeFile() Open _   Ã‚  Ã‚  C:\your file path\MyLongs.longs _   Ã‚  Ã‚  For Binary As #hFile Put #hFile, , longs Close #hFile Its a good idea to remember that the resource file doesnt change unless you delete the old one and add a new one. So, using this technique, you would have to update the program to change the values. To include the file MyLongs.longs into your program as a resource, add it to a resource file using the same steps described above, but click the  Add Custom Resource...  instead of Add Icon... Then select the MyLongs.longs file as the file to add. You also have to change the Type of the resource by right clicking that resource, selecting Properties, and changing the Type to longs. Note that this is the file type of your MyLongs.longs file. To use the resource file you have created to create a new array, first declare the Win32 CopyMemory API call: Private Declare Sub CopyMemory _   Ã‚  Ã‚  Lib kernel32 Alias _   Ã‚  Ã‚  RtlMoveMemory (Destination As Any, _   Ã‚  Ã‚  Source As Any, ByVal Length As Long) Then read the resource file: Dim bytes() As Byte bytes LoadResData(101, longs) Next, move the data from the bytes array to an array of long values. Allocate an array for the longs values using the integer value of the length of the string of bytes divided by 4 (that is, 4 bytes per long): ReDim longs(1 To (UBound(bytes)) \ 4) As Long CopyMemory longs(1), bytes(0), UBound(bytes) - 1 Now,  this may seem like a whole lot of trouble when you could just initialize the array in the Form Load event, but it does demonstrate how to use a custom resource. If you had a large set of constants that you needed to initialize the array with, it would run faster than any other method I can think of and you wouldnt have to have a separate file included with your application to do it.