Bands View Layout

The image below shows a VGridControl control with the Bands view layout applied to it.

The features specific to this layout are listed below:

• A single record (or part of one) is displayed at a time. End-users can navigate through the records using the horizontal scroll bar. (You can provide your users with a custom method of scrolling through records. See the Focus and Scroll Records topic for details.)
• The control's contents cannot be scrolled vertically. The row header cells and data cells are arranged into a number of columns that won't exceed the grid's height. These columns are bands.
• Bands can either exceed the control's width (requiring scrolling to view all the bands) or be adjusted to fit the control's width. See Scrolling Bands below for more information.
• end-users can resize bands by dragging the right border of the leftmost visible band.

The following list enumerates properties specific to this layout.

• VGridControlBase.BandCount - gets the number of bands a records occupies.
• VGridControlBase.BandWidth - gets the width of a band in pixels.
• VGridControlBase.BandMinWidth - gets the minimum width of bands in pixels. End-users cannot resize bands to a width less than that specified by this property.
• VGridControlBase.BandsInterval - specifies the interval between bands in pixels.

If the grid's BaseOptionsView.AutoScaleBands property is set to true, bands will be resized (stretched or shrunk as appropriate) to exactly occupy the grid's entire client region. Otherwise, if the total width of the bands exceeds that of the grid's client region and the grid's BaseOptionsView.AutoScaleBands property is set to false some of the bands will be outside the visible area.

If a band is partially visible, end-users can make it completely visible by clicking its data cells or by scrolling through the bands using the mouse wheel if the VGridOptionsBehavior.RecordsMouseWheel property is set to false. This property can be accessed via the grid's VGridControlBase.OptionsBehavior property.

The following sample code demonstrates how to scroll bands via code. The VGridControlBase.LeftVisibleBand property is used for this purpose. It's assumed that there are two buttons in your application: 'btnForward' and 'btnBackward'. These buttons scroll the bands forward and backwards, respectively. When the first or last band is reached the corresponding button is disabled. The handlers for the button clicks are listed below.

// handling a click on the Backward button  
private void btnBackward_Click(object sender, System.EventArgs e) {
   // scrolling backwards by one band 
   vGridControl1.LeftVisibleBand -= 1;
   // disabling the button if the first band has been reached 
   if (vGridControl1.LeftVisibleBand == 0)
      btnBackward.Enabled = false;
   // ensuring that the Forward button is enabled 
   btnForward.Enabled = true;
}

// handling the Forward button click 
private void btnForward_Click(object sender, System.EventArgs e) {
   // scrolling forwards by one band 
   vGridControl1.LeftVisibleBand += 1;
   // disabling the button if the last band has been reached 
   if (vGridControl1.LeftVisibleBand == vGridControl1.BandCount - 1)
      btnForward.Enabled = false;
   // ensuring that the Backward button is enabled 
   btnBackward.Enabled = true;
}

' handling the Backward button click 
Private Sub btnBackward_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBackward.Click
   ' scrolling backwards by one band 
   VGridControl1.LeftVisibleBand = VGridControl1.LeftVisibleBand - 1
   ' disabling the button if the first band has been reached 
   If VGridControl1.LeftVisibleBand = 0 Then 
      btnBackward.Enabled = False 
   End If 
   ' ensuring that the Forward button is enabled 
   btnForward.Enabled = True 
End Sub 

' handling the Forward button click 
Private Sub btnForward_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnForward.Click
   ' scrolling forwards by one band 
   VGridControl1.LeftVisibleBand = VGridControl1.LeftVisibleBand + 1
   ' disabling the button if the last band has been reached 
   If VGridControl1.LeftVisibleBand = VGridControl1.BandCount - 1 Then 
      btnForward.Enabled = False 
   End If 
   ' ensuring that the Backward button is enabled 
   btnBackward.Enabled = True 
End Sub