Microsoft KB Archive/108812

= BackColor Erases Existing Graphics on Form or Picture Control =

Article ID: 108812

Article Last Modified on 12/9/2003

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APPLIES TO


 * Microsoft Visual Basic 2.0 Standard Edition
 * Microsoft Visual Basic 3.0 Professional Edition
 * Microsoft Visual Basic 2.0 Professional Edition
 * Microsoft Visual Basic 3.0 Professional Edition

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This article was previously published under Q108812



SUMMARY
Setting the BackColor property on forms or picture boxes at run time erases all previous printed graphics and output, including a persistent bitmap. This behavior is by design. Setting the ForeColor property does not affect the graphics or print output that are already drawn.

Setting the BackColor property on other controls, such as list boxes, text boxes, or combo boxes, does not erase previously added items.



MORE INFORMATION
NOTE: A persistent bitmap is a bitmap, accessed with the Image property, that stores output from graphics methods in memory. For more information, see the following items in the Visual Basic Help menu:


 * AutoRedraw property
 * persistent bitmap

Steps to Reproduce Behavior
 Start a new project in Visual Basic. Form1 is created by default. Add a list box and a picture box to Form1.  Double-click the form to open the code window. Add the following code to the Form Load event: Sub Form_Load form1.Show 'In Load event, must show form before Print works

picture1.ForeColor = QBColor(1) picture1.BackColor = QBColor(11) picture1.Print "color1" form1.ForeColor = QBColor(1) form1.BackColor = QBColor(12) form1.Print "color1" list1.ForeColor = QBColor(1) list1.BackColor = QBColor(11) list1.AddItem "color1"

MsgBox "click to see next color" picture1.ForeColor = QBColor(2) picture1.BackColor = QBColor(10) 'This BackColor erases picture1 picture1.Print "color1" form1.ForeColor = QBColor(2) form1.BackColor = QBColor(13) 'This BackColor erases form1 form1.Print "color1" list1.ForeColor = QBColor(2) list1.BackColor = QBColor(10) 'This BackColor doesn't erase List1 list1.AddItem "color2"

MsgBox "click to see next color" picture1.ForeColor = QBColor(4) picture1.BackColor = QBColor(14) 'This BackColor erases picture1 picture1.Print "color1" form1.ForeColor = QBColor(4) form1.BackColor = QBColor(8) 'This BackColor erases form1 form1.Print "color1" list1.ForeColor = QBColor(4) list1.BackColor = QBColor(14) 'This BackColor doesn't erase List1 list1.AddItem "color3"

End Sub  Start the program or press the F5 key. Click OK to see the next color. To end the program, close the form.

Here are the results:


 * Changing the Form1.BackColor property erases the text that you previously printed on Form1.
 * Changing the Picture1.BackColor property erases the text that you previously printed on Picture1.
 * Changing the List1.BackColor property does not erase the text that you previously added to the List1 list box.

All of this behavior is by design.

Additional query words: 2.00 3.00 delete remove blank out

Keywords: KB108812

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