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To add an overlay condition to a tree view:
| 1. | Use the Windows Designer catalog to open the window or dialog that contains the tree view. |
| 2. | Open the Property Inspector and select the tree view node for which you want to display an overlay image. |
| 3. | On the Visual tab page, first set the Image property. |
| This is obligatory for displaying overlay images. An example of an icon that is not visible is: |
transpar.ico
| 4. | On the Behavior tab page, set the Overlay Condition property to determine if and when the icon specified by the Image property should have a second image superimposed on it. |
| The general form of an overlay condition is: |
SELECT '' FROM ... WHERE ...
| You can use variables to refer to columns selected in the SQL Query property of this tree view node. For example: |
SELECT ''
FROM emp
WHERE :EMP_NAME != 'John'
| This will display an overlay image for all employees except John. |
| 5. | Set the Overlay Image property. The overlay image will now be displayed if the overlay condition is met, or if no overlay condition is specified. |
| NOTE: You can define more than one overlay image per tree view node. When a column in the SQL Query of a tree view node has an alias TREE_IMAGE_OVERLAY, the value will be transferred to an image and used as overlay image superimposed on the image. The image properties are still available but a definition of an overlay image in the SELECT list overrules the Overlay Image property. |
SELECT <value>, 'OverlayImage.ico' "TREE_IMAGE_OVERLAY" FROM <table>
| When the columns of the overlay condition are added to the end of the SELECT list of the Query SQL, an overlay image becomes update-notify aware. Therefore: |
Query SQL:
SELECT ONE_LINER FROM MY_TABLE
Overlay Condition:
SELECT '' FROM MY_TABLE WHERE ID>10
| should change to the following to become an update-notify aware overlay image (even though the overlay condition does not change): |
Query SQL:
SELECT ONE_LINER,ID FROM MY_TABLE
Overlay Condition:
SELECT '' FROM MY_TABLE WHERE ID>10
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