Since: http://blog.5d.cn/user2/skyline-moon/200901/511240.html recently because of their own a small program needs, the requirements in the ComboBox drop-down Project (each item) display tooltip, search several times with Google, codeproject browsing several times, I found that there are few introductions and the methods described are mainly based on API capture. The code of this method seems complicated (for more complete implementation code, see [3]). After carefully reading the ComboBox content on msdn [1], you can see that the simpler implementation is through the drawitem of ComboBox (events generated when drawing the drop-down menu ). The following is the implementation code obtained by referring to [1] and [2. The main idea is to display the tooltip when the drop-down project is highlighted (drawitemstate. Selected) (here we need an instance of a new tooltip, And this is tooltip1 ). If you have multiple comboboxes that need to display tooltip, you should consider creating an inherited class for ComboBox. Here, I suggest using the method described in document [2]. The method in document [2] can also implement a function, that is, if the content length of the drop-down project does not exceed the width of the ComboBox, tooltip is not displayed. Note that when using the code in document [2], you need to change the condition for displaying tooltip to (E. State
& Drawitemstate. Selected) = drawitemstate. Selected
Delete the condition statement after Else. Otherwise, the expected result may not be obtained. Recently, due to the need of a small program, it is required to display ToolTip in the ComboBox drop-down Project (each item), search several circles with Google, and view the ToolTip several times on the Codeproject, I found that there are few introductions and the methods described are mainly based on api capture. The code of this method seems complicated (for more complete implementation code, see [3]). After carefully reading the ComboBox content on msdn [1], you can see that the simpler implementation is through the DrawItem of ComboBox (events generated when drawing the drop-down menu ). The following is the implementation code obtained by referring to [1] and [2. The main idea is to display the TooLTip when the drop-down project is highlighted (DrawItemState. Selected) (here we need an instance of a new ToolTip, And this is toolTip1 ). If you have multiple comboboxes that need to display ToolTip, you should consider creating an inherited class for ComboBox. Here, I suggest using the method described in document [2]. The method in document [2] can also implement a function, that is, if the content length of the drop-down project does not exceed the width of the ComboBox, toolTip is not displayed. Note that when using the code in document [2], you need to change the condition for displaying ToolTip to (e. State
& DrawItemState. Selected) = DrawItemState. Selected and delete the condition statement after Else. Otherwise, the expected result may not be obtained.
// [Code in the interface design, desigener] // create the kineticFileComboBox drop-down form this. kineticFileComboBox. formattingEnabled = true; this. kineticFileComboBox. location = new System. drawing. points (213,197); this. kineticFileComboBox. name = "kineticFileComboBox"; this. kineticFileComboBox. size = new System. drawing. size (170, 20); this. kineticFileComboBox. tabIndex = 14; this. kineticFileComboBox. text = "Please load the file first... "; // redraw the drop-down list window. You need to add the following sentence in the window design code: this. kineticFileComboBox. drawMode = System. windows. forms. drawMode. ownerDrawFixed; // The drop-down form redraws the event this. kineticFileComboBox. drawItem + = new System. windows. forms. drawItemEventHandler (kineticFileComboBox_DrawItem); this. kineticFileComboBox. dropDownClosed + = new System. eventHandler (kineticFileComboBox_DropDownClosed); // [code in the main program] private void kineticFileComboBox_DrawItem (object sender, System. windows. forms. drawItemEventArgs e) {// draw background e. drawBackground (); // draw a list Project e. graphics. drawString (kineticFileComboBox. items [e. index]. toString (), e. font, System. drawing. brushes. black, e. bounds); // pass the text of the highlighted list item to toolTip1 (an instance of ToolTip created earlier) if (e. state & DrawItemState. selected) = DrawItemState. selected) toolTip1.Show (kineticFileComboBox. items [e. index]. toString (), kineticFileComboBox, e. bounds. X + e. bounds. width, e. bounds. Y + e. bounds. height); e. drawFocusRectangle ();} // when the list is closed, the private void kineticFileComboBox_DropDownClosed (object sender, System. eventArgs e) {toolTip1.Hide (kineticFileComboBox );}()
