Changing row height in owner drawn control

When you change the font of a list view control, the control or its parent window does not get a chance to respecify the height of the rows. No WM_MEASUREITEM message is sent to the controls parent window. The net effect is that when the font is changed for the control, the row height is no longer valid.

Here's a work around that forces the WM_MEASUREITEM message to be generated.

Step 1: Add handler for WM_SETFONT

The WM_MEASUREITEM message is sent when the control is created. Fortunately this message is also sent whenever the control is resized. Since we want the row height to be adjusted when the font changes, what better place to do thin than in the WM_SETFONT handler. In OnSetFont() we fool Windows into thinking that the window size of the control has changed. We do this by sending the WM_WINDOWPOSCHANGED message to the control which then gets handled by the default window procedure for the control. Note that we haven't specified the SWP_NOSIZE flag and we set the width and height field in the WINDOWPOS structure equal to the existing dimension.