Customizing Magnifying Glass Painting

LEADTOOLS provides several properties, methods and events that let the user provide custom magnifying glass painting, including the painting of annotations in the magnifying glass. After the StartMagGlass method has been called and the magnifying glass paints itself to the DC, but before the magnifying glass is displayed on the screen, the user can change what is in the DC, through the MagGlassOwnerDraw event. In order to generate this event, the EnableMagGlassDraw property must be set to TRUE. This feature lets you render magnified annotations, which may be overlaid on the currently displayed image, or just simply override what is currently in the magnifying glass display area.

If the user provides custom magnifying glass painting that does not include annotations, then all the user must do is set the EnableMagGlassDraw property to TRUE and provide the necessary code for the MagGlassOwnerDraw event. Setting the EnableMagGlassDraw property to TRUE enables the generation of the MagGlassOwnerDraw event.

If the user provides custom magnifying glass painting that does involve annotations, the user must:

• set the EnableMagGlassDraw property to TRUE so the MagGlassOwnerDraw event will be generated

• set the AnnEnableMagGlass property to TRUE so the annotations can be painted

• call the AnnMagGlass method within the MagGlassOwnerDraw event to actually draw the annotations

To stop generating MagGlassOwnerDraw events, set the EnableMagGlassDraw property to FALSE.