Một vòng tròn đầy cho thấy có nội dung trong khung hình, trong khi một vòng tròn trống cho thấy khung trống. Sau khi bạn xác định các khung hình chính, bạn có thể cho flash làm tất cả các công việc tính toán sự xuất hiện của các khung hình tạm thời. | Symbol Types In the Timeline you will notice that your symbol has a unique set of frames specific to buttons Figure 3-4 . They are labeled and represent the Up Over and Down button states as well as a fourth state called the Hit state. The Hit state is invisible at runtime and defines the areas of the button that will react to the mouse. Any nontransparent object will trigger button detection and mouse feedback. Semitransparent pixels are not supported. They will be seen as nontransparent and therefore as part of the button. Figure 3-4. The button s Timeline Because the ar t in the Hit state defines the areas of the button that react to the mouse it is possible to create hot areas that are larger or smaller than the button. For example if a button must appear to be very small and is hard to click with the mouse as a result you can add area to the Hit state. This added area will not be visible but will increase the area s with which the mouse can interact. Similarly you could adjust the Hit state of a button that looked like a target by removing all but the bull s-eye from the target. This would prevent the outer rings of the target from being treated like a button limiting mouse interaction solely to the bull s-eye. Finally if no Hit state is used Flash automatically uses the Up state to define the hot area s of the button. To see a visual change in your button resulting from state changes in addition to cursor changes it is necessary to create one or more of the labeled Timeline frames and populate them with altered artwork. Follow these steps to give it a try 11. Click in the frame labeled Over so the frame appears selected. Use the Insert--Timeline-Keyframe menu command F6 to add a keyframe. This feature creates a new keyframe and duplicates the contents of the previous frame. Because you ve created a keyframe rather than adding another frame to the existing frame span you can transform the contents of each keyframe independently. 12. Create another keyframe by
