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Wildform is the creator of the SWfX SWF text effects generator and the Flix SWF video encoder. last modified November 14, 2000 ©2000 Wildform, Inc. |
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| Flash 5 Load Movie Basics |
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| Concepts Covered |
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| Load Movie Unload Movie Set Property Levels Movie Clips With Animating Empty Movie Clips Buttons Alpha |
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| Introduction |
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| Load Movie is an essential command to any serious Flash developer, as well as any user of third-party SWF software such as SWfX, since Macromedia Flash can not import Flash 4 or 5 SWFs. Despite its importance, however, very little information is available on the Load Movie command and how to use it.
This tutorial covers the basics of using Load Movie in Flash 5. After reading it, and studying the attached (simple) FLAs, you will be able to load and control multiple SWFs, using button or frame actions, with very little hassle. |
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| Basics |
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| Empty Movie Clips vs. Levels |
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There are two types of locations into which one may load an external SWF -- a level, or an empty movie clip. In general, I prefer and recommend working with empty movie clips, as they are more controllable and agile at design-time (when you are building your FLA) and at run-time (dynamically, by ActionScript, when your movie is running).
Loading movies into layers is most useful for loading many, or an undetermined number of external SWFs, since levels do not need to be created before loading an SWF into one. To load several SWFs into movie clips requires the manual placement and naming of the empty movie clips in Flash, or the use of the Duplicate Movie Clip command (if you are interested in learning how to use the Duplicate Movie Clip command for this purpose, please view the Wildform Banner Ad Engine tutorial, which is intended for advanced Flash developers). But, on the whole, I find loading SWFs into empty movie clips more reliable and useful, and the examples in this tutorial are based on that method. That said, however, with the exception of the final example, "Controlling SWFs Once Loaded", all of these samples could just as well apply to loading a movie into a layer rather than an empty movie clip - simply replace the target of the Load and Unload Movie Clip commands with a level number. |
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| Positioning Your SWF |
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The most common question concerning Load Movie concerns the placement of external SWFs using empty movie clips. The center point of your empty movie clip in Flash (the dot on your stage, or the cross-hair when you edit the movie clip) is where the upper left corner of your external SWF will be located. That's it. That's the only rule. If you get it, you should skip the following paragraphs, which contain a bit more detailed explanation.
Perhaps it might be easiest to think of it in these terms. The upper left corner of the preview window in SWfX (which is the upper left corner of the SWF you create) is the 0,0 x-y position. So, for example, if you place your animation at 20, 30 in SWfX, it will begin 20 points from the left side and 30 points from the top of the preview window. In Flash, the 0,0 coordinate in your empty movie clip is the cross hair that appears in the middle of your stage when you edit the movie clip. So, an object that appears at (20,30) would appear 20 points to the right and 30 points below the cross hair. So, to align your movies, all you have to do is align your (0,0) points - the center-point of your empty movie clip and the upper-left corner of your SWF. |
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| Loading Single SWFs |
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| Frame Action |
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| In this movie, the SWF is loaded and nothing else happens. This FLA for this SWF is very simple. There is one timeline, with two frames. An empty movie clip is on both frames. To create an empty movie clip, view the Library (CTRL-L if it is not currently visible). On the upper right of the window, select "Options" and "New Symbol". Give it whatever name you wish, and be sure to select "Movie Clip" under behavior. Do not do anything else with this movie clip.
Then, return to your main timeline (CTRL-E if it is not currently visible) and drag the new movie clip from the library onto your stage (see "Positioning" above for proper placement of your movie clip). Now you need to name this instance of your movie clip. Make sure the movie clip is still selected, view the Instance Properties panel (CTRL-I if it is not currently visible) and enter a name. I have used "empty" for simplicity. In the first frame, there is a Load Movie command.  To do this, select the frame in the timeline, and then view the Actions window (Window -> Actions, or CTRL-ALT-A). Then, under basic actions select Load Movie. At the bottom of the actions panel, enter the URL you wish to load, and the target (in this case, the movie clip "empty").
Then, the second frame contains a stop command. Please note that the stop command can not immediately follow the Load Movie command on the same frame, because such code would fail to load the external SWF. |
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| Button Action -- Simple |
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| Taking this previous example one step further, let us apply the Load Movie command to a button, so we can choose when to load the animation. So, in this example, the movie waits until the user clicks the Load button to load the animation.
To add the Load Movie action to a button, select the button and view the Actions window.  Under "Basic Actions", select "On MouseEvent". I have chosen On Release, meaning that this action is executed on mouse up. Then, select the Load Movie command in the same Basic Actions list and fill in the appropriate information at the bottom of the Actions window.
 Once the user clicks the "Load" button, the Flash player runs the Load Movie command and then proceeds to the frame "unload" as indicated by the ActionScript. Now, the button changes to "Unload" and now has an "Unload Movie Clip" command. The Unload Movie command is directly beneath the Load Movie command in the Basic Actions list. All you have to do is enter the target. Click the "Unload" button in the SWF, and you will notice the animation disappear.
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| Loading Multiple SWFs |
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| Button Action -- Load Multiple SWFs into Multiple Movie Clips |
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Building directly on top of the previous example, let's say that we have six different movies to load. And, we need to be able to view all six simultaneously.  This means that we need to create 6 copies of that "load/unload" button and 6 empty movie clip instances (just drag the movie clip from the library on to your stage six times - you do not need to create 6 separate movie clips in your library), with 6 different instance names ("empty1", "empty2", etc). Each load button loads an animation into the corresponding empty movie clip. And, as in the previous example, when the "load" button is clicked, it becomes an "unload" button, which empties the appropriate movie clip and returns the button to its default "load" state.
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| Button Action -- Load Multiple SWFs into One Movie Clip |
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| Now, as with the previous example, let's assume that you need to load several external SWFs - but this time no more than one needs to be visible at once. This fact is important because, unlike in the previous example, here we need only one empty movie clip instance since all the animations one can be loaded into the same movie clip.
Each load button differs from the others in the name of the file that it loads -  however, the target movie clip specified in the Load Movie command on each button is identical (labeled "empty"). The "Load" buttons in this sample are just load buttons - not two-frame "Load/Unload" buttons as in the previous two samples. To unload whichever animation is currently loaded, click the "unload" button at the bottom of the SWF.
When you load an SWF into an empty movie clip, any SWF that might already have been loaded into that location is automatically purged, or unloaded, from the SWF. For example, if you click "Load 1", the first animation appears. If you click "unload", the first animation disappears. If you then click "Load 2", the second animation appears. Now, instead of clicking "unload" before clicking "Load 3", you just click "Load 3". You will notice that the second animation disappears and is replaced by the third animation - there was no separate Unload Movie command necessary. |
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| Controlling SWFs Once Loaded |
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| Now that you've learned how to load single and multiple movies into single and multiple locations, what do you do with them once they are loaded? You can do anything that you can do to movie clips in Flash. As you increase your grasp of ActionScript, you will realize the possibilities of working with and manipulating movie clips.
As a simple demonstration, I have prepared three separate actions - the three most common questions that we receive regarding manipulating loaded SWFs: fade, move and hide.  The actions on these buttons are quite simple. I will start with "hide", since that is by far the easiest command of the three. As you can see, it's a simple SetProperty command. As with the buttons in the previous sample, this button action is triggered On Release. Then, under the "Actions" list (directly beneath "Basic Actions"), choose "setProperty" and fill out the command to read  setProperty ("_root.empty_holder.empty", _visible, "0");. To return visibility, simply click show, which issues almost the identical command, with the "0" (which means invisible), with a "1" (meaning visible).
While it is possible to move and fade movie clips with ActionScript (by shifting the _alpha, _x, and _y properties for the movie clip), that is not the easiest method, and it is not the method I have chosen to illustrate here. You will notice that in this example, I have placed the empty movie clip within another movie clip, labeled "empty_holder". The timeline for "empty_holder" contains 66 frames. There is an instance of "empty" on the stage in all of these 66 frames. There are three labels in the actions layer of this timeline: normal, fade_out, and move.  At normal, "empty" is in its proper location at 100% alpha, and there is a stop action. At "fade_out", "empty" is also in the right place at 100% alpha. From here, the timeline plays to frame 19, where "empty" is at 0% alpha, where the motion tween (the animation) stops. The timeline continues animating until frame 28, when it is told to return to "normal" and stop. At "move_out", "empty" is in the right place at 100% alpha. Then, over the next 16 frames, there are 6 keyframes, with "empty" in various positions. The motion tween creates the animation, rather than sudden jumps. The timeline continues playing until frame 66, when it is told to return to "normal" and stop.  With this timeline constructed, building the "fade" and "move" buttons was quite easy. Using the "With" command,  clicking the fade button tells the "empty_holder" movie clip to go to the frame labeled "fade_out" and play. And clicking the move button instructs the "empty_holder" to go to the frame labeled "move" and play. Both of these result in the desired animation, at the conclusion of which "empty_holder" returns to its normal, default state.
Since the buttons are active at all times, they can interfere with each other. For example, clicking "move" when the clip is in the middle of fading, will make "empty_holder" jump to "move_out" - thus immediately returning to 100% alpha. |
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| ©2000 Wildform, Inc. |