Adobe Flex Authors: Matthew Lobas, PR.com Newswire, Shelly Palmer, Kevin Benedict

Related Topics: Adobe Flex

Adobe Flex: Article

Flash Player 8: Using Bitmap Caching in Flash

Developers and designers use Flash to do a lot more than just animation

As most of you know, Flash began as a tool for creating vector animations on the web. Flash Player was designed specifically as a lightweight animation viewer to display moving vector objects, which are, in their simplest form, mathematical equations that describe complex shapes made up of points, lines, curves, and fills.

 However, today, developers and designers use Flash to do a lot more than just animation; today, we use Flash for everything from interactive banner ads to games and large applications with complex user interfaces. We are now pushing Flash to its limits, and our frame rates are starting to suffer as we develop content that is more application-centric.

Previous versions of Flash Player showed some obvious performance limitations. The vector renderer inside the player generally coughed and spluttered when it attempted to play Flash applications with a lot of objects on the Stage. This is because the player was not optimized to deal with large amounts of static content. By design, on each frame, Flash Player 7 and previous versions had to update and redraw all the vector objects on the Stage, even if they had not changed. This was an intensive and unnecessary process.

Flash Player 8 addresses these visual performance issues with various improvements and optimizations to the renderer. There are also various new performance-enhancing authoring features in Flash Professional 8, which developers can use to take advantage of these significant changes.

This article will show you how to effectively use these new performance-related features to increase the frame rates of your Flash applications. An intermediate to advanced familiarity with ActionScript and Flash Player functionality is required.

Bitmap Caching
One of the most significant additions to Flash Player 8 has to be bitmap caching. This feature gives developers that are experiencing poor frame rates the power to greatly increase the speed at which large amounts of objects are updated and drawn onto the Stage by the renderer. The renderer is a very important part of Flash Player; it is responsible for everything that you see when you view a Flash application, as it draws all the vector and bitmap data onto the Stage. On each frame, the renderer has to update the Stage and the various objects it contains to reflect any changes that have occurred since the last frame. This process can become quite intensive when the application updates a large amount of information on any given frame. Using this feature gives the developer some control over the amount of work that the renderer has to perform in each frame ­ the less work you give the renderer, the faster and smoother your Flash application will run.

How Bitmap Caching Works
When you turn on bitmap caching for any given movie clip, the player converts the contents of the movie clip into a bitmap, which it generates and then stores in memory alongside the original vector data equivalent. The renderer then displays this bitmap in the place of the vector data by copying the image from memory onto the Stage.

This process essentially makes the renderer's life easier, because it doesn't have to update the movie clip each frame. Instead the process only has to draw the bitmap it generated once, and from then on it simply copies the bitmap from memory onto the Stage. If you change the movie clip or its contents, Flash regenerates the bitmap. There is little or no visual difference when a movie clip has bitmap caching turned on. You may notice a very slight difference because the vector data is snapped to the nearest whole pixel when the bitmap is generated. Bitmap caching also works perfectly well with nested movie clips (movie clips inside movie clips).

To put it in simple terms, by turning on bitmap caching for a movie clip, you are essentially telling Flash Player, "Hey Renderer, I'll make your life a little easier. Freeze this movie clip and display it as a bitmap instead, because this movie clip or its contents are not going to change very often, if at all. They are static."

Turning Bitmap Caching On and Off
Bitmap caching comes in the form of an additional movie clip property that can be switched on or off at author-time using the Property inspector and at runtime using ActionScript, on a per movie clip basis.

Using the Authoring Environment
You can turn bitmap caching on or off for any movie clip in the authoring environment using the Property inspector. Selecting this option disables bitmap caching for all movie clips by default.

To turn bitmap caching on select the desired movie clip instance on Stage by clicking on it. Then, open the Property Inspector from the Window menu. Select Window > Properties > Properties, or use the keyboard shortcut Control + F3.

In the lower right corner of the Property inspector underneath the Blend field, select the Use Runtime Bitmap Caching option for the selected movie clip by clicking the checkbox. Bitmap caching is deselected or turned off by default for all movie clips.

Using ActionScript
You can also turn bitmap caching on and off at runtime using ActionScript. Every movie clip object now has a new ActionScript property called cacheAsBitmap. To turn bitmap caching on for a movie clip, you simply need to set the value of its cacheAsBitmap property to true using the following code:

someMovieClip.cacheAsBitmap=true; //Turn Bitmap Caching ON

Similarly, to turn bitmap caching off for a movie clip using ActionScript, you simply need to set the value of its cacheAsBitmap property to false as follows:

someMovieClip.cacheAsBitmap=false; //Turn Bitmap Caching OFF

You can also determine if a movie clip has bitmap caching turned on by retrieving the value of the cacheAsBitmap property:


When to Use Bitmap Caching
If used correctly, bitmap caching can dramatically reduce the amount of updating instructions that the renderer has to process in every frame, and your applications should, in practice, run a lot quicker and smoother. However, in certain circumstances bitmap caching could have a detrimental effect on the performance of your Flash application, therefore you should choose the movie clips you cache wisely.

Bitmap caching works best for movie clips whose visual appearance doesn't change often or not at all. This is because when a cached movie clip or its contents change, Flash regenerates the bitmap with new data for the area or region of vector data that changed and updates the bitmap held in memory. The renderer then displays the new bitmap.

Bitmap caching also works well for movie clips that contain complex vector data (for example, shapes with lots of curves or gradient fills), as it is quicker for the renderer to copy a bitmap from memory onto the Stage than to draw all those vectors to the Stage.

Every time you rotate, scale, or change the alpha of a cached movie clip, the whole bitmap has to be regenerated. So, turning on bitmap caching for a movie clip that is constantly rotating, changing in size, or contains an animation doesn't make much sense because in every frame the renderer has to update the bitmap to reflect the new appearance of the movie clip as well as redraw it to the Stage, which adds overhead.

On the other hand, bitmap caching works well for both static movie clips and movie clips that move, as long as they don't change visually. It is perfectly fine to move a cached movie clip around the Stage, either with ActionScript or with Timeline animation, because moving it around won't change its visual appearance. The cached bitmap doesn't have to be updated, and the renderer will merely draw the bitmap at its new position.

More Stories By Guy Watson

Guy Watson (aka FlashGuru) has been a well-recognized figure in the Flash community for around four years, supporting the community with tutorials and source files, moderating the large Flash community forums, and running his own Flash resource Web site - FlashGuru's MX 101. Guy was one of the two developers that created the award-winning zoom interface for Relevare and now works for Endemol UK, the creative force behind reality television, producing programs such as Big Brother and The Salon. Guy now spends most of his time developing Flash games and applications for high-profile clients such as Channel 5 Television, Ladbrookes, and UK Style.

Comments (1) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.

Most Recent Comments
SYS-CON Belgium News Desk 01/18/06 07:20:50 PM EST

As most of you know, Flash began as a tool for creating vector animations on the web. Flash Player was designed specifically as a lightweight animation viewer to display moving vector objects, which are, in their simplest form, mathematical equations that describe complex shapes made up of points, lines, curves, and fills.

@ThingsExpo Stories
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
Widespread fragmentation is stalling the growth of the IIoT and making it difficult for partners to work together. The number of software platforms, apps, hardware and connectivity standards is creating paralysis among businesses that are afraid of being locked into a solution. EdgeX Foundry is unifying the community around a common IoT edge framework and an ecosystem of interoperable components.
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.
It is of utmost importance for the future success of WebRTC to ensure that interoperability is operational between web browsers and any WebRTC-compliant client. To be guaranteed as operational and effective, interoperability must be tested extensively by establishing WebRTC data and media connections between different web browsers running on different devices and operating systems. In his session at WebRTC Summit at @ThingsExpo, Dr. Alex Gouaillard, CEO and Founder of CoSMo Software, presented ...
WebRTC is great technology to build your own communication tools. It will be even more exciting experience it with advanced devices, such as a 360 Camera, 360 microphone, and a depth sensor camera. In his session at @ThingsExpo, Masashi Ganeko, a manager at INFOCOM Corporation, introduced two experimental projects from his team and what they learned from them. "Shotoku Tamago" uses the robot audition software HARK to track speakers in 360 video of a remote party. "Virtual Teleport" uses a multip...
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, whic...
SYS-CON Events announced today that Evatronix will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Evatronix SA offers comprehensive solutions in the design and implementation of electronic systems, in CAD / CAM deployment, and also is a designer and manufacturer of advanced 3D scanners for professional applications.
Leading companies, from the Global Fortune 500 to the smallest companies, are adopting hybrid cloud as the path to business advantage. Hybrid cloud depends on cloud services and on-premises infrastructure working in unison. Successful implementations require new levels of data mobility, enabled by an automated and seamless flow across on-premises and cloud resources. In his general session at 21st Cloud Expo, Greg Tevis, an IBM Storage Software Technical Strategist and Customer Solution Architec...
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
An increasing number of companies are creating products that combine data with analytical capabilities. Running interactive queries on Big Data requires complex architectures to store and query data effectively, typically involving data streams, an choosing efficient file format/database and multiple independent systems that are tied together through custom-engineered pipelines. In his session at @BigDataExpo at @ThingsExpo, Tomer Levi, a senior software engineer at Intel’s Advanced Analytics gr...