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Imagegif sourcekeeper hajcgwf9/5/2023 Value of 90 would result in bottom-to-top reading text.Ĭharacter (roughly the lower-left corner of the character). Higher values represent a counter-clockwise rotation. The angle in degrees, with 0 degrees being left-to-right reading text. This library fully supports the GIF87A and GIF89A format, and the Netscape Application Block.Getting Started Introduction A simple tutorial Language Reference Basic syntax Types Variables Constants Expressions Operators Control Structures Functions Classes and Objects Namespaces Enumerations Errors Exceptions Fibers Generators Attributes References Explained Predefined Variables Predefined Exceptions Predefined Interfaces and Classes Predefined Attributes Context options and parameters Supported Protocols and Wrappers Security Introduction General considerations Installed as CGI binary Installed as an Apache module Session Security Filesystem Security Database Security Error Reporting User Submitted Data Hiding PHP Keeping Current Features HTTP authentication with PHP Cookies Sessions Dealing with XForms Handling file uploads Using remote files Connection handling Persistent Database Connections Command line usage Garbage Collection DTrace Dynamic Tracing Function Reference Affecting PHP's Behaviour Audio Formats Manipulation Authentication Services Command Line Specific Extensions Compression and Archive Extensions Cryptography Extensions Database Extensions Date and Time Related Extensions File System Related Extensions Human Language and Character Encoding Support Image Processing and Generation Mail Related Extensions Mathematical Extensions Non-Text MIME Output Process Control Extensions Other Basic Extensions Other Services Search Engine Extensions Server Specific Extensions Session Extensions Text Processing Variable and Type Related Extensions Web Services Windows Only Extensions XML Manipulation GUI Extensions Keyboard Shortcuts ? This help j Next menu item k Previous menu item g p Previous man page g n Next man page G Scroll to bottom g g Scroll to top g h Goto homepage g s Goto searchĪ GdImage object, returned by one of the image creation functions, The library is tested to be able to smoothly render a 70MB GIF on the hardware of a Lumia 640 phone, and should work on all Windows Phone hardware. In case of a phone app, each GIF will continually check app memory usage and stop caching frames when the memory usage exceeds a limit of 60% of app allowance, and clear all cached frames when it exceeds 80%. This makes it as efficient as possible on small GIFs, while also supporting smooth playback of very large GIFs. It caches frames up to a limit of 50 frames, and then starts a task that buffers 5 frames ahead of the current frame. This library uses a tweaked combination of the above methods. This solution uses more cpu on smaller gifs due to the constant need to read data from the stream even after the first playback, but uses no more memory then the current and previous frame, and the CPU usage is always more or less constant.Ī problem with this solution is that it is susceptible to slowdowns or stuttering if the system can't read the frames fast enough. The alternative is to read frames from the stream in real time, drawing on top of the previous frame each time. A GIF can have hundreds of frames, so after 200 frames you could end up drawing 200 bitmaps every 20 milliseconds! The CPU usage can also steadily climb the longer the GIF plays, since it has to draw more and more bitmaps for each frame. Loading large GIFs could easily exceed the apps memory limit and crash the app. Depending on color depth and resolution, a 10MB GIF can use 100MB of device memory or more. The library is written as a Windows Runtime Component in C++, and will work on all Windows Runtime and UWP projects.Ī GIF is not necessarily a series of independent frames drawn one after another, but a series of images drawn upon each other, each one adding to the complete picture.Ī common strategy to make this work is to read all frames into memory, and then draw all frames that need to be rendered in series for each frame.įor small GIFs this is a cpu efficient way to do it, but a problem occurs when you load a large GIF. I deciced to create this project to combine the strenghts into one library, capable of efficiently rendering everything from the smallest 5kb emoticon, to high resolution GIFs with sizes in the dozens or even hundreds of MB. Some did not follow all GIF specifications and rendered GIFs wrong, and some demanded too much of the CPU which lead to choppy playback on mobile hardware. Some had good cpu performance but used too much memory, which lead to crashes on mobile. Having a need for a GIF rendering library for a project, i tried out existing open source libraries out there. It's up to the app author using this library to clean up these resources as they see fit. Downloaded images are cached in a folder named "GifImageSource" in the ApplicationData.TemporaryFolder.
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