Android应用源码之ImageViewEx 支持Gif显示的ImageView-IT计算机-毕业设计.zip

#ImageViewEx --- Extension of Android's ImageView that supports animated GIFs and includes a better density management. ##Author **Francesco Pontillo** and **Sebastiano Poggi** ##Description The **ImageViewEx** is an extension of the standard Android `ImageView` that fills in one of the biggest gaps in the standard `ImageView`: displaying **animated GIFs**. The Android Framework `Drawable` class, in fact, only supports static GIFs. This View is able to receive a raw image in `byte[]` form, bypassing the standard `Drawable`s handling and thus providing broader support. The `ImageViewEx` also allows you to specify what has to be considered the default image density when loading images from raw data. Android defaults to considering `mdpi` as the baseline, but using `setInDensity` you can choose to change it to whatever value you like (we suggest to stick to standard abstracted density buckets like `hdpi` thou). The following is a brief documentation of the classes, methods and views included in this library. ##Index 1. [Import and usage](#import) 2. [ImageViewEx](#imageviewex) * [Animated GIF](#animated-gifs) * [Conditional animation](#conditional-animation) * [Density level](#density-level) * [Fill direction](#fillDirection) * [Regular behavior](#regular-behavior) * [Example of use](#imageviewex-example) 3. [ImageViewNext](#imageviewnext) * [Remote loading and caching of images](#remote-loading) * [Loading and Error Drawables](#loading-error-drawables) * [Getting images from the Internet](#getting-from-internet) * [Handling network failures](#network-failures) * [Maximum number of threads](#thread-number) * [Example of use](#imageviewnext-example) 4. [Known issues and workarounds](#issues-workarounds) 5. [Some boring stuff](#boring-stuff) 6. [Version history](#history) 7. [License](#license) <a name="import"/> ##Import and usage This library requires Android **API level 8** (Android 2.2) as minimum, and targets the Android **API level 17**. You need to include in your destination project: * [JakeWharton/DiskLruCache](https://github.com/JakeWharton/DiskLruCache) library, used for caching on disk. * [foxykeep/DataDroid](https://github.com/foxykeep/DataDroid) library, used for handling async operations. * [square/okhttp](https://github.com/square/okhttp) library, for a better connection management. The Eclipse project included specifies this is a library project, although it provides two basic Activities for testing the extended `ImageView`s provided. For your application, you need to include the permissions specified in the AndroidManifest of the library, which are: * `android.permission.INTERNET` for getting images on the internet * `android.permission.ACCESS_NETWORK_STATE` to monitor the network state * `android.permission.WRITE_EXTERNAL_STORAGE` for making the cache access and write the SD card The `ImageViewExService` service is also internally used by `ImageViewNext` for handling asynchronous operation. You need to declare this service in your `AndroidManifest.xml`: ```xml <service android:name="net.frakbot.imageviewex.service.ImageViewExService"/> ``` <a name="imageviewex"/> ##ImageViewEx `ImageViewEx` is an extended `ImageView` that supports some additional methods for your every-day life. <a name="animated-gifs"/> ###Animated GIF The best thing about `ImageViewEx` is its **automatic handling of animated GIF images** starting from a simple `byte[]`. Simply call `img.setSource(mGIF)` and see your GIF animating. Note that there may be some issues under some conditions (see [Known issues and workarounds](#known-issues-and-workarounds)). What if you don't know if an image is a GIF or a regular one? No problem, simply call `setSource` and `ImageViewEx` will do the rest, displaying your image as a regular one or an animated GIF when necessary. Accessory methods are: * `void setFramesDuration(int duration)` to set the duration, in milliseconds, of each frame during the GIF animation (it is the refresh period) * `void setFPS(float fps)` to set the number of frames per second during the GIF animation * `boolean isPlaying()` to know if your GIF is playing * `boolean canPlay()` to know if your source set by `setSource` was an animated GIF after all * `int getFramesDuration()` to get the frame duration, in milliseconds * `float getFPS()` to get the number of frames per second during the GIF animation * `void play()` to start the GIF, if it hasn't started yet. * `void pause()` to pause the GIF, if it has started * `void stop()` to stop playing the GIF, if it has started <a name="conditional-animation"/> ###Conditional animation As mentioned earlier, you may not want to animate some GIF under some conditions. So we've provided you with a **conditional method** that gets triggered just before each animation begins, `boolean canAnimate()`. This method should be overridden by your custom implementation. By default, it always returns `true`. This method decides whether animations can be started for this instance of `ImageViewEx`. If you don't want to have another class extending `ImageViewEx` and your `canAnimate()` returns the same value throughout your application, you can use the following ```java ImageViewNext.setCanAlwaysAnimate(false); ``` to specify you never want to animate GIFs. If you don't set any value to `setCanAlwaysAnimate`, it defaults to `true`. The result you get by setting the value to `false` is that it will stop all animations, no matter what `canAnimate()` returns. You can check the current behavior by calling the `static boolean getCanAlwaysAnimate()` method. <a name="density-level"/> ###Density Level You can set a **specific density to simulate** for every instance of `ImageViewEx` by using the following methods: * `static void setClassLevelDensity(int classLevelDensity)` to set a specific density for every image * `static void removeClassLevelDensity()` to remove the class-level customization * `static boolean isClassLevelDensitySet()`, checks if a class-level density has been set * `static int getClassLevelDensity()`, gets the set class-level density, or null if none has been set You can even set a density for just one of your `ImageViewEx`s: * `void setDensity(int fixedDensity)`, to set the density for a particular instance of `ImageViewEx` * `int getDensity()`, gets the set density for a particular instance of `ImageViewEx` (an instance-level density has higher priority over a class-level density) * `void dontOverrideDensity()`, restores the regular density of the `ImageViewEx` <a name="fillDirection"/> ###Fill direction The `ImageViewEx` has one unique feature: it allows you to decide which direction to fit the image on, and then resize the other dimension (this function implies `adjustViewBounds`) to show the scaled image. For example, you can use this to show a banner which fills the whole horizontal available space (the `ImageViewEx` has `android:layout_width="match_parent"` and `android:layout_height="wrap_content"`, plus `android:adjustViewBounds="true"`). Setting `fillDirection="horizontal"` will prioritize filling the available horizontal space while keeping the image aspect ratio and expanding the `ImageViewEx` to fit the height. <a name="regular-behavior"/> ###Regular behavior `ImageViewEx` is, after all, a regular `ImageView`, so you can go ahead and use its regular methods: * `void setImageResource(int resId)` * `void setImageDrawable(Drawable drawable)` * `void setImageBitmap(Bitmap bm)` * and so on. <a name="imageviewex-example"/> ###Example of use ```java // Disables animation, behaving like a regular ImageView, // except you can still set byte[] as the source ImageViewEx.setCanAlwaysAnimate(false); // Sets a default density for all of the images in each ImageViewEx. ImageViewEx.setClassLevelDensity(DisplayMetrics.DENSITY_MEDIUM); // Sets a density for the img1 only. // Changing the density after an object has