xyz.zpayh.hdimage.util

类 ImageCache

java.lang.Object

xyz.zpayh.hdimage.util.ImageCache

public class ImageCache
extends java.lang.Object

嵌套类概要

嵌套类

限定符和类型	类和说明
static class	ImageCache.ImageCacheParams A holder class that contains cache parameters.
static class	ImageCache.RetainFragment A simple non-UI Fragment that stores a single Object and is retained over configuration changes.

方法概要

限定符和类型	方法和说明
void	addBitmapToCache(java.lang.String data, android.graphics.drawable.BitmapDrawable value) Adds a bitmap to both memory and disk cache.
static int	calculateInSampleSize(android.graphics.BitmapFactory.Options options, int reqWidth, int reqHeight) Calculate an inSampleSize for use in a BitmapFactory.Options object when decoding bitmaps using the decode* methods from BitmapFactory.
void	clearCache() Clears both the memory and disk cache associated with this ImageCache object.
void	close() Closes the disk cache associated with this ImageCache object.
static android.graphics.Bitmap	decodeSampledBitmapFromDescriptor(java.io.FileDescriptor fileDescriptor, int reqWidth, int reqHeight, ImageCache cache) Decode and sample down a bitmap from a file input stream to the requested width and height.
void	flush() Flushes the disk cache associated with this ImageCache object.
android.graphics.Bitmap	getBitmapFromDiskCache(java.lang.String data) Get from disk cache.
protected android.graphics.Bitmap	getBitmapFromReusableSet(android.graphics.BitmapFactory.Options options)
static int	getBitmapSize(android.graphics.drawable.BitmapDrawable value) Get the size in bytes of a bitmap in a BitmapDrawable.
static java.io.File	getDiskCacheDir(android.content.Context context, java.lang.String uniqueName) Get a usable cache directory (external if available, internal otherwise).
static java.io.File	getExternalCacheDir(android.content.Context context) Get the external app cache directory.
static ImageCache	getInstance(android.support.v4.app.FragmentManager fragmentManager, ImageCache.ImageCacheParams cacheParams) Return an ImageCache instance.
static long	getUsableSpace(java.io.File path) Check how much usable space is available at a given path.
static java.lang.String	hashKeyForDisk(java.lang.String key) A hashing method that changes a string (like a URL) into a hash suitable for using as a disk filename.
void	initDiskCache() Initializes the disk cache.
static boolean	isExternalStorageRemovable() Check if external storage is built-in or removable.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

方法详细资料

getInstance

public static ImageCache getInstance(android.support.v4.app.FragmentManager fragmentManager,
                                     ImageCache.ImageCacheParams cacheParams)

Return an ImageCache instance. A ImageCache.RetainFragment is used to retain the ImageCache object across configuration changes such as a change in device orientation.

参数:

fragmentManager - The fragment manager to use when dealing with the retained fragment.

cacheParams - The cache parameters to use if the ImageCache needs instantiation.

返回:

An existing retained ImageCache object or a new one if one did not exist

initDiskCache

public void initDiskCache()

Initializes the disk cache. Note that this includes disk access so this should not be executed on the main/UI thread. By default an ImageCache does not initialize the disk cache when it is created, instead you should call initDiskCache() to initialize it on a background thread.

addBitmapToCache

public void addBitmapToCache(java.lang.String data,
                             android.graphics.drawable.BitmapDrawable value)

Adds a bitmap to both memory and disk cache.

参数:

data - Unique identifier for the bitmap to store

value - The bitmap drawable to store

getBitmapFromDiskCache

public android.graphics.Bitmap getBitmapFromDiskCache(java.lang.String data)

Get from disk cache.

参数:

data - Unique identifier for which item to get

返回:

The bitmap if found in cache, null otherwise

decodeSampledBitmapFromDescriptor

public static android.graphics.Bitmap decodeSampledBitmapFromDescriptor(java.io.FileDescriptor fileDescriptor,
                                                                        int reqWidth,
                                                                        int reqHeight,
                                                                        ImageCache cache)

Decode and sample down a bitmap from a file input stream to the requested width and height.

参数:

fileDescriptor - The file descriptor to read from

reqWidth - The requested width of the resulting bitmap

reqHeight - The requested height of the resulting bitmap

cache - The ImageCache used to find candidate bitmaps for use with inBitmap

返回:

A bitmap sampled down from the original with the same aspect ratio and dimensions that are equal to or greater than the requested width and height

calculateInSampleSize

public static int calculateInSampleSize(android.graphics.BitmapFactory.Options options,
                                        int reqWidth,
                                        int reqHeight)

Calculate an inSampleSize for use in a BitmapFactory.Options object when decoding bitmaps using the decode* methods from BitmapFactory. This implementation calculates the closest inSampleSize that is a power of 2 and will result in the final decoded bitmap having a width and height equal to or larger than the requested width and height.

参数:

options - An options object with out* params already populated (run through a decode* method with inJustDecodeBounds==true

reqWidth - The requested width of the resulting bitmap

reqHeight - The requested height of the resulting bitmap

返回:

The value to be used for inSampleSize

getBitmapFromReusableSet

protected android.graphics.Bitmap getBitmapFromReusableSet(android.graphics.BitmapFactory.Options options)

参数:

options - - BitmapFactory.Options with out* options populated

返回:

Bitmap that case be used for inBitmap

clearCache

public void clearCache()

Clears both the memory and disk cache associated with this ImageCache object. Note that this includes disk access so this should not be executed on the main/UI thread.

flush

public void flush()

Flushes the disk cache associated with this ImageCache object. Note that this includes disk access so this should not be executed on the main/UI thread.

close

public void close()

Closes the disk cache associated with this ImageCache object. Note that this includes disk access so this should not be executed on the main/UI thread.

getDiskCacheDir

public static java.io.File getDiskCacheDir(android.content.Context context,
                                           java.lang.String uniqueName)

Get a usable cache directory (external if available, internal otherwise).

参数:

context - The context to use

uniqueName - A unique directory name to append to the cache dir

返回:

The cache dir

hashKeyForDisk

public static java.lang.String hashKeyForDisk(java.lang.String key)

A hashing method that changes a string (like a URL) into a hash suitable for using as a disk filename.

getBitmapSize

public static int getBitmapSize(android.graphics.drawable.BitmapDrawable value)

Get the size in bytes of a bitmap in a BitmapDrawable. Note that from Android 4.4 (KitKat) onward this returns the allocated memory size of the bitmap which can be larger than the actual bitmap data byte count (in the case it was re-used).

参数:

value -

返回:

size in bytes

isExternalStorageRemovable

public static boolean isExternalStorageRemovable()

Check if external storage is built-in or removable.

返回:

True if external storage is removable (like an SD card), false otherwise.

getExternalCacheDir

public static java.io.File getExternalCacheDir(android.content.Context context)

Get the external app cache directory.

参数:

context - The context to use

返回:

The external cache dir

getUsableSpace

public static long getUsableSpace(java.io.File path)

Check how much usable space is available at a given path.

参数:

path - The path to check

返回:

The space available in bytes