ImageCache Class Reference

A global cache of images that have been loaded from files or memory. More...

Static Public Member Functions
static Image	getFromFile (const File &file)
	Loads an image from a file, (or just returns the image if it's already cached). More...
static Image	getFromMemory (const void *imageData, int dataSize)
	Loads an image from an in-memory image file, (or just returns the image if it's already cached). More...
static Image	getFromHashCode (int64 hashCode)
	Checks the cache for an image with a particular hashcode. More...
static void	addImageToCache (const Image &image, int64 hashCode)
	Adds an image to the cache with a user-defined hash-code. More...
static void	setCacheTimeout (int millisecs)
	Changes the amount of time before an unused image will be removed from the cache. More...
static void	releaseUnusedImages ()
	Releases any images in the cache that aren't being referenced by active Image objects. More...

Detailed Description

A global cache of images that have been loaded from files or memory.

If you're loading an image and may need to use the image in more than one place, this is used to allow the same image to be shared rather than loading multiple copies into memory.

Another advantage is that after images are released, they will be kept in memory for a few seconds before it is actually deleted, so if you're repeatedly loading/deleting the same image, it'll reduce the chances of having to reload it each time.

See also

Image, ImageFileFormat

Member Function Documentation

getFromFile()

static Image ImageCache::getFromFile ( const File &  file )

static

Loads an image from a file, (or just returns the image if it's already cached).

If the cache already contains an image that was loaded from this file, that image will be returned. Otherwise, this method will try to load the file, add it to the cache, and return it.

Remember that the image returned is shared, so drawing into it might affect other things that are using it! If you want to draw on it, first call Image::duplicateIfShared()

Parameters

file	the file to try to load

Returns

the image, or null if it there was an error loading it

See also

getFromMemory, getFromCache, ImageFileFormat::loadFrom

getFromMemory()

static Image ImageCache::getFromMemory ( const void *  imageData, int  dataSize  )

static

Loads an image from an in-memory image file, (or just returns the image if it's already cached).

If the cache already contains an image that was loaded from this block of memory, that image will be returned. Otherwise, this method will try to load the file, add it to the cache, and return it.

Remember that the image returned is shared, so drawing into it might affect other things that are using it! If you want to draw on it, first call Image::duplicateIfShared()

Parameters

imageData	the block of memory containing the image data
dataSize	the data size in bytes

Returns

the image, or an invalid image if it there was an error loading it

See also

getFromMemory, getFromCache, ImageFileFormat::loadFrom

getFromHashCode()

static Image ImageCache::getFromHashCode ( int64  hashCode )

static

Checks the cache for an image with a particular hashcode.

If there's an image in the cache with this hashcode, it will be returned, otherwise it will return an invalid image.

Parameters

hashCode

the hash code that was associated with the image by addImageToCache()

See also

addImageToCache

addImageToCache()

static void ImageCache::addImageToCache ( const Image &  image, int64  hashCode  )

static

Adds an image to the cache with a user-defined hash-code.

The image passed-in will be referenced (not copied) by the cache, so it's probably a good idea not to draw into it after adding it, otherwise this will affect all instances of it that may be in use.

Parameters

image	the image to add
hashCode	the hash-code to associate with it

See also

getFromHashCode

setCacheTimeout()

static void ImageCache::setCacheTimeout ( int  millisecs )

static

Changes the amount of time before an unused image will be removed from the cache.

By default this is about 5 seconds.

releaseUnusedImages()

static void ImageCache::releaseUnusedImages ( )

static

Releases any images in the cache that aren't being referenced by active Image objects.

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The documentation for this class was generated from the following file:

• juce_ImageCache.h