how to display bitmaps efficiently in java

8/10/2019 How to Display Bitmaps Efficiently in JAVA

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Displaying Bitmaps

Efficiently

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Displaying Bitmaps Efficiently

Number of reasons why loading bitmaps in Android application

+obile de&ices typically ha&e constrained system reso!rces. Androi

can ha&e as little as +B of memory a&ailable to a single applicatio

0he Android 1ompatibility Definition Doc!ment #1DD%( 2ection 3.4.

+achine 1ompatibility gi&es the re!ired minim!m application me

&ario!s screen si,es and densities. Applications sho!ld be optimi,e

!nder this minim!m memory limit. 5owe&er( keep in mind many de

config!red with higher limits.




Bitmaps take !p a lot of memory( especially for rich images like

photographs. 6or example( the camera on the 7alaxy Nex!s take

to 89:8x:3 pixels #9 megapixels%. If the bitmap config!ration

is A;7B<==== #the defa!lt from the Android 8.3 onward% then lo

image into memory takes abo!t :+B of memory #89:8>:3>?

immediately exha!sting the per@app limit on some de&ices.




Android app $Is fre!ently re!ire se&eral bitmaps to be loaded

1omponents s!ch as ist-iew( 7rid-iew and -iewCager common

m!ltiple bitmaps on@screen at once with many more potentially

ready to show at the flick of a finger.



oading arge Bitmaps

An image with a higher resol!tion does not pro&ide any &isible benefit

takes !p precio!s memory and inc!rs additional performance o&erhea

additional on the fly scaling.B!t 'e can also decoding large bitmaps w

exceeding the per application memory limit by loading a smaller s!b s

&ersion in memory.

0he Bitmap6actory class pro&ides se&eral decoding methods s!ch as

decodeByteArray#%( decode6ile#%( decode;eso!rce#%( etc. for creating

a Bitmap from &ario!s so!rces.



oading arge Bitmaps

1hoose the most appropriate decode method based on image data so!

methods attempt to allocate memory for the constr!cted bitmap and t

easily res!lt in an *!t*f+emory exception.

Each type of decode method has additional signat!res that help to spe

decoding options &ia the Bitmap6actory.*ptions class.

2etting the in!stDecodeBo!nds property to tr!e while decoding a&oi

allocation( ret!rning n!ll for the bitmap ob"ect b!t setting o!t'idth(o!

o!t+ime0ype



oading arge Bitmaps

Example:

Bitmap6actory.*ptions options F new Bitmap6actory.*ptions#%G

options.in!stDecodeBo!nds F tr!eG

Bitmap6actory.decode;eso!rce#get;eso!rces#%( ;.id.myimage( optio

int image5eight F options.o!t5eightG

int image'idth F options.o!t'idthG

2tring image0ype F options.o!t+ime0ype



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how to display bitmaps efficiently in java

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