Develop Reference

Volley Image Loader throws ParseError

I've met annoying problem using NetworkImageView. It throws ParseError in ImageRequest.doParse(NetworkResponse response) library method.
private Response<Bitmap> doParse(NetworkResponse response) {
byte[] data = response.data;
BitmapFactory.Options decodeOptions = new BitmapFactory.Options();
Bitmap bitmap = null;
if (mMaxWidth == 0 && mMaxHeight == 0) {
decodeOptions.inPreferredConfig = mDecodeConfig;
bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);
} else {
// If we have to resize this image, first get the natural bounds.
decodeOptions.inJustDecodeBounds = true;
BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);
int actualWidth = decodeOptions.outWidth;
int actualHeight = decodeOptions.outHeight;
// Then compute the dimensions we would ideally like to decode to.
int desiredWidth = getResizedDimension(mMaxWidth, mMaxHeight,
actualWidth, actualHeight);
int desiredHeight = getResizedDimension(mMaxHeight, mMaxWidth,
actualHeight, actualWidth);
// Decode to the nearest power of two scaling factor.
decodeOptions.inJustDecodeBounds = false;
// TODO(ficus): Do we need this or is it okay since API 8 doesn't support it?
// decodeOptions.inPreferQualityOverSpeed = PREFER_QUALITY_OVER_SPEED;
decodeOptions.inSampleSize =
findBestSampleSize(actualWidth, actualHeight, desiredWidth, desiredHeight);
Bitmap tempBitmap =
BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);
// If necessary, scale down to the maximal acceptable size.
if (tempBitmap != null && (tempBitmap.getWidth() > desiredWidth ||
tempBitmap.getHeight() > desiredHeight)) {
bitmap = Bitmap.createScaledBitmap(tempBitmap,
desiredWidth, desiredHeight, true);
tempBitmap.recycle();
} else {
bitmap = tempBitmap;
}
}
if (bitmap == null) {
return Response.error(new ParseError(response));
} else {
return Response.success(bitmap, HttpHeaderParser.parseCacheHeaders(response));
}
}
It throws it because of
bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, decodeOptions);
returns null. But it returns null not on all devices.
I've tested it on :
HTC Sensation XE
Nexus 5
Samsung S4
Samsung Note
and only Samsung Note has this error.
Url is OK - I can open it in browser (and yes it's an image)
Data should be OK as it can be decoded in other devices
decodeByteArray documantaion says :
Returns
The decoded bitmap, or null if the image data could not be decoded, or, if opts is non->null, if opts requested only the size be returned (in opts.outWidth and opts.outHeight)
I've tried to pass null as opts parameter, but it still returns null. So anybody know what is happening here ?
Thanks

The problem was in Image format. It was JFIF. Seems that not all devices supports it. As I had an access to server side I just changed Image there. Other way you need to implement your own decode method to support this format in all devices.
Cheers

Draw over Asset png efficiently and cache

I’m using thquinn’s DraggableGridView and load ~60 images into it. This all works fine. I had all the images needed in my assets, but want to create them at runtime since first of only the Text on the images change which seems redundant and I can reduce the appsize and the second reason is that I need to sometimes change the icons over the Air where adding wouldn’t be the problem but deleting from assets isn’t possible and would use unnecessary space. That briefly to explain my motives here.
So I’ve used the method from this Post to draw text over my Asset png and then convert it into a Bitmap to be able to use them in the LRUcache. This works with a few images but as soon as I try and display all needed Images I get an OutOfMemory error. The Base Images are 200x200 px which I think should also be scaled to the need size depending on screensize and density.
First of, this method doesn’t seem efficient because I create a Bitmap canvas then make a LayerdDrawable which I make into a Bitmap (for caching) again. Not sure, but it just feels like I’m creating to much temp images which clutter up the memory.
And then I’m using a BitmapDrawable which is depreciated. How would this method look without the BitmapDrawable??
Am I going about this the right way in general and How would I make this method efficiently so I don’t get the OOM error?!?
BTW. When I don’t use LRUcache and just return the LayerdDrawable for the GridView the images load fine but I get the Exception after a couple of Orientation changes!
This is the method as I have it atm:
private Bitmap createIcon(Drawable backgroundImage, String text,
int width, int height) {
String key = text.toLowerCase();
Bitmap cachedBitmap = getBitmapFromMemCache(key);
if (cachedBitmap != null){
Log.d("TRACE", "is cached");
return cachedBitmap;
}
else{
Bitmap canvasBitmap = Bitmap.createBitmap(width, height,
Bitmap.Config.ARGB_8888);
Canvas imageCanvas = new Canvas(canvasBitmap);
Typeface font = Typeface.createFromAsset(getActivity().getAssets(), "myriadpro.ttf");
Paint imagePaint = new Paint();
imagePaint.setTextAlign(Paint.Align.CENTER);
imagePaint.setTextSize(26);//
imagePaint.setTypeface(font);
imagePaint.setAntiAlias(true);
imagePaint.setColor(Color.parseColor("#562b12"));
backgroundImage.draw(imageCanvas);
imageCanvas.drawText(text, (width / 2)+4, (height / 2)-8, imagePaint);
LayerDrawable layerDrawable = new LayerDrawable(
new Drawable[]{backgroundImage, new BitmapDrawable(canvasBitmap)});
int w = layerDrawable.getIntrinsicWidth();
int h = layerDrawable.getIntrinsicHeight();
Bitmap bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
layerDrawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
layerDrawable.draw(canvas);
addBitmapToMemoryCache(key,bitmap);
return bitmap;
}
}
Update:
I have tried with another method now, which seems better because it’s not using BitmapDrawable. But I still get OOM error. Also it generally doesn’t seem to realy use the cached images, when I change orientation only 1 or 2 images come from the cache.
I also failed to metion before the this is inside a Fragment. Not sure if it matters. But in portrait mode i have only this Fragment and in Landscape there can be another one if the width allows it.
public Bitmap drawTextToBitmap(Context mContext, int resourceId, String mText) {
try {
int memory = (int) (Runtime.getRuntime().freeMemory() / 1024);
Log.d("TRACE", "memory " + memory);
Log.d("TRACE", mText);
String key = mText.toLowerCase();
Bitmap cachedBitmap = getBitmapFromMemCache(key);
if (cachedBitmap != null){
Log.d("TRACE", "is cached");
return cachedBitmap;
}
else{
Resources resources = mContext.getResources();
float scale = resources.getDisplayMetrics().density;
Bitmap bitmap = BitmapFactory.decodeResource(resources, resourceId);
android.graphics.Bitmap.Config bitmapConfig = bitmap.getConfig();
// set default bitmap config if none
if(bitmapConfig == null) {
bitmapConfig = android.graphics.Bitmap.Config.ARGB_8888;
}
bitmap = bitmap.copy(bitmapConfig, true); // OOE error happens here
Canvas canvas = new Canvas(bitmap);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.rgb(110,110, 110));
paint.setTextSize((int) (25 * scale));
Rect bounds = new Rect();
paint.getTextBounds(mText, 0, mText.length(), bounds);
int x = (bitmap.getWidth() - bounds.width())/6;
int y = (bitmap.getHeight() + bounds.height())/5;
canvas.drawText(mText, x * scale, y * scale, paint);
addBitmapToMemoryCache(key,bitmap);
return bitmap;
}
} catch (Exception e) {
// TODO: handle exception
return null;
}
}

I worked on an app which needed to constantly hold 3-4 very large images in memory, and I was struggling with a problem very similar to yours. I loaded a bitmap from a byte array, then I needed to copy it to make it mutable, so that I could draw on it. This copy would cause there to be 1 too many bitmaps in memory, and then cause an OOM crash.
Eventually I found a way to load it once, and make it mutable at the same time:
Options options = new Options();
options.inMutable = true;
BitmapFactory.decodeResource(getResources(), id, options);
Use this, instead of copying the bitmap to make it mutable. I'm not sure if you really need the ARGB_8888 configuration, but if you don't, this should at least improve your memory efficiency.
Note: This will only work with Android 3.0 and above. For versions that need to run on 2.x and above, you can use a little reflection magic to see if the "inMutable" field exists in runtime. While this won't help on pre-3.0 devices, it will still provide a good improvement for most devices (and I've also noticed that devices running 2.x tend to have more memory flexibility).
Here's the code:
Options options = new Options();
options.inPurgeable = true;
options.inInputShareable = true;
Bitmap mutableBitmap = null;
try
{
Options.class.getField("inMutable").set(options, Boolean.TRUE);
Bitmap decodedBitmap = BitmapFactory.decodeResource(getResources(), id, options);
mutableBitmap = decodedBytes;
}
catch (NoSuchFieldException noFieldException)
{
Bitmap decodedBitmap = BitmapFactory.decodeResource(getResources(), id, options);
mutableBitmap = decodedBitmap .copy(decodedBitmap .getConfig(), true);
decodedBitmap .recycle();
}

Out of memory when processing multiple large bitmaps

In the app I'm working on, part of the user's input is a series of images. Some of these might be 4MB large in their raw form. I resize and rotate them, then save them in the app's portion of the device memory for later use. The problem I'm experiencing is that I seem to run out of memory even though I recycle each Bitmap after it's saved.
Here's the main processing
private class SaveImagesTask extends AsyncTask<Long, Void, Void>{
#Override
protected Void doInBackground(Long... ids){
long id = ids[0];
Iterator<ImageButton> itImg = arrBtnImage.iterator();
Iterator<TextView> itLbl = arrLblImage.iterator();
while(itImg.hasNext() && itLbl.hasNext()){
String imgPath = (String) itImg.next().getTag();
String imgLbl = itLbl.next().getText().toString().trim();
String imgName = imgLbl.replace(" ", "_").replace(",", "_");
imgName += ".jpg";
if(imgPath != null){
/* Save resized version of image */
File dir = getApplicationContext().getFilesDir();
dir = new File(dir, "temp/" + Long.toString(plantId));
boolean madeDir = dir.mkdirs();
File path = new File(dir, imgName);
Bitmap toSave = getScaledBitmap(imgPath, IMAGE_MAX_SIDE_LENGTH, IMAGE_MAX_SIDE_LENGTH);
try{
BufferedOutputStream outStream = new BufferedOutputStream(new FileOutputStream(path));
boolean insertSuccess = toSave.compress(Bitmap.CompressFormat.JPEG, 90, outStream);
outStream.close();
}
catch(FileNotFoundException e){
e.printStackTrace();
}
catch(IOException e){
e.printStackTrace();
}
toSave.recycle();
}//if
}//while(more images to process)
}// method: doInBackground(params)
}// inner class: saveImages extends AsyncTask
And here's where I resize the image
private Bitmap getScaledBitmap(String picturePath, int newWidth, int newHeight){
/* Size */
BitmapFactory.Options sizeOptions = new BitmapFactory.Options();
sizeOptions.inJustDecodeBounds = true;
BitmapFactory.decodeFile(picturePath, sizeOptions);
int sampleSize = 1;
int rawHeight = sizeOptions.outHeight;
int rawWidth = sizeOptions.outWidth;
if(rawHeight > newHeight || rawWidth > newWidth){
/* Find the dimension that needs to change the most */
int heightRatio = Math.round((float) rawHeight / (float) newHeight);
int widthRatio = Math.round((float) rawWidth / (float) newWidth);
sampleSize = (heightRatio > widthRatio ? heightRatio : widthRatio);
}//if(raw image is wider or taller than it should be){reduce size so neither is too large}
sizeOptions.inJustDecodeBounds = false;//Load pixels for display.
sizeOptions.inSampleSize = sampleSize;//Set shrink factor.
Bitmap scaledBitmap = BitmapFactory.decodeFile(picturePath, sizeOptions);
/* Rotation */
int rotation = 1;
try{
ExifInterface exif = new ExifInterface(picturePath);
rotation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
}
catch(IOException e){
e.printStackTrace();
}
int rotationInDegrees = 0;
if(rotation == ExifInterface.ORIENTATION_ROTATE_90)
rotationInDegrees = 90;
else if(rotation == ExifInterface.ORIENTATION_ROTATE_180)
rotationInDegrees = 180;
else if(rotation == ExifInterface.ORIENTATION_ROTATE_270)
rotationInDegrees = 270;
Matrix matrix = new Matrix();
if(rotation != 0f)
matrix.preRotate(rotationInDegrees);
return Bitmap.createBitmap(scaledBitmap, 0, 0,
scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
}// method: getScaledBitmap(String, int, int)
Before I start getting comments about this being so common of a question, I'll point out that I'm not displaying these images, so it's not like I'm trying to keep all of these in memory. I need to keep large images because users will want to be able to zoom in on the pictures, but I'm resizing them because they don't need to be ridiculously huge. Pretty much any other solution I've seen on SO for images and OOM errors don't apply to my back-to-back access of multiple images.
So like I said, I'm recycling each Bitmap after it's saved, but they still seem to be using memory. Any idea what I'm missing?

You're not recycling scaledBitmap in getScaledBitmap. Fixing that should help. Change this line:
return Bitmap.createBitmap(scaledBitmap, 0, 0,
scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
to something like:
Bitmap newBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0,
scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
scaledBitmap.recycle();
return newBitmap;

If you have multiple threads working on large bitmaps, you will use a lot of memory on some cases.
What you need is to find the best approach according to your needs. here are some things you can do and/or need to know:
use a single thread for the images handling.
always recycle old bitmaps that you don't need anymore, as soon as possible. it's true that the GC will help you, but that can help it too, and it will work even on pre-honeycomb devices.
do the image manipulations via NDK (so you won't need to have 2 bitmaps for each image manipulation), for example using this.
downsample the image to the minimal size that you need, and never assume that the memory is large enough for any given image (unless you are 100% sure that the images are small).
remember that the requirements for android devices are still very low in terms of RAM per app (heap size) - the bare minimal is still 16MB per app.
you can use android:largeHeap="true" in the manifest, but that doesn't mean anything about how much more you will get, if at all.

Bad image quality after resizing/scaling bitmap

I'm writing a card game and need my cards to be different sizes in different circumstances. I am storing my images as bitmaps so that they can be quickly drawn and redrawn (for animation).
My problem is that no matter how I try and scale my images (whether through a matrix.postScale, a matrix.preScale, or a createScaledBitmap function) they always come out pixelated and blurry. I know that its the scaling thats causing the problem because the images look perfect when drawn without resizing.
I have worked through every solution described in these two threads:
android quality of the images resized in runtime
quality problems when resizing an image at runtime
but still haven't gotten anywhere.
I store my bitmaps (into a hashmap) with this code:
cardImages = new HashMap<Byte, Bitmap>();
cardImages.put(GameUtil.hearts_ace, BitmapFactory.decodeResource(r, R.drawable.hearts_ace));
and draw them with this method (in a Card class):
public void drawCard(Canvas c)
{
//retrieve the cards image (if it doesn't already have one)
if (image == null)
image = Bitmap.createScaledBitmap(GameUtil.cardImages.get(ID),
(int)(GameUtil.standardCardSize.X*scale), (int)(GameUtil.standardCardSize.Y*scale), false);
//this code (non-scaled) looks perfect
//image = GameUtil.cardImages.get(ID);
matrix.reset();
matrix.setTranslate(position.X, position.Y);
//These methods make it look worse
//matrix.preScale(1.3f, 1.3f);
//matrix.postScale(1.3f, 1.3f);
//This code makes absolutely no difference
Paint drawPaint = new Paint();
drawPaint.setAntiAlias(false);
drawPaint.setFilterBitmap(false);
drawPaint.setDither(true);
c.drawBitmap(image, matrix, drawPaint);
}
Any insight would be greatly appreciated. Thanks

Use createScaledBitmap will make your image looks very bad.
I've met this problem and I've resolved it.
Below code will fix the problem:
public Bitmap BITMAP_RESIZER(Bitmap bitmap,int newWidth,int newHeight) {
Bitmap scaledBitmap = Bitmap.createBitmap(newWidth, newHeight, Config.ARGB_8888);
float ratioX = newWidth / (float) bitmap.getWidth();
float ratioY = newHeight / (float) bitmap.getHeight();
float middleX = newWidth / 2.0f;
float middleY = newHeight / 2.0f;
Matrix scaleMatrix = new Matrix();
scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);
Canvas canvas = new Canvas(scaledBitmap);
canvas.setMatrix(scaleMatrix);
canvas.drawBitmap(bitmap, middleX - bitmap.getWidth() / 2, middleY - bitmap.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));
return scaledBitmap;
}

I had blury images on low screen resolutions until I disabled scaling on bitmap load from resources:
Options options = new BitmapFactory.Options();
options.inScaled = false;
Bitmap source = BitmapFactory.decodeResource(a.getResources(), path, options);

createScaledBitmap has a flag where you can set if the scaled image should be filtered or not. That flag improves the quality of the bitmap...

use as
mPaint = new Paint(Paint.FILTER_BITMAP_FLAG);
Paint.FILTER_BITMAP_FLAG is work for me

I assume you are writing code for a version of Android lower than 3.2 (API level < 12), because since then the behavior of the methods
BitmapFactory.decodeFile(pathToImage);
BitmapFactory.decodeFile(pathToImage, opt);
bitmapObject.createScaledBitmap(bitmap, desiredWidth, desiredHeight, false /*filter?*/);
has changed.
On older platforms (API level < 12) the BitmapFactory.decodeFile(..) methods try to return a Bitmap with RGB_565 config by default, if they can't find any alpha, which lowers the quality of an iamge. This is still ok, because you can enforce an ARGB_8888 bitmap using
options.inPrefferedConfig = Bitmap.Config.ARGB_8888
options.inDither = false
The real problem comes when each pixel of your image has an alpha value of 255 (i.e. completely opaque). In that case the Bitmap's flag 'hasAlpha' is set to false, even though your Bitmap has ARGB_8888 config. If your *.png-file had at least one real transparent pixel, this flag would have been set to true and you wouldn't have to worry about anything.
So when you want to create a scaled Bitmap using
bitmapObject.createScaledBitmap(bitmap, desiredWidth, desiredHeight, false /*filter?*/);
the method checks whether the 'hasAlpha' flag is set to true or false, and in your case it is set to false, which results in obtaining a scaled Bitmap, which was automatically converted to the RGB_565 format.
Therefore on API level >= 12 there is a public method called
public void setHasAlpha (boolean hasAlpha);
which would have solved this issue. So far this was just an explanation of the problem.
I did some research and noticed that the setHasAlpha method has existed for a long time and it's public, but has been hidden (#hide annotation). Here is how it is defined on Android 2.3:
/**
* Tell the bitmap if all of the pixels are known to be opaque (false)
* or if some of the pixels may contain non-opaque alpha values (true).
* Note, for some configs (e.g. RGB_565) this call is ignore, since it does
* not support per-pixel alpha values.
*
* This is meant as a drawing hint, as in some cases a bitmap that is known
* to be opaque can take a faster drawing case than one that may have
* non-opaque per-pixel alpha values.
*
* #hide
*/
public void setHasAlpha(boolean hasAlpha) {
nativeSetHasAlpha(mNativeBitmap, hasAlpha);
}
Now here is my solution proposal. It does not involve any copying of bitmap data:
Checked at runtime using java.lang.Reflect if the current
Bitmap implementation has a public 'setHasAplha' method.
(According to my tests it works perfectly since API level 3, and i haven't tested lower versions, because JNI wouldn't work). You may have problems if a manufacturer has explicitly made it private, protected or deleted it.
Call the 'setHasAlpha' method for a given Bitmap object using JNI.
This works perfectly, even for private methods or fields. It is official that JNI does not check whether you are violating the access control rules or not.
Source: http://java.sun.com/docs/books/jni/html/pitfalls.html (10.9)
This gives us great power, which should be used wisely. I wouldn't try modifying a final field, even if it would work (just to give an example). And please note this is just a workaround...
Here is my implementation of all necessary methods:
JAVA PART:
// NOTE: this cannot be used in switch statements
private static final boolean SETHASALPHA_EXISTS = setHasAlphaExists();
private static boolean setHasAlphaExists() {
// get all puplic Methods of the class Bitmap
java.lang.reflect.Method[] methods = Bitmap.class.getMethods();
// search for a method called 'setHasAlpha'
for(int i=0; i<methods.length; i++) {
if(methods[i].getName().contains("setHasAlpha")) {
Log.i(TAG, "method setHasAlpha was found");
return true;
}
}
Log.i(TAG, "couldn't find method setHasAlpha");
return false;
}
private static void setHasAlpha(Bitmap bitmap, boolean value) {
if(bitmap.hasAlpha() == value) {
Log.i(TAG, "bitmap.hasAlpha() == value -> do nothing");
return;
}
if(!SETHASALPHA_EXISTS) { // if we can't find it then API level MUST be lower than 12
// couldn't find the setHasAlpha-method
// <-- provide alternative here...
return;
}
// using android.os.Build.VERSION.SDK to support API level 3 and above
// use android.os.Build.VERSION.SDK_INT to support API level 4 and above
if(Integer.valueOf(android.os.Build.VERSION.SDK) <= 11) {
Log.i(TAG, "BEFORE: bitmap.hasAlpha() == " + bitmap.hasAlpha());
Log.i(TAG, "trying to set hasAplha to true");
int result = setHasAlphaNative(bitmap, value);
Log.i(TAG, "AFTER: bitmap.hasAlpha() == " + bitmap.hasAlpha());
if(result == -1) {
Log.e(TAG, "Unable to access bitmap."); // usually due to a bug in the own code
return;
}
} else { //API level >= 12
bitmap.setHasAlpha(true);
}
}
/**
* Decodes a Bitmap from the SD card
* and scales it if necessary
*/
public Bitmap decodeBitmapFromFile(String pathToImage, int pixels_limit) {
Bitmap bitmap;
Options opt = new Options();
opt.inDither = false; //important
opt.inPreferredConfig = Bitmap.Config.ARGB_8888;
bitmap = BitmapFactory.decodeFile(pathToImage, opt);
if(bitmap == null) {
Log.e(TAG, "unable to decode bitmap");
return null;
}
setHasAlpha(bitmap, true); // if necessary
int numOfPixels = bitmap.getWidth() * bitmap.getHeight();
if(numOfPixels > pixels_limit) { //image needs to be scaled down
// ensures that the scaled image uses the maximum of the pixel_limit while keeping the original aspect ratio
// i use: private static final int pixels_limit = 1280*960; //1,3 Megapixel
imageScaleFactor = Math.sqrt((double) pixels_limit / (double) numOfPixels);
Bitmap scaledBitmap = Bitmap.createScaledBitmap(bitmap,
(int) (imageScaleFactor * bitmap.getWidth()), (int) (imageScaleFactor * bitmap.getHeight()), false);
bitmap.recycle();
bitmap = scaledBitmap;
Log.i(TAG, "scaled bitmap config: " + bitmap.getConfig().toString());
Log.i(TAG, "pixels_limit = " + pixels_limit);
Log.i(TAG, "scaled_numOfpixels = " + scaledBitmap.getWidth()*scaledBitmap.getHeight());
setHasAlpha(bitmap, true); // if necessary
}
return bitmap;
}
Load your lib and declare the native method:
static {
System.loadLibrary("bitmaputils");
}
private static native int setHasAlphaNative(Bitmap bitmap, boolean value);
Native section ('jni' folder)
Android.mk:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := bitmaputils
LOCAL_SRC_FILES := bitmap_utils.c
LOCAL_LDLIBS := -llog -ljnigraphics -lz -ldl -lgcc
include $(BUILD_SHARED_LIBRARY)
bitmapUtils.c:
#include <jni.h>
#include <android/bitmap.h>
#include <android/log.h>
#define LOG_TAG "BitmapTest"
#define Log_i(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define Log_e(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
// caching class and method IDs for a faster subsequent access
static jclass bitmap_class = 0;
static jmethodID setHasAlphaMethodID = 0;
jint Java_com_example_bitmaptest_MainActivity_setHasAlphaNative(JNIEnv * env, jclass clazz, jobject bitmap, jboolean value) {
AndroidBitmapInfo info;
void* pixels;
if (AndroidBitmap_getInfo(env, bitmap, &info) < 0) {
Log_e("Failed to get Bitmap info");
return -1;
}
if (info.format != ANDROID_BITMAP_FORMAT_RGBA_8888) {
Log_e("Incompatible Bitmap format");
return -1;
}
if (AndroidBitmap_lockPixels(env, bitmap, &pixels) < 0) {
Log_e("Failed to lock the pixels of the Bitmap");
return -1;
}
// get class
if(bitmap_class == NULL) { //initializing jclass
// NOTE: The class Bitmap exists since API level 1, so it just must be found.
bitmap_class = (*env)->GetObjectClass(env, bitmap);
if(bitmap_class == NULL) {
Log_e("bitmap_class == NULL");
return -2;
}
}
// get methodID
if(setHasAlphaMethodID == NULL) { //initializing jmethodID
// NOTE: If this fails, because the method could not be found the App will crash.
// But we only call this part of the code if the method was found using java.lang.Reflect
setHasAlphaMethodID = (*env)->GetMethodID(env, bitmap_class, "setHasAlpha", "(Z)V");
if(setHasAlphaMethodID == NULL) {
Log_e("methodID == NULL");
return -2;
}
}
// call java instance method
(*env)->CallVoidMethod(env, bitmap, setHasAlphaMethodID, value);
// if an exception was thrown we could handle it here
if ((*env)->ExceptionOccurred(env)) {
(*env)->ExceptionDescribe(env);
(*env)->ExceptionClear(env);
Log_e("calling setHasAlpha threw an exception");
return -2;
}
if(AndroidBitmap_unlockPixels(env, bitmap) < 0) {
Log_e("Failed to unlock the pixels of the Bitmap");
return -1;
}
return 0; // success
}
That's it. We are done. I've posted the whole code for copy-and-paste purposes.
The actual code isn't that big, but making all these paranoid error checks makes it a lot bigger. I hope this could be helpful to anyone.

Good downscaling algorithm (not nearest neighbor like, so no pixelation is added) consists of just 2 steps (plus calculation of the exact Rect for input/output images crop):
downscale using BitmapFactory.Options::inSampleSize -> BitmapFactory.decodeResource() as close as possible to the resolution that you need but not less than it
get to the exact resolution by downscaling a little bit using Canvas::drawBitmap()
Here is detailed explanation how SonyMobile resolved this task: https://web.archive.org/web/20171011183652/http://developer.sonymobile.com/2011/06/27/how-to-scale-images-for-your-android-application/
Here is the source code of SonyMobile scale utils:
https://web.archive.org/web/20170105181810/http://developer.sonymobile.com:80/downloads/code-example-module/image-scaling-code-example-for-android/

You will never have a perfect result if you scale your bitmaps up.
You should start with the highest resolution you need and scale down.
When scaling a bitmap up, the scaling can't guess what are the missing points between each existing point, so it either duplicates a neighbour (=> edgy) or calculates a mean value between neighbours (=> blurry).

I just used flag filter=true in
bitmap = Bitmap.createScaledBitmap(bitmap, width, height, true);
for blur.

If you want high quality result, so use [RapidDecoder][1] library. It is simple as follow:
import rapid.decoder.BitmapDecoder;
...
Bitmap bitmap = BitmapDecoder.from(getResources(), R.drawable.image)
.scale(width, height)
.useBuiltInDecoder(true)
.decode();
Don't forget to use builtin decoder if you want to scale down less than 50% and a HQ result. I tested it on API 8.

Had this issue upon updating Android Target Framework from Android 8.1 to Android 9 and manifested on my ImageEntryRenderer. Hope this helps
public Bitmap ProcessScaleBitMap(Bitmap bitmap, int newWidth, int newHeight)
{
newWidth = newWidth * 2;
newHeight = newHeight * 2;
Bitmap scaledBitmap = CreateBitmap(newWidth, newHeight, Config.Argb8888);
float scaleDensity = ((float)Resources.DisplayMetrics.DensityDpi / 160);
float scaleX = newWidth / (bitmap.Width * scaleDensity);
float scaleY = newHeight / (bitmap.Height * scaleDensity);
Matrix scaleMatrix = new Matrix();
scaleMatrix.SetScale(scaleX, scaleY);
Canvas canvas = new Canvas(scaledBitmap);
canvas.Matrix = scaleMatrix;
canvas.DrawBitmap(bitmap, 0, 0, new Paint(PaintFlags.FilterBitmap));
return scaledBitmap;
}
Note: I am developing under Xamarin 3.4.0.10 framework

private static Bitmap createScaledBitmap(Bitmap bitmap,int newWidth,int newHeight) {
Bitmap scaledBitmap = Bitmap.createBitmap(newWidth, newHeight, bitmap.getConfig());
float scaleX = newWidth / (float) bitmap.getWidth();
float scaleY = newHeight / (float) bitmap.getHeight();
Matrix scaleMatrix = new Matrix();
scaleMatrix.setScale(scaleX, scaleY, 0, 0);
Canvas canvas = new Canvas(scaledBitmap);
canvas.setMatrix(scaleMatrix);
Paint paint = new Paint(Paint.FILTER_BITMAP_FLAG);
paint.setAntiAlias(true);
paint.setDither(true);
paint.setFilterBitmap(true);
canvas.drawBitmap(bitmap, 0, 0, paint);
return scaledBitmap;
}

Quality problems when resizing an image at runtime

I have a image file on the disk and I am resizing the file and saving it back to disk as a new image file. For the sake of this question, I am not bringing them into memory in order to display them on the screen, only to resize them and resave them. This all works just fine. However, the scaled images have artifacts on them like shown here: android: quality of the images resized in runtime
They are saved with this distortion, as I can pull them off the disk and look at them on my computer and they still have the same issue.
I am using code similar to this Strange out of memory issue while loading an image to a Bitmap object to decode the bitmap into memory:
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(imageFilePathString, options);
int srcWidth = options.outWidth;
int srcHeight = options.outHeight;
int scale = 1;
while(srcWidth / 2 > desiredWidth){
srcWidth /= 2;
srcHeight /= 2;
scale *= 2;
}
options.inJustDecodeBounds = false;
options.inDither = false;
options.inSampleSize = scale;
Bitmap sampledSrcBitmap = BitmapFactory.decodeFile(imageFilePathString, options);
Then I am doing the actual scaling with:
Bitmap scaledBitmap = Bitmap.createScaledBitmap(sampledSrcBitmap, desiredWidth, desiredHeight, false);
Lastly, the new resized image is saved to disk with:
FileOutputStream out = new FileOutputStream(newFilePathString);
scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 100, out);
Then, as I mentioned, if I pull that file off the disk and look at it, it has that quality issue linked above and looks terrible. If I skip the createScaledBitmap and just save the sampledSrcBitmap right back to disk there is no problem, it seems to only happen if the size changes.
I have tried, as you can see in the code, setting inDither to false as mentioned here http://groups.google.com/group/android-developers/browse_thread/thread/8b1abdbe881f9f71 and as mentioned in the very first linked post above. That didn't change anything. Also, in the first post I linked, Romain Guy said:
Instead of resizing at drawing time
(which is going to be very costly),
try to resize in an offscreen bitmap
and make sure that Bitmap is 32 bits
(ARGB888).
However, I have no idea how to make sure the Bitmap stays as 32 bits through the whole process.
I have also read a couple other articles such as this http://android.nakatome.net/2010/04/bitmap-basics.html but they all seemed to be addressing drawing and displaying the Bitmap, I just want to resize it and save it back to disk without this quality problem.
Thanks much

After experimenting I have finally found a way to do this with good quality results. I'll write this up for anyone that might find this answer helpful in the future.
To solve the first problem, the artifacts and weird dithering introduced into the images, you need to insure your image stays as a 32-bit ARGB_8888 image. Using the code in my question, you can simply add this line to the options before the second decode.
options.inPreferredConfig = Bitmap.Config.ARGB_8888;
After adding that, the artifacts were gone but edges throughout the images came through jagged instead of crisp. After some more experimentation I discovered that resizing the bitmap using a Matrix instead of Bitmap.createScaledBitmap produced much crisper results.
With those two solutions, the images are now resizing perfectly. Below is the code I am using in case it benefits someone else coming across this problem.
// Get the source image's dimensions
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(STRING_PATH_TO_FILE, options);
int srcWidth = options.outWidth;
int srcHeight = options.outHeight;
// Only scale if the source is big enough. This code is just trying to fit a image into a certain width.
if(desiredWidth > srcWidth)
desiredWidth = srcWidth;
// Calculate the correct inSampleSize/scale value. This helps reduce memory use. It should be a power of 2
// from: https://stackoverflow.com/questions/477572/android-strange-out-of-memory-issue/823966#823966
int inSampleSize = 1;
while(srcWidth / 2 > desiredWidth){
srcWidth /= 2;
srcHeight /= 2;
inSampleSize *= 2;
}
float desiredScale = (float) desiredWidth / srcWidth;
// Decode with inSampleSize
options.inJustDecodeBounds = false;
options.inDither = false;
options.inSampleSize = inSampleSize;
options.inScaled = false;
options.inPreferredConfig = Bitmap.Config.ARGB_8888;
Bitmap sampledSrcBitmap = BitmapFactory.decodeFile(STRING_PATH_TO_FILE, options);
// Resize
Matrix matrix = new Matrix();
matrix.postScale(desiredScale, desiredScale);
Bitmap scaledBitmap = Bitmap.createBitmap(sampledSrcBitmap, 0, 0, sampledSrcBitmap.getWidth(), sampledSrcBitmap.getHeight(), matrix, true);
sampledSrcBitmap = null;
// Save
FileOutputStream out = new FileOutputStream(NEW_FILE_PATH);
scaledBitmap.compress(Bitmap.CompressFormat.JPEG, 100, out);
scaledBitmap = null;
EDIT: After continual work on this I have found that the images still aren't 100% perfect. I'll make an update if I can improve it.
Update: After revisting this, I found this question on SO and there was an answer that mentioned the inScaled option. This helped with the quality as well so I added updated the answer above to include it. I also now null the bitmaps after they are done being used.
Also, as a side note, if you are using these images in a WebView, make sure you take this post into consideration.
Note: you should also add a check to make sure the width and height are valid numbers (not -1). If they are, it will cause the inSampleSize loop to become infinite.

In my situation I am drawing the image to the screen. Here's what I did to get my images to look correct (a combination of littleFluffyKitty's answer, plus a few other things).
For my options when I actually load the image (using decodeResource) I set the following values:
options.inScaled = false;
options.inDither = false;
options.inPreferredConfig = Bitmap.Config.ARGB_8888;
When I actually draw the image, I set up my paint object like this:
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setFilterBitmap(true);
paint.setDither(true);
Hopefully someone else finds that useful too. I wish there were just options for "Yes, let my resized images look like garbage" and "No, please don't force my users to gouge their eyes out with spoons" instead of all the myriad of different options. I know they want to give us lots of control, but maybe some helper methods for common settings could be useful.

I created simple library based on littleFluffyKitty answer which does resize and does some other things like crop and rotation so please free to use it and improve it - Android-ImageResizer.

"However, I have no idea how to make sure the Bitmap stays as 32 bits
through the whole process."
I wanted to post an alternative solution, which takes care of keeping the ARGB_8888 config untouched. NOTE: This code only decodes bitmaps and needs to be extended, so you could store a Bitmap.
I assume you are writing code for a version of Android lower than 3.2 (API level < 12), because since then the behavior of the methods
BitmapFactory.decodeFile(pathToImage);
BitmapFactory.decodeFile(pathToImage, opt);
bitmapObject.createScaledBitmap(bitmap, desiredWidth, desiredHeight, false /*filter?*/);
has changed.
On older platforms (API level < 12) the BitmapFactory.decodeFile(..) methods try to return a Bitmap with RGB_565 config by default, if they can't find any alpha, which lowers the quality of an iamge. This is still ok, because you can enforce an ARGB_8888 bitmap using
options.inPrefferedConfig = Bitmap.Config.ARGB_8888
options.inDither = false
The real problem comes when each pixel of your image has an alpha value of 255 (i.e. completely opaque). In that case the Bitmap's flag 'hasAlpha' is set to false, even though your Bitmap has ARGB_8888 config. If your *.png-file had at least one real transparent pixel, this flag would have been set to true and you wouldn't have to worry about anything.
So when you want to create a scaled Bitmap using
bitmapObject.createScaledBitmap(bitmap, desiredWidth, desiredHeight, false /*filter?*/);
the method checks whether the 'hasAlpha' flag is set to true or false, and in your case it is set to false, which results in obtaining a scaled Bitmap, which was automatically converted to the RGB_565 format.
Therefore on API level >= 12 there is a public method called
public void setHasAlpha (boolean hasAlpha);
which would have solved this issue. So far this was just an explanation of the problem.
I did some research and noticed that the setHasAlpha method has existed for a long time and it's public, but has been hidden (#hide annotation). Here is how it is defined on Android 2.3:
/**
* Tell the bitmap if all of the pixels are known to be opaque (false)
* or if some of the pixels may contain non-opaque alpha values (true).
* Note, for some configs (e.g. RGB_565) this call is ignore, since it does
* not support per-pixel alpha values.
*
* This is meant as a drawing hint, as in some cases a bitmap that is known
* to be opaque can take a faster drawing case than one that may have
* non-opaque per-pixel alpha values.
*
* #hide
*/
public void setHasAlpha(boolean hasAlpha) {
nativeSetHasAlpha(mNativeBitmap, hasAlpha);
}
Now here is my solution proposal. It does not involve any copying of bitmap data:
Checked at runtime using java.lang.Reflect if the current
Bitmap implementation has a public 'setHasAplha' method.
(According to my tests it works perfectly since API level 3, and i haven't tested lower versions, because JNI wouldn't work). You may have problems if a manufacturer has explicitly made it private, protected or deleted it.
Call the 'setHasAlpha' method for a given Bitmap object using JNI.
This works perfectly, even for private methods or fields. It is official that JNI does not check whether you are violating the access control rules or not.
Source: http://java.sun.com/docs/books/jni/html/pitfalls.html (10.9)
This gives us great power, which should be used wisely. I wouldn't try modifying a final field, even if it would work (just to give an example). And please note this is just a workaround...
Here is my implementation of all necessary methods:
JAVA PART:
// NOTE: this cannot be used in switch statements
private static final boolean SETHASALPHA_EXISTS = setHasAlphaExists();
private static boolean setHasAlphaExists() {
// get all puplic Methods of the class Bitmap
java.lang.reflect.Method[] methods = Bitmap.class.getMethods();
// search for a method called 'setHasAlpha'
for(int i=0; i<methods.length; i++) {
if(methods[i].getName().contains("setHasAlpha")) {
Log.i(TAG, "method setHasAlpha was found");
return true;
}
}
Log.i(TAG, "couldn't find method setHasAlpha");
return false;
}
private static void setHasAlpha(Bitmap bitmap, boolean value) {
if(bitmap.hasAlpha() == value) {
Log.i(TAG, "bitmap.hasAlpha() == value -> do nothing");
return;
}
if(!SETHASALPHA_EXISTS) { // if we can't find it then API level MUST be lower than 12
// couldn't find the setHasAlpha-method
// <-- provide alternative here...
return;
}
// using android.os.Build.VERSION.SDK to support API level 3 and above
// use android.os.Build.VERSION.SDK_INT to support API level 4 and above
if(Integer.valueOf(android.os.Build.VERSION.SDK) <= 11) {
Log.i(TAG, "BEFORE: bitmap.hasAlpha() == " + bitmap.hasAlpha());
Log.i(TAG, "trying to set hasAplha to true");
int result = setHasAlphaNative(bitmap, value);
Log.i(TAG, "AFTER: bitmap.hasAlpha() == " + bitmap.hasAlpha());
if(result == -1) {
Log.e(TAG, "Unable to access bitmap."); // usually due to a bug in the own code
return;
}
} else { //API level >= 12
bitmap.setHasAlpha(true);
}
}
/**
* Decodes a Bitmap from the SD card
* and scales it if necessary
*/
public Bitmap decodeBitmapFromFile(String pathToImage, int pixels_limit) {
Bitmap bitmap;
Options opt = new Options();
opt.inDither = false; //important
opt.inPreferredConfig = Bitmap.Config.ARGB_8888;
bitmap = BitmapFactory.decodeFile(pathToImage, opt);
if(bitmap == null) {
Log.e(TAG, "unable to decode bitmap");
return null;
}
setHasAlpha(bitmap, true); // if necessary
int numOfPixels = bitmap.getWidth() * bitmap.getHeight();
if(numOfPixels > pixels_limit) { //image needs to be scaled down
// ensures that the scaled image uses the maximum of the pixel_limit while keeping the original aspect ratio
// i use: private static final int pixels_limit = 1280*960; //1,3 Megapixel
imageScaleFactor = Math.sqrt((double) pixels_limit / (double) numOfPixels);
Bitmap scaledBitmap = Bitmap.createScaledBitmap(bitmap,
(int) (imageScaleFactor * bitmap.getWidth()), (int) (imageScaleFactor * bitmap.getHeight()), false);
bitmap.recycle();
bitmap = scaledBitmap;
Log.i(TAG, "scaled bitmap config: " + bitmap.getConfig().toString());
Log.i(TAG, "pixels_limit = " + pixels_limit);
Log.i(TAG, "scaled_numOfpixels = " + scaledBitmap.getWidth()*scaledBitmap.getHeight());
setHasAlpha(bitmap, true); // if necessary
}
return bitmap;
}
Load your lib and declare the native method:
static {
System.loadLibrary("bitmaputils");
}
private static native int setHasAlphaNative(Bitmap bitmap, boolean value);
Native section ('jni' folder)
Android.mk:
LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := bitmaputils
LOCAL_SRC_FILES := bitmap_utils.c
LOCAL_LDLIBS := -llog -ljnigraphics -lz -ldl -lgcc
include $(BUILD_SHARED_LIBRARY)
bitmapUtils.c:
#include <jni.h>
#include <android/bitmap.h>
#include <android/log.h>
#define LOG_TAG "BitmapTest"
#define Log_i(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define Log_e(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
// caching class and method IDs for a faster subsequent access
static jclass bitmap_class = 0;
static jmethodID setHasAlphaMethodID = 0;
jint Java_com_example_bitmaptest_MainActivity_setHasAlphaNative(JNIEnv * env, jclass clazz, jobject bitmap, jboolean value) {
AndroidBitmapInfo info;
void* pixels;
if (AndroidBitmap_getInfo(env, bitmap, &info) < 0) {
Log_e("Failed to get Bitmap info");
return -1;
}
if (info.format != ANDROID_BITMAP_FORMAT_RGBA_8888) {
Log_e("Incompatible Bitmap format");
return -1;
}
if (AndroidBitmap_lockPixels(env, bitmap, &pixels) < 0) {
Log_e("Failed to lock the pixels of the Bitmap");
return -1;
}
// get class
if(bitmap_class == NULL) { //initializing jclass
// NOTE: The class Bitmap exists since API level 1, so it just must be found.
bitmap_class = (*env)->GetObjectClass(env, bitmap);
if(bitmap_class == NULL) {
Log_e("bitmap_class == NULL");
return -2;
}
}
// get methodID
if(setHasAlphaMethodID == NULL) { //initializing jmethodID
// NOTE: If this fails, because the method could not be found the App will crash.
// But we only call this part of the code if the method was found using java.lang.Reflect
setHasAlphaMethodID = (*env)->GetMethodID(env, bitmap_class, "setHasAlpha", "(Z)V");
if(setHasAlphaMethodID == NULL) {
Log_e("methodID == NULL");
return -2;
}
}
// call java instance method
(*env)->CallVoidMethod(env, bitmap, setHasAlphaMethodID, value);
// if an exception was thrown we could handle it here
if ((*env)->ExceptionOccurred(env)) {
(*env)->ExceptionDescribe(env);
(*env)->ExceptionClear(env);
Log_e("calling setHasAlpha threw an exception");
return -2;
}
if(AndroidBitmap_unlockPixels(env, bitmap) < 0) {
Log_e("Failed to unlock the pixels of the Bitmap");
return -1;
}
return 0; // success
}
That's it. We are done. I've posted the whole code for copy-and-paste purposes.
The actual code isn't that big, but making all these paranoid error checks makes it a lot bigger. I hope this could be helpful to anyone.

onScreenResults = Bitmap.createScaledBitmap(tempBitmap, scaledOSRW, scaledOSRH, true); <----
setting the filter to true worked for me.

So, createScaledBitmap and createBitmap (with matrix that scales) on immutable bitmap (like when decoded) will ignore original Bitmap.Config and create bitmap with Bitmap.Config.ARGB_565 if original doesn't have any transparency (hasAlpha == false).
But it won't do it on mutable bitmap.
So, if your decoded bitmap is b:
Bitmap temp = Bitmap.createBitmap(b.getWidth(), b.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(temp);
canvas.drawBitmap(b, 0, 0, null);
b.recycle();
Now you can rescale temp and it should retain Bitmap.Config.ARGB_8888.

Image scaling can also be accomplished by this means with absolutely no quality loss!
//Bitmap bmp passed to method...
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.JPEG, 100, stream);
Image jpg = Image.getInstance(stream.toByteArray());
jpg.scalePercent(68); // or any other number of useful methods.