Develop Reference

High resolution background image gives performance issues in Android

I want to have a background image that scales to fit any screen size in Android. The image is static and doesn't need to scroll. I made the image at 4K resolution to cover what is a likely resolution to exist on tablets in the next 2-3 years (2560 x 1600 already exist). The image is a JPG with a 137KB file size. Similar resolution images seem to work fine in Android web browsers. Why am I getting a lot of slow down in Android (on Samsung Galaxy S3, which should have plenty of CPU/RAM to handle an image like this)? I don't feel like I am doing anything out of the ordinary.
This loads the image in the XML layout. The image is currently stored in drawable-nodpi.
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/logo_background"
android:scaleType="centerCrop" />
Making different size images for each category of screen resolution is difficult as I cannot find information on what the current maximum resolution for a device in each category is only a minimum.
I want to use the same background image again and again between a variety of fragments. Is there a way to have the image resized once to the width of the screen (preferably asynchronously) and then load that resized image each time? Could this be done with Picasso?
Please don't give answers like "of course larger images result in performance issues" or link me to Google's Supporting Different Densities. This is a real issue that is going to become more of an issue as screen resolutions continue to increase. I am amazed that handling and resizing large images is not already optimised in the ImageView class, which makes me think I am doing something wrong.

The problem is that what you are trying to do is not relying on the SDK. By having one image and having to change the image on runtime, you are causing more work to be done on the UI thread in onDraw().
Of course you would be able to create a Bitmap for a specific size, but why do such complicated work when you can rely on the SDK?
Currently there are a bunch of different folders that you can use in order to get what you are looking for, and then in the future you can get a 4k image put into a specific folder. Things like this might work:
drawable-xhdpi
drawable-xxhdpi
drawable-xlarge-xhdpi - May not be specific enough for what you are trying to accomplish
drawable-sw600dp - This allows you to specify a folder for an image where the screen width is greater than 600dp. This qualifier will probably be helpful for your case, in the future where you will be using 4k images.

You dont even need Picasso mate.Here you get the screen size:
LinearLayout layout = (LinearLayout)findViewById(R.id.YOUR_VIEW_ID);
ViewTreeObserver vto = layout.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
this.layout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
int width = layout.getMeasuredWidth();
int height = layout.getMeasuredHeight();
}
});
And here you resize your image with your new dimensions:
public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth){
int width = bm.getWidth();
int height = bm.getHeight();
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// create a matrix for the manipulation
Matrix matrix = new Matrix();
// resize the bit map
matrix.postScale(scaleWidth, scaleHeight);
// recreate the new Bitmap
Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false);
return resizedBitmap;
}
Using a matrix to resize is relatively fast. Although user1090347s answer would be best practice.

The problem is that android uses Bitmap to render images to canvas. It is like BMP image format for me. So, you have no gain from JPG format, cuz all information lost from jpg conversion are lost forever and you will end up will fullsize bitmap anyway. The problem with big resolution is that, you have to address few bytes for every pixel, no conversion applied! In particular, smaller devices have lower memory class as bigger ones. So, you have to handle the image resolution based on device screen size and memory class.
You can properly convert your background bitmap at runtime with these helper functions:
public void getScreenSizePixels(Resources resources, int widthHeightInPixels[/*2*/])
{
Configuration config = resources.getConfiguration();
DisplayMetrics dm = resources.getDisplayMetrics();
double screenWidthInPixels = (double)config.screenWidthDp * dm.density;
double screenHeightInPixels = screenWidthInPixels * dm.heightPixels / dm.widthPixels;
widthHeightInPixels[0] = (int)(screenWidthInPixels + .5);
widthHeightInPixels[1] = (int)(screenHeightInPixels + .5);
}
--
public static Bitmap getBitmap(byte[] imageAsBytes, int reqWidth, int reqHeight) {
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inJustDecodeBounds = true;
BitmapFactory.decodeByteArray(
imageAsBytes,
0,
imageAsBytes.length,
opt);
int width = opt.outWidth;
int height = opt.outHeight;
int scale = 1;
while (reqWidth < (width / scale) || reqHeight < (height / scale)) {
scale++;
}
//bitmap.recycle();
opt.inJustDecodeBounds = false;
opt.inSampleSize = scale;
Bitmap bitmap = BitmapFactory.decodeByteArray(
imageAsBytes,
0,
imageAsBytes.length,
opt);
return bitmap;
}

aspect ratio is lost when using Bitmap.createScaledBitmap

I am trying to make a square larger by using createScaledBitmap. However, the square becomes a rectangle with width longer than height. What is the proper way to do this in order to keep the aspect ratio constant?
public Bitmap getScaledBitmap(Bitmap bitmap){
dm = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(dm);
scaledBitmapW = (int)(dm.widthPixels/(10)); *//make the square just 1/10 of the screen width*
scaledBitmapH = (int)(scaledBitmapW*(bitmap.getHeight()/bitmap.getWidth()));
scaledBitmap = Bitmap.createScaledBitmap(bitmap, scaledBitmapW, scaledBitmapH, true);
return scaledBitmap;
}

How to fit the Home Screen Wallpaper based on the Emulator Size

Hi i am programmatically set a Home Screen Wallpaper. It's working fine. How to fit the Home Screen Wallpaper based on the Emulator Size. My Sample Code is here...
WallpaperManager wallpaperManager = WallpaperManager.getInstance(this);
Drawable drawable = getResources().getDrawable(R.drawable.sample);
Bitmap wallpaper = ((BitmapDrawable) drawable).getBitmap();
DisplayMetrics displaymetrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
int screenHeight = displaymetrics.heightPixels;
int screenWidth = displaymetrics.widthPixels;
Bitmap bmp2 = Bitmap.createScaledBitmap(wallpaper, screenWidth, screenHeight, true);
try
{
wallpaperManager.setBitmap(wallpaper);
}
catch (IOException e)
{
e.printStackTrace();
}
Based on the Emulator Size to fit Home Screen Wallpaper, How?Please reply your comments and results are valuable me. Thanks.

Android WallpaperManager crops image

I am working on a simple wallpaper app of some images that I have. They are .png files in drawable folders.
Here are some code snippets:
WallpaperManager myWallpaperManager = WallpaperManager.getInstance(getApplicationContext());
....
myWallpaperManager.setResource(R.drawable.image1);
No matter what size or resolution I seem to use, when the wallpaper is set it crops the original image. When I use the same image as a background it is the correct size and shows the entire image. I thought it might be a problem with my emulator so I have tried running it on an actual device (HTC eris) and I am having the same problem. I have made the image the screen size and resolution for the eris and it is still cropping it. I then made the image only one inch high and a resolution of 100 dpi. It was very pixelated on the eris, but still cropped the image.
Any help would be greatly appreciated.
I attempted to add some images to show the before and after, but as a newer user I was prevented from doing so.

Check the values returned by http://developer.android.com/reference/android/app/WallpaperManager.html#getDesiredMinimumWidth() and http://developer.android.com/reference/android/app/WallpaperManager.html#getDesiredMinimumHeight() and try to use these values as the dimensions of your wallpaper.

Maybe I can help.
// 1. Get screen size.
DisplayMetrics metrics = new DisplayMetrics();
Display display = getWindowManager().getDefaultDisplay();
display.getMetrics(metrics);
final int screenWidth = metrics.widthPixels;
final int screenHeight = metrics.heightPixels;
// 2. Make the wallpaperManager fit the screen size.
final WallpaperManager wallpaperManager = WallpaperManager.getInstance(ViewWallpaperActivity.this);
wallpaperManager.suggestDesiredDimensions(screenWidth, screenHeight);
// 3. Get the desired size.
final int width = wallpaperManager.getDesiredMinimumWidth();
final int height = wallpaperManager.getDesiredMinimumHeight();
// 4. Scale the wallpaper.
Bitmap bitmap = getBitmap(); // getBitmap(): Get the image to be set as wallpaper.
Bitmap wallpaper = Bitmap.createScaledBitmap(bitmap, width, height, true);
// 5. Set the image as wallpaper.
try {
wallpaperManager.setBitmap(wallpaper);
} catch (IOException e) {
e.printStackTrace();
}
Note that you should call suggestDesiredDimensions, then call getDesiredMinimumWidth and getDesiredMinimumHeight to get the size to be scaled to.

I had the same problem. I made an image that is the size of the screen and adding padding to the image so that it is as large as the WallpaperManager getDesiredMinimumWidth() and getDesiredMinimumHeight().
It seemed better to have some code automatically add the padding so that is what I used below. Make sure the image is the same size as the screen.
private void setWallpaper() {
try {
WallpaperManager wallpaperManager = WallpaperManager.getInstance(this);
//import non-scaled bitmap wallpaper
BitmapFactory.Options options = new BitmapFactory.Options();
options.inScaled = false;
Bitmap wallpaper = BitmapFactory.decodeResource(getResources(), R.drawable.wallpaper, options);
if (wallpaperManager.getDesiredMinimumWidth() > wallpaper.getWidth() &&
wallpaperManager.getDesiredMinimumHeight() > wallpaper.getHeight()) {
//add padding to wallpaper so background image scales correctly
int xPadding = Math.max(0, wallpaperManager.getDesiredMinimumWidth() - wallpaper.getWidth()) / 2;
int yPadding = Math.max(0, wallpaperManager.getDesiredMinimumHeight() - wallpaper.getHeight()) / 2;
Bitmap paddedWallpaper = Bitmap.createBitmap(wallpaperManager.getDesiredMinimumWidth(), wallpaperManager.getDesiredMinimumHeight(), Bitmap.Config.ARGB_8888);
int[] pixels = new int[wallpaper.getWidth() * wallpaper.getHeight()];
wallpaper.getPixels(pixels, 0, wallpaper.getWidth(), 0, 0, wallpaper.getWidth(), wallpaper.getHeight());
paddedWallpaper.setPixels(pixels, 0, wallpaper.getWidth(), xPadding, yPadding, wallpaper.getWidth(), wallpaper.getHeight());
wallpaperManager.setBitmap(paddedWallpaper);
} else {
wallpaperManager.setBitmap(wallpaper);
}
} catch (IOException e) {
Log.e(TAG,"failed to set wallpaper");
}
}

creating scaled bitmap leads to invalid image

I've created a function that scales a bitmap directly to a specific surface area. The function first gets the width and height of the bitmap and then finds the sample size closest to the required size. Lastly the image is scaled to the exact size. This is the only way I could find to decode a scaled bitmap. The problem is that the bitmap returned from BitmapFactory.createScaledBitmap(src,width,height,filter) always comes back with a width and height of -1. I've already implemented other functions that use the createScaledBitmap() method with out this error and I can not find any reason why creating a scaled bitmap would produce invalid output. I've also found that if I create a copy of the image bitmap that is mutable causes the same error. Thanks
public static Bitmap load_scaled_image( String file_name, int area) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(file_name, options);
double ratio = (float)options.outWidth / (float)options.outHeight;
int width, height;
if( options.outWidth > options.outHeight ) {
width = (int)Math.sqrt(area/ratio);
height = (int)(width*ratio);
}
else {
height = (int)Math.sqrt(area/ratio);
width = (int)(height*ratio);
}
BitmapFactory.Options new_options = new BitmapFactory.Options();
new_options.inSampleSize = Math.max( (options.outWidth/width), (options.outHeight/height) );
Bitmap image = BitmapFactory.decodeFile(file_name, new_options);
return Bitmap.createScaledBitmap(image, width, height, true);
}
I added this function to scale large camera images to a specific number of mega pixels. So a typical area passed in would be 1000000 for 1 megapixel. The camera image after being decoded yields a outWidth of 1952 and a outHieght of 3264. I then calculate the ratio this way I can keep the same height to width ratio with the scaled image, in this case the ratio is 0.598... Using the ratio and the new surface area I can find the new width which is 773 and a height of 1293. 773x1293=999489 which is just about 1 megapixel. Next I calculate the sample size for which to decode the new image, in this case the sample size is 4 and the image is decoded to 976x1632. So I'm passing in a width of 773 a height of 1293.

I was having a similar problem (getting -1 for height and width of the scaled bitmap).
Following this stackOverflow thread:
Android how to create runtime thumbnail
I've tried to use the same bitmap twice while calling the function:
imageBitmap = Bitmap.createScaledBitmap(imageBitmap, THUMBNAIL_SIZE,
THUMBNAIL_SIZE, false);
For some reason, this solved my problem, perhaps it would solve yours too.