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Draw in a canvas and save it to a larger image

I have a requirement, like drawing something in canvas and saving it to a larger image. As of now whatever I draw inside onDraw() method and save, it gives device provided image/canvas size, say something around 538(w)/852(h). I need image of almost double size, around 1000(w)/1500(h) without losing resolution. Any sample code, reference link would help definitely. Thanks in advance.

One way is to create Bitmap of desired size and draw on it using canvas:
int w = 1000, h = 1500;
Bitmap.Config conf = Bitmap.Config.ARGB_8888;
Bitmap bmp = Bitmap.createBitmap(w, h, conf);
Canvas canvas = new Canvas(bmp);
Finally you will have you bmp with your drawing and necessary dimentions.
EDIT::
#Override
protected void onDraw(Canvas canvas) {
int w = 1000, h = 1500;
Bitmap.Config conf = Bitmap.Config.ARGB_8888;
Bitmap bmp = Bitmap.createBitmap(w, h, conf);
Canvas mycanvas = new Canvas(bmp);
super.onDraw(mycanvas);
...
}

First get bitmap of your view using the function getDrawingCache(), then scale the bitmap as per your requirements.
view.buildDrawingCache();
Bitmap bitmap = view.getDrawingCache();
//bitmap = bitmap.createScaledBitmap(..as your requirements..);
EDIT
You are saying that you want image in higher quality. You can't simply get a higher quality image from a lower quality image. However you can apply bitmap filtering to get slightly better quality.
Bitmap bitmap = getDrawingCache();
Bitmap output = Bitmap.createBitmap(/*width, height, bla bla bla*/);
Canvas canvas = new Canvas(output);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);
Rect srcRect = new Rect(0,0,bitmap.getWidth(), bitmap.getHeight());
Rect destRect = new Rect(0,0,output.getWidth(), output.getHeight());
canvas.drawBitmap(bitmap, srcRect, destRect, paint);

Scaling an Image and positioning it at 0,0 in WPF

I have created BitMapSource from a list of RGBA pixels:
BitmapSource bmp = BitmapSource.Create(imageStrideInPixels, height, 96, 96, PixelFormats.Bgra32, null, imageData, imageStrideInPixels * pixelWidth);
I then create an image from the BitMapSource:
// create image and set image as source
Image BmpImg = new Image();
BmpImg.SetValue(Canvas.ZIndexProperty, 0);
BmpImg.Width = imageScaleWidth;
BmpImg.Height = imageScaleHeight;
BmpImg.Source = bmp;
I then add the Image to the Canvas:
mycanvas.Width = imageScaleWidth;
mycanvas.Height = imageScaleHeight;
mycanvas.Children.Clear();
mycanvas.Children.Add(BmpImg);
Canvas.SetLeft(BmpImg, 0); // to set position (x,y)
Canvas.SetTop(BmpImg, 0);
The problem is that it is not getting scaled to imageScaleWidth and imageScaleHeight, and it is being displayed half way down the canvas.
Note, I was able to do this in Java SWT by:
imageData = imageData.scaledTo(imageScaleWidth, imageScaleHeight);
gc.drawImage(imageData, 0, 0);

You can scale your image using a ScaleTransform:
// scale the original bitmap source
var transformedBitmap = new TransformedBitmap(
bmp,
new ScaleTransform(
imageScaleWidth / (double) bmp.PixelWidth,
imageScaleHeight / (double) bmp.PixelHeight));
// create image and set image as source
Image bmpImg = new Image();
bmpImg.SetValue(Canvas.ZIndexProperty, 0);
bmpImg.Source = transformedBitmap;
mycanvas.Width = imageScaleWidth;
mycanvas.Height = imageScaleHeight;
mycanvas.Children.Clear();
mycanvas.Children.Add(bmpImg);
Note that your image will be positioned at offset 0, 0 by default.

Instead of this
mycanvas.Children.Add(BmpImg);
Try this
mycanvas.Background = new VisualBrush(BmpImg);
This should render properly.

Are you sure the image is half way down the canvas and not the canvas itself is centered in its parent? I tested it and it appears that you can control the canvas position by setting vertical/horizontal alignment on canvas' parent. And also it scales properly when using the code you provided. However I created a BitmapSource in a different way. I used the following code:
PngBitmapDecoder decoder = new PngBitmapDecoder(new Uri(#"..."), BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
BitmapSource bmp = decoder.Frames[0];

Android Camera Preview - take only a part of the screen data

I want to take only a part of the the screen data from a preview video callback to reduce the time of the process. The probleme is I only know how to take the whole screen with OnPreviewFrame:
#Override
public void onPreviewFrame(byte[] data, Camera camera) {
myData = data;
// +get camera resolution x, y
}
And then with this data get the image :
private Bitmap getBitmapFromYUV(byte[] data, int width, int height)
{
ByteArrayOutputStream out = new ByteArrayOutputStream();
YuvImage yuvImage = new YuvImage(data, ImageFormat.NV21, width, height, null);
yuvImage.compressToJpeg(new Rect(0, 0, width, height), 100, out);
byte[] imageBytes = out.toByteArray();
Bitmap image = BitmapFactory.decodeByteArray(imageBytes, 0, imageBytes.length);
return image;
}
And then I take the part of the image taken I want :
cutImage = Bitmap.createBitmap(image, xOffset, yOffset, customWidth, customHeight);
The problem is that I need to take lots of images to apply some image processing on it and that's why I want to reduce the time it takes to get the images. Instead of taking the whole screen and then crop it, I want to immediatly get the cropped image. Is there a way to get the part of the screen data ?

Ok I finally found something, I still record all the data of the camera but when using compressToJpeg I crop the picture with a custom Rect. Maybe there is something better to do before this but this is still a good improvement. Here are my changes :
yuvImage.compressToJpeg(new Rect(offsetX, offsetY, sizeCaptureX + offsetX, sizeCaptureY + offsetY ), 100, out);

Draw Line or Rectangular on Jpg image and Save it in Android app

I have the coordinates and I would like to draw a line or rectangular on a jpg image which is saved in my android device and then save the new file.
Is it possible? I am trying to us ImageIO but it isn't available in android or something goes wrong and it isn't acceptable?
Any idea or code?

This is how I was able to draw a green box on an existing JPEG.
Bitmap workingBitmap = BitmapFactory.decodeFile( mFullFilePath );
Bitmap mutableBitmap = workingBitmap.copy(Bitmap.Config.ARGB_8888, true);
// bitmap needs to be mutable
Canvas tmpCanvas = new Canvas(mutableBitmap);
// setup paint parameters
Paint paint = new Paint();
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth( 5 );
paint.setColor(Color.GREEN);
// Rect object was passed; use below to test
// Rect rect = new Rect( 0, 0, 10, 10 );
tmpCanvas.drawRect(rect, paint);
// write the updated file out as a JPG
writeExternalToCache( mutableBitmap, mFullFilePath );
see also:
https://stackoverflow.com/a/13119762/3474698
https://stackoverflow.com/a/8801391/3474698

Android: Creating a high quality thumbnail image

I have some difficulties creating a high quality thumbnail for my captured images. I understand that there are many snippet codes and tutorials in the web to create a thumbnail. I tried them and my problem is I can't produce a high quality thumbnail image. The output is always pixelated. Any suggestion ,library or links guys? thanks in advance.
I tried this one but its low quality also.
public static Bitmap scaleBitmap(Bitmap bitmap, int wantedWidth, int wantedHeight) {
Bitmap output = Bitmap.createBitmap(wantedWidth, wantedHeight, Config.ARGB_8888);
Canvas canvas = new Canvas(output);
Matrix m = new Matrix();
m.setScale((float) wantedWidth / bitmap.getWidth(), (float) wantedHeight / bitmap.getHeight());
canvas.drawBitmap(bitmap, m, new Paint());
return output;
}

Use RapidDecoder 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 decoders if you want to scale down less than 50% and a HQ result.

Did you try this,
Bitmap src = Thumbnails.getThumbnail(getContentResolver(), ContentUris.parseId(sourceUri), Thumbnails.MINI_KIND, options);

Try this
Bitmap ThumbImage =ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(imagePath),THUMBSIZE, THUMBSIZE);
This Utility is available from API_LEVEl 8. [Source]