Develop Reference

Slow perofromance when drawing transformationd bitmap on canvas in Android

I am trying to further process a Camera2 image. Because the cameras in devices have different rotations and flipped based on back and front camera, I use transforms to properly rotate it.
transformationMatrix is that matrix for the front camera that has 270 rotation.
Then from that transformed camera image, I want to copy a scrolling window to another bitmap. I want to retain that bitmap/state and draw a line before drawing finalBitmapWithScanner on the phone screen.
Is there a way to do this more efficiently and fast? The second line takes 200ms to complete which is the main issue here.
Canvas canvas = new Canvas(tempBitmap);
canvas.drawBitmap(cameraBitmap, transformationMatrix, paint); // <= 200ms
Rect src = new Rect((int) lastXPos, 0, (int) mXPos, mViewHeight);
Canvas canvas2 = new Canvas(finalBitmap);
canvas2.drawBitmap(tempBitmap, src, src, paint);
Canvas canvas3 = new Canvas(finalBitmapWithScanner);
canvas3.drawBitmap(finalBitmap, 0, 0, paint);
canvas3.drawLine(mXPos, 0, mXPos, mViewHeight/2, scrollerPaint);
transformationMatrix.reset();
transformationMatrix.setRotate(270, imageHeight, 0);
transformationMatrix.postTranslate(-imageHeight, 0);
transformationMatrix.postScale(scaleFactor, scaleFactor);
transformationMatrix.postScale(-1f, 1f, mViewWidth / 2f, mViewHeight / 2f);

There are bunch of ways you can try to achieve fast rendering:
You can pass parameters "paint" an null.
also you can use function CreateScaledBitmap and notice you have to set scale and size before rendering as see in below:
As you can see in documentation enter link description here; you have to resize and rescale your bitmap before rendering so you can use code below for your BitmapFactory.Options :
mBitmapOptions.inScaled = true;
mBitmapOptions.inDensity = srcWidth;
mBitmapOptions.inTargetDensity = dstWidth;
// will load & resize the image to be 1/inSampleSize dimensions
mCurrentBitmap = BitmapFactory.decodeResources(getResources(),
mImageIDs, mBitmapOptions);
use canvas.restore() after draw func.

Canvas' drawBitmap method causes bad performance after scaling

I'm trying to create a simple translational movement for a Bitmap object. I'm doing this by creating a canvas and passing a framebuffer to it, which had previously been initialized to a resolution of 1080/1920. I then proceeding to draw a bitmap with a call to canvas' method drawBitmap() like so:
this.canvas = new Canvas(frameBuffer);
...
canvas.drawBitmap(bitmap, null, destinationRect, paint);
In a different thread which is set as the Content View for the main activity I'm scaling the framebuffer to fit the actual screen size and then draw it with all its contents with these lines:
Canvas canvas = holder.lockCanvas();
canvas.getClipBounds(dstRect);
...
canvas.drawBitmap(framebuffer, null, dstRect, paint);
holder.unlockCanvasAndPost(canvas);
This results in very poor performance, both measuring manually with delta time and by monitoring with the Android Studio tools. Even visually you can see a trailing after the bitmap accompanied with very low fps.
I can't seem to find the cause of this, but I suspect that the scaling process that drawBitmap executes implicitly is doing something heavy. I tried changing the filter settings without success. I also doubt that I should head for openGL for this simple need.
Should I use bitmaps with different sizes and decide on runtime what size is the closest to my need or is there a more straightforward solution to this problem?
EDIT:
Here's how I gain a few more frames per second with the matrix.postScale() method:
int width = framebuffer.getWidth();
int height = framebuffer.getHeight();
float scaleWidth = ((float) game.size.x) / width;
float scaleHeight = ((float) game.size.y) / 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(framebuffer, 0, 0, width, height, matrix, true);
canvas.drawColor(Color.parseColor("#013501"));
canvas.drawBitmap(resizedBitmap, null, dstRect, paint);
holder.unlockCanvasAndPost(canvas);

Rotate bitmap in fixed point like a clock hand in SurfaceView

I have an image in drawable folder for clock hand. I want to rotate it in fixed point like a clock hand. I have tried below code which rotates the hand in circular path around a fixed point but not as like clock hand.
Matrix matrix = new Matrix();
matrix.reset();
matrix.preTranslate(0, 0);
matrix.postRotate(angleRotation, -0, -0);
matrix.postTranslate(240, 480);
canvas.drawColor(Color.WHITE);
canvas.drawBitmap(bitmap, matrix, null);
I am struggling for hours to get it sorted out. Any help will be greatly appreciated.
I have tried below links for help as well with no success.
SurfaceView, draw image and reduce size, rotate image
Android: How to rotate a bitmap on a center point
How to rotate a bitmap in Android about images center smoothly without oscillatory movement

I found the answer. Let px and py be any point on canvas. bitmap.getWidth()/2 is middle point along bitmap width. It can be any point for x cordinate. For y cordinate I have taken it as 10. angleRotation is the angle that is as per required.
So matrix.postTranslate(-bitmap.getWidth()/2, -10); is the point of rotation.
Below is the code.
Matrix matrix = new Matrix();
matrix.reset();
Paint paint = new Paint();
float px = 240;
float py = 480;
matrix.postTranslate(-bitmap.getWidth()/2, -10);
matrix.postRotate(angleRotation);
matrix.postTranslate(px, py);
canvas.drawBitmap(bitmap, matrix, paint);
Above code satisfy my requirements. Please modify it as per your need.

I use this to rotate my bitmaps.
private Bitmap rotateImage(Bitmap src,int degrees) {
Matrix matrix = new Matrix();
matrix.postRotate(degrees);
return Bitmap.createBitmap(src, 0, 0, src.getWidth(), src.getHeight(), matrix, true);
}

Getting output rectangle of drawBitmap has drawn a Bitmap using a Matrix

Bitmap b;
Matrix mMatrix;
mMatrix.reset();
// move the view so that it's center point is located in 0,0
mMatrix.postTranslate(-sizeX, -sizeY);
// scale the view
mMatrix.postScale(mScaleFactor, mScaleFactor);
// re-move the view to it's desired location
mMatrix.postTranslate(mTouchX, mTouchY);
canvas.drawBitmap(b, mMatrix, null);
I need to know if there is an built in method to tell the info like corner coordinates of where the Bitmap is printed, etc.
Hope it is clear.
Thanks.

yes, it's called mapRect https://developer.android.com/reference/android/graphics/Matrix.html#mapRect(android.graphics.RectF)
RectF r = new RectF(0, 0, b.getHeight(), b.getWidth());
mMatrix.mapRect(r);
// r now have the coordinates where the bitmap was drawn,
// you can test it by calling
canvas.drawRect(r, paint);

Water reflection effect on bitmap

I trying to achieve water reflection effect on bitmap. As I saw some apps called water reflection. I know how to do the reflection of the image but the wave on the image is what making me confused on how it is done.
see this image for example
I did many apps on bitmap manipulation but this is quite hard to achieve.
So any idea on where to start. Just an idea to start can be helpful.

For any one needed, I tried some simple tricks to get as closer as water reflection effect. It is not great but it looks fine to me.
I used two methods
Bitmap reflection method (give bitmap as a parameter)
public static Bitmap Reflection(Bitmap imageBitmap) {
int width = imageBitmap.getWidth();
int height = imageBitmap.getHeight();
Matrix matrix = new Matrix();
matrix.preScale(1, -1);
Bitmap reflectionImage = Bitmap.createBitmap(imageBitmap, 0,
0, width, height , matrix, false);
Bitmap newbit=Bitmap.createScaledBitmap(reflectionImage, reflectionImage.getWidth()/8, reflectionImage.getHeight()/8, true);
Bitmap newbit1=Bitmap.createScaledBitmap(newbit, newbit.getWidth()*8, newbit.getHeight()*8, true);
Bitmap scalednew=Bitmap.createScaledBitmap(newbit1, width, height-(height/4), true);
Bitmap newscaledone=overlay(scalednew);
reflectionImage=newscaledone;
Bitmap reflectedBitmap = Bitmap.createBitmap(width,
(height + height), Config.ARGB_8888);
Canvas canvas = new Canvas(reflectedBitmap);
canvas.drawBitmap(imageBitmap, 0, 0, null);
Paint defaultPaint = new Paint();
canvas.drawRect(0, height, width, height, defaultPaint);
canvas.drawBitmap(reflectionImage, 0, height , null);
Paint paint = new Paint();
paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
canvas.drawRect(0, height, width, reflectedBitmap.getHeight()
, paint);
return reflectedBitmap;
}
Bitmap overlay method. I am taking a wave bitmap with some opacity to overlay on the reflected image. So that it may look like water.
Bitmap wavebitmap=BitmapFactory.decodeResource(getResources(), R.drawable.waves1);
private static Bitmap overlay( Bitmap bmp2) {
Bitmap bmp1=WaterReflectionMainActivity.wavebitmap;
Bitmap bmp1new =Bitmap.createScaledBitmap(bmp1, bmp2.getWidth(), bmp2.getHeight(), true);
Bitmap bmOverlay = Bitmap.createBitmap(bmp1new.getWidth(), bmp1new.getHeight(), bmp1new.getConfig());
Canvas canvas = new Canvas(bmOverlay);
canvas.drawBitmap(bmp2, new Matrix(), null);
canvas.drawBitmap(bmp1new, new Matrix(), null);
return bmOverlay;
}
Well this is my version of water effect, I know this looks shit.
So if anyone still got some better effect please share your code .
thank you

Tutorial related to this: http://www.xaraxone.com/webxealot/workbook34/page_4.htm
Also have a read at this question: Add water effect on bitmap android.
Have a read at both of them, i hope you will get an idea from this
You may also want to look through these: 1, 2, 3

This is just an idea but basically, what you need is to apply a deformation on the bottom part of the image, meaning that for each pixel on the bottom half, you compute a position to get it's color from the top picture.
Here's a pseudo code to give you a hint :
for (int x = 0; x < width; x++) {
for (int y = 0; y < img.height; y++) {
// Compute a position on the original image
// tweak the values heres to get the effect you want
sourceX = x + (int) (cos(10000.0 / y) * 20);
sourceY = img.height - y - 1 +(int)( sin(y* 0.5) * 20);
// Maybe check the range of sourceX and source Y
int color = img.getColor(sourceX, sourceY)
outptut.setColor(x, y + img.height, color);
}
}

you can achieve this by masking may this code will help you
http://www.seeques.com/22527681/how-can-do-this-effect-in-android-may-be-android-bitmap-masking-effect.html
EDIT
also see this for reference
http://code.google.com/p/android-ripple-demo/source/browse/#svn%2Ftrunk%2Fsrc%2Fcom%2Fkesalin%2FRippleDemo
https://github.com/esteewhy/whater
http://code.google.com/p/waterrippleeffect/source/browse/trunk/src/com/example/android/watereffect/WaterEffectView.java?r=3
android noise effect on bitmap