Get two merged bitmap from canvas - android

I have two bitmaps which are drawn in one canvas side by side.How do i get the merged bitmaps again. I think it is not possible to get them from canvas. What are the other options to get the bitmap of the merged bitmap from the canvas.


It is possible to get the bitmap object of merged bitmaps .
first of all create a canvas with a blank bit map
Bitmap.Config conf = Bitmap.Config.ARGB_8888;
Bitmap bitmap_object = Bitmap.createBitmap(width, height, conf);
Canvas canvas_object = new Canvas(bitmap_object);
now draw your bitmaps on this canvas_object using drawBitmap (Bitmap bitmap, Matrix matrix, Paint paint) api,
now use the bitmap_object to get merged bitmap..

Related

Android ImageView get bitmap after zoom using setImageMatrix

In Android I have an ImageView which user can manipulate the position and zoom level in the UI.
Is it possible to get the zoomed image (changed image) from the ImageView instead of original one.
Here are the methods I tried but no use.
imageView.buildDrawingCache(true);
Bitmap bmp = imageView.getDrawingCache(true);
I can get the Matrix but don't know how to use it.
Matrix m = imageView.getImageMatrix();

The zoom effect is applied at the Canvas level. So, what you can do is get the current Canvas augmentations and then draw your Bitmap into a new one with the changes.
Matrix transformMatrix = imageView.getImageMatrix()
Bitmap original = bmp;
Bitmap adjusted = Bitmap.createBitmap(original.getWidth(),
original.getHeight(),
original.getConfig());
Canvas canvas = new Canvas(adjusted);
canvas.setMatrix(transformMatrix);
canvas.drawBitmap(original, 0, 0, null);
//at this point adjusted bitmap contains the zoomed image

When you get a Matrix from an ImageView, make changes to t, then use imageView.setImageMatrix(m) apply the changes back to the ImageView. You will want to look into using one of the postScale() matrix methods to make a change in the size of image rendered.

Draw on a large canvas, scroll it, save it, reload it ... works, but only the viewport part is saved

My program can draw 2D shapes on a canvas. The result can be scrolled. , When I save the result, then ONLY the image in the viewport is saved.
I use a View and draw on it's canvas.
Saving the drawing/updated result is:
setDrawingCacheEnabled(true);
buildDrawingCache();
Bitmap bmp = Bitmap.createBitmap( this.getDrawingCache());
setDrawingCacheEnabled( false);
// the bitmap I can save into a file
bm.compress( Bitmap.CompressFormat.PNG, 90, new FileOutputStream( new File( filepath)));
When I use a large view/canvas, then I get errors that my drawingCache is not big enough. When I use a regualar view/canvas size, then nearly all drawings outside the viewport are clipped.
==> Can I draw on a bitmap and have that bitmap immediately drawn on the view's canvas?
So, after some drawing, the initial bitmap is updated with the newly added drawing?

Happily, there is a simple solution to this question.
Create a large bitmap with your own size;
Create your own cachedCanvas = new Canvas( largeBitmap);
Draw first on the cachedCanvas'.
In onDraw() do: canvas.drawBitmap( cachedBitmap, 0, 0, null);
Saving your own largeBitmap is easy!

Android creating a circle bitmap without drawing it on canvas

My question is: is there any way to create a circle and then make it bitmap and not to display it on canvas??For example make a black circle then convert it to a bitmap but not using the canvas.setBitmap(Bitmap bitmap).Thanks in advance.

You can easily get a bitmap object using Bitmap static method (Bitmap.create) and then use that object to draw anything on it by instantiating a canvas object with bitmapObject.
your code should look something like this:
Bitmap bitmap = Bitmap.create(width, height, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
//draw on your canvas.

Rotating a bitmap using matrix

While rotating a bitmap using matrix, vertex is not stable..
Matrix matrix = new Matrix();
matrix.postRotate(mDegree,100,100);
mCompasstemp = Bitmap.createBitmap(mCompPic, 0, 0, mCompPic.getWidth(), mCompPic.getHeight(), matrix, true);
mCompassHud.setImageBitmap(mCompasstemp);
Output of my code is like
-bitmap will rotate.
-vertex of my bitmap is not stable.
-Bitmap is resizing
I need disable image resizing and make the rotation stable.Can you please suggest a solution for this?

Rather than creating your new Bitmap directly from the original, another (more straight-forward, imho) option is to create the resultant Bitmap, create a Canvas with that Bitmap, then do your rotation/translation/scaling on the Canvas and draw the original Bitmap onto the new Bitmap via the Canvas.
Basically, you're looking, then, at:
scaledImage = Bitmap.createBitmap (croppedWidth, croppedHeight, Bitmap.Config.ARGB_8888);
Canvas offscreenCanvas = new Canvas (scaledImage);
Matrix matrix = new Matrix();
matrix.setRotate (rotations, centreX, centreY);
matrix.postScale(scaleX, scaleY);
offscreenCanvas.setMatrix (matrix);
offscreenCanvas.drawBitmap (pickedImage, 0, 0, new Paint(Paint.DITHER_FLAG));

Not sure if this is what your looking for but it might help.
Android uses its built in compatibility features to scale and render a bitmap appropriately for screens with different pixel densities. There are two methods of scaling, pre-scaling and auto-scaling.
It will pre-scale bitmaps' from resources and auto-scales when the bitmap is being drawn internally (which is what your doing be using createBitmap).
Go to http://developer.android.com/guide/practices/screens_support.html and check under:
4.Use density and/or size-specific resources:
Pre-scaling and auto-scaling of bitmaps and nine-patches

I have tried this code, and the rotate is stable at the center of the bitmap
matrix.reset();
matrix.setRotate(degree, Xpos+bitmap.getWidth()/2, Ypos+bitmap.getHeight()/2);
and then in canvas doDraw()
canvas.setMatrix(matrix);
canvas.drawBitmap(bitmap, Xpos, Ypos, null);
canvas.setMatrix(null);
The Xpos and Ypos is the X and Y position of the bitmap
The setMatrix(null), set the matrix to null, so that the rotate didn't affect the after bitmap
And it didn't always create new bitmap, so it's great for performance
I hope that help

I know its an old question but, all answers with code imply a canvas, so heres a solution without a canvas that worked for me :
Matrix matrix = new Matrix();
matrix.postRotate(mDegree,100,100);
mCompasstemp = Bitmap.createBitmap(mCompPic, 0, 0, mCompPic.getWidth(),
mCompPic.getHeight(), matrix, true);
mCompasstemp = Bitmap.createScaledBitmap(mCompassTemp, mCompPic.getWidth(),
mCompic.getHeight(), false);
mCompassHud.setImageBitmap(mCompasstemp);
So basically after rotating your bitmap you rescale it to the desired size. Might not be best practice, but at least you dont have to create an extra canvas if you dont want/need to, since the involving Paint() Object is not an inexpensive operation either.

how to convert a paint image to bitmap

I am able to save the source image but not able save the image with colorfilter:
paint.setColorFilter(new ColorMatrixColorFilter(cm));
If this image is converted into bitmap it can be saved easily,
but I don't know how to do this. Is there anyone to give solution?

Have your original bitmap.
Create a new clean Bitmap that has the same width/height as your original bitmap.
Create a new Canvas using this clean Bitmap.
Set your paint object, etc for this new Canvas.
Draw your original bitmap into this new Canvas.
Since this new Canvas is backed by a Bitmap (point 3.), any drawing you do in this Canvas will become part of the new Bitmap (point 2.). Now just call 'compress' on this Bitmap from point 2. and the bitmap will be saved as a jpg/png.

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