I would like to use Canvas to "shift a bitmap"; to create a Bitmap from a Bitmap, but with a y offset such that all the pixels in the Bitmap are either shifted down (with blank pixels at the top) or shifted up (with blank pixels at the bottom). I am using the below code to do this. The code works fine as long as I am shifting up (shiftY is negative), but it gives a garbage bitmap if I try to shift down.
The second set of code is my work around for this, but this has the very undesirable effect of doubling my memory usage.
Is there any way to shift a Bitmap whitout using a second Bitmap?
//create canvas from the current Bitmap.
Canvas canvas = new Canvas (m_Bitmap);
/*draw into the current Bitmap into the canvas with an offset, thereby drawing over itself
shifted pixels*/
canvas.drawBitmap(m_Bitmap, 0, shiftY, null);
`
//create the canvas from a temp bitmap
Canvas canvas = new Canvas (m_2ndBitmap);
//draw the shifted pixels into the temp bitmap
canvas.drawBitmap(m_BackBuffer, shiftX, shiftY, null);
//swap the bitmaps
Bitmap temp = m_Bitmap;
m_Bitmap = m_2ndBitmap;
m_2ndBitmap = temp;
You can do it yourself if you copy row by row from the bottom. The problem is that your source and destination are the same and it's copying from the top, destroying the rows beneath before you can copy them lower.
When you are referencing a "new" or new Bitmap to an already existing Bitmap, the already existing Bitmap will be available for garbage collection.
However, do not create objects during runtime: just use two Bitmaps that you are allocating up front, when your Canvas has been created and skip creating the new Canvas.
Try:
canvas.drawBitmap(Bitmap.createBitmap(m_BackBuffer), shiftX, shiftY, null);
instead of:
canvas.drawBitmap(m_BackBuffer, shiftX, shiftY, null);
Related
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.
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!
I have some SVGs in my assets folder and I need to dynamically set them in my widget (on an ImageView).
I am using this library: http://code.google.com/p/svg-android/
This library returns a Picture or a PictureDrawable.
The only methods I can see to use on RemoteViews are setImageViewBitmap which obviously takes a bitmap.
I tried looking for code to convert a Drawable to a Bitmap like this:
PictureDrawable pictureDrawable = svg.createPictureDrawable();
Bitmap bitmap = Bitmap.createBitmap(pictureDrawable.getIntrinsicWidth(), pictureDrawable.getIntrinsicHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
canvas.drawPicture(pictureDrawable.getPicture());
currentBitmap = bitmap;
But the bitmap is too small. When I create the bitmap in Illustrator I set the artboard size to 65 which is what comes through on the intrinsic width/height.
My widgets can be resized so the ImageView sizes are variable. Even if I set the width and height statically to some large number like this...
Bitmap bitmap = Bitmap.createBitmap(300, 300, Config.ARGB_8888);
then the resulting bitmap just has a bunch of whitespace below and to the right of a tiny image.
I guess I need to somehow draw the picture at a scaled up value as well as creating the Bitmap at size 300. Ideally I could figure out the size of the ImageView at runtime and set the proper sized Bitmap if I knew that. Is this the best approach and how would I do this? Perhaps there is a better approach I don't even know about?
I've not used android-svg but if it's using vanilla PictureDrawables, then it should be just a matter of not using the intrinsic bounds.
Try the following:
PictureDrawable pictureDrawable = svg.createPictureDrawable();
Bitmap bitmap = Bitmap.createBitmap(300, 300, Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
pictureDrawable.setBounds(0, 0, bitmap.getWidth(), bitmap.getHeight());
pictureDrawable.draw(canvas); // do not access the Picture directly, that defeats the purpose
currentBitmap = bitmap;
In short, use the Drawable, not its Picture and set the Drawable's bounds to be the full canvas.
Have you tried createScaledBitmap?
createScaledBitmap()
I have tried svg-android and it has not worked for me for this very reason. Not to mention its severely limited feature set.
The point of using vector graphics is that I can generate images of any appropriate size to fit the UI View size. Which means the generation method must accept the size requirements at run-time, and not always use width,height declared in <svg> tag.
Hence I used the native implementation: libsvg-android, which exactly does that.
It directly renders to a canvas with given size:
long objId = SvgRaster.svgAndroidCreate();
SvgRaster.svgAndroidParseBuffer(objId, readString(mInputStream, "UTF-8"));
SvgRaster.svgAndroidSetAntialiasing(objId, true);
SvgRaster.svgAndroidRenderToArea(objId, mCanvas, 0, 0, mWidth, mHeight);
I ended up modifying the underlying Artboard size to be 300. None of the scaling up methods worked. So the final code I used was that which I originally posted:
PictureDrawable pictureDrawable = svg.createPictureDrawable();
Bitmap bitmap = Bitmap.createBitmap(pictureDrawable.getIntrinsicWidth(), pictureDrawable.getIntrinsicHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
canvas.drawPicture(pictureDrawable.getPicture());
currentBitmap = bitmap;
Once I had a 300x300 Bitmap I was able to set it into the RemoteViews using setImageViewBitmap .
This kind of defeated the purpose of using SVGs in the first place (at least as far as using them in widgets was concerned).
My problem was not the same as User117. Perhaps he did not name the outer layer 'bounds' as was required in the library. Either way, I managed to get the library working, albeit by having to modify the SVG Artboard size.
Hopefully with the increase in screen resolution Android will introduce SVGs as part of the platform soon.
I know - the title may sounds strange. Let me explain:
I created an image to show you, what I'm talking about:
I got an image (Bitmap (1)), that as the size of 150w/200h.
Now I need to make the bitmap bigger ((2) 400w/400h), but the original image must have the same size. So that the image is embedded in white background.
I think one way to solve it is this:
* create a big bitmap
* create a canvas for it
* draw the original bitmap on the canvas
* draw the canvas
* generate a bitmap of the canvas
The problem for me is, that it must be done in a background thread without drawing a view.
I hope you understand me.
You can use the code bellow to achive it. Where smallBitmap is your original image and bigBitmap is the final image:
Bitmap bigBitmap = Bitmap.createBitmap(width, height , Bitmap.Config.ARGB_8888);
canvas = new Canvas(bigBitmap);
canvas.drawBitmap(smallBitmap, left, top, new Paint());
Regards.
This should do the trick.
Create a thread and in that thread object:
Create a new bitmap.
Create a canvas based on that bitmap.
Draw your bitmap to that canvas
and voila!
I hope this helps.
I am trying to create a bitmap from a View that is not displayed yet to set it as a texture with OpenGL in android.
The problem is that when I create my bitmap the layout parameters of my View have 0 value cause the onLayout() function has not been called yet.
Is there a way to "simulate" a layout or do a "background layout" to get the right layout params ?
I was thinking about a Frame layout having two views, the background one would be used to create my bitmap as the layout would have been done.
Thanks.
You indeed need to layout your View before drawing it into a Bitmap. Simply call
myView.measure(...);
then
myView.layout(0, 0, myView.getMeasuredWidth(), myView.getMeasuredHeight());
I have posted an example on how to do this in one of the following presentations: http://www.curious-creature.org/2010/12/02/android-graphics-animations-and-tips-tricks/
So, some edits after the question was clarified :)
I suggest you create the bitmap independently of the view, then scale it to the same size as the view once the view is created. Create an arbitrary size bitmap that allows you to render what you want to it ..
// This in some class that renders your bitmap independently, and can be
// queried to get the bitmap ...
Bitmap b = Bitmap.createBitmap(100, 100, Bitmap.Config.ARGB_4444);
// render something to your bitmap here
Then after your view is created, take the precreated bitmap and rescale it to the right size (I've not actually checked this by compiling it -- might be errors):
Rect original = new Rect(0, 0, 100, 100);
RectF destination = new RectF(0.0, 0.0, (float)myView.getWidth(), (float)myView.getHeight());
Canvas canvas = new Canvas();
canvas.drawBitmap(myRenderingClass.b, original, destination, null);
myView.draw(canvas);