How can I crop a triangle from an image (given the degree) using it's center.
for e.g. In the below image, fig_1 is the original image. I want to cut it like fig_2, fig_3 and fig_4 where, x, y and z are the degree of the angles.
Any help would be appreciated. Thanks.
Not sure if this is the best solution but you might want to use the BitMap class. First write the contents of the image to a Buffer, then use copyPixelsFromBuffer(Buffer) in BitMap class to get a BitMap. Then write the logic to edit the BitMap, e.g. you can use eraseColor(int). Then copy your edited BitMap to an ImageView using setImageBitMap(BitMap) method in ImageView class.
Related
I need to save a number of formatted circles to a Bitmap whenever a button is pushed, and then draw those circles to the canvas. I was looking around, but had a great deal of trouble finding resources on how to save a shape I had created that was not an already created resource file. Any advice on how to go about this would be appreciated.
Say you are in your custom view, but it should work also with a OnTouchListener in any view.
Create a mutable bitmap with Bitmap.createBitmap() with the same width and height of your view
use your logic for getting information of the circles, for example you can use onTouchEvent() to get the coordinates of you finger(s)
with this information you can use Bitmap.setPixel() to save it to the bitmap
optional, onDraw() you can draw your bitmap with Canvas.drawBitmap()
In case you need to draw shapes to the bitmap you can create a new Canvas(bitmap) and draw on this canvas: the pixels will be set on the bitmap.
I know we can crop a bitmap in rectangular shape using:
Bitmap.createBitmap(source, x, y, width, height)
But I want to know to crop a bitmap in freehand mode or some polygon shape. Its best example can be seen in Jigsaw Puzzle game
I have spent a lot of time googling about this but found no help. Can anybody help me in this regard?
You can use a Path to determine a clip area on your Canvas when drawing a Bitmap.
For a full example see:
Android - Crop an image from multipoints
and also:
Cutting a multipoint ploygon out of Bitmap and placing it on transparency
I'm trying to dynamically create images in android by taking an existing Bitmap and removing the centre of it in order to make a "cropped" version. The resulting image's height would naturally be smaller than the original, something like the attached example.
I've got a rough way of doing this by creating two new Bitmaps from the original, one containing the top of the image above the crop section (e.g. the android's head in the example) and the other containing the remaining image below the crop section (the android's feet) using the Bitmap.createBitmap(source, x, y, width, height) method, then drawing both of these bitmaps onto a canvas of a size equal to the original image minus the removed space.
This feels a bit clunky, and as I could be calling this method several times a second, it seems wasteful to create two bitmaps each time.
I was wondering if there was a more efficient way of doing this. Something like drawing the original Bitmap onto a canvas using a Path with it's Paint's xfermode set to a
new PorterDuffXfermode(Mode.DST_OUT) in order to cut out the portion of the image I wish to delete. But this seems to clear that area and not shrink the image down i.e. it leaves a big empty gap in the Android's middle.
Any suggestions greatly appreciated!
Why do you create two bitmaps? You only need to create one bitmap and then do canvas.drawBitmap() twice.
Bitmap bmpOriginal;
Bitmap bmpDerived = Bitmap.create(...);
Canvas canvas = new Canvas(bmpDerived);
canvas.drawBitmap(bmpOriginal, rectTopSrc, rectTopDst, null);
canvas.drawBitmap(bmpOriginal, rectBottomSrc, rectBottomDst, null);
Done.
I have an ImageView from which I want to copy a piece of it in the shape of a circle that I can then re-display to the user at a larger than original size to simulate a zoom effect. Would I use bitmaps for that? Thanks.
Yes.... you can try to get a Bitmap that represents the ImageView you are working with. Before, you have to enable the caching (by invoking the setDrawingCacheEnabled(true) method). To get the Bitmap representation of the image, you can use the getDrawingCache() method.
Once you get that Bitmap, you can resize it or make any other changes you want. Then, you can create a Rect object with the portion of the bitmap you want to draw, then you draw that rect using this method: drawBitmap(Bitmap, Rect origin, Rect destination, Paint).
I have a class that extends View. I override the onDraw method and allow the user to draw on the screen. I am at the point where I want to save this view as an image. I Can use buildDrawingCache and getDrawingCache to create a bitmap that I can write to the SD card. However, the image is not good quality at a large size, it has jagged edges. Since I have a View and I use Paths I can transform all by drawing to a bigger size. I just don't know how to make the Canvas bigger so when I call getDrawingCache it doesn't crop all the paths I am just transformed. What is happening is I transform all my paths but when I write the Bitmap to file I am only getting the "viewport" of the actual screen size. I want something much bigger. Any help in the right direction would be greatly appreciated. I have been reading the docs and books and am at a loss.
Thanks
Jon
You can create another Canvas backed by a Bitmap that you create and draw all the paths to that. Then the Bitmap will hold the larger, higher resolution image. It would look something like this:
Bitmap largeBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Canvas largeCanvas = new Canvas(largeBitmap);
// Draw the paths to this canvas and then use largeBitmap to save to a file.