Perplexed by the pixel value in the bitmap (pre-multiplied color using setPixel)

Question

I can't explain this (screenshot from Eclipse debugging):

The pixel in (0,0) has no meaning for which it was set!

All other pixels are in order, they have the same value to which they were assigned.

EDIT I did some more digging, and the code for setPixel calls its own function:

1391    public void setPixel(int x, int y, int color) {
1392        checkRecycled("Can't call setPixel() on a recycled bitmap");
1393        if (!isMutable()) {
1394            throw new IllegalStateException();
1395        }
1396        checkPixelAccess(x, y);
1397        nativeSetPixel(mNativeBitmap, x, y, color, mIsPremultiplied);
1398    }

setPixel (0,0) , , OK setPixel (0,1).
. : - , . , , 0xB0 OK.
, , . , , .

    source.setPixel(0, 0, Color.argb(0x40, 0x1A, 0x11, 0x12));
    int sp00 = source.getPixel(0, 0); // sp00   1075580948 [0x401c1014] BAD

    source.setPixel(0, 0, Color.argb(0xFE, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -16781602 [0xfeffeede]  OK!
    source.setPixel(0, 0, Color.argb(0x40, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   1090514911 [0x40ffefdf] BAD
    source.setPixel(0, 0, Color.argb(0xFE, 0x1A, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -31789346 [0xfe1aeede]  OK!
    source.setPixel(0, 0, Color.argb(0xFE, 0xFF, 0x11, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -16838178 [0xfeff11de]  OK!
    source.setPixel(0, 0, Color.argb(0xFE, 0xFF, 0xEE, 0x12));
    sp00 = source.getPixel(0, 0); // sp00   -16781806 [0xfeffee12]  OK!

    source.setPixel(0, 0, Color.argb(0x00, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   0 [0x0] Strange, why Color has to police the alpha value?
    source.setPixel(0, 0, Color.argb(0x10, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   285208543 [0x10ffefdf]  BAD
    source.setPixel(0, 0, Color.argb(0x20, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   553643999 [0x20ffefdf]  BAD
    source.setPixel(0, 0, Color.argb(0x30, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   822079455 [0x30ffefdf]  BAD
    source.setPixel(0, 0, Color.argb(0x50, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   1358950367 [0x50ffefdf] BAD 
    source.setPixel(0, 0, Color.argb(0x60, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   1627385823 [0x60ffefdf] BAD
    source.setPixel(0, 0, Color.argb(0x70, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   1895821279 [0x70ffefdf] BAD
    source.setPixel(0, 0, Color.argb(0x80, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -2130711075 [0x80ffeddd] BAD but change of pattern
    source.setPixel(0, 0, Color.argb(0x90, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1862275619 [0x90ffeddd] BAD    
    source.setPixel(0, 0, Color.argb(0xA0, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1593840162 [0xa0ffedde] BAD but change of pattern again
    source.setPixel(0, 0, Color.argb(0xB0, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1325404450 [0xb0ffeede] OK!    
    source.setPixel(0, 0, Color.argb(0xC0, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1056968994 [0xc0ffeede] OK!
    source.setPixel(0, 0, Color.argb(0xD0, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -788533538 [0xd0ffeede] OK!
    source.setPixel(0, 0, Color.argb(0xE0, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -520098082 [0xe0ffeede] OK!
    source.setPixel(0, 0, Color.argb(0xF0, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -251662626 [0xf0ffeede] OK!

    source.setPixel(0, 0, Color.argb(0xA7, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1476399395 [0xa7ffeedd] BAD
    source.setPixel(0, 0, Color.argb(0xA3, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1543508258 [0xa3ffeede] OK!
    source.setPixel(0, 0, Color.argb(0xA1, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1577062690 [0xa1ffeede] OK!
    source.setPixel(0, 0, Color.argb(0xAB, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1409290274 [0xabffefde] BAD
    source.setPixel(0, 0, Color.argb(0xA9, 0xFF, 0xEE, 0xDE));
    sp00 = source.getPixel(0, 0); // sp00   -1442844962 [0xa9ffeede] OK!    

Answer 1

, , .
"pre-multiplied Alpha" Bitmaps, api19 , , .
api19 Bitmap: isPremultiplied() setPremultiplied ()
:

, RGB -. , 50% (128, 255, 0, 0), (128, 128, 0, 0).

. , :

    Bitmap source = Bitmap.createBitmap(2, 2, Config.ARGB_8888);
    source.setPixel(0, 0, Color.argb(0x02, 0x10, 0x20, 0x30));
    source.setPixel(0, 1, Color.argb(0x03, 0x10, 0x20, 0x30));
    source.setPixel(1, 0, Color.argb(0x05, 0x78, 0x96, 0x64));
    source.setPixel(1, 1, Color.argb(128, 255, 200, 150));

    int sp00 = source.getPixel(0, 0); // sp00   33554432 [0x2000000]    
    int sp01 = source.getPixel(0, 1); // sp01   50331733 [0x3000055]    
    int sp10 = source.getPixel(1, 0); // sp10   90610022 [0x5669966]    
    int sp11 = source.getPixel(1, 1); // sp11   -2130720875 [0x80ffc795]

(. .).
, .
, , .

, , Bitmap:

    Bitmap source = Bitmap.createBitmap(2, 2, Config.ARGB_8888);
    IntBuffer data = IntBuffer.wrap(new int[] {
            Color.argb(0x06, 0xff, 0xa0, 0x8d),
            Color.argb(0x2a, 0xab, 0xce, 0x9f),
            Color.argb(0x8f, 0xfe, 0x05, 0x18),
            Color.argb(0xff, 0xc8, 0xcf, 0xd4)
    });
    source.copyPixelsFromBuffer(data);

, :

    IntBuffer sourceData = IntBuffer.allocate(4);
    source.copyPixelsToBuffer(sourceData);

.