setBackgroundColor

View.java
    /**
     * Sets the background color for this view.
     * @param color the color of the background
     */
    @RemotableViewMethod
    public void setBackgroundColor(int color) {
        if (mBGDrawable instanceof ColorDrawable) {
            ((ColorDrawable) mBGDrawable).setColor(color);
        } else {
            setBackgroundDrawable(new ColorDrawable(color));
        }
    }
    
    
2316 private Drawable mBGDrawable;


================================================    

ColorDrawable.java
   /**
     * Creates a new ColorDrawable with the specified color.
     *
     * @param color The color to draw.
     */
    public ColorDrawable(int color) {
        this(null);
        setColor(color);
    }

================================================    

ColorDrawable.java

159  final static class ColorState extends ConstantState {
        int mBaseColor; // base color, independent of setAlpha()
        int mUseColor;  // basecolor modulated by setAlpha()
        int mChangingConfigurations;

        ColorState(ColorState state) {
            if (state != null) {
                mBaseColor = state.mBaseColor;
                mUseColor = state.mUseColor;
            }
        }

        @Override
        public Drawable newDrawable() {
            return new ColorDrawable(this);
        }

        @Override
        public Drawable newDrawable(Resources res) {
            return new ColorDrawable(this);
        }

        @Override
        public int getChangingConfigurations() {
            return mChangingConfigurations;
        }
    }

================================================    
ColorDrawable.java

   /**
     * Sets the drawable's color value. This action will clobber the results of prior calls to
     * {@link #setAlpha(int)} on this object, which side-affected the underlying color.
     *
     * @param color The color to draw.
     */
    public void setColor(int color) {
        if (mState.mBaseColor != color || mState.mUseColor != color) {
            invalidateSelf();
            mState.mBaseColor = mState.mUseColor = color;
        }
    }


================================================    
Color.Drawable.java
    private ColorDrawable(ColorState state) {
        mState = new ColorState(state);
    }
    
    
    
================================================    
View.java
11712    
     /**
     * Set the background to a given Drawable, or remove the background. If the
     * background has padding, this View's padding is set to the background's
     * padding. However, when a background is removed, this View's padding isn't
     * touched. If setting the padding is desired, please use
     * {@link #setPadding(int, int, int, int)}.
     *
     * @param d The Drawable to use as the background, or null to remove the
     *        background
     */
    public void setBackgroundDrawable(Drawable d) {
        if (d == mBGDrawable) {
            return;
        }

        boolean requestLayout = false;

        mBackgroundResource = 0;

        /*
         * Regardless of whether we're setting a new background or not, we want
         * to clear the previous drawable.
         */
        if (mBGDrawable != null) {
            mBGDrawable.setCallback(null);
            unscheduleDrawable(mBGDrawable);
        }

        if (d != null) {
            Rect padding = sThreadLocal.get();
            if (padding == null) {
                padding = new Rect();
                sThreadLocal.set(padding);
            }
            if (d.getPadding(padding)) {
                switch (d.getResolvedLayoutDirectionSelf()) {
                    case LAYOUT_DIRECTION_RTL:
                        setPadding(padding.right, padding.top, padding.left, padding.bottom);
                        break;
                    case LAYOUT_DIRECTION_LTR:
                    default:
                        setPadding(padding.left, padding.top, padding.right, padding.bottom);
                }
            }

            // Compare the minimum sizes of the old Drawable and the new.  If there isn't an old or
            // if it has a different minimum size, we should layout again
            if (mBGDrawable == null || mBGDrawable.getMinimumHeight() != d.getMinimumHeight() ||
                    mBGDrawable.getMinimumWidth() != d.getMinimumWidth()) {
                requestLayout = true;
            }

            d.setCallback(this);
            if (d.isStateful()) {
                d.setState(getDrawableState());
            }
            d.setVisible(getVisibility() == VISIBLE, false);
            mBGDrawable = d;

            if ((mPrivateFlags & SKIP_DRAW) != 0) {
                mPrivateFlags &= ~SKIP_DRAW;
                mPrivateFlags |= ONLY_DRAWS_BACKGROUND;
                requestLayout = true;
            }
        } else {
            /* Remove the background */
            mBGDrawable = null;

            if ((mPrivateFlags & ONLY_DRAWS_BACKGROUND) != 0) {
                /*
                 * This view ONLY drew the background before and we're removing
                 * the background, so now it won't draw anything
                 * (hence we SKIP_DRAW)
                 */
                mPrivateFlags &= ~ONLY_DRAWS_BACKGROUND;
                mPrivateFlags |= SKIP_DRAW;
            }

            /*
             * When the background is set, we try to apply its padding to this
             * View. When the background is removed, we don't touch this View's
             * padding. This is noted in the Javadocs. Hence, we don't need to
             * requestLayout(), the invalidate() below is sufficient.
             */

            // The old background's minimum size could have affected this
            // View's layout, so let's requestLayout
            requestLayout = true;
        }

        computeOpaqueFlags();

        if (requestLayout) {
            requestLayout();
        }

        mBackgroundSizeChanged = true;
        invalidate(true);
    }

================================================    
ColorDrawable.java
129
    public int getOpacity() {
        switch (mState.mUseColor >>> 24) {
            case 255:
                return PixelFormat.OPAQUE;
            case 0:
                return PixelFormat.TRANSPARENT;
        }
        return PixelFormat.TRANSLUCENT;
    }