Java Code Examples for android.view.Gravity#RIGHT

/**
 * @return True, if adjustments were made that require the view to be invalidated.
 */
private boolean adjustBottomLines() {
  // Bail out if we have a zero width; lines will be adjusted during next layout.
  if (getWidth() == 0) {
    return false;
  }
  int destBottomLines;
  textPaint.setTextSize(bottomTextSize);
  if (tempErrorText != null || helperText != null) {
    Layout.Alignment alignment = (getGravity() & Gravity.RIGHT) == Gravity.RIGHT || isRTL() ?
        Layout.Alignment.ALIGN_OPPOSITE : (getGravity() & Gravity.LEFT) == Gravity.LEFT ?
        Layout.Alignment.ALIGN_NORMAL : Layout.Alignment.ALIGN_CENTER;
    textLayout = new StaticLayout(tempErrorText != null ? tempErrorText : helperText, textPaint, getWidth() - getBottomTextLeftOffset() - getBottomTextRightOffset() - getPaddingLeft() - getPaddingRight(), alignment, 1.0f, 0.0f, true);
    destBottomLines = Math.max(textLayout.getLineCount(), minBottomTextLines);
  } else {
    destBottomLines = minBottomLines;
  }
  if (bottomLines != destBottomLines) {
    getBottomLinesAnimator(destBottomLines).start();
  }
  bottomLines = destBottomLines;
  return true;
}
 

int getGravity() {
    switch (this) {
        case TOP_LEFT:
            return Gravity.TOP | Gravity.LEFT;
        case TOP_CENTER:
            return Gravity.TOP | Gravity.CENTER_HORIZONTAL;
        case TOP_RIGHT:
            return Gravity.TOP | Gravity.RIGHT;
        case CENTER_LEFT:
            return Gravity.LEFT | Gravity.CENTER_VERTICAL;
        case CENTER:
            return Gravity.CENTER;
        case CENTER_RIGHT:
            return Gravity.RIGHT | Gravity.CENTER_VERTICAL;
        case BOTTOM_LEFT:
            return Gravity.BOTTOM | Gravity.LEFT;
        case BOTTOM_CENTER:
            return Gravity.BOTTOM | Gravity.CENTER_HORIZONTAL;
        case BOTTOM_RIGHT:
            return Gravity.BOTTOM | Gravity.RIGHT;
    }
    return Gravity.CENTER;
}
 

public MarginDrawerLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);

    final float density = getResources().getDisplayMetrics().density;
    mMinDrawerMargin = (int) (MIN_DRAWER_MARGIN * density + 0.5f);
    final float minVel = MIN_FLING_VELOCITY * density;

    mLeftCallback = new ViewDragCallback(Gravity.LEFT);
    mRightCallback = new ViewDragCallback(Gravity.RIGHT);

    mLeftDragger = ViewDragHelper.create(this, TOUCH_SLOP_SENSITIVITY, mLeftCallback);
    mLeftDragger.setEdgeTrackingEnabled(ViewDragHelper.EDGE_LEFT);
    mLeftDragger.setMinVelocity(minVel);
    mLeftCallback.setDragger(mLeftDragger);

    mRightDragger = ViewDragHelper.create(this, TOUCH_SLOP_SENSITIVITY, mRightCallback);
    mRightDragger.setEdgeTrackingEnabled(ViewDragHelper.EDGE_RIGHT);
    mRightDragger.setMinVelocity(minVel);
    mRightCallback.setDragger(mRightDragger);

    // So that we can catch the back button
    setFocusableInTouchMode(true);

    ViewCompat.setAccessibilityDelegate(this, new AccessibilityDelegate());
    ViewGroupCompat.setMotionEventSplittingEnabled(this, false);
}
 

/**
 * Set a simple drawable used for the left or right shadow.
 * The drawable provided must have a nonzero intrinsic width.
 *
 * @param shadowDrawable Shadow drawable to use at the edge of a drawer
 * @param gravity Which drawer the shadow should apply to
 */
public void setDrawerShadow(Drawable shadowDrawable, @EdgeGravity int gravity) {
    /*
     * TODO Someone someday might want to set more complex drawables here.
     * They're probably nuts, but we might want to consider registering callbacks,
     * setting states, etc. properly.
     */

    final int absGravity = GravityCompat.getAbsoluteGravity(gravity,
            ViewCompat.getLayoutDirection(this));
    if ((absGravity & Gravity.LEFT) == Gravity.LEFT) {
        mShadowLeft = shadowDrawable;
        invalidate();
    }
    if ((absGravity & Gravity.RIGHT) == Gravity.RIGHT) {
        mShadowRight = shadowDrawable;
        invalidate();
    }
}
 

private void measuredOutContentStart(String content) {
    Rect rect = new Rect();
    paintOuterText.getTextBounds(content, 0, content.length(), rect);
    switch (mGravity) {
        case Gravity.CENTER:
            if (isOptions || label == null || label.equals("") || !isCenterLabel) {
                drawOutContentStart = (int) ((measuredWidth - rect.width()) * 0.5);
            } else {//只显示中间label时，时间选择器内容偏左一点，留出空间绘制单位标签
                drawOutContentStart = (int) ((measuredWidth - rect.width()) * 0.25);
            }
            break;
        case Gravity.LEFT:
            drawOutContentStart = 0;
            break;
        case Gravity.RIGHT:
            drawOutContentStart = measuredWidth - rect.width() - (int) CENTER_CONTENT_OFFSET;
            break;
    }
}
 

/**
 * @return True, if adjustments were made that require the view to be invalidated.
 */
private boolean adjustBottomLines() {
  // Bail out if we have a zero width; lines will be adjusted during next layout.
  if (getWidth() == 0) {
    return false;
  }
  int destBottomLines;
  textPaint.setTextSize(bottomTextSize);
  if (tempErrorText != null || helperText != null) {
    Layout.Alignment alignment = (getGravity() & Gravity.RIGHT) == Gravity.RIGHT || isRTL() ?
      Layout.Alignment.ALIGN_OPPOSITE : (getGravity() & Gravity.LEFT) == Gravity.LEFT ?
      Layout.Alignment.ALIGN_NORMAL : Layout.Alignment.ALIGN_CENTER;
    textLayout = new StaticLayout(tempErrorText != null ? tempErrorText : helperText, textPaint, getWidth() - getBottomTextLeftOffset() - getBottomTextRightOffset() - getPaddingLeft() - getPaddingRight(), alignment, 1.0f, 0.0f, true);
    destBottomLines = Math.max(textLayout.getLineCount(), minBottomTextLines);
  } else {
    destBottomLines = minBottomLines;
  }
  if (bottomLines != destBottomLines) {
    getBottomLinesAnimator(destBottomLines).start();
  }
  bottomLines = destBottomLines;
  return true;
}
 

public KlyphDrawerLayout(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);

    final float density = getResources().getDisplayMetrics().density;
    mMinDrawerMargin = (int) (MIN_DRAWER_MARGIN * density + 0.5f);
    final float minVel = MIN_FLING_VELOCITY * density;

    mLeftCallback = new ViewDragCallback(Gravity.LEFT);
    mRightCallback = new ViewDragCallback(Gravity.RIGHT);

    mLeftDragger = ViewDragHelper.create(this, 0.5f, mLeftCallback);
    mLeftDragger.setEdgeTrackingEnabled(ViewDragHelper.EDGE_LEFT);
    mLeftDragger.setMinVelocity(minVel);
    mLeftCallback.setDragger(mLeftDragger);

    mRightDragger = ViewDragHelper.create(this, 0.5f, mRightCallback);
    mRightDragger.setEdgeTrackingEnabled(ViewDragHelper.EDGE_RIGHT);
    mRightDragger.setMinVelocity(minVel);
    mRightCallback.setDragger(mRightDragger);

    // So that we can catch the back button
    setFocusableInTouchMode(true);

    ViewCompat.setAccessibilityDelegate(this, new AccessibilityDelegate());
    ViewGroupCompat.setMotionEventSplittingEnabled(this, false);
}
 

@Override
public void onDrawerSlide(@NonNull View drawerView, float slideOffset) {
    int gravity = getSideMenuGravity(drawerView);
    if (gravity == Gravity.LEFT) {
        dispatchSideMenuVisibilityEvents(left, prevLeftSlideOffset, slideOffset);
        prevLeftSlideOffset = slideOffset;
    } else if (gravity == Gravity.RIGHT) {
        dispatchSideMenuVisibilityEvents(right, prevRightSlideOffset, slideOffset);
        prevRightSlideOffset = slideOffset;
    }
}
 

private static NavigationBarPosition gravityToNavigationBarPosition(int gravity) {
    switch (gravity) {
        case Gravity.BOTTOM:
            return NavigationBarPosition.BOTTOM;
        case Gravity.LEFT:
            return NavigationBarPosition.LEFT;
        case Gravity.RIGHT:
            return NavigationBarPosition.RIGHT;
        default:
            return NavigationBarPosition.UNKNOWN;
    }
}
 

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mRootView = findViewById(R.id.layout_root);

    Button toogleButton = new Button(this);
    toogleButton.setText("切换");
    toogleButton.setOnClickListener(this);
    FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
            ViewGroup.LayoutParams.WRAP_CONTENT, Gravity.RIGHT);
    addContentView(toogleButton, params);
}
 

private void applyLayoutParams() {

		FrameLayout.LayoutParams lp = new FrameLayout.LayoutParams(
				LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);

		switch (badgePosition) {
		case POSITION_TOP_LEFT:
			lp.gravity = Gravity.LEFT | Gravity.TOP;
			lp.setMargins(badgeMarginH, badgeMarginV, 0, 0);
			break;
		case POSITION_TOP_RIGHT:
			lp.gravity = Gravity.RIGHT | Gravity.TOP;
			lp.setMargins(0, badgeMarginV, badgeMarginH, 0);
			break;
		case POSITION_BOTTOM_LEFT:
			lp.gravity = Gravity.LEFT | Gravity.BOTTOM;
			lp.setMargins(badgeMarginH, 0, 0, badgeMarginV);
			break;
		case POSITION_BOTTOM_RIGHT:
			lp.gravity = Gravity.RIGHT | Gravity.BOTTOM;
			lp.setMargins(0, 0, badgeMarginH, badgeMarginV);
			break;
		case POSITION_CENTER:
			lp.gravity = Gravity.CENTER;
			lp.setMargins(0, 0, 0, 0);
			break;
		default:
			break;
		}
		setLayoutParams(lp);
	}
 

public Builder(Activity activity) {
    this.activity = activity;

    // Default FloatingActionButton settings
    int size = activity.getResources().getDimensionPixelSize(R.dimen.action_button_size);
    int margin = activity.getResources().getDimensionPixelSize(R.dimen.action_button_margin);
    LayoutParams layoutParams = new LayoutParams(size, size, Gravity.BOTTOM | Gravity.RIGHT);
    layoutParams.setMargins(margin, margin, margin, margin);
    setLayoutParams(layoutParams);
    setTheme(FloatingActionButton.THEME_LIGHT);
    setPosition(FloatingActionButton.POSITION_BOTTOM_RIGHT);
}
 

private int getDotGravity() {
    switch (mDotLocation){
        case 0:
            return Gravity.CENTER;
        case 1:
            return Gravity.RIGHT;
        case -1:
            return Gravity.LEFT;
    }
    return -1;
}
 

@Override
public void onParseValueFinished() {
    super.onParseValueFinished();
    mNative.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
    mNative.setBorderColor(mBorderColor);
    mNative.setBorderWidth(mBorderWidth);
    mNative.setBorderTopLeftRadius(mBorderTopLeftRadius);
    mNative.setBorderTopRightRadius(mBorderTopRightRadius);
    mNative.setBorderBottomLeftRadius(mBorderBottomLeftRadius);
    mNative.setBorderBottomRightRadius(mBorderBottomRightRadius);
    mNative.setBackgroundColor(mBackground);
    mNative.setTextColor(mTextColor);

    int flag = Paint.ANTI_ALIAS_FLAG;
    if (0 != (mTextStyle & TextBaseCommon.BOLD)) {
        flag |= Paint.FAKE_BOLD_TEXT_FLAG;
    }
    if (0 != (mTextStyle & TextBaseCommon.STRIKE)) {
        flag |= Paint.STRIKE_THRU_TEXT_FLAG;
    }
    if (0 != (mTextStyle & TextBaseCommon.UNDERLINE)) {
        flag |= Paint.UNDERLINE_TEXT_FLAG;
    }
    mNative.setPaintFlags(flag);

    if (0 != (mTextStyle & TextBaseCommon.ITALIC)) {
        mNative.setTypeface(null, Typeface.BOLD_ITALIC);
    }

    if (mLines > 0) {
        mNative.setLines(mLines);
    }

    if (mEllipsize >= 0) {
        mNative.setEllipsize(TextUtils.TruncateAt.values()[mEllipsize]);
    }

    int gravity = 0;
    if (0 != (mGravity & ViewBaseCommon.LEFT)) {
        gravity |= Gravity.LEFT;
    } else if (0 != (mGravity & ViewBaseCommon.RIGHT)) {
        gravity |= Gravity.RIGHT;
    } else if (0 != (mGravity & ViewBaseCommon.H_CENTER)) {
        gravity |= Gravity.CENTER_HORIZONTAL;
    }

    if (0 != (mGravity & ViewBaseCommon.TOP)) {
        gravity |= Gravity.TOP;
    } else if (0 != (mGravity & ViewBaseCommon.BOTTOM)) {
        gravity |= Gravity.BOTTOM;
    } else if (0 != (mGravity & ViewBaseCommon.V_CENTER)) {
        gravity |= Gravity.CENTER_VERTICAL;
    }
    mNative.setGravity(gravity);

    mNative.setLineSpacing(mLineSpaceExtra, mLineSpaceMultipiler);

    if (!TextUtils.isEmpty(mText)) {
        setRealText(mText);
    } else {
        setRealText("");
    }
}
 

@Override
public void onCreate ()
{
	super.onCreate ();

	this.wm = (WindowManager) this.getSystemService (WINDOW_SERVICE);

	LayoutInflater inflater = (LayoutInflater) this.getSystemService (Service.LAYOUT_INFLATER_SERVICE);
	this.layout = (LinearLayout) inflater.inflate (R.layout.service_launcher, null, false);

	this.llLauncher = (LinearLayout) this.layout.findViewById (R.id.llLauncher);
	this.llListenerContainer = (LinearLayout) this.layout.findViewById (R.id.llListenerContainer);
	this.llListener = (LinearLayout) this.layout.findViewById (R.id.llListener);
	this.llShadow = (LinearLayout) this.layout.findViewById (R.id.llShadow);

	WindowManager.LayoutParams params = new WindowManager.LayoutParams(
		WindowManager.LayoutParams.WRAP_CONTENT,
		WindowManager.LayoutParams.MATCH_PARENT,
		WindowManager.LayoutParams.TYPE_PHONE,
		WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
		PixelFormat.TRANSLUCENT);

	params.gravity = Gravity.TOP | Gravity.LEFT;
	params.x = 0;
	params.y = 0;

	be.robinj.distrohopper.desktop.launcher.AppLauncher lalBfb = (be.robinj.distrohopper.desktop.launcher.AppLauncher) this.layout.findViewById (R.id.lalBfb);
	lalBfb.setColour (R.color.transparentblack80);
	lalBfb.init ();

	SharedPreferences prefs = Preferences.getSharedPreferences(this, Preferences.PREFERENCES);
	boolean right = prefs.getInt(Preference.LAUNCHER_EDGE.getName(), Location.LEFT.n) == Location.RIGHT.n;

	this.touchListener = new TouchListener (this, right);
	if (right)
	{
		params.gravity = Gravity.TOP | Gravity.RIGHT;

		this.layout.removeView (this.llLauncher);
		this.layout.removeView (this.llListenerContainer);
		this.layout.removeView (this.llShadow);

		this.llShadow.setBackgroundResource (R.drawable.launcherservice_shadow_right);

		this.layout.addView (this.llShadow);
		this.layout.addView (this.llListenerContainer);
		this.layout.addView (this.llLauncher);
	}

	lalBfb.setOnTouchListener (this.touchListener);
	this.llListener.setOnTouchListener (this.touchListener);
	this.llShadow.setOnTouchListener (this.touchListener);

	/*
	LayoutTransition layout_transition = new LayoutTransition ();
	layout_transition.setStartDelay (LayoutTransition.APPEARING, 0);
	layout_transition.setStartDelay (LayoutTransition.DISAPPEARING, 0);
	this.layout.setLayoutTransition (layout_transition);
	*/

	this.wm.addView (this.layout, params);
}
 

@OnClick({R.id.btn_color, R.id.btn_left, R.id.btn_top, R.id.btn_triangle,
        R.id.btn_text1_minus, R.id.btn_text1_plus, R.id.btn_height1_minus, R.id.btn_height1_plus,
        R.id.btn_text2_minus, R.id.btn_text2_plus, R.id.btn_height2_minus, R.id.btn_height2_plus})
@Override
public void onClick(View v) {
    super.onClick(v);
    switch (v.getId()) {
        case R.id.btn_color:
            labelView.setFillColor(0xff000000 | RandomUtils.getRandom(0, 0xffffff));
            break;
        case R.id.btn_left:
            if (mIsLeft) {
                labelView.right();
            } else {
                labelView.left();
            }
            mIsLeft = !mIsLeft;
            FrameLayout.LayoutParams lp = (FrameLayout.LayoutParams) labelView.getLayoutParams();
            lp.gravity = (mIsLeft ? Gravity.LEFT : Gravity.RIGHT) | (mIsTop ? Gravity.TOP : Gravity.BOTTOM);
            labelView.setLayoutParams(lp);
            break;
        case R.id.btn_top:
            if (mIsTop) {
                labelView.bottom();
            } else {
                labelView.top();
            }
            mIsTop = !mIsTop;
            FrameLayout.LayoutParams lp2 = (FrameLayout.LayoutParams) labelView.getLayoutParams();
            lp2.gravity = (mIsLeft ? Gravity.LEFT : Gravity.RIGHT) | (mIsTop ? Gravity.TOP : Gravity.BOTTOM);
            labelView.setLayoutParams(lp2);
            break;
        case R.id.btn_triangle:
            mIsTriangle = !mIsTriangle;
            labelView.triangle(mIsTriangle);
            break;
        case R.id.btn_text1_minus:
            mText1Index = (mText1Index - 1 + TEXTS.length) % TEXTS.length;
            labelView.setText1(TEXTS[mText1Index]);
            break;
        case R.id.btn_text1_plus:
            mText1Index = (mText1Index + 1) % TEXTS.length;
            labelView.setText1(TEXTS[mText1Index]);
            break;
        case R.id.btn_height1_minus:
            if (mText1Height < 8) break;
            mText1Height -= 2;
            convertPx = SizeUtils.spConvertPx(mText1Height);
            labelView.setTextHeight1(convertPx);
            labelView.setPaddingTop(convertPx);
            labelView.setPaddingCenter(convertPx / 3);
            labelView.setPaddingBottom(convertPx / 3);
            break;
        case R.id.btn_height1_plus:
            if (mText1Height > 30) break;
            mText1Height += 2;
            convertPx = SizeUtils.spConvertPx(mText1Height);
            labelView.setTextHeight1(convertPx);
            labelView.setPaddingTop(convertPx);
            labelView.setPaddingCenter(convertPx / 3);
            labelView.setPaddingBottom(convertPx / 3);
            break;
        case R.id.btn_text2_minus:
            mText2Index = (mText2Index + 5 - 1) % 5;
            labelView.setText2("1234567890".substring(0, mText2Index));
            break;
        case R.id.btn_text2_plus:
            mText2Index = (mText2Index + 5 + 1) % 5;
            labelView.setText2("1234567890".substring(0, mText2Index));
            break;
        case R.id.btn_height2_minus:
            if (mText2Height < 4) break;
            mText2Height -= 2;
            convertPx = SizeUtils.spConvertPx(mText2Height);
            labelView.setTextHeight2(convertPx);
            break;
        case R.id.btn_height2_plus:
            if (mText2Height > 20) break;
            mText2Height += 2;
            convertPx = SizeUtils.spConvertPx(mText2Height);
            labelView.setTextHeight2(convertPx);
            break;
    }
}
 

protected void layoutOtherView(View child, int parentRight, int parentBottom) {
    final int width = child.getMeasuredWidth();
    final int height = child.getMeasuredHeight();
    int childLeft, childTop;
    final LayoutParams lp = (LayoutParams) child.getLayoutParams();
    final int gravity = lp.gravity;
    final int layoutDirection = ViewCompat.getLayoutDirection(this);
    final int absoluteGravity = GravityCompat.getAbsoluteGravity(gravity, layoutDirection);
    final int verticalGravity = gravity & Gravity.VERTICAL_GRAVITY_MASK;
    switch (absoluteGravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
        case Gravity.CENTER_HORIZONTAL:
            childLeft =
                    (int)
                            (getPaddingLeft()
                                    + (parentRight - getPaddingLeft() - width) / 2f
                                    + lp.leftMargin
                                    - lp.rightMargin);
            break;
        case Gravity.RIGHT:
            childLeft = parentRight - width - lp.rightMargin;
            break;
        default:
            childLeft = getPaddingLeft() + lp.leftMargin;
    }
    switch (verticalGravity) {
        case Gravity.CENTER_VERTICAL:
            childTop =
                    (int)
                            (getPaddingTop()
                                    + (parentBottom - getPaddingTop() - height) / 2f
                                    + lp.topMargin
                                    - lp.bottomMargin);
            break;
        case Gravity.BOTTOM:
            childTop = parentBottom - height - lp.bottomMargin;
            break;
        default:
            childTop = getPaddingTop() + lp.topMargin;
    }
    child.layout(childLeft, childTop, childLeft + width, childTop + height);
    if (sDebug) {
        Log.d(
                TAG,
                String.format(
                        "onLayout(): child: %d %d %d %d",
                        childLeft, childTop, childLeft + width, childTop + height));
    }
}
 

/**
 * 创建
 */
@SuppressLint("RtlHardcoded")
public BasePopupWindow create() {

    // 判断布局是否为空
    if (mContentView == null) {
        throw new IllegalArgumentException("are you ok?");
    }

    // 如果当前没有设置重心，就设置一个默认的重心
    if (mGravity == DEFAULT_ANCHORED_GRAVITY) {
        mGravity = Gravity.CENTER;
    }

    // 如果当前没有设置动画效果，就设置一个默认的动画效果
    if (mAnimations == AnimAction.NO_ANIM) {
        switch (mGravity) {
            case Gravity.TOP:
                mAnimations = AnimAction.TOP;
                break;
            case Gravity.BOTTOM:
                mAnimations = AnimAction.BOTTOM;
                break;
            case Gravity.LEFT:
                mAnimations = AnimAction.LEFT;
                break;
            case Gravity.RIGHT:
                mAnimations = AnimAction.RIGHT;
                break;
            default:
                mAnimations = AnimAction.DEFAULT;
                break;
        }
    }

    mPopupWindow = createPopupWindow(mContext);
    mPopupWindow.setContentView(mContentView);
    mPopupWindow.setWidth(mWidth);
    mPopupWindow.setHeight(mHeight);
    mPopupWindow.setAnimationStyle(mAnimations);
    mPopupWindow.setTouchable(mTouchable);
    mPopupWindow.setFocusable(mFocusable);
    mPopupWindow.setOutsideTouchable(mOutsideTouchable);
    mPopupWindow.setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
    mPopupWindow.setBackgroundDimAmount(mBackgroundDimAmount);

    if (mOnShowListeners != null) {
        mPopupWindow.setOnShowListeners(mOnShowListeners);
    }

    if (mOnDismissListeners != null) {
        mPopupWindow.setOnDismissListeners(mOnDismissListeners);
    }

    for (int i = 0; mClickArray != null && i < mClickArray.size(); i++) {
        mContentView.findViewById(mClickArray.keyAt(i)).setOnClickListener(new BasePopupWindow.ViewClickWrapper(mPopupWindow, mClickArray.valueAt(i)));
    }
    return mPopupWindow;
}
 

/**
 * Creates an approximated cubic gradient using a multi-stop linear gradient. See
 * <a href="https://plus.google.com/+RomanNurik/posts/2QvHVFWrHZf">this post</a> for more
 * details.
 */
public static Drawable makeCubicGradientScrimDrawable(int baseColor, int numStops, int gravity) {

    // Generate a cache key by hashing together the inputs, based on the method described in the Effective Java book
    int cacheKeyHash = baseColor;
    cacheKeyHash = 31 * cacheKeyHash + numStops;
    cacheKeyHash = 31 * cacheKeyHash + gravity;

    Drawable cachedGradient = cubicGradientScrimCache.get(cacheKeyHash);
    if (cachedGradient != null) {
        return cachedGradient;
    }

    numStops = Math.max(numStops, 2);

    PaintDrawable paintDrawable = new PaintDrawable();
    paintDrawable.setShape(new RectShape());

    final int[] stopColors = new int[numStops];

    int red = Color.red(baseColor);
    int green = Color.green(baseColor);
    int blue = Color.blue(baseColor);
    int alpha = Color.alpha(baseColor);

    for (int i = 0; i < numStops; i++) {
        float x = i * 1f / (numStops - 1);
       /* float opacity = MathUtil.constrain(0, 1, (float) Math.pow(x, 3));
        stopColors[i] = Color.argb((int) (alpha * opacity), red, green, blue);*/
    }

    final float x0, x1, y0, y1;
    switch (gravity & Gravity.HORIZONTAL_GRAVITY_MASK) {
        case Gravity.LEFT:  x0 = 1; x1 = 0; break;
        case Gravity.RIGHT: x0 = 0; x1 = 1; break;
        default:            x0 = 0; x1 = 0; break;
    }
    switch (gravity & Gravity.VERTICAL_GRAVITY_MASK) {
        case Gravity.TOP:    y0 = 1; y1 = 0; break;
        case Gravity.BOTTOM: y0 = 0; y1 = 1; break;
        default:             y0 = 0; y1 = 0; break;
    }

    paintDrawable.setShaderFactory(new ShapeDrawable.ShaderFactory() {
        @Override
        public Shader resize(int width, int height) {
            LinearGradient linearGradient = new LinearGradient(
                    width * x0,
                    height * y0,
                    width * x1,
                    height * y1,
                    stopColors, null,
                    Shader.TileMode.CLAMP);
            return linearGradient;
        }
    });

    cubicGradientScrimCache.put(cacheKeyHash, paintDrawable);
    return paintDrawable;
}
 

/**
 * This method will be invoked when the current page is scrolled, either as part
 * of a programmatically initiated smooth scroll or a user initiated touch scroll.
 * If you override this method you must call through to the superclass implementation
 * (e.g. super.onPageScrolled(position, offset, offsetPixels)) before onPageScrolled
 * returns.
 *
 * @param position Position index of the first page currently being displayed.
 *                 Page position+1 will be visible if positionOffset is nonzero.
 * @param offset Value from [0, 1) indicating the offset from the page at position.
 * @param offsetPixels Value in pixels indicating the offset from position.
 */
protected void onPageScrolled(int position, float offset, int offsetPixels) {
    // Offset any decor views if needed - keep them on-screen at all times.
    if (mDecorChildCount > 0) {
        final int scrollX = getScrollX();
        int paddingLeft = getPaddingLeft();
        int paddingRight = getPaddingRight();
        final int width = getWidth();
        final int childCount = getChildCount();
        for (int i = 0; i < childCount; i++) {
            final View child = getChildAt(i);
            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
            if (!lp.isDecor) continue;

            final int hgrav = lp.gravity & Gravity.HORIZONTAL_GRAVITY_MASK;
            int childLeft = 0;
            switch (hgrav) {
                default:
                    childLeft = paddingLeft;
                    break;
                case Gravity.LEFT:
                    childLeft = paddingLeft;
                    paddingLeft += child.getWidth();
                    break;
                case Gravity.CENTER_HORIZONTAL:
                    childLeft = Math.max((width - child.getMeasuredWidth()) / 2,
                            paddingLeft);
                    break;
                case Gravity.RIGHT:
                    childLeft = width - paddingRight - child.getMeasuredWidth();
                    paddingRight += child.getMeasuredWidth();
                    break;
            }
            childLeft += scrollX;

            final int childOffset = childLeft - child.getLeft();
            if (childOffset != 0) {
                child.offsetLeftAndRight(childOffset);
            }
        }
    }

    if (mOnPageChangeListener != null) {
        mOnPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    if (mInternalPageChangeListener != null) {
        mInternalPageChangeListener.onPageScrolled(position, offset, offsetPixels);
    }
    mCalledSuper = true;
}