Android9.0 狀態欄圖標顯示“點號”怎麼辦

現象

狀態欄圖標顯示的個數有兩個限制：
1.最大個數限制8個（包括battery）：
2.寬度限制；
最終能夠顯示的圖標個數取這兩個限制的較小值。

相關代碼邏輯在com.android.systemui.statusbar.phone/StatusIconContainer.java類中：

 // Max 8 status icons including battery
 private static final int MAX_ICONS = 7;

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        mMeasureViews.clear();
        int mode = MeasureSpec.getMode(widthMeasureSpec);
        final int width = MeasureSpec.getSize(widthMeasureSpec);
        final int count = getChildCount();
        // Collect all of the views which want to be laid out
        for (int i = 0; i < count; i++) {
            StatusIconDisplayable icon = (StatusIconDisplayable) getChildAt(i);
            if (icon.isIconVisible() && !icon.isIconBlocked()) {
                mMeasureViews.add((View) icon);
            }
        }

        int visibleCount = mMeasureViews.size();
        int maxVisible = visibleCount <= MAX_ICONS ? MAX_ICONS : MAX_ICONS - 1;
        int totalWidth = mPaddingLeft + mPaddingRight;
        boolean trackWidth = true;

        // Measure all children so that they report the correct width
        int childWidthSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.UNSPECIFIED);
        mNeedsUnderflow = mShouldRestrictIcons && visibleCount > MAX_ICONS;
        for (int i = 0; i < mMeasureViews.size(); i++) {
            // Walking backwards
            View child = mMeasureViews.get(visibleCount - i - 1);
            measureChild(child, childWidthSpec, heightMeasureSpec);
            if (mShouldRestrictIcons) {
                if (i < maxVisible && trackWidth) {
                    totalWidth += getViewTotalMeasuredWidth(child);
                } else if (trackWidth) {
                    // We've hit the icon limit; add space for dots
                    totalWidth += mUnderflowWidth;
                    trackWidth = false;
                }
            } else {
                totalWidth += getViewTotalMeasuredWidth(child);
            }
        }

        if (mode == MeasureSpec.EXACTLY) {
            if (!mNeedsUnderflow && totalWidth > width) {
                mNeedsUnderflow = true;
            }
            setMeasuredDimension(width, MeasureSpec.getSize(heightMeasureSpec));
        } else {
            if (mode == MeasureSpec.AT_MOST && totalWidth > width) {
                mNeedsUnderflow = true;
                totalWidth = width;
            }
            setMeasuredDimension(totalWidth, MeasureSpec.getSize(heightMeasureSpec));
        }
    }

 /**
     * Layout is happening from end -> start
     */
    private void calculateIconTranslations() {
        mLayoutStates.clear();
        float width = getWidth();
        float translationX = width - getPaddingEnd();
        float contentStart = getPaddingStart();
        int childCount = getChildCount();
        // Underflow === don't show content until that index
        if (DEBUG) android.util.Log.d(TAG, "calculateIconTranslations: start=" + translationX
                + " width=" + width + " underflow=" + mNeedsUnderflow);

        // Collect all of the states which want to be visible
        for (int i = childCount - 1; i >= 0; i--) {
            View child = getChildAt(i);
            StatusIconDisplayable iconView = (StatusIconDisplayable) child;
            StatusIconState childState = getViewStateFromChild(child);

            if (!iconView.isIconVisible() || iconView.isIconBlocked()) {
                childState.visibleState = STATE_HIDDEN;
                if (DEBUG) Log.d(TAG, "skipping child (" + iconView.getSlot() + ") not visible");
                continue;
            }

            childState.visibleState = STATE_ICON;
            childState.xTranslation = translationX - getViewTotalWidth(child);
            mLayoutStates.add(0, childState);

            translationX -= getViewTotalWidth(child);
        }

        // Show either 1-MAX_ICONS icons, or (MAX_ICONS - 1) icons + overflow
        int totalVisible = mLayoutStates.size();
        int maxVisible = totalVisible <= MAX_ICONS ? MAX_ICONS : MAX_ICONS - 1;

        mUnderflowStart = 0;
        int visible = 0;
        int firstUnderflowIndex = -1;
        for (int i = totalVisible - 1; i >= 0; i--) {
            StatusIconState state = mLayoutStates.get(i);
            // Allow room for underflow if we found we need it in onMeasure
            if (mNeedsUnderflow && (state.xTranslation < (contentStart + mUnderflowWidth))||
                    (mShouldRestrictIcons && visible >= maxVisible)) {
                firstUnderflowIndex = i;
                break;
            }
            mUnderflowStart = (int) Math.max(contentStart, state.xTranslation - mUnderflowWidth);
            visible++;
        }

        if (firstUnderflowIndex != -1) {
            int totalDots = 0;
            int dotWidth = mStaticDotDiameter + mDotPadding;
            int dotOffset = mUnderflowStart + mUnderflowWidth - mIconDotFrameWidth;
            for (int i = firstUnderflowIndex; i >= 0; i--) {
                StatusIconState state = mLayoutStates.get(i);
                if (totalDots < MAX_DOTS) {
                    state.xTranslation = dotOffset;
                    state.visibleState = STATE_DOT;
                    dotOffset -= dotWidth;
                    totalDots++;
                } else {
                    state.visibleState = STATE_HIDDEN;
                }
            }
        }

        // Stole this from NotificationIconContainer. Not optimal but keeps the layout logic clean
        if (isLayoutRtl()) {
            for (int i = 0; i < childCount; i++) {
                View child = getChildAt(i);
                StatusIconState state = getViewStateFromChild(child);
                state.xTranslation = width - state.xTranslation - child.getWidth();
            }
        }
    }

寬度設定，可以看status_bar.xml:

<FrameLayout
            android:layout_height="match_parent"
            android:layout_width="0dp"
            android:layout_weight="1">

            <include layout="@layout/heads_up_status_bar_layout" />

            <!-- The alpha of the left side is controlled by PhoneStatusBarTransitions, and the
             individual views are controlled by StatusBarManager disable flags DISABLE_CLOCK and
             DISABLE_NOTIFICATION_ICONS, respectively -->
            <LinearLayout
                android:id="@+id/status_bar_left_side"
                android:layout_height="match_parent"
                android:layout_width="match_parent"
                android:clipChildren="false"
            >
                <com.android.systemui.statusbar.AlphaOptimizedFrameLayout
                    android:id="@+id/notification_icon_area"
                    android:layout_width="0dp"
                    android:layout_height="match_parent"
                    android:layout_weight="1"
                    android:orientation="horizontal"
                    android:clipChildren="false"/>

            </LinearLayout>
        </FrameLayout>

        <!-- Space should cover the notch (if it exists) and let other views lay out around it -->
        <android.widget.Space
            android:id="@+id/cutout_space_view"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:gravity="center_horizontal|center_vertical"
        />

        <com.android.keyguard.AlphaOptimizedLinearLayout android:id="@+id/system_icon_area"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:orientation="horizontal"
            android:gravity="center_vertical|end"
            >

            <include layout="@layout/system_icons" />
        </com.android.keyguard.AlphaOptimizedLinearLayout>

結論：從代碼可見通知圖標區域@+id/notification_icon_area和狀態欄圖標區域@+id/system_icon_area的layout_weight的比例是1:1，可以修改比例爲1:2或者3:4，增大狀態欄圖標的比例，從而能顯示更多的圖標。