core/java/com/android/internal/widget/ImageFloatingTextView.java

/*
 * Copyright (C) 2015 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License
 */

package com.android.internal.widget;

import android.annotation.Nullable;
import android.content.Context;
import android.os.Trace;
import android.text.BoringLayout;
import android.text.Layout;
import android.text.StaticLayout;
import android.text.TextUtils;
import android.text.method.TransformationMethod;
import android.util.AttributeSet;
import android.view.RemotableViewMethod;
import android.widget.RemoteViews;
import android.widget.TextView;

/**
 * A TextView that can float around an image on the end.
 *
 * @hide
 */
@RemoteViews.RemoteView
public class ImageFloatingTextView extends TextView {

    /** Number of lines from the top to indent. */
    private int mIndentLines = 0;
    /** Whether or not there is an image to indent for. */
    private boolean mHasImage = false;

    /** Resolved layout direction */
    private int mResolvedDirection = LAYOUT_DIRECTION_UNDEFINED;
    private int mMaxLinesForHeight = -1;
    private int mLayoutMaxLines = -1;
    private int mImageEndMargin;

    public ImageFloatingTextView(Context context) {
        this(context, null);
    }

    public ImageFloatingTextView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public ImageFloatingTextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr, 0);
    }

    public ImageFloatingTextView(Context context, AttributeSet attrs, int defStyleAttr,
            int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        setHyphenationFrequency(Layout.HYPHENATION_FREQUENCY_FULL_FAST);
        setBreakStrategy(Layout.BREAK_STRATEGY_HIGH_QUALITY);
    }

    @Override
    protected Layout makeSingleLayout(int wantWidth, BoringLayout.Metrics boring, int ellipsisWidth,
            Layout.Alignment alignment, boolean shouldEllipsize,
            TextUtils.TruncateAt effectiveEllipsize, boolean useSaved) {
        Trace.beginSection("ImageFloatingTextView#makeSingleLayout");
        TransformationMethod transformationMethod = getTransformationMethod();
        CharSequence text = getText();
        if (transformationMethod != null) {
            text = transformationMethod.getTransformation(text, this);
        }
        text = text == null ? "" : text;
        StaticLayout.Builder builder = StaticLayout.Builder.obtain(text, 0, text.length(),
                getPaint(), wantWidth)
                .setAlignment(alignment)
                .setTextDirection(getTextDirectionHeuristic())
                .setLineSpacing(getLineSpacingExtra(), getLineSpacingMultiplier())
                .setIncludePad(getIncludeFontPadding())
                .setUseLineSpacingFromFallbacks(true)
                .setBreakStrategy(getBreakStrategy())
                .setHyphenationFrequency(getHyphenationFrequency());
        int maxLines;
        if (mMaxLinesForHeight > 0) {
            maxLines = mMaxLinesForHeight;
        } else {
            maxLines = getMaxLines() >= 0 ? getMaxLines() : Integer.MAX_VALUE;
        }
        builder.setMaxLines(maxLines);
        mLayoutMaxLines = maxLines;
        if (shouldEllipsize) {
            builder.setEllipsize(effectiveEllipsize)
                    .setEllipsizedWidth(ellipsisWidth);
        }

        // we set the endmargin on the requested number of lines.
        int[] margins = null;
        if (mHasImage && mIndentLines > 0) {
            margins = new int[mIndentLines + 1];
            for (int i = 0; i < mIndentLines; i++) {
                margins[i] = mImageEndMargin;
            }
        }
        if (mResolvedDirection == LAYOUT_DIRECTION_RTL) {
            builder.setIndents(margins, null);
        } else {
            builder.setIndents(null, margins);
        }

        final StaticLayout result = builder.build();
        Trace.endSection();
        return result;
    }

    /**
     * @param imageEndMargin the end margin (in pixels) to indent the first few lines of the text
     */
    @RemotableViewMethod
    public void setImageEndMargin(int imageEndMargin) {
        if (mImageEndMargin != imageEndMargin) {
            mImageEndMargin = imageEndMargin;
            invalidateTextIfIndenting();
        }
    }

    /**
     * @param imageEndMarginDp the end margin (in dp) to indent the first few lines of the text
     */
    @RemotableViewMethod
    public void setImageEndMarginDp(float imageEndMarginDp) {
        setImageEndMargin(
                (int) (imageEndMarginDp * getResources().getDisplayMetrics().density));
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        Trace.beginSection("ImageFloatingTextView#onMeasure");
        int availableHeight = MeasureSpec.getSize(heightMeasureSpec) - mPaddingTop - mPaddingBottom;
        if (getLayout() != null && getLayout().getHeight() != availableHeight) {
            // We've been measured before and the new size is different than before, lets make sure
            // we reset the maximum lines, otherwise the last line of text may be partially cut off
            mMaxLinesForHeight = -1;
            nullLayouts();
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        Layout layout = getLayout();
        if (layout.getHeight() > availableHeight) {
            // With the existing layout, not all of our lines fit on the screen, let's find the
            // first one that fits and ellipsize at that one.
            int maxLines = layout.getLineCount();
            while (maxLines > 1 && layout.getLineBottom(maxLines - 1) > availableHeight) {
                maxLines--;
            }
            if (getMaxLines() > 0) {
                maxLines = Math.min(getMaxLines(), maxLines);
            }
            // Only if the number of lines is different from the current layout, we recreate it.
            if (maxLines != mLayoutMaxLines) {
                mMaxLinesForHeight = maxLines;
                nullLayouts();
                super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            }
        }
        Trace.endSection();
    }

    @Override
    public void onRtlPropertiesChanged(int layoutDirection) {
        super.onRtlPropertiesChanged(layoutDirection);

        if (layoutDirection != mResolvedDirection && isLayoutDirectionResolved()) {
            mResolvedDirection = layoutDirection;
            invalidateTextIfIndenting();
        }
    }

    private void invalidateTextIfIndenting() {
        if (mHasImage && mIndentLines > 0) {
            // Invalidate layout.
            nullLayouts();
            requestLayout();
        }
    }

    /**
     * @param hasImage whether there is an image to wrap text around.
     */
    @RemotableViewMethod
    public void setHasImage(boolean hasImage) {
        setHasImageAndNumIndentLines(hasImage, mIndentLines);
    }

    /**
     * @param lines the number of lines at the top that should be indented by indentEnd
     */
    @RemotableViewMethod
    public void setNumIndentLines(int lines) {
        setHasImageAndNumIndentLines(mHasImage, lines);
    }

    private void setHasImageAndNumIndentLines(boolean hasImage, int lines) {
        int oldEffectiveLines = mHasImage ? mIndentLines : 0;
        int newEffectiveLines = hasImage ? lines : 0;
        mIndentLines = lines;
        mHasImage = hasImage;
        if (oldEffectiveLines != newEffectiveLines) {
            // always invalidate layout.
            nullLayouts();
            requestLayout();
        }
    }
}