java/src/com/android/inputmethod/keyboard/TypefaceUtils.java

/*
 * Copyright (C) 2013 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.inputmethod.keyboard;

import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Typeface;
import android.util.SparseArray;

import com.android.inputmethod.latin.CollectionUtils;

public final class TypefaceUtils {
    private TypefaceUtils() {
        // This utility class is not publicly instantiable.
    }

    // This sparse array caches key label text height in pixel indexed by key label text size.
    private static final SparseArray<Float> sTextHeightCache = CollectionUtils.newSparseArray();
    // Working variable for the following method.
    private static final Rect sTextHeightBounds = new Rect();

    public static float getCharHeight(final char[] referenceChar, final Paint paint) {
        final int key = getCharGeometryCacheKey(referenceChar[0], paint);
        synchronized (sTextHeightCache) {
            final Float cachedValue = sTextHeightCache.get(key);
            if (cachedValue != null) {
                return cachedValue;
            }

            paint.getTextBounds(referenceChar, 0, 1, sTextHeightBounds);
            final float height = sTextHeightBounds.height();
            sTextHeightCache.put(key, height);
            return height;
        }
    }

    // This sparse array caches key label text width in pixel indexed by key label text size.
    private static final SparseArray<Float> sTextWidthCache = CollectionUtils.newSparseArray();
    // Working variable for the following method.
    private static final Rect sTextWidthBounds = new Rect();

    public static float getCharWidth(final char[] referenceChar, final Paint paint) {
        final int key = getCharGeometryCacheKey(referenceChar[0], paint);
        synchronized (sTextWidthCache) {
            final Float cachedValue = sTextWidthCache.get(key);
            if (cachedValue != null) {
                return cachedValue;
            }

            paint.getTextBounds(referenceChar, 0, 1, sTextWidthBounds);
            final float width = sTextWidthBounds.width();
            sTextWidthCache.put(key, width);
            return width;
        }
    }

    private static int getCharGeometryCacheKey(final char referenceChar, final Paint paint) {
        final int labelSize = (int)paint.getTextSize();
        final Typeface face = paint.getTypeface();
        final int codePointOffset = referenceChar << 15;
        if (face == Typeface.DEFAULT) {
            return codePointOffset + labelSize;
        } else if (face == Typeface.DEFAULT_BOLD) {
            return codePointOffset + labelSize + 0x1000;
        } else if (face == Typeface.MONOSPACE) {
            return codePointOffset + labelSize + 0x2000;
        } else {
            return codePointOffset + labelSize;
        }
    }

    public static float getLabelWidth(final String label, final Paint paint) {
        final Rect textBounds = new Rect();
        paint.getTextBounds(label, 0, label.length(), textBounds);
        return textBounds.width();
    }
}