LatinIME/java/src/com/android/inputmethod/keyboard/internal/KeyPreviewView.java

/*
 * Copyright (C) 2014 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.internal;

import android.content.Context;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.text.TextPaint;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.Gravity;
import android.widget.TextView;

import com.android.inputmethod.keyboard.Key;
import com.android.inputmethod.latin.R;

import java.util.HashSet;

/**
 * The pop up key preview view.
 */
public class KeyPreviewView extends TextView {
    public static final int POSITION_MIDDLE = 0;
    public static final int POSITION_LEFT = 1;
    public static final int POSITION_RIGHT = 2;

    private final Rect mBackgroundPadding = new Rect();
    private static final HashSet<String> sNoScaleXTextSet = new HashSet<>();

    public KeyPreviewView(final Context context, final AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public KeyPreviewView(final Context context, final AttributeSet attrs, final int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        setGravity(Gravity.CENTER);
    }

    public void setPreviewVisual(final Key key, final KeyboardIconsSet iconsSet,
            final KeyDrawParams drawParams) {
        // What we show as preview should match what we show on a key top in onDraw().
        final int iconId = key.getIconId();
        if (iconId != KeyboardIconsSet.ICON_UNDEFINED) {
            setCompoundDrawables(null, null, null, key.getPreviewIcon(iconsSet));
            setText(null);
            return;
        }

        setCompoundDrawables(null, null, null, null);
        setTextColor(drawParams.mPreviewTextColor);
        setTextSize(TypedValue.COMPLEX_UNIT_PX, key.selectPreviewTextSize(drawParams));
        setTypeface(key.selectPreviewTypeface(drawParams));
        // TODO Should take care of temporaryShiftLabel here.
        setTextAndScaleX(key.getPreviewLabel());
    }

    private void setTextAndScaleX(final String text) {
        setTextScaleX(1.0f);
        setText(text);
        if (sNoScaleXTextSet.contains(text)) {
            return;
        }
        // TODO: Override {@link #setBackground(Drawable)} that is supported from API 16 and
        // calculate maximum text width.
        final Drawable background = getBackground();
        if (background == null) {
            return;
        }
        background.getPadding(mBackgroundPadding);
        final int maxWidth = background.getIntrinsicWidth() - mBackgroundPadding.left
                - mBackgroundPadding.right;
        final float width = getTextWidth(text, getPaint());
        if (width <= maxWidth) {
            sNoScaleXTextSet.add(text);
            return;
        }
        setTextScaleX(maxWidth / width);
    }

    public static void clearTextCache() {
        sNoScaleXTextSet.clear();
    }

    private static float getTextWidth(final String text, final TextPaint paint) {
        if (TextUtils.isEmpty(text)) {
            return 0.0f;
        }
        final int len = text.length();
        final float[] widths = new float[len];
        final int count = paint.getTextWidths(text, 0, len, widths);
        float width = 0;
        for (int i = 0; i < count; i++) {
            width += widths[i];
        }
        return width;
    }

    // Background state set
    private static final int[][][] KEY_PREVIEW_BACKGROUND_STATE_TABLE = {
        { // POSITION_MIDDLE
            {},
            { R.attr.state_has_morekeys }
        },
        { // POSITION_LEFT
            { R.attr.state_left_edge },
            { R.attr.state_left_edge, R.attr.state_has_morekeys }
        },
        { // POSITION_RIGHT
            { R.attr.state_right_edge },
            { R.attr.state_right_edge, R.attr.state_has_morekeys }
        }
    };
    private static final int STATE_NORMAL = 0;
    private static final int STATE_HAS_MOREKEYS = 1;

    public void setPreviewBackground(final boolean hasMoreKeys, final int position) {
        final Drawable background = getBackground();
        if (background == null) {
            return;
        }
        final int hasMoreKeysState = hasMoreKeys ? STATE_HAS_MOREKEYS : STATE_NORMAL;
        background.setState(KEY_PREVIEW_BACKGROUND_STATE_TABLE[position][hasMoreKeysState]);
    }
}