Android自定义字母选择侧边栏

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
package com.zb.customview.widgets;
 
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
 
import androidx.annotation.Nullable;
 
import com.zb.customview.R;
 
public class LetterSideBar extends View {
 
    private Paint mPaint;
    private int color, selectedColor;
    private float textSize, spacing;
    private String mChoosing = "Z";
    private OnLetterSelectedListener listener;
    private int width, height;
 
    private String[] LETTERS = new String[] {"#", "A", "B", "C", "D", "E", "F",
            "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V",
            "W", "X", "Y", "Z"};
 
    public interface OnLetterSelectedListener {
        //空表示取消选中
        void onSelected(String letter);
    }
 
    public void setOnLetterSelectedListener(OnLetterSelectedListener listener) {
        this.listener = listener;
    }
 
    public LetterSideBar(Context context) {
        this(context, null);
    }
 
    public LetterSideBar(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        if(null != attrs) {
            TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.LetterSideBar);
            color = ta.getColor(R.styleable.LetterSideBar_LetterSideBar_textColor, Color.BLACK);
            selectedColor = ta.getColor(R.styleable.LetterSideBar_LetterSideBar_textSelectedColor, Color.RED);
            textSize = ta.getDimensionPixelSize(R.styleable.LetterSideBar_LetterSideBar_textSize, sp2px(12));
            spacing = ta.getDimensionPixelSize(R.styleable.LetterSideBar_LetterSideBar_spacing, dp2px(5));
            ta.recycle();
        }
        init();
    }
 
    private void init() {
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setColor(color);
        mPaint.setTextSize(textSize);
    }
 
    @Override
    protected void onDraw(Canvas canvas) {
        drawText(canvas);
        drawSelectedText(canvas, mChoosing);
    }
 
    private void drawText(Canvas canvas) {
        mPaint.setColor(color);
        for (int i=0; i<LETTERS.length; i++) {
            drawLetterAt(canvas, i, LETTERS[i]);
        }
    }
 
    private void drawSelectedText(Canvas canvas, String selected) {
        if(TextUtils.isEmpty(selected))
            return;
        mPaint.setColor(selectedColor);
        int position = -1;
        for(int i=0; i<LETTERS.length; i++) {
            if(selected.equals(LETTERS[i])) {
                position = i;
                break;
            }
        }
        if(position < 0 || position >= LETTERS.length)
            return;
        drawLetterAt(canvas, position, selected);
    }
 
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int action = event.getAction();
        switch (action) {
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_MOVE:
                float x = event.getX();
                float y = event.getY();
                if(isTouchInsideView(x, y)) {
                    //触摸在控件内
                    int position = caculatePosition(y);
                    if(position >= 0 && position < LETTERS.length) {
                        //合规位置
                        String letter = LETTERS[position];
                        if(!letter.equals(mChoosing)) { //与选中的不符 去刷新控件
                            mChoosing = letter;
                            performListener(mChoosing);
                            invalidate();
                        }
                    } else {
                        //不合规位置
                        if(null != mChoosing) {
                            mChoosing = null;
                            performListener(mChoosing);
                            invalidate();
                        }
                    }
                } else if(null != mChoosing) { //点击事件不在view内部
                    mChoosing = null;
                    performListener(mChoosing);
                    invalidate();//触摸在view之外 取消选中
                }
                return true;
            default:
                if(mChoosing != null) {
                    mChoosing = null;
                    performListener(mChoosing);
                    invalidate();
                }
                break;
        }
        return super.onTouchEvent(event);
    }
 
    private void performListener(String letter) {
        if(null != listener)
            listener.onSelected(letter);
    }
 
    private boolean isTouchInsideView(float x, float y) {
        //左右可以适当判断在控件内
        if(x >= 0 && x <= width && y >= getPaddingTop() && y < height)
            return true;
        return false;
    }
 
    /**
     * 计算触摸的位置
     * @param y
     * @return
     */
    private int caculatePosition(float y) {
        float heightWithOutPadding = height - getPaddingTop() - getPaddingBottom();
        float eachElementHeight = heightWithOutPadding / LETTERS.length;
        y -= getPaddingTop();
        int position = (int) (y / eachElementHeight);
        return position;
    }
 
    private void drawLetterAt(Canvas canvas, int position, String letter) {
 
        float heightForEach = ((height * 1f - getPaddingTop() - getPaddingBottom())
                - (LETTERS.length - 1) * spacing) / LETTERS.length;
        float spacingInUp = spacing * (position - 1);
        if(spacingInUp < 0)
            spacingInUp = 0;
        float currentTop = getPaddingTop() + (heightForEach * position) + spacingInUp;
        float currentBottom = currentTop + heightForEach;
        Paint.FontMetrics fmi = mPaint.getFontMetrics();
        float x = (width - getPaddingLeft() - getPaddingRight() - mPaint.measureText(letter)) / 2f + getPaddingLeft();
        float baseLine = (fmi.descent + Math.abs(fmi.ascent)) / 2f - fmi.descent;
        float y = (currentBottom + currentTop) / 2f + baseLine;
        canvas.drawText(letter, 0, 1, x, y, mPaint);
    }
 
    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        if(changed) {
            width = getWidth();
            height = getHeight();
        }
    }
 
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int textWidth = (int) (getPaddingLeft() + getPaddingRight() + mPaint.measureText("A"));
        Rect textBounds = new Rect();
        mPaint.getTextBounds("A", 0, 1, textBounds);
        int singleTextHeight = textBounds.height();
        int totalHeight = (int) (27f * singleTextHeight + 26f * spacing) + getPaddingBottom() + getPaddingTop();//26个字母+1个#
 
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(widthMeasureSpec);
        int specWidth = MeasureSpec.getSize(widthMeasureSpec);
        int specHeight = MeasureSpec.getSize(widthMeasureSpec);
        int realWidth, realHeight;
        if(widthMode == MeasureSpec.EXACTLY) {
            realWidth = specWidth;
        } else {
            realWidth = textWidth;
        }
        if(heightMode == MeasureSpec.EXACTLY) {
            realHeight = specHeight;
        } else {
            realHeight = totalHeight;
        }
        setMeasuredDimension(realWidth, realHeight);
    }
 
    protected int dp2px(int dp) {
        return (int) (getContext().getResources().getDisplayMetrics().density * dp + 0.5);
    }
    protected int sp2px(int sp) {
        return (int) (getContext().getResources().getDisplayMetrics().scaledDensity * sp + 0.5);
    }
}

1
2
3
4
5
6
<declare-styleable name="LetterSideBar"> 
<attr name="LetterSideBar_textColor" format="color"/> 
<attr name="LetterSideBar_textSelectedColor" format="color"/> 
<attr name="LetterSideBar_textSize" format="dimension"/> 
<attr name="LetterSideBar_spacing" format="dimension"/> 
</declare-styleable>

1
2
3
4
5
6
7
8
9
10
11
12
13
<com.zb.customview.widgets.LetterSideBar
        android:id="@+id/letterSideBar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:LetterSideBar_textSize="14sp"
        app:LetterSideBar_textColor="#FFFFFF"
        android:padding="10dp"
        app:LetterSideBar_textSelectedColor="#FF0000"
        app:LetterSideBar_spacing="2dp"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        android:background="#A4A4A4"/>

1
2
3
4
5
6
7
8
9
10
11
12
13
sideBar.setOnLetterSelectedListener(new LetterSideBar.OnLetterSelectedListener() {
            @Override
            public void onSelected(String letter) {
                if(TextUtils.isEmpty(letter)) {
                    P.p("取消选中");
                    letterTxt.setVisibility(View.GONE);
                } else {
                    P.p("选中" + letter);
                    letterTxt.setText(letter);
                    letterTxt.setVisibility(View.VISIBLE);
                }
            }
        });