Android 自定义控件三种实现方法为:组合控件,自己绘制,继承原生控件.
2.自己绘制控件
熟悉view的绘制原理
1.measure用来测量View的宽和高。
2.layout用来确定View在父容器中放置的位置。
3.draw用来将view绘制在屏幕上
创建一个类CustomView继承View,实现点击事件接口OnClickListener
package t.s.com;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;
/**
* Created by Administrator on 2017/10/19.
*/
public class CustomView extends View implements View.OnClickListener {
// 定义画笔
private Paint mPaint;
// 用于获取文字的宽和高
private Rect mRect;
// 计数值,每点击一次本控件,其值增加1
private int mCount=0;
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
// 初始化画笔、Rect
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mRect = new Rect();
// 本控件的点击事件
setOnClickListener(this);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
mPaint.setColor(Color.BLACK);
// 绘制一个填充色为蓝色的矩形
canvas.drawRect(0, 0, getWidth(), getHeight(), mPaint);
mPaint.setColor(Color.WHITE);
mPaint.setTextSize(50);
String text = String.valueOf(mCount);
// 获取文字的宽和高
mPaint.getTextBounds(text, 0, text.length(), mRect);
float textWidth = mRect.width();
float textHeight = mRect.height();
// 绘制字符串
canvas.drawText("点了我"+text+"次", getWidth() / 2 - textWidth / 2, getHeight() / 2
+ textHeight / 2, mPaint);
}
@Override
public void onClick(View view) {
mCount++;
invalidate();
}
}
在activity_main.xml中引入该自定义布局:
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="t.s.com.MainActivity">
android:layout_width="match_parent"
android:layout_height="wrap_content" />
android:layout_width="300dp"
android:layout_height="200dp"
android:layout_gravity="center"/>
运行效果图
3.继承原生控件 下面以一个不允许输入表情的EditText作为例子
package t.s.com;
import android.annotation.SuppressLint;
import android.content.Context;
import android.text.Editable;
import android.text.Selection;
import android.text.Spannable;
import android.text.TextWatcher;
import android.util.AttributeSet;
import android.widget.EditText;
import android.widget.Toast;
/**
* Created by Administrator on 2017/6/5 0005.
*/
@SuppressLint("AppCompatCustomView")
public class EmoEditText extends EditText {
//输入表情前的光标位置
private int cursorPos;
//输入表情前EditText中的文本
private String inputAfterText;
//是否重置了EditText的内容
private boolean resetText;
private Context mContext;
public EmoEditText(Context context) {
super(context);
this.mContext = context;
initEditText();
}
public EmoEditText(Context context, AttributeSet attrs) {
super(context, attrs);
this.mContext = context;
initEditText();
}
public EmoEditText(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
this.mContext = context;
initEditText();
}
// 初始化edittext 控件
private void initEditText() {
addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int before, int count) {
if (!resetText) {
cursorPos = getSelectionEnd();
// 这里用s.toString()而不直接用s是因为如果用s,
// 那么,inputAfterText和s在内存中指向的是同一个地址,s改变了,
// inputAfterText也就改变了,那么表情过滤就失败了
inputAfterText= s.toString();
}
}
@Override
public void onTextChanged(CharSequence s, int start, int before, int count) {
if (!resetText) {
if (count >= 2) {//表情符号的字符长度最小为2
CharSequence input = s.subSequence(cursorPos, cursorPos + count);
if (containsEmoji(input.toString())) {
resetText = true;
Toast.makeText(mContext, "暂不支持表情评论哦", Toast.LENGTH_SHORT).show();
//是表情符号就将文本还原为输入表情符号之前的内容
setText(inputAfterText);
CharSequence text = getText();
if (text instanceof Spannable) {
Spannable spanText = (Spannable) text;
Selection.setSelection(spanText, text.length());
}
}
}
} else {
resetText = false;
}
}
@Override
public void afterTextChanged(Editable editable) {
}
});
}
/**
* 检测是否有emoji表情
*
* @param source
* @return
*/
public static boolean containsEmoji(String source) {
int len = source.length();
for (int i = 0; i < len; i++) {
char codePoint = source.charAt(i);
if (!isEmojiCharacter(codePoint)) { //如果不能匹配,则该字符是Emoji表情
return true;
}
}
return false;
}
/**
* 判断是否是Emoji
*
* @param codePoint 比较的单个字符
* @return
*/
private static boolean isEmojiCharacter(char codePoint) {
return (codePoint == 0x0) || (codePoint == 0x9) || (codePoint == 0xA) ||
(codePoint == 0xD) || ((codePoint >= 0x20) && (codePoint <= 0xD7FF)) ||
((codePoint >= 0xE000) && (codePoint <= 0xFFFD)) || ((codePoint >= 0x10000)
&& (codePoint <= 0x10FFFF));
}
}
然后在activity_main.xml引入该控件就可以了
android:layout_width="match_parent"
android:layout_height="wrap_content" />