看到带下划线的Edittext，估计大家会嗤之以鼻，Edittext本就自带下划线，但我要实现的是下划线是有间隔的。我们先看看效果，如果觉得有值得学习的地方再往下看，省得浪费时间。
下划线EdittextView.jpg
相信各位看官看了效果，应该不会觉得那么简单了吧，但其实也不难。我们可以通过继承Edittext自定义View来实现。为啥非得继承Edittext呢？原因很简单，系统提供的Edittext可以获取键盘的输入，省去了我们不少麻烦事。开始我也是想通过继承View来实现的，显得更高大上，有逼可装。但在适配过程中发现，国内有的手机厂商的手机我们是监听不到用户键盘点击事件的，除了删除等一些公用的（估计是为了用户信息安全考虑），因此也就放弃了这种实现方式。啰嗦了半天，现在我们正式进入正题（下面是实现核心代码）：
private void init(AttributeSet attrs) {
density = getContext().getResources().getDisplayMetrics().density;
initDefaultAttributes();
initCustomAttributes(attrs);
initDataStructures();
initPaint();
}
private void initDataStructures() {
underlines = new Underline[underlineAmount];
}
private void initPaint() {
underlinePaint = new Paint();
underlinePaint.setColor(underlineColor);
underlinePaint.setStrokeWidth(underlineStrokeWidth);
underlinePaint.setStyle(Paint.Style.STROKE);
textPaint = new Paint();
textPaint.setTextSize(textSize);
textPaint.setColor(textColor);
textPaint.setAntiAlias(true);
textPaint.setTextAlign(Paint.Align.CENTER);
backgroundPaint = new Paint();
backgroundPaint.setColor(backgroundColor);
}
@Override
protected void onSelectionChanged(int selStart, int selEnd) {
super.onSelectionChanged(selStart, selEnd);
if (selStart == selEnd){
//使光标一直处于文末
setSelection(getText().length());
}
}
//设置下划线数量
public void setCodes(int codes) {
underlineAmount = codes;
initDataStructures();
}
private void initCustomAttributes(AttributeSet attrs) {
TypedArray attributes = getContext().obtainStyledAttributes(attrs, R.styleable.EditTextView);
try {
underlineColor = attributes.getColor(R.styleable.EditTextView_underline_color, underlineColor);
underlineAmount = attributes.getInt(R.styleable.EditTextView_codes, underlineAmount);
textColor = attributes.getInt(R.styleable.EditTextView_text_color, textColor);
textSize = attributes.getDimension(R.styleable.EditTextView_text_size, textSize);
backgroundColor = attributes.getColor(R.styleable.EditTextView_background_color, backgroundColor);
} finally {
attributes.recycle();
}
}
private void initDefaultAttributes() {
underlineStrokeWidth = 2 * density;
underlineWidth = 35 * density;
underlineReduction = 5 * density;
textSize = 15 * density;
textMarginBottom = 15 * density;
underlineColor = Color.parseColor("#cccccc");
textColor = Color.parseColor("#000000");
viewHeight = 50 * density;
underlineAmount = DEFAULT_CODES;
backgroundColor = Color.parseColor("#ffffff");
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged((int) ((underlineWidth + underlineReduction) * underlineAmount - underlineReduction), (int) viewHeight, oldw, oldh);
height = h;
width = w;
initRect();
initUnderline();
}
private void initRect() {
rectBackground = new RectF(0, 0, width, height);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension((int) ((underlineWidth + underlineReduction) * underlineAmount - underlineReduction), (int) viewHeight);
}
private void initUnderline() {
for (int i = 0; i < underlineAmount; i++) {
underlines[i] = createPath(i, underlineWidth);
}
}
private Underline createPath(int position, float sectionWidth) {
float fromX = (sectionWidth + underlineReduction) * (float) position;
return new Underline(fromX, height, fromX + sectionWidth, height);
}
@Override
protected void onDraw(Canvas canvas) {
//绘制白色背景将原有edittext遮住
canvas.drawRect(rectBackground, backgroundPaint);
for (int i = 0; i < underlines.length; i++) {
Underline sectionpath = underlines[i];
float fromX = sectionpath.getFromX();
float fromY = sectionpath.getFromY();
float toX = sectionpath.getToX();
float toY = sectionpath.getToY();
drawSection(fromX, fromY, toX, toY, canvas);
}
for (int i = 0; i < textLength; i++) {
drawCharacter(underlines[i].getFromX(), underlines[i].getToX(), getText().toString().charAt(i), canvas);
}
}
//绘制下划线
private void drawSection(float fromX, float fromY, float toX, float toY, Canvas canvas) {
Paint paint = underlinePaint;
canvas.drawLine(fromX, fromY, toX, toY, paint);
}
//绘制文字
private void drawCharacter(float fromX, float toX, Character character, Canvas canvas) {
float actualWidth = toX - fromX;
float centerWidth = actualWidth / 2;
float centerX = fromX + centerWidth;
canvas.drawText(String.valueOf(character), centerX, height - textMarginBottom, textPaint);
}
@Override
protected void onTextChanged(CharSequence text, int start, int lengthBefore, int lengthAfter) {
super.onTextChanged(text, start, lengthBefore, lengthAfter);
this.textLength = text.toString().length();
Editable text1 = getText();
if (text1.length() > underlineAmount){
setText(text1.subSequence(0, underlineAmount));
this.textLength = underlineAmount;
}
}
/**
* 下划线
*/
class Underline {
float fromX;
float fromY;
float toX;
float toY;
public Underline() {
}
public Underline(float fromX, float fromY, float toX, float toY) {
this.fromX = fromX;
this.fromY = fromY;
this.toX = toX;
this.toY = toY;
}
public void from(float x, float y) {
this.fromX = x;
this.fromY = y;
}
public void to(float x, float y) {
this.toX = x;
this.toY = y;
}
public float getFromX() {
return fromX;
}
public void setFromX(float fromX) {
this.fromX = fromX;
}
public float getFromY() {
return fromY;
}
public void setFromY(float fromY) {
this.fromY = fromY;
}
public float getToX() {
return toX;
}
public void setToX(float toX) {
this.toX = toX;
}
public float getToY() {
return toY;
}
public void setToY(float toY) {
this.toY = toY;
}
}
<declare-styleable name="EditTextView">
<!--下划线颜色-->
<attr name="underline_color" format="color" />
<!--文字颜色-->
<attr name="text_color" format="color" />
<!--下划线数量-->
<attr name="codes" format="integer" />
<!--字体大小-->
<attr name="text_size" format="dimension"/>
<!--背景颜色-->
<attr name="background_color" format="color"/>
</declare-styleable>
没错就是这么简单，一个能够控制输入数量、下划线颜色可设置且携带所有Edittext属性的自定义View就这么实现了。若要查看源码可访问我的仓库。欢迎Star、Fork或者有更好的实现方式的建议可在下面留言，谢谢。
