最近有个需求就是文字显示指定行数比如3行，超过3行时就在第三行的末尾显示省略号加“全文”。
效果类似今日头条和微博：
image.png
实现如下：
1、ShowAllTextView 继承TextView类
public class ShowAllTextView extends TextView {
/**全文按钮点击事件*/
private ShowAllSpan.OnAllSpanClickListener onAllSpanClickListener;
private int maxShowLines = 0; //最大显示行数
public ShowAllTextView(Context context) {
super(context);
}
public ShowAllTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}
/**调用此方法才有效果*/
public void setMyText(CharSequence text) {
super.setText(text);
post(new Runnable() {
@Override
public void run() {
addEllipsisAndAllAtEnd();
}
});
}
/**调用此方法才有效果*/
public void setMyText(int resId){
setMyText(getContext().getResources().getText(resId));
}
/**超过规定行数时, 在文末添加 "...全文"*/
private void addEllipsisAndAllAtEnd(){
if (maxShowLines > 0 && maxShowLines < getLineCount()) {
try {
int moreWidth = PaintUtils.getTheTextNeedWidth(getPaint(), "...全文");
/**加上...全文 长度超过了textView的宽度, 则多减去5个字符*/
if (getLayout().getLineRight(maxShowLines - 1) + moreWidth >= getLayout().getWidth()){
this.setText(getText().subSequence(0, getLayout().getLineEnd(maxShowLines - 1) - 5));
/**避免减5个字符后还是长度还是超出了,这里再减4个字符*/
if (getLayout().getLineRight(maxShowLines - 1) + moreWidth >= getLayout().getWidth()){
this.setText(getText().subSequence(0, getLayout().getLineEnd(maxShowLines - 1) - 4));
}
}else {
this.setText(getText().subSequence(0, getLayout().getLineEnd(maxShowLines - 1)));
}
if (getText().toString().endsWith("\n") && getText().length() >= 1){
this.setText(getText().subSequence(0, getText().length() - 1));
}
this.append("...");
SpannableString sb = new SpannableString("全文");
sb.setSpan(new ShowAllSpan(getContext(), onAllSpanClickListener), 0, sb.length(), Spanned.SPAN_INCLUSIVE_INCLUSIVE);
this.append(sb);
}catch (Exception e){}
}
}
public void setOnAllSpanClickListener(ShowAllSpan.OnAllSpanClickListener onAllSpanClickListener) {
this.onAllSpanClickListener = onAllSpanClickListener;
}
public int getMaxShowLines() {
return maxShowLines;
}
public void setMaxShowLines(int maxShowLines) {
this.maxShowLines = maxShowLines;
}
//实现span的点击
private ClickableSpan mPressedSpan = null;
private boolean result = false;
@Override
public boolean onTouchEvent(MotionEvent event) {
CharSequence text = getText();
Spannable spannable = Spannable.Factory.getInstance().newSpannable(text);
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
mPressedSpan = getPressedSpan(this, spannable, event);
if (mPressedSpan != null){
if (mPressedSpan instanceof ShowAllSpan){
((ShowAllSpan) mPressedSpan).setPressed(true);
}
Selection.setSelection(spannable, spannable.getSpanStart(mPressedSpan), spannable.getSpanEnd(mPressedSpan));
result = true;
}else {
result = false;
}
break;
case MotionEvent.ACTION_MOVE:
ClickableSpan mClickSpan = getPressedSpan(this, spannable, event);
if (mPressedSpan != null && mPressedSpan != mClickSpan){
if (mPressedSpan instanceof ShowAllSpan){
((ShowAllSpan) mPressedSpan).setPressed(false);
}
mPressedSpan = null;
Selection.removeSelection(spannable);
}
break;
case MotionEvent.ACTION_UP:
if (mPressedSpan != null){
if (mPressedSpan instanceof ShowAllSpan){
((ShowAllSpan) mPressedSpan).setPressed(false);
}
mPressedSpan.onClick(this);
}
mPressedSpan = null;
Selection.removeSelection(spannable);
break;
}
return result;
}
private ClickableSpan getPressedSpan(TextView textView, Spannable spannable, MotionEvent event) {
ClickableSpan mTouchSpan = null;
int x = (int) event.getX();
int y = (int) event.getY();
x -= textView.getTotalPaddingLeft();
x += textView.getScrollX();
y -= textView.getTotalPaddingTop();
y += textView.getScrollY();
Layout layout = getLayout();
int line = layout.getLineForVertical(y);
int off = layout.getOffsetForHorizontal(line, x);
ShowAllSpan[] spans = spannable.getSpans(off, off, ShowAllSpan.class);
if (spans != null && spans.length > 0){
mTouchSpan = spans[0];
}
return mTouchSpan;
}
}
2、ShowAllSpan 可点击的“全文”的span类
public class ShowAllSpan extends ClickableSpan {
private OnAllSpanClickListener clickListener;
private boolean isPressed = false;
private Context context;
public ShowAllSpan(Context context, OnAllSpanClickListener clickListener){
this.context = context;
this.clickListener = clickListener;
}
@Override
public void onClick(View widget) {
if (clickListener != null){
clickListener.onClick(widget);
}
}
public void setPressed(boolean pressed) {
isPressed = pressed;
}
public interface OnAllSpanClickListener{
void onClick(View widget);
}
@Override
public void updateDrawState(TextPaint ds) {
if (isPressed){
ds.bgColor = context.getResources().getColor(android.R.color.darker_gray);
}else {
ds.bgColor = context.getResources().getColor(android.R.color.transparent);
}
ds.setColor(context.getResources().getColor(android.R.color.holo_blue_light));
ds.setUnderlineText(false);
}
}
3、PaintUtils 画笔工具类
public class PaintUtils
/** 计算指定画笔下指定字符串需要的宽度*/
public static int getTheTextNeedWidth(Paint thePaint, String text) {
float[] widths = new float[text.length()];
thePaint.getTextWidths(text, widths);
int length = widths.length, nowLength = 0;
for (int i = 0; i < length; i++) {
nowLength += widths[i];
}
return nowLength;
}
}
4、测试demo：
public class ShowAllTextActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_showalltext);
ShowAllTextView tv_1 = (ShowAllTextView) findViewById(R.id.tv_1);
ShowAllTextView tv_2 = (ShowAllTextView) findViewById(R.id.tv_2);
tv_1.setMaxShowLines(3);
tv_1.setMyText("Dwayne Jones was a Jamaican 16-year-old who was killed by a violent mob " +
"in Montego Bay on the night of 21 July 2013, after he attended a dance party " +
"dressed in women's clothing. Perceived as effeminate, Jones had been bullied " +
"in school and rejected by his father, and had moved into a derelict house in " +
"Montego Bay with transgender friends. When some men at the dance party discovered " +
"that the cross-dressing Jones was not a woman, they confronted and attacked him. " +
"He was beaten, stabbed, shot, and run over by a car. Police investigated, " +
"but the murder remains unsolved. The death made news internationally. " +
"While voices on social media accused Jones of provoking his killers by ");
tv_1.setOnAllSpanClickListener(new ShowAllSpan.OnAllSpanClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(ShowAllTextActivity.this, "点击了全文1", Toast.LENGTH_SHORT).show();
}
});
tv_2.setMaxShowLines(5);
tv_2.setMyText("水温刚刚合适，服侍我的是那个面目清秀的男孩，他把手慢慢的挪到我两腿之间，抚摸着我白皙的长腿，他小心翼翼的为我脱毛，神情紧张，生怕弄疼了我。\n" +
"我就这样躺在白砂做的浴缸里，男孩轻轻的在我胸口，腹部均匀的涂抹浴盐，又在我的背部涂抹类似于橄榄油一样的护肤品。\n" +
"男孩从一旁取出一些瓶瓶罐罐的香料，他把一些类似于花瓣一样的红色的颗粒撒在我的周围，并用纱布把那种名贵的香料挤出汁液淋在我身上。我的身体愈加的酥软，真的太舒服了，男孩的手法娴熟，让我如痴如醉，他不断的在我沐浴的水中添加美白和使我皮肤细腻的香料。\n" +
"水温有些升高了。\n" +
"男孩突然把我已经瘫软的身体翻了过来，他分开我的双腿……\n" +
"他，他拿出了相机，居然在拍照，作为一只鸡，被偷拍是我们这一行的大忌，男孩把照片印在一本花名册上，我打赌那上面一定有很多鸡的照片，可能都是他找过的吧。\n" +
"可是我却，我却居然有些喜欢上这个男孩了。\n" +
"他还给我在水中沐浴的照片起了个奇怪的名字：“枸杞炖鸡汤。");
tv_2.setOnAllSpanClickListener(new ShowAllSpan.OnAllSpanClickListener() {
@Override
public void onClick(View view) {
Toast.makeText(ShowAllTextActivity.this, "点击了全文2", Toast.LENGTH_SHORT).show();
}
});
}
}
效果如下：
image.png
待优化：
int moreWidth = PaintUtils.getTheTextNeedWidth(getPaint(), "...全文");
/**加上...全文 长度超过了textView的宽度, 则多减去5个字符*/
if (getLayout().getLineRight(maxShowLines - 1) + moreWidth >= getLayout().getWidth()){
this.setText(getText().subSequence(0, getLayout().getLineEnd(maxShowLines - 1) - 5));
/**避免减5个字符后还是长度还是超出了,这里再减4个字符*/
if (getLayout().getLineRight(maxShowLines - 1) + moreWidth >= getLayout().getWidth()){
this.setText(getText().subSequence(0, getLayout().getLineEnd(maxShowLines - 1) - 4));
}
}
判断全文是否超出了本行的逻辑处理比较简单，需求没那么严格，暂时就这样。如果要严格在行末的位置，可以一个一个的减字符，直到可以刚好把“...全文”放下。
