增加ExpendTextView(textView增加...全文按钮)

app/src/main/java/com/gh/common/view/ExpendTextView.java

@@ -0,0 +1,107 @@
+package com.gh.common.view;
+
+import android.content.Context;
+import android.os.Build;
+import android.support.v4.content.ContextCompat;
+import android.text.Layout;
+import android.text.SpannableStringBuilder;
+import android.text.Spanned;
+import android.text.TextPaint;
+import android.text.method.LinkMovementMethod;
+import android.text.style.ClickableSpan;
+import android.util.AttributeSet;
+import android.view.View;
+
+import com.gh.gamecenter.R;
+
+public class ExpendTextView extends android.support.v7.widget.AppCompatTextView {
+
+    private CharSequence mSnapshotText;
+
+    private String mExpendText = "...全文";
+
+    private int mMaxLines = 3; // 由于sdk版本限制(getMaxLines) 这里设置默认值
+
+    private boolean mInitLayout = false;
+    private boolean mOpenLayout = false;
+
+    public ExpendTextView(Context context) {
+        super(context);
+    }
+
+    public ExpendTextView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+    }
+
+    public ExpendTextView(Context context, AttributeSet attrs, int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
+            mMaxLines = getMaxLines();
+        }
+    }
+
+    @Override
+    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
+        super.onLayout(changed, left, top, right, bottom);
+        if (mInitLayout && !mOpenLayout && getLineCount() > mMaxLines) {
+            mSnapshotText = getText();
+            mInitLayout = false;
+            showExpendButton();
+        }
+    }
+
+    @Override
+    public void setText(CharSequence text, BufferType type) {
+        mInitLayout = true;
+        super.setText(text, type);
+    }
+
+    private void showExpendButton() {
+        Layout layout = getLayout();
+        int start = layout.getLineStart(0);
+        int lastLineEnd = layout.getLineEnd(mMaxLines - 1);
+        int lastLineStart = layout.getLineStart(mMaxLines - 1);
+        float lastLineRight = layout.getLineRight(mMaxLines - 1);
+
+        int viewWidth = getWidth() - getPaddingRight() - getPaddingLeft();
+
+        TextPaint paint = getPaint();
+        float expendTextWidth = paint.measureText(mExpendText);
+        CharSequence content = mSnapshotText.subSequence(start, lastLineEnd);
+        if (viewWidth - lastLineRight > expendTextWidth) {
+            content = content.toString().trim() + mExpendText;
+        } else {
+            CharSequence lastText = mSnapshotText.subSequence(lastLineStart, lastLineEnd);
+            for (int i = 0; i < lastText.length(); i++) {
+                CharSequence sequence = lastText.subSequence(0, i);
+                float w = paint.measureText(sequence.toString());
+                if (viewWidth - w > expendTextWidth) {
+                    content = mSnapshotText.subSequence(start, lastLineStart + i) + mExpendText;
+                }
+            }
+        }
+        SpannableStringBuilder msp = new SpannableStringBuilder(content);
+        int length = msp.length();
+        msp.replace(length - mExpendText.length(), length, mExpendText);
+        msp.setSpan(new ClickableSpan() {
+            @Override
+            public void updateDrawState(TextPaint ds) {
+                super.updateDrawState(ds);
+                ds.setColor(ContextCompat.getColor(getContext(), R.color.theme));
+                ds.setUnderlineText(false);
+            }
+
+            @Override
+            public void onClick(View widget) {
+                mOpenLayout = true;
+                setMaxLines(Integer.MAX_VALUE);
+                setText(mSnapshotText);
+
+            }
+        }, length - mExpendText.length(), length, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
+
+        setText(msp);
+        setMovementMethod(LinkMovementMethod.getInstance());
+    }
+
+}