android中提前獲取TextView行數
一般情況下,TextView的行數要等到其佈局完成後才能獲取到,否則如果直接呼叫textView.getLineCount()
函式獲取到的結果只會為0,那能不能提前獲取到TextView的行數呢,當然是肯定的。TextView內部的換行是通過一個StaticLayout的類來處理的,而且我們呼叫的getLineCount()方法最後也是呼叫的StaticLayout類中的getLineCount()方法,所以我們只需要建立一個和TextView內部一樣的StaticLayout就可以了,然後呼叫staticLayout.getLineCount()
方法就可以獲取到和當前TextView行數一樣的值了,但要注意一個前提條件就是保證TextView的width是已知的,否則也無法獲取到正確的行數。
/** * 提前獲取textview行數 */ public class TextViewLinesUtil { public static int getTextViewLines(TextView textView, int textViewWidth) { int width = textViewWidth - textView.getCompoundPaddingLeft() - textView.getCompoundPaddingRight(); StaticLayout staticLayout; if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) { staticLayout = getStaticLayout23(textView, width); } else { staticLayout = getStaticLayout(textView, width); } int lines = staticLayout.getLineCount(); int maxLines = textView.getMaxLines(); if (maxLines > lines) { return lines; } return maxLines; } /** * sdk>=23 */ @RequiresApi(api = Build.VERSION_CODES.M) private static StaticLayout getStaticLayout23(TextView textView, int width) { StaticLayout.Builder builder = StaticLayout.Builder.obtain(textView.getText(), 0, textView.getText().length(), textView.getPaint(), width) .setAlignment(Layout.Alignment.ALIGN_NORMAL) .setTextDirection(TextDirectionHeuristics.FIRSTSTRONG_LTR) .setLineSpacing(textView.getLineSpacingExtra(), textView.getLineSpacingMultiplier()) .setIncludePad(textView.getIncludeFontPadding()) .setBreakStrategy(textView.getBreakStrategy()) .setHyphenationFrequency(textView.getHyphenationFrequency()) .setMaxLines(textView.getMaxLines() == -1 ? Integer.MAX_VALUE : textView.getMaxLines()); if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) { builder.setJustificationMode(textView.getJustificationMode()); } if (textView.getEllipsize() != null && textView.getKeyListener() == null) { builder.setEllipsize(textView.getEllipsize()) .setEllipsizedWidth(width); } return builder.build(); } /** * sdk<23 */ private static StaticLayout getStaticLayout(TextView textView, int width) { return new StaticLayout(textView.getText(), 0, textView.getText().length(), textView.getPaint(), width, Layout.Alignment.ALIGN_NORMAL, textView.getLineSpacingMultiplier(), textView.getLineSpacingExtra(), textView.getIncludeFontPadding(), textView.getEllipsize(), width); } }