Android计算字符串显示宽度

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字符串显示时的宽度通过字符串的个数/长度是没有办法取得

因为涉及到字体，大小，全角/半角，

甚至英文字i和T的宽度也是截然不同的。

使用下面的方法，可以取得字符串显示的宽度。

TextPaint paint = view.getPaint();

int width = Layout.getDesiredWidth(source, start, index, paint);

TextView view是显示字符串的TextView

CharSequence source 是字符串配列

int start是开始位置。

int index是字符个数

使用例：

mainActivity

-------------------------------------------------------------------------------------------------

        mItem = new ArrayList<String>();
        mItem.add("あいうえおーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーーー");
        if (progDataAryList != null) {
            for (int i = 0; i < progDataAryList.size(); i++) {
             mItem.add(((String[]) progDataAryList.get(i))[1]);
            }
        }

MyAdapter myAdapter = new MyAdapter(activity, R.layout.simple_list_item, R.id.simple_list_text1, mItem);

// アダプターを設定します
listView.setAdapter(myAdapter);

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private class MyAdapter extends ArrayAdapter<String> {
        private int mResource;
        private int mFieldId;
        private LayoutInflater mInflater;
        private List<String> mStringobjects = new ArrayList<String>();

public MyAdapter(Context context, int resource, int textViewResourceId, List<String> objects) {
super(context, resource, textViewResourceId, objects);

            mResource = resource;
            mFieldId = textViewResourceId;
            mInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            mStringobjects = objects;
        }

public View getView(int position, View convertView, ViewGroup parent) {

View view;
TextView text;

            if (convertView == null) {
                view = mInflater.inflate(mResource, parent, false);
            } else {
                view = convertView;
            }

            try {
                text = (TextView)view.findViewById(mFieldId);
            } catch (ClassCastException e) {
             String stack = Log.getStackTraceString(e);
                SaveLog.put(activity, stack);
                throw new IllegalStateException("resource ID error", e);
            }

text.setFilters(new InputFilter[] {new LineFeedFilter(text)});
text.setText(mStringobjects.get(position));

            ListView listView = (ListView) activity.findViewById(R.id.prog_listview1);
            if (position == listView.getCheckedItemPosition()) {
                if (convertView != null) {
                    convertView.setBackgroundResource(R.drawable.textviewtype2);
                }
            } else {
                if (convertView != null) {
                    convertView.setBackgroundColor(Color.TRANSPARENT);
                }
            }

            return view;
        }
    }

-------------------------------------------------------------------------------------------------

private class LineFeedFilter implements InputFilter {
private final TextView view;

        public LineFeedFilter(TextView view) {
            this.view = view;
        }

public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {

TextPaint paint = view.getPaint();
int width = view.getWidth() - view.getCompoundPaddingLeft() - view.getCompoundPaddingRight();

            if (width <= 0){
             ListView listView = (ListView) activity.findViewById(R.id.prog_listview1);
             width = listView.getWidth() - listView.getPaddingLeft() -listView.getPaddingRight()
               - view.getCompoundPaddingLeft() - view.getCompoundPaddingRight();
            }
            SpannableStringBuilder result = new SpannableStringBuilder();
            for (int index = start; index < end; index++) {
                if (Layout.getDesiredWidth(source, start, index + 1, paint) > width) {
                 // 幅を越えたら改行を挿入
                    result.append(source.subSequence(start, index));
                    result.append("\n");
                    start = index;

                } else if (source.charAt(index) == '\n') {
                 // 改行文字があれば、ここまで出力
                    result.append(source.subSequence(start, index));
                    start = index;
                }
            }

            if (start < end) {
             // 残りの文字を追加
                result.append(source.subSequence(start, end));
            }
            return result;
        }
    }

http://blog.sina.com.cn/s/blog_54109a580101beiw.html

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