Bug- solve the display length limitation of log distinguished character encoding (edittext+lengthfilter)

BUG Fix Log 001 EditText Distinguish the display length limit of character encoding

EditText Distinguish the display length limit of character encoding

This article uses ： adopt EditText.setFilter() To put the expanded Filter（ filter ） Customize related functions

First, let's take the native implementation as an example

// TextView(EditView)#setFilters
public void setFilters(InputFilter[] filters) {
    
        if (filters == null) {
    
            throw new IllegalArgumentException();
        }

        mFilters = filters;

        if (mText instanceof Editable) {
    
            setFilters((Editable) mText, filters);
        }
    }

private InputFilter[] mFilters = NO_FILTERS;

private static final InputFilter[] NO_FILTERS = new InputFilter[0];

You can see in the EditText in ,xml attribute maxLens The function resolves to In code LengthFilter Realized

if (maxlength >= 0) {
    
	setFilters(new InputFilter[] {
     new InputFilter.LengthFilter(maxlength) });
} else {
    
	setFilters(NO_FILTERS);
}

// LengthFilter  yes  InputFilter  The only implemented internal static class 

public static class LengthFilter implements InputFilter {
    
        @UnsupportedAppUsage
        private final int mMax;

        public LengthFilter(int max) {
    
            mMax = max;
        }
		//  The important filtering logic is here 
        public CharSequence filter(CharSequence source, int start, int end, Spanned dest,
                int dstart, int dend) {
    
            int keep = mMax - (dest.length() - (dend - dstart));
            if (keep <= 0) {
    
                return "";
            } else if (keep >= end - start) {
    
                return null; // keep original
            } else {
    
                keep += start;
                if (Character.isHighSurrogate(source.charAt(keep - 1))) {
    
                    --keep;
                    if (keep == start) {
    
                        return "";
                    }
                }
                return source.subSequence(start, keep);
            }
        }

        /** * @return the maximum length enforced by this input filter */
        public int getMax() {
    
            return mMax;
        }
    }

We can go straight to LengthFilter Transform the packaging to achieve its own functions

public static class DisEngAndChLengthFilter extents InputFilter.LengthFilter {
    
	@override
	public CharSequence filter(CharSequence source, int start, int end, Spanned dest,
                                   int dstart, int dend) {
    
                                   
            CharSequence content = dest;
            int parseLen = 0;
            int ctnLen = content.length();
            int size = content.length();
            if(size > 0){
    
                while(ctnLen > 0){
    
                    char tmp =  content.charAt(size-ctnLen);
                    if(tmp >= 0x4E00 &&  tmp <= 0x9FA5){
    
                        parseLen+=2;
                    }else {
    
                        parseLen+=1;
                    }
                    ctnLen--;
                }
            }
            //mMax = parseLen;
            LogUtil.d(TAG+"sourceLen"+source.length()+"source"+source+"start:"+start+"end:"+end+"dest:"+dest+"dstart:"+dstart+"dend:"+dend);
        
            int keep = mMax - (parseLen - (dend - dstart));
            if (keep <= 0) {
    
                return "";
            } else if (keep >= end - start) {
    
                return null; // keep original
            } else {
    
                keep += start;
                if (Character.isHighSurrogate(source.charAt(keep - 1))) {
    
                    --keep;
                    if (keep == start) {
    
                        return "";
                    }
                }
                return source.subSequence(start, keep);
            }
        }

}

thus , Can achieve , Or customize your own functions