Android add padding for spanned text

Question

In my app, I fetch and parse html content and show it using Spanned. I use Spanned like that:

String html = "<p>Html Content</p>"
Spanned htmlSpan = Html.fromHtml(html, imageParser, null);

I've tried to use apache commons library to set padding but it didn't work.

Is there any way to set left and right padding?

Edit: forgot to mention, I also have images in that html content. I've tried to add padding to the TextView itself, but that way, all images also have padding.

Answer 1

Generally speaking, the easiest solution to display HTML is using a WebView . It is not the best solution, but it will also work with css and javascript.

To apply padding on spanned text in a TextView you can use <blockquote> which Html.fromHtml() will convert to a QuoteSpan . If you don't like the format of that span, you can replace it and add your own implementation of LeadingMarginSpan . The same would work by adding a TagHandler to create and handle your own tag on the spannable string.

You can search and replace the span by using something like the following

 QuoteSpan[] spans = text.getSpans(0, text.length(), QuoteSpan.class);
text.setSpan(YOUR_SPAN, text.getSpanStart(spans[0]), text.getSpanEnd(spans[0]), 0);

Working with spans is poorly documented and there are little tutorials, but you could look at this for further reading.

Answer 2

I have chosen the hard way.

https://developer.android.com/reference/android/text/style/QuoteSpan#quotespan

It shows Android P Developer Preview will have following constructor

QuoteSpan (int color, 
                int stripeWidth, 
                int gapWidth)

How unfortunate

Therefore the only way is to implement a new QuoteText as David expected. Fortunately Android is open sourced.

https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/text/style/QuoteSpan.java

Where is the Android P source? I still cannot locate it.

Copy the source and implement the constructor then.

import android.graphics.Canvas;
import android.graphics.Paint;
import android.os.Parcel;
import android.support.annotation.ColorInt;
import android.text.Layout;
import android.text.ParcelableSpan;
import android.text.TextUtils;
import android.text.style.LeadingMarginSpan;

// https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/text/style/QuoteSpan.java
public class MyQuoteSpan implements LeadingMarginSpan, ParcelableSpan {
    private int mStripWidth = 2;
    private int mGapWidth = 2;
    private final int mColor;
    public MyQuoteSpan() {
        super();
        mColor = 0xff0000ff;
    }
    public MyQuoteSpan(@ColorInt int color, int stripeWidth, int gapWidth) {
        super();
        mColor = color;
        mStripWidth = stripeWidth;
        mGapWidth = gapWidth;
    }
    public MyQuoteSpan(Parcel src) {
        mColor = src.readInt();
    }
    public int getSpanTypeId() {
        return getSpanTypeIdInternal();
    }
    /** @hide */
    public int getSpanTypeIdInternal() {
        //return TextUtils.QUOTE_SPAN;
        return 9;
    }
    public int describeContents() {
        return 0;
    }
    public void writeToParcel(Parcel dest, int flags) {
        writeToParcelInternal(dest, flags);
    }
    /** @hide */
    public void writeToParcelInternal(Parcel dest, int flags) {
        dest.writeInt(mColor);
    }
    @ColorInt
    public int getColor() {
        return mColor;
    }
    public int getLeadingMargin(boolean first) {
        return mStripWidth + mGapWidth;
    }
    public void drawLeadingMargin(Canvas c, Paint p, int x, int dir,
                                  int top, int baseline, int bottom,
                                  CharSequence text, int start, int end,
                                  boolean first, Layout layout) {
        Paint.Style style = p.getStyle();
        int color = p.getColor();
        p.setStyle(Paint.Style.FILL);
        p.setColor(mColor);
        c.drawRect(x, top, x + dir * mStripWidth, bottom, p);
        p.setStyle(style);
        p.setColor(color);
    }
}

Finally use it

String html = "<blockquote>Html Content</blockquote>";
Spannable contentNative;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
   contentNative = (Spannable)Html.fromHtml(content, Html.FROM_HTML_MODE_COMPACT, null, null);
} else {
    contentNative = (Spannable)Html.fromHtml(content, null, null);
}
QuoteSpan[] quoteSpans = contentNative.getSpans(0, contentNative.length(), QuoteSpan.class);
int primaryColor = ResourcesCompat.getColor(getResources(), R.color.colorPrimary, null);
int quoteStripWidth = 2;
int quoteGapWidth = 8;
for (int i = 0, len = quoteSpans.length; i < len; i++) {
    MyQuoteSpan newSpan = new MyQuoteSpan(primaryColor, quoteStripWidth, quoteGapWidth);
    int start = contentNative.getSpanStart(quoteSpans[i]);
    int end = contentNative.getSpanEnd(quoteSpans[i]);
    contentNative.removeSpan(quoteSpans[i]);
    contentNative.setSpan(newSpan, start, end, 0);
}