EmojiCompat.GlyphChecker

public static interface EmojiCompat.GlyphChecker

androidx.emoji.text.EmojiCompat.GlyphChecker


Interface to check if a given emoji exists on the system.

Summary

Public methods

abstract boolean hasGlyph(CharSequence charSequence, int start, int end, int sdkAdded)

Return true if the emoji that is in charSequence between start(inclusive) and end(exclusive) can be rendered on the system using the default Typeface.

Public methods

hasGlyph

public abstract boolean hasGlyph (CharSequence charSequence, 
                int start, 
                int end, 
                int sdkAdded)

Return true if the emoji that is in charSequence between start(inclusive) and end(exclusive) can be rendered on the system using the default Typeface.

This function is called after an emoji is identified in the given charSequence and EmojiCompat wants to know if that emoji can be rendered on the system. The result of this call will be cached and the same emoji sequence won't be asked for the same EmojiCompat instance.

When the function returns true, it will mean that the system can render the emoji. In that case if EmojiCompat.Config.setReplaceAll(boolean) is set to false, then no EmojiSpan will be added in the final emoji processing result.

When the function returns false, it will mean that the system cannot render the given emoji, therefore an EmojiSpan will be added to the final emoji processing result.

The default implementation of this class uses PaintCompat.hasGlyph(Paint, String) function to check if the emoji can be rendered on the system. This is required even if EmojiCompat knows about the SDK Version that the emoji was added on AOSP. Just the sdkAdded information is not enough to reliably decide if emoji can be rendered since this information may not be consistent across all the OEMs and all the Android versions.

With this interface you can apply your own heuristics to check if the emoji can be rendered on the system. For example, if you'd like to rely on the sdkAdded information, and some predefined OEMs, it is possible to write the following code snippet.

static class MyGlyphChecker implements EmojiCompat.GlyphChecker {
    private TextPaint mTextPaint = new TextPaint();

    @Override
    public boolean hasGlyph(@NonNull CharSequence charSequence, int start, int end,
            int sdkAdded) {
        if (isOnDeviceX()) {
            // if on this specific device we only rely on sdkAdded
            return sdkAdded < Build.VERSION.SDK_INT;
        } else {
            String string = createString(charSequence, start, end);
            return PaintCompat.hasGlyph(mTextPaint, string);
        }
    }

}

Parameters
charSequence CharSequence: the CharSequence that is being processed

start int: the inclusive starting offset for the emoji in the charSequence

end int: the exclusive end offset for the emoji in the charSequence

sdkAdded int: the API version that the emoji was added in AOSP

Returns
boolean true if the given sequence can be rendered as a single glyph, otherwise false.