Skip to content

Instantly share code, notes, and snippets.

@KKorvin
Last active November 8, 2018 07:39
Show Gist options
  • Save KKorvin/65bd537759f4afa6ac280e03979ab6d3 to your computer and use it in GitHub Desktop.
Save KKorvin/65bd537759f4afa6ac280e03979ab6d3 to your computer and use it in GitHub Desktop.
Create multi color squares with letter. For Android.
/**
* Orginal http://stackoverflow.com/questions/23122088/colored-boxed-with-letters-a-la-gmail
* Used to create a {@link Bitmap} that contains a letter used in the English
* alphabet or digit, if there is no letter or digit available, a default image
* is shown instead.
*
* Only English language supported.
*/
public class LetterBitmap {
/**
* The number of available tile colors
*/
private static final int NUM_OF_TILE_COLORS = 8;
/**
* The {@link TextPaint} used to draw the letter onto the tile
*/
private final TextPaint mPaint = new TextPaint();
/**
* The bounds that enclose the letter
*/
private final Rect mBounds = new Rect();
/**
* The {@link Canvas} to draw on
*/
private final Canvas mCanvas = new Canvas();
/**
* The first char of the name being displayed
*/
private final char[] mFirstChar = new char[1];
/**
* The background colors of the tile
*/
private final TypedArray mColors;
/**
* The font size used to display the letter
*/
private final int mTileLetterFontSize;
/**
* The default image to display
*/
private final Bitmap mDefaultBitmap;
/**
* Constructor for <code>LetterTileProvider</code>
*
* @param context The {@link Context} to use
*/
public LetterBitmap(Context context) {
final Resources res = context.getResources();
mPaint.setTypeface(Typeface.create("sans-serif-light", Typeface.NORMAL));
mPaint.setColor(Color.WHITE);
mPaint.setTextAlign(Paint.Align.CENTER);
mPaint.setAntiAlias(true);
mColors = res.obtainTypedArray(R.array.letter_tile_colors);
mTileLetterFontSize = res.getDimensionPixelSize(R.dimen.tile_letter_font_size);
mDefaultBitmap = BitmapFactory.decodeResource(res, android.R.drawable.sym_def_app_icon);
}
/**
* @param displayName The name used to create the letter for the tile
* @param key The key used to generate the background color for the tile
* @param width The desired width of the tile
* @param height The desired height of the tile
* @return A {@link Bitmap} that contains a letter used in the English
* alphabet or digit, if there is no letter or digit available, a
* default image is shown instead
*/
public Bitmap getLetterTile(String displayName, String key, int width, int height) {
final Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
char firstChar = displayName.charAt(0);
final Canvas c = mCanvas;
c.setBitmap(bitmap);
c.drawColor(pickColor(key));
if (!isEnglishLetterOrDigit(firstChar)) {
firstChar = 'A';
}
mFirstChar[0] = Character.toUpperCase(firstChar);
mPaint.setTextSize(mTileLetterFontSize);
mPaint.getTextBounds(mFirstChar, 0, 1, mBounds);
c.drawText(mFirstChar, 0, 1, 0 + width / 2, 0 + height / 2
+ (mBounds.bottom - mBounds.top) / 2, mPaint);
return bitmap;
}
/**
* @param c The char to check
* @return True if <code>c</code> is in the English alphabet or is a digit,
* false otherwise
*/
private static boolean isEnglishLetterOrDigit(char c) {
return 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9';
}
/**
* @param key The key used to generate the tile color
* @return A new or previously chosen color for <code>key</code> used as the
* tile background color
*/
private int pickColor(String key) {
// String.hashCode() is not supposed to change across java versions, so
// this should guarantee the same key always maps to the same color
final int color = Math.abs(key.hashCode()) % NUM_OF_TILE_COLORS;
try {
return mColors.getColor(color, Color.BLACK);
} finally {
mColors.recycle();
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment