ASCIIEncoder.java

/*
 * Copyright 2006-2007 Jeremias Maerki.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.zxing.datamatrix.encoder;

final class ASCIIEncoder implements Encoder {

	@Override
	public int getEncodingMode() {
		return HighLevelEncoder.ASCII_ENCODATION;
	}

	@Override
	public void encode(EncoderContext context) {
		// step B
		int n = HighLevelEncoder.determineConsecutiveDigitCount(
				context.getMessage(), context.pos);
		if (n >= 2) {
			context.writeCodeword(encodeASCIIDigits(context.getMessage()
					.charAt(context.pos),
					context.getMessage().charAt(context.pos + 1)));
			context.pos += 2;
		} else {
			char c = context.getCurrentChar();
			int newMode = HighLevelEncoder.lookAheadTest(context.getMessage(),
					context.pos, getEncodingMode());
			if (newMode != getEncodingMode()) {
				switch (newMode) {
				case HighLevelEncoder.BASE256_ENCODATION:
					context.writeCodeword(HighLevelEncoder.LATCH_TO_BASE256);
					context.signalEncoderChange(HighLevelEncoder.BASE256_ENCODATION);
					return;
				case HighLevelEncoder.C40_ENCODATION:
					context.writeCodeword(HighLevelEncoder.LATCH_TO_C40);
					context.signalEncoderChange(HighLevelEncoder.C40_ENCODATION);
					return;
				case HighLevelEncoder.X12_ENCODATION:
					context.writeCodeword(HighLevelEncoder.LATCH_TO_ANSIX12);
					context.signalEncoderChange(HighLevelEncoder.X12_ENCODATION);
					break;
				case HighLevelEncoder.TEXT_ENCODATION:
					context.writeCodeword(HighLevelEncoder.LATCH_TO_TEXT);
					context.signalEncoderChange(HighLevelEncoder.TEXT_ENCODATION);
					break;
				case HighLevelEncoder.EDIFACT_ENCODATION:
					context.writeCodeword(HighLevelEncoder.LATCH_TO_EDIFACT);
					context.signalEncoderChange(HighLevelEncoder.EDIFACT_ENCODATION);
					break;
				default:
					throw new IllegalStateException("Illegal mode: " + newMode);
				}
			} else if (HighLevelEncoder.isExtendedASCII(c)) {
				context.writeCodeword(HighLevelEncoder.UPPER_SHIFT);
				context.writeCodeword((char) (c - 128 + 1));
				context.pos++;
			} else {
				context.writeCodeword((char) (c + 1));
				context.pos++;
			}

		}
	}

	private static char encodeASCIIDigits(char digit1, char digit2) {
		if (HighLevelEncoder.isDigit(digit1)
				&& HighLevelEncoder.isDigit(digit2)) {
			int num = (digit1 - 48) * 10 + (digit2 - 48);
			return (char) (num + 130);
		}
		throw new IllegalArgumentException("not digits: " + digit1 + digit2);
	}

}