draw Text on Canvas using TextPaint - Android Graphics

Android examples for Graphics:Canvas

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Description

draw Text on Canvas using TextPaint

Demo Code

/*//w  w w.j  av  a  2s  . c om
 * Copyright (C) 2012 www.amsoft.cn
 * 
 * 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.
 */
import java.util.ArrayList;
import java.util.List;
import android.graphics.Canvas;
import android.graphics.Paint.FontMetrics;
import android.text.Layout;
import android.text.TextPaint;

public class Main{
    
    public static int drawText(Canvas canvas, String text, int maxWPix,
            TextPaint paint, int left, int top) {

        List<String> mStrList = getDrawRowStr(text, maxWPix, paint);

        int hSize = (int) getDesiredHeight(paint);

        for (int i = 0; i < mStrList.size(); i++) {
   
            int x = left;
            int y = top + hSize / 2 + hSize * i;
            String textLine = mStrList.get(i);
            canvas.drawText(textLine, x, y, paint);

        }
        return mStrList.size();
    }
    
    public static List<String> getDrawRowStr(String text, int maxWPix,
            TextPaint paint) {
        String[] texts = null;
        if (text.indexOf("\n") != -1) {
            texts = text.split("\n");
        } else {
            texts = new String[1];
            texts[0] = text;
        }

        List<String> mStrList = new ArrayList<String>();

        for (int i = 0; i < texts.length; i++) {
            String textLine = texts[i];

            while (true) {
        
                int endIndex = subStringLength(textLine, maxWPix, paint);
                if (endIndex <= 0) {
                    mStrList.add(textLine);
                } else {
                    if (endIndex == textLine.length() - 1) {
                        mStrList.add(textLine);
                    } else {
                        mStrList.add(textLine.substring(0, endIndex + 1));
                    }

                }
                if (textLine.length() > endIndex + 1) {

                    textLine = textLine.substring(endIndex + 1);
                } else {
                    break;
                }
            }
        }

        return mStrList;
    }
    
    public static float getDesiredHeight(TextPaint paint) {
        FontMetrics fm = paint.getFontMetrics();
        return (float) Math.ceil(fm.descent - fm.ascent);
    }
    
    public static int subStringLength(String str, int maxPix,
            TextPaint paint) {
        if (AbStrUtil.isEmpty(str)) {
            return 0;
        }
        int currentIndex = 0;
        for (int i = 0; i < str.length(); i++) {
            //???????? 
            String temp = str.substring(0, i + 1);
            float valueLength = paint.measureText(temp);
            if (valueLength > maxPix) {
                currentIndex = i - 1;
                break;
            } else if (valueLength == maxPix) {
                currentIndex = i;
                break;
            }
        }
        if (currentIndex == 0) {
            currentIndex = str.length() - 1;
        }
        return currentIndex;
    }
}

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