Рисование многострочного текста в Canvas

Question

Надеюсь, быстрый вопрос, но я не могу найти ни одного примера ... Я хотел бы написать многострочный текст в пользовательский View через Canvas, а в onDraw() у меня есть:

...
String text = "This is\nmulti-line\ntext";
canvas.drawText(text, 100, 100, mTextPaint);
...

Я надеялся, что это приведет к разрывам строк, но вместо этого я вижу загадочные символы, в которых будет \n.

Любые указатели оценены.

Пол

Answer 1

Решение без StaticLayout

//Get post text
    String text = post.getText();

    //Get weight of space character in px
    float spaceWeight = paint.measureText(" ");

    //Start main algorithm of drawing words on canvas
    //Split text to words
    for (String line : text.split(" ")) {
        //If we had empty space just continue
        if (line.equals("")) continue;
        //Get weight of the line
        float lineWeight = paint.measureText(line);
        //If our word(line) doesn't have any '\n' we do next
        if (line.indexOf('\n') == -1) {
            //If word can fit into current line
            if (cnv.getWidth() - pxx - defaultMargin >= lineWeight) {
                //Draw text
                cnv.drawText(line, pxx, pxy, paint);
                //Move start x point to word weight + space weight
                pxx += lineWeight + spaceWeight;
            } else {
                //If word can't fit into current line
                //Move x point to start
                //Move y point to the next line
                pxx = defaultMargin;
                pxy += paint.descent() - paint.ascent();
                //Draw
                cnv.drawText(line, pxx, pxy, paint);
                //Move x point to word weight + space weight
                pxx += lineWeight + spaceWeight;
            }
            //If line contains '\n'
        } else {
            //If '\n' is on the start of the line
            if (line.indexOf('\n') == 0) {
                pxx = defaultMargin;
                pxy += paint.descent() - paint.ascent();
                cnv.drawText(line.replaceAll("\n", ""), pxx, pxy, paint);
                pxx += lineWeight + spaceWeight;
            } else {
                //If '\n' is somewhere in the middle
                //and it also can contain few '\n'
                //Split line to sublines
                String[] subline = line.split("\n");
                for (int i = 0; i < subline.length; i++) {
                    //Get weight of new word
                    lineWeight = paint.measureText(subline[i]);
                    //If it's empty subline that's mean that we have '\n'
                    if (subline[i].equals("")) {
                        pxx = defaultMargin;
                        pxy += paint.descent() - paint.ascent();
                        cnv.drawText(subline[i], pxx, pxy, paint);
                        continue;
                    }
                    //If we have only one word
                    if (subline.length == 1 && i == 0) {
                        if (cnv.getWidth() - pxx >= lineWeight) {
                            cnv.drawText(subline[0], pxx, pxy, paint);
                            pxx = defaultMargin;
                            pxy += paint.descent() - paint.ascent();
                        } else {
                            pxx = defaultMargin;
                            pxy += paint.descent() - paint.ascent();
                            cnv.drawText(subline[0], pxx, pxy, paint);
                            pxx = defaultMargin;
                            pxy += paint.descent() - paint.ascent();
                        }
                        continue;
                    }
                    //If we have set of words separated with '\n'
                    //it is the first word
                    //Make sure we can put it into current line
                    if (i == 0) {
                        if (cnv.getWidth() - pxx >= lineWeight) {
                            cnv.drawText(subline[0], pxx, pxy, paint);
                            pxx = defaultMargin;
                        } else {
                            pxx = defaultMargin;
                            pxy += paint.descent() - paint.ascent();
                            cnv.drawText(subline[0], pxx, pxy, paint);
                            pxx = defaultMargin;
                        }
                    } else {
                        pxx = defaultMargin;
                        pxy += paint.descent() - paint.ascent();
                        cnv.drawText(subline[i], pxx, pxy, paint);
                        pxx += lineWeight + spaceWeight;
                    }
                }

            }
        }
    }

Answer 2

Я работал с тем, что у меня было, которое уже конвертировало отдельные строки в полотна, и я отработал ответ Лумиса, и я закончил с этим.1.3 и 1.3f означают заполнение между строками относительно размера шрифта.

public static Bitmap getBitmapFromString(final String text, final String font, int textSize, final int textColor)
{
    String lines[] = text.split("\n");
    textSize = getRelX(textSize);  //a method in my app that adjusts the font size relative to the screen size
    Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setTextSize(textSize);
    paint.setColor(textColor);
    paint.setTextAlign(Paint.Align.LEFT);
    Typeface face = Typeface.createFromAsset(GameActivity.getContext().getAssets(),GameActivity.getContext().getString(R.string.font) + font + GameActivity.getContext().getString(R.string.font_ttf));
    paint.setTypeface(face);
    float baseline = -paint.ascent(); // ascent() is negative
    int width = (int) (paint.measureText(text) + 0.5f); // round
    int height = (int) (baseline + paint.descent() + 0.5f);
    Bitmap image = Bitmap.createBitmap(width, (int)(height * 1.3 * lines.length), Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(image);
    for (int i = 0; i < lines.length; ++i)
    {
        canvas.drawText(lines[i], 0, baseline + textSize * 1.3f * i, paint);
    }
    return image;
}

Answer 3

Мой пример с динамическим изменением размера текста и интервалами, отлично подходит для меня ...

public Bitmap fontTexture(String string, final Context context) {
    float text_x = 512;
    float text_y = 512;
    final float scale = context.getResources().getDisplayMetrics().density;

    int mThreshold = (int) (THRESHOLD_DIP * scale + 0.5f);

    String[] splited = string.split("\\s+");
    double longest = 0;
    for(String s:splited){
        if (s.length() > longest) {
            longest = s.length();
        }
    }
    if(longest > MAX_STRING_LENGTH) {
        double ratio = (double) MAX_STRING_LENGTH / longest;
        mThreshold = (int) ((THRESHOLD_DIP * ((float) ratio)) * scale + 0.5f);
    }

    Bitmap bitmap = Bitmap.createBitmap(1024, 1024, Bitmap.Config.ARGB_8888);

    Canvas canvas = new Canvas(bitmap);

    Typeface font = Typeface.createFromAsset(context.getAssets(),
            "fonts/dotted_font.ttf");

    TextPaint mTextPaint=new TextPaint();
    mTextPaint.setColor(Color.YELLOW);
    mTextPaint.setTextAlign(Paint.Align.CENTER);
    mTextPaint.setTextSize(mThreshold);
    mTextPaint.setTypeface(font);
    StaticLayout mTextLayout = new StaticLayout(string, mTextPaint, canvas.getWidth(), Layout.Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);

    canvas.save();

    canvas.translate(text_x, text_y);
    mTextLayout.draw(canvas);
    canvas.restore();


    return bitmap;
}