Android(安卓)TextView自适应文字大小

如何在指定的矩形框内，显示TextView 文字不会被切割，也不用指定TextView大小（指定矩形框，不指定文字大小）

有两种方式，一种是使用Matrix做矩阵变换，一种是用StaticLayout进行遍历来选取合适的TextSize

Matrix:

    public void drawText(String text, Paint paint, Canvas canvas, MyItem item) {        Rect textBound = new Rect();        paint.getTextBounds(text, 0,                text.length(), textBound);        float descent = paint.descent();        int height = textBound.height();        int width = textBound.width();        float[] startPoints = {                0, -height + descent,                width, -height + descent,                width, descent,                0, descent        };        float[] endPoints = {                item.leftTopPoint.x, item.leftTopPoint.y,                item.rightTopPoint.x, item.rightTopPoint.y,                item.rightBottomPoint.x, item.rightBottomPoint.y,                item.leftBottomPoint.x, item.leftBottomPoint.y        };        Matrix fontMatrix = new Matrix();        fontMatrix.setPolyToPoly(startPoints, 0, endPoints, 0, 4);        paint.setColor(item.getTextColor());        final int saveCount = canvas.save();        canvas.concat(fontMatrix);        canvas.drawText(text, 0, 0, paint);        canvas.restoreToCount(saveCount);    }

MyItem是我的自定义类，需要替换成你自己的。
endPoints数组中四个点，分别是矩形的左上、右上、右下、左下点的 x,y坐标

主要采用的是Matrix的PolyToPoly方法，就是给定原坐标点、目的坐标点，生成变换的Matrix

优点：

绘制矩形框不是长方形，是梯形也可以完美的贴上去

缺点：

文字会模糊，失去锐度

StaticLayout

 private void drawStatic(Paint paint, Canvas canvas, TextPaint textPaint,                            int drawWidth, int drawHeight, int drawLeft, int drawTop) {        int textHeight = initConfig(getText(), textPaint, drawWidth, drawHeight, DEFAULT_TEXT_SIZE);        if (textHeight == -1) {            return;        }        StaticLayout layout = new StaticLayout(getText(), textPaint, drawWidth, Layout.Alignment.ALIGN_NORMAL, mSpacingMulti, mSpacingAdd, true);        layout.draw(canvas);    }    /**     * 设置paint的textSize     */    int initConfig(CharSequence text, TextPaint textPaint, int viewWidth, int viewHeight, float defaultTextSize) {        // Do not resize if the view does not have dimensions or there is no text        if (text == null || text.length() == 0 || viewHeight <= 0 || viewWidth <= 0 || defaultTextSize == 0) {            return -1;        }        float targetTextSize = defaultTextSize;        int textHeight = getStaticLayoutHeight(text, textPaint, viewWidth, targetTextSize);        while (textHeight > viewHeight) {            targetTextSize = targetTextSize - 2;            textHeight = getStaticLayoutHeight(text, textPaint, viewWidth, targetTextSize);        }        float preTextSize = targetTextSize;        while (textHeight < viewHeight) {            preTextSize = targetTextSize;            targetTextSize += 2;            textHeight = getStaticLayoutHeight(text, textPaint, viewWidth, targetTextSize);        }        textPaint.setTextSize(preTextSize);        return textHeight;    }    int getStaticLayoutHeight(CharSequence source, TextPaint paint, int width, float textSize) {        paint.setTextSize(textSize);        StaticLayout layout = new StaticLayout(source, paint, width, Layout.Alignment.ALIGN_NORMAL, mSpacingMulti, mSpacingAdd, true);        return layout.getHeight();    }

StaticLayout也是TextView中负责 text 分行、测量字体库宽度的类
就是采用遍历的方法来确定文字大小
初始的文字大小，设置成矩形的高就行，这样接近点

优缺点与Matrix相对

Matrix:

优点：

缺点：

StaticLayout

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