Canvas绘制文本时，使用FontMetrics对象，计算位置的坐标。
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public static class FontMetrics { /** * The maximum distance above the baseline for the tallest glyph in * the font at a given text size. */ public float top; /** * The recommended distance above the baseline for singled spaced text. */ public float ascent; /** * The recommended distance below the baseline for singled spaced text. */ public float descent; /** * The maximum distance below the baseline for the lowest glyph in * the font at a given text size. */ public float bottom; /** * The recommended additional space to add between lines of text. */ public float leading;} |
它的各基准线可以参考下图：
上图其实是通过代码画出来的，具体代码如下：
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/** 绘制FontMetrics对象的各种线 */mPaint.reset();mPaint.setColor(Color.WHITE);mPaint.setTextSize(80);// FontMetrics对象FontMetrics fontMetrics = mPaint.getFontMetrics();String text = "abcdefg";// 计算每一个坐标float textWidth = mPaint.measureText(text);float baseX = 30;float baseY = 700;float topY = baseY + fontMetrics.top;float ascentY = baseY + fontMetrics.ascent;float descentY = baseY + fontMetrics.descent;float bottomY = baseY + fontMetrics.bottom;// 绘制文本canvas.drawText(text, baseX, baseY, mPaint);// BaseLine描画mPaint.setColor(Color.RED);canvas.drawLine(baseX, baseY, baseX + textWidth, baseY, mPaint);mPaint.setTextSize(20);canvas.drawText("base", baseX + textWidth, baseY, mPaint);// Base描画canvas.drawCircle(baseX, baseY, 5, mPaint);// TopLine描画mPaint.setColor(Color.LTGRAY);canvas.drawLine(baseX, topY, baseX + textWidth, topY, mPaint);canvas.drawText("top", baseX + textWidth, topY, mPaint);// AscentLine描画mPaint.setColor(Color.GREEN);canvas.drawLine(baseX, ascentY, baseX + textWidth, ascentY, mPaint);canvas.drawText("ascent", baseX + textWidth, ascentY + 10, mPaint);// DescentLine描画mPaint.setColor(Color.YELLOW);canvas.drawLine(baseX, descentY, baseX + textWidth, descentY, mPaint);canvas.drawText("descent", baseX + textWidth, descentY, mPaint);// ButtomLine描画mPaint.setColor(Color.MAGENTA);canvas.drawLine(baseX, bottomY, baseX + textWidth, bottomY, mPaint);canvas.drawText("buttom", baseX + textWidth, bottomY + 10, mPaint); |
相信通过以上程序，能够很好的理解topLine，buttomLine，baseLine，ascentLine，descentLine。
另外：Paint类有两个方法
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/** * Return the distance above (negative) the baseline (ascent) based on the * current typeface and text size. * * @return the distance above (negative) the baseline (ascent) based on the * current typeface and text size. */public native float ascent(); /** * Return the distance below (positive) the baseline (descent) based on the * current typeface and text size. * * @return the distance below (positive) the baseline (descent) based on * the current typeface and text size. */public native float descent(); |
ascent()：the distance above the baseline（baseline以上的height）
descent()：the distance below the baseline（baseline以下的height）
所以ascent() + descent() 可以看成文字的height。
到此为止，怎么获取文字的height和width都已经揭晓了：
获取height ： mPaint.ascent() + mPaint.descent()
获取width ： mPaint.measureText(text)
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/tianjf0514/article/details/7642656
