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這期內(nèi)容當(dāng)中小編將會(huì)給大家?guī)碛嘘P(guān)怎么在Android中使用FontMetrics對(duì)象計(jì)算坐標(biāo),文章內(nèi)容豐富且以專業(yè)的角度為大家分析和敘述,閱讀完這篇文章希望大家可以有所收獲。
Canvas繪制文本時(shí),使用FontMetrics對(duì)象,計(jì)算位置的坐標(biāo)。
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; }
它的各基準(zhǔn)線可以參考下圖:
上圖其實(shí)是通過代碼畫出來的,具體代碼如下:
/** 繪制FontMetrics對(duì)象的各種線 */ mPaint.reset(); mPaint.setColor(Color.WHITE); mPaint.setTextSize(80); // FontMetrics對(duì)象 FontMetrics fontMetrics = mPaint.getFontMetrics(); String text = "abcdefg"; // 計(jì)算每一個(gè)坐標(biāo) 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; // 繪制文本 canvas.drawText(text, baseX, baseY, mPaint); // BaseLine描畫 mPaint.setColor(Color.RED); canvas.drawLine(baseX, baseY, baseX + textWidth, baseY, mPaint); mPaint.setTextSize(20); canvas.drawText("base", baseX + textWidth, baseY, mPaint); // Base描畫 canvas.drawCircle(baseX, baseY, 5, mPaint); // TopLine描畫 mPaint.setColor(Color.LTGRAY); canvas.drawLine(baseX, topY, baseX + textWidth, topY, mPaint); canvas.drawText("top", baseX + textWidth, topY, mPaint); // AscentLine描畫 mPaint.setColor(Color.GREEN); canvas.drawLine(baseX, ascentY, baseX + textWidth, ascentY, mPaint); canvas.drawText("ascent", baseX + textWidth, ascentY + 10, mPaint); // DescentLine描畫 mPaint.setColor(Color.YELLOW); canvas.drawLine(baseX, descentY, baseX + textWidth, descentY, mPaint); canvas.drawText("descent", baseX + textWidth, descentY, mPaint); // ButtomLine描畫 mPaint.setColor(Color.MAGENTA); canvas.drawLine(baseX, bottomY, baseX + textWidth, bottomY, mPaint); canvas.drawText("buttom", baseX + textWidth, bottomY + 10, mPaint);
相信通過以上程序,能夠很好的理解topLine,buttomLine,baseLine,ascentLine,descentLine。
另外:Paint類有兩個(gè)方法
/** * 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。
到此為止,怎么獲取文字的height和width都已經(jīng)揭曉了:
獲取height : mPaint.ascent() + mPaint.descent()
獲取width : mPaint.measureText(text)
上述就是小編為大家分享的怎么在Android中使用FontMetrics對(duì)象計(jì)算坐標(biāo)了,如果剛好有類似的疑惑,不妨參照上述分析進(jìn)行理解。如果想知道更多相關(guān)知識(shí),歡迎關(guān)注億速云行業(yè)資訊頻道。
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