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PaintSourceCodeDemo

README.md

Paint源代码解析

Paint构造方法

  • 无参构造方法Paint()

使用默认的设置创建一个paint。

public Paint() {
	//调用有参构造方法Paint(int flags)，flags=0
    this(0);
}

默认设置是flags=0，调用有参构造方法Paint(int flags)：

public Paint(int flags) {
	//初始化本地paint长度
    mNativePaint = nInit();
    //使用无图占位注册本地内存分配
    NoImagePreloadHolder.sRegistry.registerNativeAllocation(this, mNativePaint);
    //设置paint的flag，使用flag枚举指定flag的值
    setFlags(flags | HIDDEN_DEFAULT_PAINT_FLAGS);
    //
    mCompatScaling = mInvCompatScaling = 1;
    //设置文本区域列表
    setTextLocales(LocaleList.getAdjustedDefault());
}

设置flag方法：

//
public void setFlags(int flags) {
    nSetFlags(mNativePaint, flags);
}
//调用native方法
private native void nSetFlags(long paintPtr, int flags);

设置文本区域列表，文本区域列表会影响文本对某些语言的绘制：

public void setTextLocales(@NonNull @Size(min=1) LocaleList locales) {
    if (locales == null || locales.isEmpty()) {
        throw new IllegalArgumentException("locales cannot be null or empty");
    }
    if (locales.equals(mLocales)) return;
    mLocales = locales;
    syncTextLocalesWithMinikin();
}

同步本地文本通过Minikin语言：

private void syncTextLocalesWithMinikin() {
    final String languageTags = mLocales.toLanguageTags();
    final Integer minikinLangListId;
    synchronized (sCacheLock) {
        minikinLangListId = sMinikinLangListIdCache.get(languageTags);
        if (minikinLangListId == null) {
            final int newID = nSetTextLocales(mNativePaint, languageTags);
            sMinikinLangListIdCache.put(languageTags, newID);
            return;
        }
    }
    nSetTextLocalesByMinikinLangListId(mNativePaint, minikinLangListId.intValue());
}

调用本地方法：

private static native void nSetTextLocalesByMinikinLangListId(long paintPtr,
            int mMinikinLangListId);
  • 有参构造方法Paint(int flags)

使用特殊的标志创建一个paint。

  • 有参构造方法Paint(Paint paint)

创建一个通过paint参数初始化的新的paint。

Paint重要方法

  • ascent()

根据当前的字体和文字大小返回上方（负）基线（上升）的距离。

public float ascent() {
    return nAscent(mNativePaint, mNativeTypeface);
}
private native float nAscent(long paintPtr, long typefacePtr);
  • breakText(char[] text,int index,int count,float maxWidth,float[] measuredWidth)

测量文本，如果测量的宽度超过maxWidth，则提早停止。返回测量的字符数，如果measuredWidth不为null，则返回测量的实际宽度。

public int breakText(char[] text, int index, int count,
                            float maxWidth, float[] measuredWidth) {
    if (text == null) {
        throw new IllegalArgumentException("text cannot be null");
    }
    if (index < 0 || text.length - index < Math.abs(count)) {
        throw new ArrayIndexOutOfBoundsException();
    }
    if (text.length == 0 || count == 0) {
        return 0;
    }
    if (!mHasCompatScaling) {
        return nBreakText(mNativePaint, mNativeTypeface, text, index, count, maxWidth,
                mBidiFlags, measuredWidth);
    }
    final float oldSize = getTextSize();
    setTextSize(oldSize * mCompatScaling);
    int res = nBreakText(mNativePaint, mNativeTypeface, text, index, count,
            maxWidth * mCompatScaling, mBidiFlags, measuredWidth);
    setTextSize(oldSize);
    if (measuredWidth != null) measuredWidth[0] *= mInvCompatScaling;
    return res;
}
  • breakText(String text,boolean measureForwards,float maxWidth, float[] measuredWidth)

测量文本，如果测量的宽度超过maxWidth，则提早停止。返回测量的字符数，如果measuredWidth不为null，则返回测量的实际宽度。

public int breakText(String text, boolean measureForwards,
                            float maxWidth, float[] measuredWidth) {
    if (text == null) {
        throw new IllegalArgumentException("text cannot be null");
    }
    if (text.length() == 0) {
        return 0;
    }
    if (!mHasCompatScaling) {
        return nBreakText(mNativePaint, mNativeTypeface, text, measureForwards,
                maxWidth, mBidiFlags, measuredWidth);
    }
    final float oldSize = getTextSize();
    setTextSize(oldSize*mCompatScaling);
    int res = nBreakText(mNativePaint, mNativeTypeface, text, measureForwards,
            maxWidth*mCompatScaling, mBidiFlags, measuredWidth);
    setTextSize(oldSize);
    if (measuredWidth != null) measuredWidth[0] *= mInvCompatScaling;
    return res;
}
  • breakText(CharSequence text,int start,int end,boolean measureForwards, float maxWidth,float[] measuredWidth)

测量文本，如果测量的宽度超过maxWidth，则提早停止。返回测量的字符数，如果measuredWidth不为null，则返回测量的实际宽度。

public int breakText(CharSequence text, int start, int end,
                     boolean measureForwards,
                     float maxWidth, float[] measuredWidth) {
    if (text == null) {
        throw new IllegalArgumentException("text cannot be null");
    }
    if ((start | end | (end - start) | (text.length() - end)) < 0) {
        throw new IndexOutOfBoundsException();
    }
    if (text.length() == 0 || start == end) {
        return 0;
    }
    if (start == 0 && text instanceof String && end == text.length()) {
        return breakText((String) text, measureForwards, maxWidth,
                         measuredWidth);
    }
    char[] buf = TemporaryBuffer.obtain(end - start);
    int result;
    TextUtils.getChars(text, start, end, buf, 0);
    if (measureForwards) {
        result = breakText(buf, 0, end - start, maxWidth, measuredWidth);
    } else {
        result = breakText(buf, 0, -(end - start), maxWidth, measuredWidth);
    }
    TemporaryBuffer.recycle(buf);
    return result;
}
  • clearShadowLayer()

清除阴影层

public void clearShadowLayer() {
    setShadowLayer(0, 0, 0, 0);
}

public void setShadowLayer(float radius, float dx, float dy, int shadowColor) {
  nSetShadowLayer(mNativePaint, radius, dx, dy, shadowColor);
}

private static native void nSetShadowLayer(long paintPtr,
            float radius, float dx, float dy, int color);
  • descent()

根据当前的字体和文字大小，返回下方（正）基线（下降）的距离

public float descent() {
    return nDescent(mNativePaint, mNativeTypeface);
}
private native float nDescent(long paintPtr, long typefacePtr);
  • getAlpha()

帮助getColor()，只返回颜色的alpha值。它与调用getColor()>>>24相同。它始终返回0（完全透明）和255（完全不透明）之间的值。

public int getAlpha() {
    return nGetAlpha(mNativePaint);
}
private native int nGetAlpha(long paintPtr);
  • getColor()

油漆的颜色。注意，颜色是一个32位的值，包含alpha和r，g，b。这个32位的值不是预先相乘，这意味着它的alpha值可以是任何值，不管r、g、b的值是多少。更多细节请参见颜色类。

@ColorInt
public int getColor() {
    return nGetColor(mNativePaint);
}
private native int nGetColor(long paintPtr);
  • getColorFilter()

获取油漆的colorfilter（可能为null）。

public ColorFilter getColorFilter() {
    return mColorFilter;
}
  • getFillPath(Path src,Path dst)

将任何/全部效果（patheffect，抚摸）应用于src，将结果返回到dst。结果是，绘制src与这个绘画将与绘制dst与默认绘画（至少从几何角度）相同。

public boolean getFillPath(Path src, Path dst) {
        return nGetFillPath(mNativePaint, src.readOnlyNI(), dst.mutateNI());
    }
  • getFlags()

返回油漆的旗帜。使用标志枚举来测试标志值。

public int getFlags() {
    return nGetFlags(mNativePaint);
}
private native int nGetFlags(long paintPtr);
  • getFontFeatureSettings()

返回字体功能设置

public String getFontFeatureSettings() {
    return mFontFeatureSettings;
}
  • getFontMetrics(Paint.FontMetrics metrics)

返回字体的推荐行间距，给出Paint的设置为fontface，textSize等。如果metrics不为null，返回其中的fontmetric值。

public float getFontMetrics(FontMetrics metrics) {
        return nGetFontMetrics(mNativePaint, mNativeTypeface, metrics);
    }

    private native float nGetFontMetrics(long paintPtr,
            long typefacePtr, FontMetrics metrics);
  • getFontMetrics()

分配一个新的FontMetrics对象，然后调用getFontMetrics(fm)，返回该对象。

public FontMetrics getFontMetrics() {
    FontMetrics fm = new FontMetrics();
    getFontMetrics(fm);
    return fm;
}
  • getFontMetricsInt(Paint.FontMetricsInt fmi)

返回字体的行间距，给出Paint的字体设置，textSize等。

public int getFontMetricsInt(FontMetricsInt fmi) {
        return nGetFontMetricsInt(mNativePaint, mNativeTypeface, fmi);
    }

    private native int nGetFontMetricsInt(long paintPtr,
            long typefacePtr, FontMetricsInt fmi);
  • getFontMetricsInt()
public FontMetricsInt getFontMetricsInt() {
    FontMetricsInt fm = new FontMetricsInt();
    getFontMetricsInt(fm);
    return fm;
}
  • getFontSpacing()

根据当前的字体和文字大小返回推荐行间距。

public float getFontSpacing() {
    return getFontMetrics(null);
}
  • getFontVariationSettings()

返回字体变体设置。



    

  • getHinting()
    • 



返回油漆的提示模式。返回HINTING_OFF或HINTING_ON。


public int getHinting() {
    return nGetHinting(mNativePaint);
}
private native int nGetHinting(long paintPtr);


    

  • getLetterSpacing()
    • 



返回油漆的文字间距。默认值为0。


public float getLetterSpacing() {
    return nGetLetterSpacing(mNativePaint);
}


    

  • getMaskFilter()
    • 



获得油漆的面具过滤器对象。


public MaskFilter getMaskFilter() {
    return mMaskFilter;
}


    

  • getOffsetForAdvance (char[] text,
int start,
int end,
int contextStart,
int contextEnd,
boolean isRtl,
float advance)
    • 



获取位置最接近指定水平位置的字符串中的字符偏移量。


public int getOffsetForAdvance(char[] text, int start, int end, int contextStart,
        int contextEnd, boolean isRtl, float advance) {
    if (text == null) {
        throw new IllegalArgumentException("text cannot be null");
    }
    if ((contextStart | start | end | contextEnd
            | start - contextStart | end - start | contextEnd - end
            | text.length - contextEnd) < 0) {
        throw new IndexOutOfBoundsException();
    }
    // TODO: take mCompatScaling into account (or eliminate compat scaling)?
    return nGetOffsetForAdvance(mNativePaint, mNativeTypeface, text, start, end,
            contextStart, contextEnd, isRtl, advance);
}


    

  • getOffsetForAdvance (CharSequence text,
int start,
int end,
int contextStart,
int contextEnd,
boolean isRtl,
float advance)
    • 



获取位置最接近指定水平位置的字符串中的字符偏移量。


public int getOffsetForAdvance(CharSequence text, int start, int end, int contextStart,
        int contextEnd, boolean isRtl, float advance) {
    if (text == null) {
        throw new IllegalArgumentException("text cannot be null");
    }
    if ((contextStart | start | end | contextEnd
            | start - contextStart | end - start | contextEnd - end
            | text.length() - contextEnd) < 0) {
        throw new IndexOutOfBoundsException();
    }
    // TODO performance: specialized alternatives to avoid buffer copy, if win is significant
    char[] buf = TemporaryBuffer.obtain(contextEnd - contextStart);
    TextUtils.getChars(text, contextStart, contextEnd, buf, 0);
    int result = getOffsetForAdvance(buf, start - contextStart, end - contextStart, 0,
            contextEnd - contextStart, isRtl, advance) + contextStart;
    TemporaryBuffer.recycle(buf);
    return result;
}


    

  • getPathEffect()
    • 



获取油漆的patheffect对象。


 public PathEffect getPathEffect() {
     return mPathEffect;
 }


    

  • getRunAdvance (char[] text,
int start,
int end,
int contextStart,
int contextEnd,
boolean isRtl,
int offset)
    • 



在文本运行中测量光标位置。


public float getRunAdvance(char[] text, int start, int end, int contextStart, int contextEnd,
        boolean isRtl, int offset) {
    if (text == null) {
        throw new IllegalArgumentException("text cannot be null");
    }
    if ((contextStart | start | offset | end | contextEnd
            | start - contextStart | offset - start | end - offset
            | contextEnd - end | text.length - contextEnd) < 0) {
        throw new IndexOutOfBoundsException();
    }
    if (end == start) {
        return 0.0f;
    }
    // TODO: take mCompatScaling into account (or eliminate compat scaling)?
    return nGetRunAdvance(mNativePaint, mNativeTypeface, text, start, end,
            contextStart, contextEnd, isRtl, offset);
}


    

  • getRunAdvance (CharSequence text,
int start,
int end,
int contextStart,
int contextEnd,
boolean isRtl,
int offset)
    • 



public float getRunAdvance(CharSequence text, int start, int end, int contextStart,
        int contextEnd, boolean isRtl, int offset) {
    if (text == null) {
        throw new IllegalArgumentException("text cannot be null");
    }
    if ((contextStart | start | offset | end | contextEnd
            | start - contextStart | offset - start | end - offset
            | contextEnd - end | text.length() - contextEnd) < 0) {
        throw new IndexOutOfBoundsException();
    }
    if (end == start) {
        return 0.0f;
    }
    // TODO performance: specialized alternatives to avoid buffer copy, if win is significant
    char[] buf = TemporaryBuffer.obtain(contextEnd - contextStart);
    TextUtils.getChars(text, contextStart, contextEnd, buf, 0);
    float result = getRunAdvance(buf, start - contextStart, end - contextStart, 0,
            contextEnd - contextStart, isRtl, offset - contextStart);
    TemporaryBuffer.recycle(buf);
    return result;
}


    

  • getShader()
    • 



获取油漆的着色器对象。


public Shader getShader() {
    return mShader;
}


    

  • getStrokeCap()
    • 



返回油漆的盖帽，控制如何处理划线和路径的开始和结束。


public Cap getStrokeCap() {
        return sCapArray[nGetStrokeCap(mNativePaint)];
    }