Android关于Paint你所知道的和不知道的一切

零、前言：

1.曾经也算半个艺术家，深知笔的重要性与复杂性
2.Android里的Paint设置项好多基本上都是setXXX,getXXX，很多文字相关的内容都在Paint里
3.主要由画笔常规配置，画笔类型、画笔特效(线效,着色，滤色)、画笔文字
4.本文暂时还无法覆盖Paint的所有API,能用的吾尽量都会涉及一下

最主要的还是set方法

paint的Set一览.png

一、画笔的常规配置

public void setColor(@ColorInt int color) //设置颜色
public void setAlpha(int a)//设置透明度
public void setARGB(int a, int r, int g, int b)//设置ARGB颜色
public void setStrokeWidth(float width)//设置宽度
public void setAntiAlias(boolean aa)//设置抗锯齿

基本设置.png

二、笔的样式：`Paint.Style.`：[#`FILL`|`STROKE`|`FILL_AND_STROKE`]

/**
 * 样式测试
 * @param canvas
 */
private void testStyle(Canvas canvas) {
    Rect rect = new Rect(0, 0, 100, 100);
    mRedPaint.setStrokeWidth(15);
    canvas.save();
    
    mRedPaint.setStyle(Paint.Style.FILL);
    canvas.translate(50, 450);
    canvas.drawRect(rect, mRedPaint);
    
    canvas.translate(150, 0);
    mRedPaint.setStyle(Paint.Style.STROKE);
    canvas.drawRect(rect, mRedPaint);
    
    canvas.translate(150 , 0);
    mRedPaint.setStyle(Paint.Style.FILL_AND_STROKE);
    canvas.drawRect(rect, mRedPaint);
    canvas.restore();
    mRedPaint.setStrokeWidth(40);
}

画笔样式测试.png

三、线帽：`Paint.Cap.`：[#`BUTT`|`ROUND`|`SQUARE`]

1.绘制圆形的点:Paint.Cap.ROUND

/**
 * 绘制圆形的点
 *
 * @param canvas
 */
private void drawPos(Canvas canvas) {
    //设置画笔圆帽
    mRedPaint.setStrokeCap(Paint.Cap.ROUND);
    mRedPaint.setStrokeWidth(20);
    //绘制点
    canvas.drawPoint(100, 100, mRedPaint);
    canvas.drawPoints(new float[]{
            400, 400, 500, 500,
            600, 400, 700, 350,
            800, 300, 900, 300
    }, mRedPaint);
}

绘制圆点.png

2.三种线帽比较

/**
 * 线帽型状测试：Paint.Cap.BUTT、Paint.Cap.ROUND、Paint.Cap.SQUARE
 *
 * @param canvas
 */
private void testOfCap(Canvas canvas) {
    canvas.save();
    canvas.translate(150, 200);
    //线帽测试：
    mRedPaint.setStrokeCap(Paint.Cap.BUTT);//无头(默认)
    canvas.drawLine(0, 0, 0, 200, mRedPaint);
    canvas.translate(50, 0);
    mRedPaint.setStrokeCap(Paint.Cap.ROUND);//圆头
    canvas.drawLine(0, 0, 0, 200, mRedPaint);
    canvas.translate(50, 0);
    mRedPaint.setStrokeCap(Paint.Cap.SQUARE);//方头
    canvas.drawLine(0, 0, 0, 200, mRedPaint);
    canvas.restore();
}

线帽型状测试.png

四、线交角测试：`Paint.Join.`：[#`BEVEL`|`ROUND`|`MITER`]

注意：只有路径绘制的线才有交角效果

/**
 * 角型测试：Paint.Join.BEVEL、Paint.Join.ROUND、Paint.Join.MITER
 *
 * @param canvas
 */
private void testOfJoin(Canvas canvas) {
    mRedPaint.setStyle(Paint.Style.STROKE);
    mRedPaint.setStrokeWidth(40);
    Path path = new Path();
    path.moveTo(30, 0);
    path.lineTo(0, 100);
    path.lineTo(100, 100);
    
    canvas.save();
    canvas.translate(600, 100);
    mRedPaint.setStrokeJoin(Paint.Join.BEVEL);//直线(默认)
    canvas.drawPath(path, mRedPaint);
    
    canvas.translate(150, 0);
    mRedPaint.setStrokeJoin(Paint.Join.ROUND);//圆角
    canvas.drawPath(path, mRedPaint);
    
    canvas.translate(150, 0);
    mRedPaint.setStrokeJoin(Paint.Join.MITER);//锐角
    canvas.drawPath(path, mRedPaint);
    canvas.restore();
}

线交角测试.png

五、Paint的路径效果

1.虚线：DashPathEffect(new float[]{a, b, a1, b1...}, offSet)

第一参为显隐线段的长度，第二参为偏移值
下面会动的线是不断改变偏移量：mDashOffSet的结果

虚线效果.gif

/**
 * 虚线测试
 *
 * @param canvas
 */
private void dashEffect(Canvas canvas) {
    mEffectPaint = new Paint(mRedPaint);
    mEffectPaint.setStrokeCap(Paint.Cap.BUTT);
    //显示100，隐藏50,显示50，隐藏50,的循环
    mEffectPaint.setPathEffect(new DashPathEffect(new float[]{100, 50, 50, 50}, 0));
    Path path = new Path();
    path.moveTo(100, 650);
    path.lineTo(1000, 650);
    canvas.drawPath(path, mEffectPaint);
    //显示100，隐藏50,显示60，隐藏50,的循环,偏移：mDashOffSet
    mEffectPaint.setPathEffect(new DashPathEffect(new float[]{100, 50, 50, 50}, mDashOffSet));
    Path pathOffset50 = new Path();
    pathOffset50.moveTo(100, 750);
    pathOffset50.lineTo(1000, 750);
    canvas.drawPath(pathOffset50, mEffectPaint);
}

2.折角弧：CornerPathEffect(corner)

动画是不断改变圆角大小：mEffectCorner的结果

折角弧.gif

/**
 * 圆角折线
 *
 * @param canvas
 */
private void cornerEffect(Canvas canvas) {
    mEffectPaint.setPathEffect(new CornerPathEffect(mEffectCorner));
    mEffectPaint.setStyle(Paint.Style.STROKE);
    mEffectPaint.setStrokeWidth(40);
    Path path = new Path();
    path.moveTo(550, 550);
    path.lineTo(900, 300);
    path.lineTo(1000, 550);
    canvas.drawPath(path, mEffectPaint);
    //蓝色辅助线
    Paint tempPaint = new Paint();
    tempPaint.setStyle(Paint.Style.STROKE);
    tempPaint.setColor(Color.BLUE);
    tempPaint.setStrokeWidth(2);
    tempPaint.setPathEffect(new DashPathEffect(new float[]{20, 20}, 0));
    Path helpPath = new Path();
    helpPath.moveTo(550, 550);
    helpPath.lineTo(900, 300);
    helpPath.lineTo(1000, 550);
    canvas.drawPath(helpPath, tempPaint);
}

3.离散路径：DiscretePathEffect(小段长，偏移量)

离散路径.png

/**
 * 离散路径
 *
 * @param canvas
 */
private void discreteEffect(Canvas canvas) {
    canvas.save();//保存画布状态
    canvas.translate(0, 950);
    //第一个参数：将原来的路径切成多长的线段,越小，所切成的小线段越多
    //第二参数：被切成的每个小线段的可偏移距离。越大，每个线段的可偏移距离就越大。
    Path path = new Path();
    // 定义路径的起点
    path.moveTo(100, 0);
    path.lineTo(600, -100);
    path.lineTo(1000, 0);
    
    mEffectPaint.setPathEffect(new DiscretePathEffect(2, 5));
    mEffectPaint.setStrokeWidth(2);
    canvas.drawPath(path, mEffectPaint);
    canvas.translate(0, 100);
    mEffectPaint.setPathEffect(new DiscretePathEffect(20, 5));
    canvas.drawPath(path, mEffectPaint);
    canvas.restore();//重新储存画布状态
}

4.路径点样：PathDashPathEffect(路径,间距，偏移，样式)

路径样点.gif

通过动图可以很清楚得看出三个样式的区别动图是不断改变偏移量：mDashOffSet的结果

//Path shape:表示[路径点样],这里是一个五角星
//float advance：表示两个[路径点样]间的距离
//float phase：路径绘制偏移距离
//Style style：表示在遇到转角时的过渡样式
// ----Style.ROTATE表示通过旋转[路径点样]来过渡转角；
// ----Style.MORPH表示通过变形[路径点样]来过渡转角；
// ----Style.TRANSLATE表示通过位移[路径点样]来过渡转角。

/**
 * 路径点样路径样式
 *
 * @param canvas
 */
private void PathDashEffect(Canvas canvas) {
    canvas.save();
    canvas.translate(0, 1100);
    Path path = new Path();
    // 定义路径的起点
    path.moveTo(100, 80);
    path.lineTo(600, -100);
    path.lineTo(1000, 80);
    //变形过渡
    mEffectPaint.setPathEffect(new PathDashPathEffect(
            CommonPath.nStarPath(5, 16, 8), 40, mDashOffSet, PathDashPathEffect.Style.ROTATE));
    canvas.drawPath(path, mEffectPaint);
    canvas.restore();
    //旋转过渡
    canvas.save();
    canvas.translate(0, 1200);
    mEffectPaint.setPathEffect(new PathDashPathEffect(
            CommonPath.nStarPath(5, 16, 8), 40, mDashOffSet, PathDashPathEffect.Style.MORPH));
    canvas.drawPath(path, mEffectPaint);
    canvas.restore();
    //移动过渡
    canvas.save();
    canvas.translate(0, 1300);
    mEffectPaint.setPathEffect(new PathDashPathEffect(
            CommonPath.nStarPath(5, 16, 8), 40, mDashOffSet, PathDashPathEffect.Style.TRANSLATE));
    canvas.drawPath(path, mEffectPaint);
    canvas.restore();
}
/**
 * 离散路径
 *
 * @param canvas
 */
private void discreteEffect(Canvas canvas) {
    canvas.save();//保存画布状态
    canvas.translate(0, 950);
    //第一个参数：将原来的路径切成多长的线段,越小，所切成的小线段越多
    //第二参数：被切成的每个小线段的可偏移距离。越大，每个线段的可偏移距离就越大。
    Path path = new Path();
    // 定义路径的起点
    path.moveTo(100, 0);
    path.lineTo(600, -100);
    path.lineTo(1000, 0);
    mEffectPaint.setPathEffect(new DiscretePathEffect(2, 5));
    mEffectPaint.setStrokeWidth(2);
    canvas.drawPath(path, mEffectPaint);
    canvas.translate(0, 100);
    mEffectPaint.setPathEffect(new DiscretePathEffect(20, 5));
    canvas.drawPath(path, mEffectPaint);
    canvas.restore();//重新储存画布状态
}

n角星路径封装：

    /**
     * n角星路径
     *
     * @param num 几角星
     * @param R   外接圆半径
     * @param r   内接圆半径
     * @return n角星路径
     */
    public static Path nStarPath(int num, float R, float r) {
        Path path = new Path();
        float perDeg = 360 / num;
        float degA = perDeg / 2 / 2;
        float degB = 360 / (num - 1) / 2 - degA / 2 + degA;

        path.moveTo(
                (float) (Math.cos(rad(degA + perDeg * 0)) * R + R * Math.cos(rad(degA))),
                (float) (-Math.sin(rad(degA + perDeg * 0)) * R + R));
        for (int i = 0; i < num; i++) {
            path.lineTo(
                    (float) (Math.cos(rad(degA + perDeg * i)) * R + R * Math.cos(rad(degA))),
                    (float) (-Math.sin(rad(degA + perDeg * i)) * R + R));
            path.lineTo(
                    (float) (Math.cos(rad(degB + perDeg * i)) * r + R * Math.cos(rad(degA))),
                    (float) (-Math.sin(rad(degB + perDeg * i)) * r + R));
        }
        path.close();
        return path;
    }

    /**
     * 角度制化为弧度制
     *
     * @param deg 角度
     * @return 弧度
     */
    public static float rad(float deg) {
        return (float) (deg * Math.PI / 180);
    }

5.叠加特效：PathDashPathEffect(e1,e2...)(此处演示：离散效果+样点效果)

特效叠加.gif

/**
 * 叠加样式
 *
 * @param canvas
 */
private void composeEffect(Canvas canvas) {
    mEffectPaint.setStyle(Paint.Style.STROKE);
    mEffectPaint.setStrokeWidth(40);
    canvas.save();
    canvas.translate(0, 1400);
    Path path = new Path();
    // 定义路径的起点
    path.moveTo(100, 80);
    path.lineTo(600, -100);
    path.lineTo(1000, 80);
    PathDashPathEffect effect1 = new PathDashPathEffect(
            CommonPath.nStarPath(5, 16, 8), 40, mDashOffSet, PathDashPathEffect.Style.ROTATE);
    DiscretePathEffect effect2 = new DiscretePathEffect(20, 5);
    mEffectPaint.setPathEffect(new ComposePathEffect(effect1, effect2));//离散效果+样点效果
    canvas.drawPath(path, mEffectPaint);
    canvas.restore();
}

6.路径叠加

路径叠加.gif

/**
 * 路径叠加
 *
 * @param canvas
 */
private void sumEffect(Canvas canvas) {
    canvas.save();
    canvas.translate(0, 1500);
    Path path = new Path();
    // 定义路径的起点
    path.moveTo(100, 80);
    path.lineTo(600, -100);
    path.lineTo(1000, 80);
    PathDashPathEffect effect1 = new PathDashPathEffect(
            CommonPath.nStarPath(5, 16, 8), 40, mDashOffSet, PathDashPathEffect.Style.ROTATE);
    DiscretePathEffect effect2 = new DiscretePathEffect(20, 5);
    mEffectPaint.setPathEffect(new SumPathEffect(effect1, effect2));//离散效果+样点效果
    canvas.drawPath(path, mEffectPaint);
    canvas.restore();
}

六.着色器：Shader

一个很简单的类，有5个子类：

1.线性渐变：

1).new LinearGradient(渐变起点x，y,渐变终点x,y,渐变色1，渐变色2，渐变模式)

渐变模式:Shader.TileMode.[MIRROR|CLAMP|REPEAT] (图中很形象，就不解释了)

        int colorStart = Color.parseColor("#84F125");
        int colorEnd = Color.parseColor("#5825F1");
        canvas.save();
        canvas.translate(mCoo.x, mCoo.y);
        mRedPaint.setStyle(Paint.Style.FILL);
        mRedPaint.setShader(
                new LinearGradient(
                        -200, 0, 200, 0,
                        colorStart, colorEnd,
                        Shader.TileMode.MIRROR

                ));
        canvas.drawRect(-400,-200,400,-100,mRedPaint);

        canvas.translate(0, 150);
        mRedPaint.setShader(
                new LinearGradient(
                        -100, 0, 100, 0,
                        colorStart, colorEnd,
                        Shader.TileMode.CLAMP
                ));
        canvas.drawRect(-400,-200,400,-100,mRedPaint);

        canvas.translate(0, 150);
        mRedPaint.setShader(
                new LinearGradient(
                        -100, 0, 100, 0,
                        colorStart, colorEnd,
                        Shader.TileMode.REPEAT
                ));
        canvas.drawRect(-400,-200,400,-100,mRedPaint);

线性渐变.png

2).多色多点渐变：LinearGradient(渐变起点x，y,渐变终点x,y,颜色数组，位置百分点数组0~1,渐变模式)

多色渐变.png

int[] colors = new int[]{
        Color.parseColor("#F60C0C"),//红
        Color.parseColor("#F3B913"),//橙
        Color.parseColor("#E7F716"),//黄
        Color.parseColor("#3DF30B"),//绿
        Color.parseColor("#0DF6EF"),//青
        Color.parseColor("#0829FB"),//蓝
        Color.parseColor("#B709F4"),//紫
};
float[] pos = new float[]{
        1.f / 7, 2.f / 7, 3.f / 7, 4.f / 7, 5.f / 7, 6.f / 7, 1
};

canvas.translate(0, 150);
mRedPaint.setShader(
        new LinearGradient(
                -300, 0, 300, 0,
                colors, pos,
                Shader.TileMode.CLAMP

        ));
canvas.drawRect(-400, -200, 400, -100, mRedPaint);

2.径向渐变：RadialGradient

1).两色渐变：RadialGradient(渐变中心，渐变半径，颜色1，颜色2，渐变模式)

canvas.translate(mCoo.x, mCoo.y);
int colorStart = Color.parseColor("#84F125");
int colorEnd = Color.parseColor("#5825F1");
mRedPaint.setStyle(Paint.Style.FILL);
mRedPaint.setShader(
        new RadialGradient(
               0,0,50,
                colorStart, colorEnd,
                Shader.TileMode.MIRROR

        ));

canvas.drawCircle(0, 0, 150, mRedPaint);

canvas.translate(350, 0);
mRedPaint.setShader(
        new RadialGradient(
                0,0,50,
                colorStart, colorEnd,
                Shader.TileMode.CLAMP

        ));
canvas.drawCircle(0, 0, 150, mRedPaint);


canvas.translate(350, 0);
mRedPaint.setShader(
        new RadialGradient(
                0,0,50,
                colorStart, colorEnd,
                Shader.TileMode.REPEAT

        ));
canvas.drawCircle(0, 0, 150, mRedPaint);

径像渐变.png

2).多色多点径向渐变：

RadialGradient(渐变中心，渐变半径，渐变模式,颜色数组，位置百分点数组0~1,渐变模式)

多色径向渐变.png

int[] colors = new int[]{
        Color.parseColor("#F60C0C"),//红
        Color.parseColor("#F3B913"),//橙
        Color.parseColor("#E7F716"),//黄
        Color.parseColor("#3DF30B"),//绿
        Color.parseColor("#0DF6EF"),//青
        Color.parseColor("#0829FB"),//蓝
        Color.parseColor("#B709F4"),//紫
};
float[] pos = new float[]{
        1.f / 7, 2.f / 7, 3.f / 7, 4.f / 7, 5.f / 7, 6.f / 7, 1
};
mRedPaint.setStyle(Paint.Style.FILL);
mRedPaint.setShader(
        new RadialGradient(
                0, 0, 200,
                colors, pos,
                Shader.TileMode.CLAMP
        ));
canvas.drawCircle(0, 0, 250, mRedPaint);

3.扫描渐变：SweepGradient

这个要比上面的简单一点，没有渐变的模式双色扫描渐变：SweepGradient(中心点x,y,颜色1，颜色2) 多色扫描渐变：SweepGradient(中心点x,y,颜色数组，位置百分点数组0~1)

扫描渐变.png

int colorStart = Color.parseColor("#84F125");
int colorEnd = Color.parseColor("#5825F1");
mRedPaint.setStyle(Paint.Style.FILL);
mRedPaint.setShader(
        new SweepGradient(0, 0, colorStart, colorEnd));
canvas.drawCircle(0, 0, 150, mRedPaint);

canvas.translate(400, 0);
int[] colors = new int[]{
        Color.parseColor("#F60C0C"),//红
        Color.parseColor("#F3B913"),//橙
        Color.parseColor("#E7F716"),//黄
        Color.parseColor("#3DF30B"),//绿
        Color.parseColor("#0DF6EF"),//青
        Color.parseColor("#0829FB"),//蓝
        Color.parseColor("#B709F4"),//紫
};
float[] pos = new float[]{
        1.f / 7, 2.f / 7, 3.f / 7, 4.f / 7, 5.f / 7, 6.f / 7, 1
};
mRedPaint.setShader(
        new SweepGradient(0, 0, colors, pos));
canvas.drawCircle(0, 0, 150, mRedPaint);

4.图片着色器：BitmapShader(图片，着色模式x，着色模式y)

用图片的所有像素点作为画笔的颜色

1).文字的图片底色：

//加载图片，生成图片着色器
Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.mipmap.menu_bg);
BitmapShader bs = new BitmapShader(bitmap, Shader.TileMode.CLAMP,Shader.TileMode.CLAMP);
mRedPaint.setShader(bs);
mRedPaint.setTextSize(150);
mRedPaint.setStrokeWidth(10);
mRedPaint.setStyle(Paint.Style.FILL_AND_STROKE);
canvas.drawText("张风捷特烈", 0, 500, mRedPaint);

图片着色.png

2)路径+图片着色器实现裁剪图片：路径Path相关知识见上一篇：

Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.menu_bg);
BitmapShader bs = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
mRedPaint.setShader(bs);

mRedPaint.setStyle(Paint.Style.FILL);
Path path = CommonPath.nStarPath(8, 500, 250);
canvas.drawPath(path, mRedPaint);

使用路径裁剪图片.png

还有一个ComposeShader比较复杂，以后有需求会专门写一篇

七、颜色过滤器:(具体原理是颜色运算，这里全当玩玩看看吧，暂不深究)

ColorFilter只有三个子类

颜色过滤器.png

1.LightingColorFilter(颜色1，颜色2)：

看图体会一下吧...我不说了

LightingColorFilter测试.png

        Bitmap mainBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.menu_bg);
        mRedPaint.setStyle(Paint.Style.FILL);
        mRedPaint.setColorFilter(new LightingColorFilter(
                Color.parseColor("#FF0000"),//红
                Color.parseColor("#0000ff")//蓝
        ));
        canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

        canvas.translate(350, 0);
        mRedPaint.setColorFilter(new LightingColorFilter(
                Color.parseColor("#FF0000"),//红
                Color.parseColor("#00ff00")//绿
        ));
        canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

        canvas.translate(350, 0);
        mRedPaint.setColorFilter(new LightingColorFilter(
                Color.parseColor("#FF0000"),//红
                Color.parseColor("#000000")//黑
        ));
        canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);
        canvas.restore();

2.PorterDuffColorFilter(颜色，模式--PorterDuff.Mode)：

PorterDuff.Mode一共18中，在Color专题会详述，这里举几个栗子看看

PorterDuffColorFilter测试.png

Bitmap mainBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.menu_bg);
mRedPaint.setStyle(Paint.Style.FILL);

mRedPaint.setColorFilter(new PorterDuffColorFilter(
        Color.parseColor("#0000ff"), PorterDuff.Mode.DARKEN));
canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

canvas.translate(350, 0);
mRedPaint.setColorFilter(new PorterDuffColorFilter(
        Color.parseColor("#0000ff"),PorterDuff.Mode.LIGHTEN
));
canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

canvas.translate(350, 0);
mRedPaint.setColorFilter(new PorterDuffColorFilter(
        Color.parseColor("#0000ff"),PorterDuff.Mode.SCREEN
));
canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

canvas.translate(350, 0);
mRedPaint.setColorFilter(new PorterDuffColorFilter(
        Color.parseColor("#0000ff"),PorterDuff.Mode.OVERLAY
));
canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

3.ColorMatrixColorFilter(颜色变换矩阵或20个float数)

刚好前端时间对ColorMatrix有一点研究，这里拿来用用

颜色矩阵.png

        Bitmap mainBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.menu_bg);
        mRedPaint.setStyle(Paint.Style.FILL);

        //关闭RGB颜色通道(变为黑色)，后偏移红色255
        float[] matrix = new float[]{
                -1, 0, 0, 0, 255,
                0, -1, 0, 0, 0,
                0, 0, -1, 0, 0,
                0, 0, 0, 1, 0
        };
        ColorMatrix colorMatrix = new ColorMatrix(matrix);
        mRedPaint.setColorFilter(new ColorMatrixColorFilter(colorMatrix));
        canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);


        canvas.translate(350, 0);
        //关闭RGB颜色通道(变为黑色)，后偏移蓝色255
        float[] matrix2 = new float[]{
                -1, 0, 0, 0, 0,
                0, -1, 0, 0, 0,
                0, 0, -1, 0, 255,
                0, 0, 0, 1, 0
        };
        ColorMatrix colorMatrix2 = new ColorMatrix(matrix2);
        mRedPaint.setColorFilter(new ColorMatrixColorFilter(colorMatrix2));
        canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

        canvas.translate(350, 0);
        //关闭RGB颜色通道(变为黑色)，后偏移三色255
        float[] matrix3 = new float[]{
                -1, 0, 0, 0, 255,
                0, -1, 0, 0, 255,
                0, 0, -1, 0, 255,
                0, 0, 0, 1, 0
        };
        ColorMatrix colorMatrix3 = new ColorMatrix(matrix3);
        mRedPaint.setColorFilter(new ColorMatrixColorFilter(colorMatrix3));
        canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

        canvas.translate(350, 0);

        float[] matrix4 = new float[]{
                //只要把RGB三通道的色彩信息设置成一样:即：R＝G＝B,
                // 为了保证图像亮度不变，同一个通道中的R+G+B=1
                0.3086f, 0.6094f, 0.0820f, 0, 0,
                0.3086f, 0.6094f, 0.0820f, 0, 0,
                0.3086f, 0.6094f, 0.0820f, 0, 0,
                0, 0, 0, 1, 0
        };
        ColorMatrix colorMatrix4 = new ColorMatrix(matrix4);
        mRedPaint.setColorFilter(new ColorMatrixColorFilter(colorMatrix4));
        canvas.drawBitmap(mainBitmap, 0, 0, mRedPaint);

七、文字相关

字体.setTypeface(Typeface.SANS_SERIF);
对齐方式.setTextAlign(Paint.Align.LEFT);
字体大小.setTextSize(100);

1.对齐方式与内置字体：

对齐：Paint.Align.[#LEFT|RIGHT|CENTER]
内置字体:Typeface.[#DEFAULT|DEFAULT_BOLD|SANS_SERIF|SERIF|MONOSPACE]

canvas.save();
canvas.translate(550, 1600);
mTextPaint.setTypeface(Typeface.SANS_SERIF);
mTextPaint.setTextAlign(Paint.Align.LEFT);
mTextPaint.setTextSize(100);
canvas.drawText("SANS_SERIF", 0, 0, mTextPaint);
Paint tempPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
tempPaint.setStrokeWidth(4);
tempPaint.setColor(Color.RED);
tempPaint.setStyle(Paint.Style.STROKE);
canvas.drawRect(0, - 100, mWinSize.x, 0, tempPaint);

canvas.translate(0, 150);
mTextPaint.setTextAlign(Paint.Align.RIGHT);
mTextPaint.setTypeface(Typeface.SERIF);
canvas.drawText("SERIF", 0, 0, mTextPaint);
canvas.drawRect(0, - 100, mWinSize.x, 0, tempPaint);

canvas.translate(0, 150);
mTextPaint.setTypeface(Typeface.MONOSPACE);
mTextPaint.setTextAlign(Paint.Align.CENTER);
canvas.drawText("MONOSPACE", 0, 0, mTextPaint);
canvas.drawRect(0, - 100, mWinSize.x, 0, tempPaint);

canvas.restore();

文字相关.png

2.创建字体：外部字体放在assets目录下

/**
 * 创建字体
 * @param canvas
 */
private void createTypeface(Canvas canvas) {
    mTextPaint.setTextSize(50);
    canvas.save();
    canvas.translate(50, 1600);
    mTextPaint.setTypeface(Typeface.MONOSPACE);
    canvas.drawText("MONOSPACE", 0, 0, mTextPaint);
    //粗体
    canvas.translate(0, 100);
    Typeface typeface = Typeface.create(Typeface.MONOSPACE, Typeface.BOLD);
    mTextPaint.setTypeface(typeface);
    canvas.drawText("MONOSPACE+BOLD", 0, 0, mTextPaint);
    //斜体
    canvas.translate(0, 100);
    Typeface typeface2 = Typeface.create(Typeface.MONOSPACE, Typeface.ITALIC);
    mTextPaint.setTypeface(typeface2);
    canvas.drawText("MONOSPACE+ITALIC", 0, 0, mTextPaint);
    //粗斜体
    canvas.translate(0, 100);
    Typeface typeface3 = Typeface.create(Typeface.MONOSPACE, Typeface.BOLD_ITALIC);
    mTextPaint.setTypeface(typeface3);
    canvas.drawText("MONOSPACE+BOLD_ITALIC", 0, 0, mTextPaint);
    //使用外部字体
    canvas.translate(0, 100);
    Typeface myFont = Typeface.createFromAsset(getContext().getAssets(), "ACHAFSEX.TTF");
    mTextPaint.setTypeface(myFont);
    canvas.drawText("Hello I am Toly", 0, 0, mTextPaint);
    canvas.restore();
}

创建字体.png

3.文字的测量：FontMetrics

1).字体测量类：FontMetrics

    public static class FontMetrics {
        public float   top;//最顶
        public float   ascent;//
        public float   leading;
        public float   descent;
        public float   bottom;//最底
    }

2).SERIF字体测试：(试了一下不同字体这几个属性都不同的,有的字体相差很大)

字体5线.png

    /**
     * 获取字体尺寸信息
     * @param canvas
     */
    private void fontMetricsTest(Canvas canvas) {
        canvas.save();
        canvas.translate(100, 500);
        mTextPaint.setTextSize(200);
        mTextPaint.setTypeface(Typeface.SERIF);
        canvas.drawText("I am Toly", 0, 0, mTextPaint);
        //获取字体尺寸
        Paint.FontMetrics fm = mTextPaint.getFontMetrics();

        Log.e(TAG, "top: " + fm.top);
        Log.e(TAG, "ascent: " + fm.ascent);
        Log.e(TAG, "leading: " + fm.leading);
        Log.e(TAG, "descent: " + fm.descent);
        Log.e(TAG, "bottom: " + fm.bottom);

        Paint tempPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        tempPaint.setStrokeWidth(1);
        tempPaint.setColor(Color.RED);
        tempPaint.setStyle(Paint.Style.STROKE);

        canvas.drawLine(0, fm.top, mWinSize.x, fm.top, tempPaint);

        tempPaint.setColor(Color.MAGENTA);
        canvas.drawLine(0, fm.ascent, mWinSize.x, fm.ascent, tempPaint);

        tempPaint.setColor(Color.parseColor("#4C17F9"));
        canvas.drawLine(0, fm.leading, mWinSize.x, fm.leading, tempPaint);

        tempPaint.setColor(Color.GREEN);
        canvas.drawLine(0, fm.descent, mWinSize.x, fm.descent, tempPaint);

        tempPaint.setColor(Color.parseColor("#E74EDD"));
        canvas.drawLine(0, fm.bottom, mWinSize.x, fm.bottom, tempPaint);

        canvas.restore();
    }

2018-11-05 21:17:35.264 28726-28726/? E/PaintView: top: -209.57031
2018-11-05 21:17:35.264 28726-28726/? E/PaintView: ascent: -185.54688
2018-11-05 21:17:35.264 28726-28726/? E/PaintView: leading: 0.0
2018-11-05 21:17:35.264 28726-28726/? E/PaintView: descent: 48.828125
2018-11-05 21:17:35.264 28726-28726/? E/PaintView: bottom: 50.0

3).获取文字矩形区

String text = "I am Toly";
Rect textRect = new Rect();
mTextPaint.getTextBounds(text, 0, text.length(), textRect);
Log.e(TAG, textRect.toShortString());// [7,-152][886,49]
//绘制矩形
tempPaint.setColor(Color.parseColor("#66F4F628"));
tempPaint.setStyle(Paint.Style.FILL);
canvas.drawRect(textRect, tempPaint);

文字最小矩形区.png

4).文字的变形操作

mTextPaint.setTextScaleX(.5f);//水平伸缩
mTextPaint.setStrikeThruText(true);//删除线
mTextPaint.setUnderlineText(true);//下划线
mTextPaint.setTextSkewX(-.5f);//倾斜

其他效果.png

就先这样吧，还有很多不常用的，以后有需求遇到了，在加吧

续--更新：

1.设置过渡消除锯齿:setFilterBitmap效果

这个很简单，就是true/false,默认false

        Bitmap mainBitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.menu_bg);
        Matrix matrix = new Matrix();
        matrix.setScale(5, 5);//放大矩阵
        
        mRedPaint.setFilterBitmap(false);
        canvas.drawBitmap(mainBitmap, matrix, mRedPaint);
        
        canvas.translate(-500, -300);
        mRedPaint.setFilterBitmap(true);
        canvas.drawBitmap(mainBitmap, matrix, mRedPaint);

2.添加文字阴影：setShadowLayer(模糊半径，x偏移，y偏移，颜色)

注意：图片试了一下，不可以

        mRedPaint.setShadowLayer(100, 20, 20, Color.parseColor("#eeF39729"));
        mRedPaint.setTextSize(400);
        mRedPaint.setStrokeWidth(10);
        mRedPaint.setStyle(Paint.Style.FILL);
        
        //使用外置字体放在assets目录下
        Typeface myFont = Typeface.createFromAsset(getContext().getAssets(), "CHOPS.TTF");
        mRedPaint.setTypeface(myFont);
        canvas.drawText("Toly", 300, 300, mRedPaint);

添加文字阴影.png

对Path试了一下阴影效果，貌似只有Alpha值起作用，阴影跟着画笔颜色走

mRedPaint.setShadowLayer(20, 4, 4, Color.parseColor("#335064F8"));
mRedPaint.setColor(Color.BLUE);
canvas.drawPath(CommonPath.regularStarPath(8, 200),mRedPaint);

canvas.translate(600, 0);
mRedPaint.setShadowLayer(20, 4, 4, Color.parseColor("#885064F8"));
canvas.drawBitmap(mainBitmap, matrix, mRedPaint);

path阴影.png

后记：捷文规范

1.本文成长记录及勘误表

项目源码	日期	备注
V0.1--无	2018-11-7	Android关于Paint你所知道的和不知道的一切
V0.2--无	2018-11-9	增加setFilterBitmap和阴影测试

2.更多关于我

笔名	QQ	微信	爱好
张风捷特烈	1981462002	zdl1994328	语言
我的github	我的简书	我的CSDN	个人网站

3.声明

1----本文由张风捷特烈原创,转载请注明
2----欢迎广大编程爱好者共同交流
3----个人能力有限，如有不正之处欢迎大家批评指证，必定虚心改正
4----看到这里，我在此感谢你的喜欢与支持