Android 用Canvas 画几何图形，画出小黄人

看了大神 JR93的这篇文章:纯CSS3画出小黄人并实现动画效果 ，萌生了我在安卓上画小黄人的想法，同时他在文章中的步骤分解，在我的具体实现中起到了很大的帮助。话不多说，先上效果图

实现步骤

其实很简单

1. 首先找到一张小黄人的图
2. 然后调用canvas.drawBitmap()后画到画布上 - -。
   好吧，一点都不好笑

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正文

准备工作

自定义MinionView extends View，定义以下成员变量，备用（可以先不看，后面的代码看到莫名其妙出来的变量再上来看下）

    private Paint mPaint;    private float bodyWidth;    private float bodyHeigh;    private static final float BODY_SCALE = 0.6f;//身体主干占整个view的比重    private static final float BODY_WIDTH_HEIGHT_SCALE = 0.6f; //        身体的比例设定为 w:h = 3:5    private float mStrokeWidth = 4;//描边宽度    private float offset;//计算时，部分需要 考虑描边偏移    private float radius;//身体上下半圆的半径    private int colorClothes = Color.rgb(32, 116, 160);//衣服的颜色    private int colorBody = Color.rgb(249, 217, 70);//身体的颜色    private int colorStroke = Color.BLACK;    private RectF bodyRect;    private float handsHeight;//计算出吊带的高度时，可以用来做手的高度    private float footHeigh;//脚的高度，用来画脚部阴影时用

初始化参数

重写protected void onDraw(Canvas canvas)方法，首先调用 如下 （会经常看到一些奇怪的数字，做比例，别问我怎么来的，目测+一点点微调得来的- -。）

    private void initParams() {        bodyWidth = Math.min(getWidth(), getHeight() * BODY_WIDTH_HEIGHT_SCALE) * BODY_SCALE;        bodyHeigh = Math.min(getWidth(), getHeight() * BODY_WIDTH_HEIGHT_SCALE) / BODY_WIDTH_HEIGHT_SCALE * BODY_SCALE;        mStrokeWidth = Math.max(bodyWidth / 50, mStrokeWidth);        offset = mStrokeWidth / 2;        bodyRect = new RectF();        bodyRect.left = (getWidth() - bodyWidth) / 2;        bodyRect.top = (getHeight() - bodyHeigh) / 2;        bodyRect.right = bodyRect.left + bodyWidth;        bodyRect.bottom = bodyRect.top + bodyHeigh;        radius = bodyWidth / 2;        footHeigh = radius * 0.4333f;        handsHeight =  (getHeight() + bodyHeigh) / 2   + offset - radius * 1.65f ;    }

画身体

我来组成身体

显然身体是一个矩形加上，上下半圆，这边只要用一个圆角矩形，然后圆角的弧度半径用身体宽度的一半就可以达到这个效果了。
把身体的矩形外存起来，后面经常要用到其相对位置进行对其它部位的定位，代码如下。

    drawBody(canvas);//身体    drawBodyStroke(canvas);//最后画身体的描边，可以摭住一些过渡的棱角    private void drawBody(Canvas canvas) {        initPaint();        mPaint.setColor(colorBody);        mPaint.setStyle(Paint.Style.FILL);        canvas.drawRoundRect(bodyRect, radius, radius, mPaint);    }     private void drawBodyStroke(Canvas canvas) {        initPaint();        mPaint.setColor(colorStroke);        mPaint.setStrokeWidth(mStrokeWidth);        mPaint.setStyle(Paint.Style.STROKE);        canvas.drawRoundRect(bodyRect, radius, radius, mPaint);    }

画衣服

这是穿上裤子的样子

• 首先先画上底下的半圆

        RectF rect = new RectF();      rect.left = (getWidth() - bodyWidth) / 2 + offset;      rect.top = (getHeight() + bodyHeigh) / 2 - radius * 2 + offset;      rect.right = rect.left + bodyWidth - offset * 2;      rect.bottom = rect.top + radius * 2 - offset * 2;      mPaint.setColor(colorClothes);      mPaint.setStyle(Paint.Style.FILL);      mPaint.setStrokeWidth(mStrokeWidth);      canvas.drawArc(rect, 0, 180, true, mPaint);

• 再画半圆上方的矩形,w表示矩形离左边身体的距离，h矩形的高

        int h = (int) (radius * 0.5);      int w = (int) (radius * 0.3);      rect.left += w;      rect.top = rect.top + radius - h;      rect.right -= w;      rect.bottom = rect.top + h;      canvas.drawRect(rect, mPaint);

• 上面的画完之后，要在衣服上面描一层黑色的边，用canvas.drawLines把线一条条画出来吧，这边要同时考虑画笔的描边宽度，否则会出现连接点有锯齿的感觉。

        //画横线      initPaint();      mPaint.setColor(colorStroke);      mPaint.setStyle(Paint.Style.FILL);      mPaint.setStrokeWidth(mStrokeWidth);      float[] pts = new float[20];//5条线      pts[0] = rect.left - w;      pts[1] = rect.top + h;      pts[2] = pts[0] + w;      pts[3] = pts[1];      pts[4] = pts[2];      pts[5] = pts[3] + offset;      pts[6] = pts[4];      pts[7] = pts[3] - h;      pts[8] = pts[6] - offset;      pts[9] = pts[7];      pts[10] = pts[8] + (radius - w) * 2;      pts[11] = pts[9];      pts[12] = pts[10];      pts[13] = pts[11] - offset;      pts[14] = pts[12];      pts[15] = pts[13] + h;      pts[16] = pts[14] - offset;      pts[17] = pts[15];      pts[18] = pts[16] + w;      pts[19] = pts[17];      canvas.drawLines(pts, mPaint);

• 画吊带 就是一个直角梯形，把梯形的四个顶点计算出来，使用canvas.drawPath将其画上去，然后纽扣用一个实心的小圆表示

       //画左吊带      initPaint();      mPaint.setColor(colorClothes);      mPaint.setStrokeWidth(mStrokeWidth);      mPaint.setStyle(Paint.Style.FILL);      Path path = new Path();      path.moveTo(rect.left - w - offset, handsHeight);      path.lineTo(rect.left + h / 4, rect.top + h / 2);      final float smallW = w / 2 * (float) Math.sin(Math.PI / 4);      path.lineTo(rect.left + h / 4 + smallW, rect.top + h / 2 - smallW);      final float smallW2 = w / (float) Math.sin(Math.PI / 4) / 2;      path.lineTo(rect.left - w - offset, handsHeight - smallW2);      canvas.drawPath(path, mPaint);      initPaint();      mPaint.setColor(colorStroke);      mPaint.setStrokeWidth(mStrokeWidth);      mPaint.setStyle(Paint.Style.STROKE);      canvas.drawPath(path, mPaint);      initPaint();      mPaint.setStyle(Paint.Style.FILL_AND_STROKE);      canvas.drawCircle(rect.left + h / 4, rect.top + h / 4, mStrokeWidth, mPaint);      //画右吊带      initPaint();      mPaint.setColor(colorClothes);      mPaint.setStrokeWidth(mStrokeWidth);      mPaint.setStyle(Paint.Style.FILL);      path.reset();      path.moveTo(rect.left - w + 2 * radius - offset, handsHeight);      path.lineTo(rect.right - h / 4, rect.top + h / 2);      path.lineTo(rect.right - h / 4 - smallW, rect.top + h / 2 - smallW);      path.lineTo(rect.left - w + 2 * radius - offset, handsHeight- smallW2);      canvas.drawPath(path, mPaint);      initPaint();      mPaint.setColor(colorStroke);      mPaint.setStrokeWidth(mStrokeWidth);      mPaint.setStyle(Paint.Style.STROKE);      canvas.drawPath(path, mPaint);      initPaint();      mPaint.setStyle(Paint.Style.FILL_AND_STROKE);      canvas.drawCircle(rect.right - h / 4, rect.top + h / 4, mStrokeWidth, mPaint);

• 画中间的口袋 是一个下面两边是圆角的圆角矩形，但是貌似不能直接画这样的圆角矩形，所以我就用土办法，不就是一个多边形吗，用canvas.drawPath来画，在圆角的地方添加圆弧过渡path.addArc

       //中间口袋      initPaint();      mPaint.setColor(colorStroke);      mPaint.setStrokeWidth(mStrokeWidth);      mPaint.setStyle(Paint.Style.STROKE);      path.reset();      float radiusBigPokect = w / 2.0f;      path.moveTo(rect.left + 1.5f * w, rect.bottom - h / 4);      path.lineTo(rect.right - 1.5f * w, rect.bottom - h / 4);      path.lineTo(rect.right - 1.5f * w, rect.bottom + h / 4);      path.addArc(rect.right - 1.5f * w - radiusBigPokect * 2, rect.bottom + h / 4 - radiusBigPokect,              rect.right - 1.5f * w, rect.bottom + h / 4 + radiusBigPokect, 0, 90);      path.lineTo(rect.left + 1.5f * w + radiusBigPokect, rect.bottom + h / 4 + radiusBigPokect);      path.addArc(rect.left + 1.5f * w, rect.bottom + h / 4 - radiusBigPokect,              rect.left + 1.5f * w + 2 * radiusBigPokect, rect.bottom + h / 4 + radiusBigPokect, 90, 90);      path.lineTo(rect.left + 1.5f * w, rect.bottom - h / 4 - offset);      canvas.drawPath(path, mPaint);

• 左右两个小口袋也直接用一个小弧来解决掉

     //        下边一竖，分开裤子      canvas.drawLine(bodyRect.left + bodyWidth / 2, bodyRect.bottom - h * 0.8f, bodyRect.left + bodyWidth / 2, bodyRect.bottom, mPaint);//      左边的小口袋      float radiusSamllPokect = w * 1.2f;      canvas.drawArc(bodyRect.left - radiusSamllPokect, bodyRect.bottom - radius - radiusSamllPokect,              bodyRect.left + radiusSamllPokect, bodyRect.bottom - radius + radiusSamllPokect, 80, -60, false, mPaint);//      右边小口袋      canvas.drawArc(bodyRect.right - radiusSamllPokect, bodyRect.bottom - radius - radiusSamllPokect,              bodyRect.right + radiusSamllPokect, bodyRect.bottom - radius + radiusSamllPokect, 100, 60, false, mPaint);//        canvas.drawArc(left + w/5,);

• 嗯，衣服画完了。

    drawClothes(canvas);//衣服    private void drawClothes(Canvas canvas) {        initPaint();        //就是上面那一堆代码按顺序合起来啦。。。。。    }

画脚

萌萌的小短腿

脚这部分比较简单，从身体的下方，一个竖直的矩形下来，再加上一个左边圆角的圆角矩形，还是通过画Path来实现。

        drawFeet(canvas);//脚    private void drawFeet(Canvas canvas) {        mPaint.setStrokeWidth(mStrokeWidth);        mPaint.setColor(colorStroke);        mPaint.setStyle(Paint.Style.FILL_AND_STROKE);        float radiusFoot = radius / 3 * 0.4f;        float leftFootStartX = bodyRect.left + radius - offset * 2;        float leftFootStartY = bodyRect.bottom - offset;        float footWidthA = radius * 0.5f;//脚宽度大-到半圆结束        float footWidthB = footWidthA / 3;//脚宽度-比较细的部分        //      左脚        Path path = new Path();        path.moveTo(leftFootStartX, leftFootStartY);        path.lineTo(leftFootStartX, leftFootStartY + footHeigh);        path.lineTo(leftFootStartX - footWidthA + radiusFoot, leftFootStartY + footHeigh);        RectF rectF = new RectF();        rectF.left = leftFootStartX - footWidthA;        rectF.top = leftFootStartY + footHeigh - radiusFoot * 2;        rectF.right = rectF.left + radiusFoot * 2;        rectF.bottom = rectF.top + radiusFoot * 2;        path.addArc(rectF, 90, 180);        path.lineTo(rectF.left + radiusFoot + footWidthB, rectF.top);        path.lineTo(rectF.left + radiusFoot + footWidthB, leftFootStartY);        path.lineTo(leftFootStartX, leftFootStartY);        canvas.drawPath(path, mPaint);//      右脚        float rightFootStartX = bodyRect.left + radius + offset * 2;        float rightFootStartY = leftFootStartY;        path.reset();        path.moveTo(rightFootStartX, rightFootStartY);        path.lineTo(rightFootStartX, rightFootStartY + footHeigh);        path.lineTo(rightFootStartX + footWidthA - radiusFoot, rightFootStartY + footHeigh);        rectF.left = rightFootStartX + footWidthA - radiusFoot * 2;        rectF.top = rightFootStartY + footHeigh - radiusFoot * 2;        rectF.right = rectF.left + radiusFoot * 2;        rectF.bottom = rectF.top + radiusFoot * 2;        path.addArc(rectF, 90, -180);        path.lineTo(rectF.right - radiusFoot - footWidthB, rectF.top);        path.lineTo(rectF.right - radiusFoot - footWidthB, rightFootStartY);        path.lineTo(rightFootStartX, rightFootStartY);        canvas.drawPath(path, mPaint);    }

画手

这里是双手放在后背的样子

手我用的是一个等腰直角三角形来实现，斜边就是吊带到裤子，从直角顶点作高到斜边，通过小直角三角形的直角边相等就可以算出顶点的坐标。这个时候还是有个圆角，刚开始我实现的时候是像上面那些通过path.addArc加上圆角，但是这边计算好之后和原来的衔接一直有问题，在调了半天之后，偶然发现mPaint.setPathEffect(new CornerPathEffect(radiusHand));这个方法，可以使path的拐角用圆角来过渡，一下子就简单到爆了，果然科学技术是第一生产力。

        drawHands(canvas);//手    private void drawHands(Canvas canvas) {        mPaint.setStrokeWidth(mStrokeWidth);        mPaint.setStyle(Paint.Style.FILL);        mPaint.setColor(colorBody);//        左手        Path path = new Path();        float hypotenuse = bodyRect.bottom - radius - handsHeight;        float radiusHand = hypotenuse / 6;        mPaint.setPathEffect(new CornerPathEffect(radiusHand));        path.moveTo(bodyRect.left, handsHeight);        path.lineTo(bodyRect.left - hypotenuse / 2, handsHeight + hypotenuse / 2);        path.lineTo(bodyRect.left, bodyRect.bottom - radius);        canvas.drawPath(path, mPaint);        mPaint.setStrokeWidth(mStrokeWidth);        mPaint.setStyle(Paint.Style.STROKE);        mPaint.setColor(colorStroke);        canvas.drawPath(path, mPaint);//        右手        path.reset();        mPaint.setStyle(Paint.Style.FILL);        mPaint.setColor(colorBody);        path.moveTo(bodyRect.right, handsHeight);        path.lineTo(bodyRect.right + hypotenuse / 2, handsHeight + hypotenuse / 2);        path.lineTo(bodyRect.right, bodyRect.bottom - radius);        canvas.drawPath(path, mPaint);        mPaint.setStrokeWidth(mStrokeWidth);        mPaint.setStyle(Paint.Style.STROKE);        mPaint.setColor(colorStroke);        canvas.drawPath(path, mPaint);//        一个慢动作  - -||| 拐点内侧        path.reset();        mPaint.setStyle(Paint.Style.FILL);        path.moveTo(bodyRect.left, handsHeight + hypotenuse / 2 - mStrokeWidth);        path.lineTo(bodyRect.left - mStrokeWidth * 2, handsHeight + hypotenuse / 2 + mStrokeWidth * 2);        path.lineTo(bodyRect.left, handsHeight + hypotenuse / 2 + mStrokeWidth);        canvas.drawPath(path, mPaint);        path.reset();        path.moveTo(bodyRect.right, handsHeight + hypotenuse / 2 - mStrokeWidth);        path.lineTo(bodyRect.right + mStrokeWidth * 2, handsHeight + hypotenuse / 2 + mStrokeWidth * 2);        path.lineTo(bodyRect.right, handsHeight + hypotenuse / 2 + mStrokeWidth);        canvas.drawPath(path, mPaint);    }

画眼睛,嘴巴

三个字，圆圆圆

反正就是各种画圆，或者弧形，嘴巴部分偷懒也就一条小弧一笔带过了，哈哈

        drawEyesMouth(canvas);//眼睛,嘴巴private void drawEyesMouth(Canvas canvas) {        float eyesOffset = radius * 0.1f;//眼睛中心处于上半圆直径 往上的高度偏移        mPaint.setStrokeWidth(mStrokeWidth * 5);//        计算眼镜带弧行的半径 分两段，以便眼睛中间有隔开的效果        float radiusGlassesRibbon = (float) (radius / Math.sin(Math.PI / 20));        RectF rect = new RectF();        rect.left = bodyRect.left + radius - radiusGlassesRibbon;        rect.top = bodyRect.top + radius - (float) (radius / Math.tan(Math.PI / 20)) - radiusGlassesRibbon - eyesOffset;        rect.right = rect.left + radiusGlassesRibbon * 2;        rect.bottom = rect.top + radiusGlassesRibbon * 2;        canvas.drawArc(rect, 81, 3, false, mPaint);        canvas.drawArc(rect, 99, -3, false, mPaint);//眼睛半径        float radiusEyes = radius / 3;        initPaint();        mPaint.setColor(Color.WHITE);        mPaint.setStrokeWidth(mStrokeWidth);        mPaint.setStyle(Paint.Style.FILL);        canvas.drawCircle(bodyRect.left + bodyWidth / 2 - radiusEyes - offset, bodyRect.top + radius - eyesOffset, radiusEyes, mPaint);        canvas.drawCircle(bodyRect.left + bodyWidth / 2 + radiusEyes + offset, bodyRect.top + radius - eyesOffset, radiusEyes, mPaint);        mPaint.setColor(colorStroke);        mPaint.setStyle(Paint.Style.STROKE);        canvas.drawCircle(bodyRect.left + bodyWidth / 2 - radiusEyes - offset, bodyRect.top + radius - eyesOffset, radiusEyes, mPaint);        canvas.drawCircle(bodyRect.left + bodyWidth / 2 + radiusEyes + offset, bodyRect.top + radius - eyesOffset, radiusEyes, mPaint);        final float radiusEyeballBlack = radiusEyes / 3;        mPaint.setStyle(Paint.Style.FILL);        canvas.drawCircle(bodyRect.left + bodyWidth / 2 - radiusEyes - offset, bodyRect.top + radius - eyesOffset, radiusEyeballBlack, mPaint);        canvas.drawCircle(bodyRect.left + bodyWidth / 2 + radiusEyes + offset, bodyRect.top + radius - eyesOffset, radiusEyeballBlack, mPaint);        mPaint.setColor(Color.WHITE);        final float radiusEyeballWhite = radiusEyeballBlack / 2;        canvas.drawCircle(bodyRect.left + bodyWidth / 2 - radiusEyes + radiusEyeballWhite - offset * 2,                bodyRect.top + radius - radiusEyeballWhite + offset - eyesOffset,                radiusEyeballWhite, mPaint);        canvas.drawCircle(bodyRect.left + bodyWidth / 2 + radiusEyes + radiusEyeballWhite,                bodyRect.top + radius - radiusEyeballWhite + offset - eyesOffset,                radiusEyeballWhite, mPaint);//        画嘴巴，因为位置和眼睛有相对关系，所以写在一块        mPaint.setColor(colorStroke);        mPaint.setStyle(Paint.Style.STROKE);        mPaint.setStrokeWidth(mStrokeWidth);        float radiusMonth = radius;        rect.left = bodyRect.left;        rect.top = bodyRect.top - radiusMonth / 2.5f;        rect.right = rect.left + radiusMonth * 2;        rect.bottom = rect.top + radiusMonth * 2;        canvas.drawArc(rect, 95, -20, false, mPaint);    }

脚下的阴影

这是最后一步了，直接画一个非常扁的椭圆放在脚下面就可以了

不科学啊，长这么胖，为毛影子这么瘦（别在意这些细节）

        drawFeetShadow(canvas);//脚下的阴影    private void drawFeetShadow(Canvas canvas) {        mPaint.setColor(getResources().getColor(android.R.color.darker_gray));        canvas.drawOval(bodyRect.left + bodyWidth * 0.15f, bodyRect.bottom - offset + footHeigh,                bodyRect.right - bodyWidth * 0.15f, bodyRect.bottom - offset + footHeigh + mStrokeWidth * 1.3f, mPaint);    }

在onDraw方法，依次调用上述的各种方法，画完收工。

    @Override    protected void onDraw(Canvas canvas) {        initParams();        initPaint();        drawFeetShadow(canvas);//脚下的阴影        drawFeet(canvas);//脚        drawHands(canvas);//手        drawBody(canvas);//身体        drawClothes(canvas);//衣服        drawEyesMouth(canvas);//眼睛,嘴巴        drawBodyStroke(canvas);//最后画身体的描边，可以摭住一些过渡的棱角    }

画完了，好像少了点什么。。。。。对了，头发。好吧，我画的是程序猿，哪来的头发 - -，

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至此，正常画风的小黄人已经画完了，但是吧，好不容易画好，好像没啥意思，脑洞大开一下吧。
电影中的小黄人中病毒后是会变成紫色的，那我们用代码画，换个颜色还不是分分钟，不但要紫色，还要各种颜色。

三行代码搞定脑洞

    public void randomBodyColor() {        Random random = new Random();        colorBody = Color.rgb(random.nextInt(255), random.nextInt(255), random.nextInt(255));        invalidate();    }

然后效果就变成了这样。

看起来还有点小酷炫