Android 用Canvas 画几何图形,画出小黄人

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山言两语
0.4 2016.01.20 19:04* 字数 1105

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
  • 然后调用canvas.drawBitmap()后画到画布上 - -。
    好吧,一点都不好笑

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);
    }

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 - -,


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

希望大家喜欢 ,上述有任何问题或者表述不清楚的,欢迎评论交流。
完整源码 github

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