Android 用Canvas 画几何图形,画出小黄人

EulaThorp 4年前

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

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 考虑找边偏移      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);//衣服的颜色      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
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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
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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,通过sin(45度)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
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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 - -,

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,那我们用代码号,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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来自: http://www.jianshu.com/p/e1bc10e75b6d