Android 用Canvas 画几何图形，画出小黄人
EulaThorp
8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
- 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
</div> 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
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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);
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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);
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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);
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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);
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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);
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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,);
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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
</div> 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
</div> 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