Android 用Canvas 画几何图形，画出小黄人
2016-01-21 00:55 396 0
原文出处：http://www.jianshu.com/p/e1bc10e75b6d
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);//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
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，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
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
