Android 用Canvas 畫幾何圖形，畫出小黃人
看了大神JR93的這篇文章: 純CSS3畫出小黃人并實現動畫效果 ，萌生了我在安卓上畫小黃人的想法，同時他在文章中的步驟分解，在我的具體實現中起到了很大的幫助。話不多說，先上效果圖
實現步驟
其實很簡單
- 首先找到一張小黃人的圖
- 然后調用 canvas.drawBitmap() 后畫到畫布上 - -。
好吧，一點都不好笑
正文
準備工作
自定義 MinionView extends View ，定義以下成員變量，備用（可以先不看，后面的代碼看到莫名其妙出來的變量再上來看下）
private Paint mPaint;
private float bodyWidth;
private float bodyHeigh;
private static final float BODY_SCALE = 0.6f;//身體主干占整個view的比重
private static final float BODY_WIDTH_HEIGHT_SCALE = 0.6f; // 身體的比例設定為 w:h = 3:5
private float mStrokeWidth = 4;//描邊寬度
private float offset;//計算時，部分需要 考慮找邊偏移
private float radius;//身體上下半圓的半徑
private int colorClothes = Color.rgb(32, 116, 160);//衣服的顏色
private int colorBody = Color.rgb(249, 217, 70);//衣服的顏色
private int colorStroke = Color.BLACK;
private RectF bodyRect;
private float handsHeight;//計算出吊帶的高度時，可以用來做手的高度
private float footHeigh;//腳的高度，用來畫腳部陰影時用 初始化參數
重寫 protected void onDraw(Canvas canvas) 方法，首先調用 如下 （會經常看到一些奇怪的數字，做比例，別問我怎么來的，目測+一點點微調得來的- -。）
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 ;
} 畫身體
我來組成身體
顯然身體是一個矩形加上，上下半圓，這邊只要用一個圓角矩形，然后圓角的弧度半徑用身體寬度的一半就可以達到這個效果了。
把身體的矩形外存起來，后面經常要用到其相對位置進行對其它部位的定位，代碼如下。
drawBody(canvas);//身體
drawBodyStroke(canvas);//最后畫身體的描邊，可以摭住一些過渡的棱角
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);
} 畫衣服
這是穿上褲子的樣子
-
首先先畫上底下的半圓
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); -
再畫半圓上方的矩形,w表示矩形離左邊身體的距離，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); -
上面的畫完之后，要在衣服上面描一層黑色的邊，用 canvas.drawLines 把線一條條畫出來吧，這邊要同時考慮畫筆的描邊寬度，否則會出現連接點有鋸齒的感覺。
//畫橫線 initPaint(); mPaint.setColor(colorStroke); mPaint.setStyle(Paint.Style.FILL); mPaint.setStrokeWidth(mStrokeWidth); float[] pts = new float[20];//5條線 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); -
畫吊帶 就是一個直角梯形，把梯形的四個頂點計算出來，使用 canvas.drawPath 將其畫上去，然后紐扣用一個實心的小圓表示
//畫左吊帶 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); //畫右吊帶 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); -
畫中間的口袋 是一個下面兩邊是圓角的圓角矩形，但是貌似不能直接畫這樣的圓角矩形，所以我就用土辦法，不就是一個多邊形嗎，用 canvas.drawPath 來畫，在圓角的地方添加圓弧過渡 path.addArc
//中間口袋 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); -
左右兩個小口袋也直接用一個小弧來解決掉
// 下邊一豎，分開褲子 canvas.drawLine(bodyRect.left + bodyWidth / 2, bodyRect.bottom - h * 0.8f, bodyRect.left + bodyWidth / 2, bodyRect.bottom, mPaint); // 左邊的小口袋 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); // 右邊小口袋 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，衣服畫完了。
drawClothes(canvas);//衣服
private void drawClothes(Canvas canvas) {
initPaint();
//就是上面那一堆代碼按順序合起來啦。。。。。
} 畫腳
萌萌的小短腿
腳這部分比較簡單，從身體的下方，一個豎直的矩形下來，再加上一個左邊圓角的圓角矩形，還是通過畫Path來實現。
drawFeet(canvas);//腳
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;//腳寬度大-到半圓結束
float footWidthB = footWidthA / 3;//腳寬度-比較細的部分
// 左腳
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);
// 右腳
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);
} 畫手
這里是雙手放在后背的樣子
手我用的是一個等腰直角三角形來實現，斜邊就是吊帶到褲子，通過sin(45度)就可以算出頂點的坐標。這個時候還是有個圓角，剛開始我實現的時候是像上面那些通過 path.addArc 加上圓角，但是這邊計算好之后和原來的銜接一直有問題，在調了半天之后，偶然發現 mPaint.setPathEffect(new CornerPathEffect(radiusHand)); 這個方法，可以使path的拐角用圓角來過渡，一下子就簡單到爆了，果然科學技術是第一生產力。
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);
// 一個慢動作 - -||| 拐點內側
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);
} 畫眼睛,嘴巴
三個字，圓圓圓
反正就是各種畫圓，或者弧形，嘴巴部分偷懶也就一條小弧一筆帶過了，哈哈
drawEyesMouth(canvas);//眼睛,嘴巴
private void drawEyesMouth(Canvas canvas) {
float eyesOffset = radius * 0.1f;//眼睛中心處于上半圓直徑 往上的高度偏移
mPaint.setStrokeWidth(mStrokeWidth * 5);
// 計算眼鏡帶弧行的半徑 分兩段，以便眼睛中間有隔開的效果
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);
//眼睛半徑
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);
// 畫嘴巴，因為位置和眼睛有相對關系，所以寫在一塊
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);
} 腳下的陰影
這是最后一步了，直接畫一個非常扁的橢圓放在腳下面就可以了
不科學啊，長這么胖，為毛影子這么瘦（別在意這些細節）
drawFeetShadow(canvas);//腳下的陰影
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，依次調用上述的各種方法，畫完收工。
@Override
protected void onDraw(Canvas canvas) {
initParams();
initPaint();
drawFeetShadow(canvas);//腳下的陰影
drawFeet(canvas);//腳
drawHands(canvas);//手
drawBody(canvas);//身體
drawClothes(canvas);//衣服
drawEyesMouth(canvas);//眼睛,嘴巴
drawBodyStroke(canvas);//最后畫身體的描邊，可以摭住一些過渡的棱角
} 畫完了，好像少了點什么。。。。。對了，頭發。好吧，我畫的是程序猿，哪來的頭發 - -，
至此，正常畫風的小黃人已經畫完了，但是吧，好不容易畫好，好像沒啥意思，腦洞大開一下吧。電影中的小黃人中病毒后是會變成紫色的，那我們用代碼號，換個顏色還不是分分鐘，不但要紫色，還要各種顏色。
三行代碼搞定腦洞
public void randomBodyColor() {
Random random = new Random();
colorBody = Color.rgb(random.nextInt(255), random.nextInt(255), random.nextInt(255));
invalidate();
} 然后效果就變成了這樣。
看起來還有點小酷炫
希望大家喜歡 ,上述有任何問題或者表述不清楚的，歡迎評論交流。
完整源碼 github
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