程序员也是会浪漫的->打造浪漫的Android表白程序
16lz
2021-01-23
一年前，看到过有个牛人用HTML5绘制了浪漫的爱心表白动画，后来又在华超的这篇文章上看到大神用Android写出了相同的效果，于是也动手写了一下，并加了一些功能，感谢大神的指引,写给女票看她很开心呢。地址在这：浪漫程序员 HTML5爱心表白动画。发现原来程序员也是可以很浪……漫…..的。那么在Android怎么打造如此这个效果呢？参考了一下前面Html5的算法，在Android中实现了类似的效果。先贴上最终效果图：
生成心形线
心形线的表达式可以参考：桃心线。里面对桃心线的表达式解析的挺好。可以通过使用极坐标的方式，传入角度和距离（常量）计算出对应的坐标点。其中距离是常量值，不需改变，变化的是角度。
桃心线极坐标方程式为：
x=16×sin3αy=13×cosα−5×cos2α−2×cos3α−cos4α如果生成的桃心线不够大，可以把x、y乘以一个常数，使之变大。考虑到大部分人都不愿去研究具体的数学问题，我们直接把前面HTML5的JS代码直接翻译成Java代码就好。代码如下：
public Point getHeartPoint(float angle) { float t = (float) (angle / Math.PI); float x = (float) (19.5 * (16 * Math.pow(Math.sin(t), 3))); float y = (float) (-20 * (13 * Math.cos(t) - 5 * Math.cos(2 * t) - 2 * Math.cos(3 * t) - Math.cos(4 * t))); return new Point(offsetX + (int) x, offsetY + (int) y); }其中offsetX和offsetY是偏移量。使用偏移量主要是为了能让心形线处于中央。offsetX和offsetY的值分别为：
offsetX = width / 2; offsetY = height / 2 - 55;通过这个函数，我们可以将角度从（0,180）变化，不断取点并画点将这个心形线显示出来。好了，我们自定义一个View，然后把这个心形线画出来吧！
@Override protected void onDraw(Canvas canvas) { float angle = 10; while (angle < 180) { Point p = getHeartPoint(angle); canvas.drawPoint(p.x, p.y, paint); angle = angle + 0.02f; } }运行结果如下：
绘制花瓣原理
我们想要的并不是简单绘制一个桃心线，要的是将花朵在桃心线上摆放。首先，得要知道怎么绘制花朵，而花朵是由一个个花瓣组成。因此绘制花朵的核心是绘制花瓣。绘制花瓣的原理是：3次贝塞尔曲线。三次贝塞尔曲线是由两个端点和两个控制点决定。假设花芯是一个圆，有n个花瓣，那么两个端点与花芯的圆心连线之间的夹角即为360/n。因此可以根据花瓣数量和花芯半径确定每个花瓣的位置。将两个端点与花芯的圆心连线的延长线分别确定另外两个控制点。通过随机生成花芯半径、每个花瓣的起始角以及随机确定延长线得到两个控制点，可以绘制一个随机的花朵。参数的改变如下图所示：
将花朵绘制到桃心线上
首先定义花瓣类Petal：
package com.example.administrator.testheart;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.Path;public class Petal { private float stretchA;//第一个控制点延长线倍数 private float stretchB;//第二个控制点延长线倍数 private float startAngle;//起始旋转角，用于确定第一个端点 private float angle;//两条线之间夹角，由起始旋转角和夹角可以确定第二个端点 private int radius = 2;//花芯的半径 private float growFactor;//增长因子，花瓣是有开放的动画效果，这个参数决定花瓣展开速度 private int color;//花瓣颜色 private boolean isFinished = false;//花瓣是否绽放完成 private Path path = new Path();//用于保存三次贝塞尔曲线 private Paint paint = new Paint();//画笔 //构造函数，由花朵类调用 public Petal(float stretchA, float stretchB, float startAngle, float angle, int color, float growFactor) { this.stretchA = stretchA; this.stretchB = stretchB; this.startAngle = startAngle; this.angle = angle; this.color = color; this.growFactor = growFactor; paint.setColor(color); } //用于渲染花瓣，通过不断更改半径使得花瓣越来越大 public void render(Point p, int radius, Canvas canvas) { if (this.radius <= radius) { this.radius += growFactor; // / 10; } else { isFinished = true; } this.draw(p, canvas); } //绘制花瓣，参数p是花芯的圆心的坐标 private void draw(Point p, Canvas canvas) { if (!isFinished) { path = new Path(); //将向量（0，radius）旋转起始角度，第一个控制点根据这个旋转后的向量计算 Point t = new Point(0, this.radius).rotate(MyUtil.degrad(this.startAngle)); //第一个端点，为了保证圆心不会随着radius增大而变大这里固定为3 Point v1 = new Point(0, 3).rotate(MyUtil.degrad(this.startAngle)); //第二个端点 Point v2 = t.clone().rotate(MyUtil.degrad(this.angle)); //延长线，分别确定两个控制点 Point v3 = t.clone().mult(this.stretchA); Point v4 = v2.clone().mult(this.stretchB); //由于圆心在p点，因此，每个点要加圆心坐标点 v1.add(p); v2.add(p); v3.add(p); v4.add(p); path.moveTo(v1.x, v1.y); //参数分别是：第一个控制点，第二个控制点，终点 path.cubicTo(v3.x, v3.y, v4.x, v4.y, v2.x, v2.y); } canvas.drawPath(path, paint); }} 花瓣类是最重要的类，因为真正绘制在屏幕上的是一个个小花瓣。每个花朵包含一系列花瓣，花朵类Bloom如下：
package com.example.administrator.testheart;import android.graphics.Canvas;import java.util.ArrayList;public class Bloom { private int color;//整个花朵的颜色 private Point point;//花芯圆心 private int radius; //花芯半径 private ArrayList petals;//用于保存花瓣 public Point getPoint() { return point; } public Bloom(Point point, int radius, int color, int petalCount) { this.point = point; this.radius = radius; this.color = color; petals = new ArrayList<>(petalCount); float angle = 360f / petalCount; int startAngle = MyUtil.randomInt(0, 90); for (int i = 0; i < petalCount; i++) { //随机产生第一个控制点的拉伸倍数 float stretchA = MyUtil.random(Garden.Options.minPetalStretch, Garden.Options.maxPetalStretch); //随机产生第二个控制地的拉伸倍数 float stretchB = MyUtil.random(Garden.Options.minPetalStretch, Garden.Options.maxPetalStretch); //计算每个花瓣的起始角度 int beginAngle = startAngle + (int) (i * angle); //随机产生每个花瓣的增长因子（即绽放速度） float growFactor = MyUtil.random(Garden.Options.minGrowFactor, Garden.Options.maxGrowFactor); //创建一个花瓣，并添加到花瓣列表中 this.petals.add(new Petal(stretchA, stretchB, beginAngle, angle, color, growFactor)); } } //绘制花朵 public void draw(Canvas canvas) { Petal p; for (int i = 0; i < this.petals.size(); i++) { p = petals.get(i); //渲染每朵花朵 p.render(point, this.radius, canvas); } } public int getColor() { return color; }} 接下来是花园类Garden，主要用于创建花朵以及一些相关配置：
package com.example.administrator.testheart;import java.util.ArrayList;public class Garden { //创建一个随机的花朵 public Bloom createRandomBloom(int x, int y) { //创建一个随机的花朵半径 int radius = MyUtil.randomInt(Options.minBloomRadius, Options.maxBloomRadius); //创建一个随机的花朵颜色 int color = MyUtil.randomrgba(Options.minRedColor, Options.maxRedColor, Options.minGreenColor, Options.maxGreenColor, Options.minBlueColor, Options.maxBlueColor, Options.opacity); //创建随机的花朵中花瓣个数 int petalCount = MyUtil.randomInt(Options.minPetalCount, Options.maxPetalCount); return createBloom(x, y, radius, color, petalCount); } //创建花朵 public Bloom createBloom(int x, int y, int radius, int color, int petalCount) { return new Bloom(new Point(x, y), radius, color, petalCount); } static class Options { //用于控制产生随机花瓣个数范围 public static int minPetalCount = 8; public static int maxPetalCount = 15; //用于控制产生延长线倍数范围 public static float minPetalStretch = 2f; public static float maxPetalStretch = 3.5f; //用于控制产生随机增长因子范围,增长因子决定花瓣绽放速度 public static float minGrowFactor = 1f; public static float maxGrowFactor = 1.1f; //用于控制产生花朵半径随机数范围 public static int minBloomRadius = 8; public static int maxBloomRadius = 10; //用于产生随机颜色 public static int minRedColor = 128; public static int maxRedColor = 255; public static int minGreenColor = 0; public static int maxGreenColor = 128; public static int minBlueColor = 0; public static int maxBlueColor = 128; //花瓣的透明度 public static int opacity = 50;//0.1 }}考虑到刷新的比较频繁，选择使用SurfaceView作为显示视图。自定义一个HeartView继承SurfaceView。代码如下：
package com.example.administrator.testheart;import android.content.Context;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.util.AttributeSet;import android.view.SurfaceHolder;import android.view.SurfaceView;import java.util.ArrayList;public class HeartView extends SurfaceView implements SurfaceHolder.Callback { SurfaceHolder surfaceHolder; int offsetX; int offsetY; private Garden garden; private int width; private int height; private Paint backgroundPaint; private boolean isDrawing = false; private Bitmap bm; private Canvas canvas; private int heartRadio = 1; public HeartView(Context context) { super(context); init(); } public HeartView(Context context, AttributeSet attrs) { super(context, attrs); init(); } private void init() { surfaceHolder = getHolder(); surfaceHolder.addCallback(this); garden = new Garden(); backgroundPaint = new Paint(); backgroundPaint.setColor(Color.rgb(0xff, 0xff, 0xe0)); } ArrayList blooms = new ArrayList<>(); public Point getHeartPoint(float angle) { float t = (float) (angle / Math.PI); float x = (float) (heartRadio * (16 * Math.pow(Math.sin(t), 3))); float y = (float) (-heartRadio * (13 * Math.cos(t) - 5 * Math.cos(2 * t) - 2 * Math.cos(3 * t) - Math.cos(4 * t))); return new Point(offsetX + (int) x, offsetY + (int) y); } //绘制列表里所有的花朵 private void drawHeart() { canvas.drawRect(0, 0, width, height, backgroundPaint); for (Bloom b : blooms) { b.draw(canvas); } Canvas c = surfaceHolder.lockCanvas(); c.drawBitmap(bm, 0, 0, null); surfaceHolder.unlockCanvasAndPost(c); } public void reDraw() { blooms.clear(); drawOnNewThread(); } @Override public void draw(Canvas canvas) { super.draw(canvas); } //开启一个新线程绘制 private void drawOnNewThread() { new Thread() { @Override public void run() { if (isDrawing) return; isDrawing = true; float angle = 10; while (true) { Bloom bloom = getBloom(angle); if (bloom != null) { blooms.add(bloom); } if (angle >= 30) { break; } else { angle += 0.2; } drawHeart(); try { sleep(20); } catch (InterruptedException e) { e.printStackTrace(); } } isDrawing = false; } }.start(); } private Bloom getBloom(float angle) { Point p = getHeartPoint(angle); boolean draw = true; /**循环比较新的坐标位置是否可以创建花朵, * 为了防止花朵太密集 * */ for (int i = 0; i < blooms.size(); i++) { Bloom b = blooms.get(i); Point bp = b.getPoint(); float distance = (float) Math.sqrt(Math.pow(p.x - bp.x, 2) + Math.pow(p.y - bp.y, 2)); if (distance < Garden.Options.maxBloomRadius * 1.5) { draw = false; break; } } //如果位置间距满足要求，就在该位置创建花朵并将花朵放入列表 if (draw) { Bloom bloom = garden.createRandomBloom(p.x, p.y); return bloom; } return null; } @Override public void surfaceCreated(SurfaceHolder holder) { } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { this.width = width; this.height = height; //我的手机宽度像素是1080，发现参数设置为30比较合适，这里根据不同的宽度动态调整参数 heartRadio = width * 30 / 1080; offsetX = width / 2; offsetY = height / 2 - 55; bm = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565); canvas = new Canvas(bm); drawOnNewThread(); } @Override public void surfaceDestroyed(SurfaceHolder holder) { }} 还有两个比较重要的工具类
Point.java保存点信息，或者说是向量信息。包含向量的基本运算。
package com.example.administrator.testheart;public class Point { public int x; public int y; public Point(int x, int y) { this.x = x; this.y = y; } //旋转 public Point rotate(float theta) { int x = this.x; int y = this.y; this.x = (int) (Math.cos(theta) * x - Math.sin(theta) * y); this.y = (int) (Math.sin(theta) * x + Math.cos(theta) * y); return this; } //乘以一个常数 public Point mult(float f) { this.x *= f; this.y *= f; return this; } //复制 public Point clone() { return new Point(this.x, this.y); } //该点与圆心距离 public float length() { return (float) Math.sqrt(this.x * this.x + this.y * this.y); } //向量相减 public Point subtract(Point p) { this.x -= p.x; this.y -= p.y; return this; } //向量相加 public Point add(Point p) { this.x += p.x; this.y += p.y; return this; } public Point set(int x, int y) { this.x = x; this.y = y; return this; }}工具类MyUtil.java主要是产生随机数、颜色等
package com.example.administrator.testheart;import android.graphics.Color;public class MyUtil { public static float circle = (float) (2 * Math.PI); public static int rgba(int r, int g, int b, int a) { return Color.argb(a, r, g, b); } public static int randomInt(int min, int max) { return (int) Math.floor(Math.random() * (max - min + 1)) + min; } public static float random(float min, float max) { return (float) (Math.random() * (max - min) + min); } //产生随机的argb颜色 public static int randomrgba(int rmin, int rmax, int gmin, int gmax, int bmin, int bmax, int a) { int r = Math.round(random(rmin, rmax)); int g = Math.round(random(gmin, gmax)); int b = Math.round(random(bmin, bmax)); int limit = 5; if (Math.abs(r - g) <= limit && Math.abs(g - b) <= limit && Math.abs(b - r) <= limit) { return rgba(rmin, rmax, gmin, gmax); } else { return rgba(r, g, b, a); } } //角度转弧度 public static float degrad(float angle) { return circle / 360 * angle; }}Activity自动跳转及日期计时及打字机效果实现类MainActivity
package com.example.administrator.testheart;import android.graphics.Color;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.view.MotionEvent;import android.view.View;import android.widget.RelativeLayout;import android.widget.TextView;import java.util.Timer;import java.util.TimerTask;public class MainActivity extends AppCompatActivity { HeartView heartView; private TextView tv_text; private TextView tv_text_1; private TextView tv_text_2; private int clo = 0; private RelativeLayout countDown; // 倒计时 private TextView daysTv, hoursTv, minutesTv, secondsTv; private long mDay = 652; private long mHour = 15; private long mMin = 37; private long mSecond = 00;// 天 ,小时,分钟,秒 private boolean isRun = true; private Handler timeHandler = new Handler() { @Override public void handleMessage(Message msg) { super.handleMessage(msg); if (msg.what==1) { computeTime(); daysTv.setText(mDay+""); hoursTv.setText(mHour+""); minutesTv.setText(mMin+""); secondsTv.setText(mSecond+""); if (mDay==0&&mHour==0&&mMin==0&&mSecond==0) { countDown.setVisibility(View.GONE); } } } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); heartView = (HeartView) findViewById(R.id.surfaceView); tv_text = (TextView) findViewById(R.id.myword); tv_text_1 = (TextView) findViewById(R.id.myword_1); tv_text_2 = (TextView) findViewById(R.id.myword_2); shark(); countDown = (RelativeLayout) findViewById(R.id.countdown_layout); daysTv = (TextView) findViewById(R.id.days_tv); hoursTv = (TextView) findViewById(R.id.hours_tv); minutesTv = (TextView) findViewById(R.id.minutes_tv); secondsTv = (TextView) findViewById(R.id.seconds_tv); startRun(); } @Override public boolean onTouchEvent(MotionEvent event) { heartView.reDraw(); return super.onTouchEvent(event); } public void reDraw(View v) { heartView.reDraw(); } private void shark() { Timer timer = new Timer(); TimerTask taskcc = new TimerTask() { public void run() { runOnUiThread(new Runnable() { public void run() { if (clo == 0) { clo = 1; tv_text.setTextColor(Color.TRANSPARENT); tv_text_1.setTextColor(Color.TRANSPARENT); tv_text_2.setTextColor(Color.TRANSPARENT); } else { if (clo == 1) { clo = 2; tv_text.setTextColor(Color.YELLOW); tv_text_1.setTextColor(Color.YELLOW); tv_text_2.setTextColor(Color.YELLOW); } else if (clo == 2) { clo = 3; tv_text.setTextColor(Color.RED); tv_text_1.setTextColor(Color.RED); tv_text_2.setTextColor(Color.RED); } else if (clo == 3){ clo = 4; tv_text.setTextColor(Color.BLACK); tv_text_1.setTextColor(Color.BLACK); tv_text_2.setTextColor(Color.BLACK); } else if (clo == 4){ clo = 5; tv_text.setTextColor(Color.WHITE); tv_text_1.setTextColor(Color.WHITE); tv_text_2.setTextColor(Color.WHITE); }else if (clo == 5){ clo = 6; tv_text.setTextColor(Color.GREEN); tv_text_1.setTextColor(Color.GREEN); tv_text_2.setTextColor(Color.GREEN); } else if (clo == 6){ clo = 7; tv_text.setTextColor(Color.MAGENTA); tv_text_1.setTextColor(Color.MAGENTA); tv_text_2.setTextColor(Color.MAGENTA); }else if (clo == 7){ clo = 8; tv_text.setTextColor(Color.CYAN); tv_text_1.setTextColor(Color.CYAN); tv_text_2.setTextColor(Color.CYAN); }else if (clo == 8){ clo = 9; tv_text.setTextColor(Color.DKGRAY); tv_text_1.setTextColor(Color.DKGRAY); tv_text_2.setTextColor(Color.DKGRAY); } else if (clo == 9){ clo = 10; tv_text.setTextColor(Color.GRAY); tv_text_1.setTextColor(Color.GRAY); tv_text_2.setTextColor(Color.GRAY); }else if (clo == 10){ clo = 11; tv_text.setTextColor(Color.LTGRAY); tv_text_1.setTextColor(Color.LTGRAY); tv_text_2.setTextColor(Color.LTGRAY); }else { clo = 0; tv_text.setTextColor(Color.BLUE); tv_text_1.setTextColor(Color.BLUE); tv_text_2.setTextColor(Color.BLUE); } } } }); } }; timer.schedule(taskcc, 1, 1500); //第二个参数分别是delay（多长时间后执行），第三个参数是：duration（执行间隔）单位为：ms } /** * 开启计时 */ private void startRun() { new Thread(new Runnable() { @Override public void run() { // TODO Auto-generated method stub while (isRun) { try { Thread.sleep(1000); // sleep 1000ms Message message = Message.obtain(); message.what = 1; timeHandler.sendMessage(message); } catch (Exception e) { e.printStackTrace(); } } } }).start(); } /** * 倒计时计算 */ private void computeTime() { mSecond++; if (mSecond > 60) { mSecond = 0; mMin++; if (mMin > 60) { mMin = 0; mHour++; if (mHour > 24) { mHour = 0; // 倒计时结束 mDay++; } } } }}到了这一步就可以实现上面的效果了。
源码地址在这。