1、贝塞尔曲线：http://baike.baidu.com/view/60154.htm，在这里理解什么是贝塞尔曲线
2、直接上图：
3、100多行代码就可以画出贝塞尔曲线，直接上代码
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package
com.example.bezier;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import
android.graphics.Paint;
import
android.graphics.Paint.Style;
import
android.graphics.Path;
import
android.os.Bundle;
import
android.view.View;
import
android.view.Window;
import
android.view.WindowManager;
public
class MainActivity extends
Activity {
@Override
public
void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(new
BezierView(this));
}
}class
BezierView extends
View {
/**
*
* @author liqiongwei
* @param context
*
*/
public
BezierView(Context context) {
super(context);
}
protected
void onDraw(Canvas canvas) {
List<Float> points = new
ArrayList<Float>();
Paint paint = new
Paint();
// 添加第一个点(118.0, 294.0),
points.add((float) 118.0);// X轴
points.add((float) 294.0);// Y轴
// 添加第二个点
points.add((float) 206.0);
points.add((float) 294.0);
// 添加第三个点
points.add((float) 294.0);
points.add((float) 118.0);
// 添加第四个点
points.add((float) 382.0);
points.add((float) 206.0);
points.add((float) 470.0);
points.add((float) 118.0);
// 通过画折线和贝塞尔曲线可以知道，点得位置是不一样的。
// 画折线
for
(int i = 0; i < points.size() - 2; i = i + 2) {
canvas.drawLine(points.get(i), points.get(i + 1), points.get(i + 2), points.get(i + 3), paint);
canvas.drawCircle(points.get(i), points.get(i + 1), 3, paint);
}
canvas.drawCircle(points.get(points.size() - 2), points.get(points.size() - 1), 3, paint);
// 贝塞尔曲线
paint.setColor(Color.BLUE);
Path p = new
Path();
Point p1 = new
Point();
Point p2 = new
Point();
Point p3 = new
Point();
float
xp = points.get(0);
float
yp = points.get(1);
// 设置第一个点开始
p.moveTo(xp, yp);
canvas.drawCircle(xp, yp, 5, paint);
int
length = points.size();
// 设置第一个控制点33%的距离
float
mFirstMultiplier = 0.3f;
// 设置第二个控制点为66%的距离
float
mSecondMultiplier = 1
- mFirstMultiplier;
for
(int b = 0; b < length; b += 2) {
int
nextIndex = b + 2
< length ? b + 2
: b;
int
nextNextIndex = b + 4
< length ? b + 4
: nextIndex;
// 设置第一个控制点
calc(points, p1, b, nextIndex, mSecondMultiplier);
// 设置第二个控制点
p2.setX(points.get(nextIndex));
p2.setY(points.get(nextIndex + 1));
// 设置第二个控制点
calc(points, p3, nextIndex, nextNextIndex, mFirstMultiplier);
// 最后一个点就是赛贝尔曲线上的点
p.cubicTo(p1.getX(), p1.getY(), p2.getX(), p2.getY(), p3.getX(), p3.getY());
// 画点
canvas.drawCircle(p3.getX(), p3.getY(), 5, paint);
}
// 设置为线
paint.setStyle(Style.STROKE);
canvas.drawPath(p, paint);
invalidate();
}
/**
* 计算控制点，此方法来源于Achartengine
* @param points
* @param result
* @param index1
* @param index2
* @param multiplier
*/
private
void calc(List<Float> points, Point result, int
index1, int
index2, final
float multiplier) {
float
p1x = points.get(index1);
float
p1y = points.get(index1 + 1);
float
p2x = points.get(index2);
float
p2y = points.get(index2 + 1);
float
diffX = p2x - p1x;
float
diffY = p2y - p1y;
result.setX(p1x + (diffX * multiplier));
result.setY(p1y + (diffY * multiplier));
}
} |
4、定义点的类
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package
com.example.bezier;
import java.io.Serializable;
/** * 点的类，来源于Achartengine
*/
public final class Point implements
Serializable {
private
float mX;
private
float mY;
public
Point() {
}
public
Point(float
x, float
y) {
mX = x;
mY = y;
}
public
float getX() {
return
mX;
}
public
float getY() {
return
mY;
}
public
void setX(float
x) {
mX = x;
}
public
void setY(float
y) {
mY = y;
}
} |
5、下载地址：http://files.cnblogs.com/liqw/Bezier.zip
本文来源于：http://www.cnblogs.com/liqw/p/3631137.html
有问题，请提问，大家一起研究！