Android(安卓)曲线绘制Demo

一个可交互的Android绘制曲线的demo：

Java代码

packagecom.ray.demo;
importandroid.app.Activity;
importandroid.content.Context;
importandroid.graphics.Canvas;
importandroid.graphics.Color;
importandroid.graphics.Paint;
importandroid.graphics.Paint.Style;
importandroid.graphics.Path;
importandroid.graphics.Point;
importandroid.graphics.RectF;
importandroid.os.Bundle;
importandroid.view.MotionEvent;
importandroid.view.View;
publicclassLineFunActivityextendsActivity{
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(newSampleView(this));
}
privateclassSampleViewextendsView{
publicstaticfinalintRECT_SIZE=8;
privatePointmSelectedPoint=null;
publicstaticfinalintPOINT_ARRAY_SIZE=7;
publicstaticfinalintC_START=0;
publicstaticfinalintC_END=1;
publicstaticfinalintC_CONTROL_1=2;
publicstaticfinalintC_CONTROL_2=3;
publicstaticfinalintQ_START=4;
publicstaticfinalintQ_END=5;
publicstaticfinalintQ_CONTROL=6;
privatePoint[]mPoints=newPoint[POINT_ARRAY_SIZE];
publicSampleView(Contextcontext){
super(context);
mPoints[C_START]=newPoint(100,100);
mPoints[C_END]=newPoint(200,200);
mPoints[C_CONTROL_1]=newPoint(150,100);
mPoints[C_CONTROL_2]=newPoint(150,200);
mPoints[Q_START]=newPoint(100,300);
mPoints[Q_END]=newPoint(150,400);
mPoints[Q_CONTROL]=newPoint(200,350);
}
@Override
protectedvoidonDraw(Canvascanvas){
super.onDraw(canvas);
canvas.drawColor(Color.WHITE);
//setuppaint
Paintpaint=newPaint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.BLACK);
//drawthecubicline
Pathpath=newPath();
path.moveTo(mPoints[C_START].x,mPoints[C_START].y);
path.cubicTo(mPoints[C_CONTROL_1].x,mPoints[C_CONTROL_1].y,
mPoints[C_CONTROL_2].x,mPoints[C_CONTROL_2].y,
mPoints[C_END].x,mPoints[C_END].y);
paint.setStrokeWidth(2);
paint.setStyle(Style.STROKE);
canvas.drawPath(path,paint);
canvas.drawLine(mPoints[C_START].x,mPoints[C_START].y,
mPoints[C_CONTROL_1].x,mPoints[C_CONTROL_1].y,paint);
canvas.drawLine(mPoints[C_END].x,mPoints[C_END].y,
mPoints[C_CONTROL_2].x,mPoints[C_CONTROL_2].y,paint);
//drawthequadline
paint.setColor(Color.BLACK);
paint.setStyle(Style.FILL);
paint.setStrokeWidth(2);
path.reset();
path.moveTo(mPoints[Q_START].x,mPoints[Q_START].y);
path.quadTo(mPoints[Q_CONTROL].x,mPoints[Q_CONTROL].y,
mPoints[Q_END].x,mPoints[Q_END].y);
canvas.drawPath(path,paint);
canvas.drawLine(mPoints[Q_START].x,mPoints[Q_START].y,
mPoints[Q_CONTROL].x,mPoints[Q_CONTROL].y,paint);
canvas.drawLine(mPoints[Q_END].x,mPoints[Q_END].y,
mPoints[Q_CONTROL].x,mPoints[Q_CONTROL].y,paint);
//drawcontrolpoints
paint.setColor(Color.RED);
paint.setStyle(Style.FILL);
for(inti=0;i<POINT_ARRAY_SIZE;i++){
canvas.drawRect(pointToRect(mPoints[i]),paint);
}
}
@Override
publicbooleanonTouchEvent(MotionEventevent){
switch(event.getAction()){
caseMotionEvent.ACTION_DOWN:
for(inti=0;i<POINT_ARRAY_SIZE;i++){
if(pointToRect(mPoints[i]).contains(event.getX(),event.getY())){
mSelectedPoint=mPoints[i];
}
}
break;
caseMotionEvent.ACTION_MOVE:
if(null!=mSelectedPoint){
mSelectedPoint.x=(int)event.getX();
mSelectedPoint.y=(int)event.getY();
invalidate();
}
break;
caseMotionEvent.ACTION_UP:
mSelectedPoint=null;
break;
default:
break;
}
returntrue;
}
privateRectFpointToRect(Pointp){
returnnewRectF(p.x-RECT_SIZE/2,p.y-RECT_SIZE/2,
p.x+RECT_SIZE/2,p.y+RECT_SIZE/2);
}
}
}

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