初學Android,圖形影象之使用Path類(二十六)
阿新 • • 發佈:2018-12-23
Path類可以預先在View上將N個點連成一條"路徑",然後呼叫Canvas的drawPath(path,paint)即可沿著路徑繪製圖形
Android還為路徑繪製提供了PathEffect來定義繪製效果,PathEffect包含如下子類
ComposePathEffect
CornerPathEffect
DashPathEffect
DiscretePathEffect
PathDashPathEffect
SumPathEffect
下面的示例將會逐一使用上面的繪製效果
效果如下package WangLi.Graphics.PathTest; import android.app.Activity; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.ComposePathEffect; import android.graphics.CornerPathEffect; import android.graphics.DashPathEffect; import android.graphics.DiscretePathEffect; import android.graphics.Paint; import android.graphics.Path; import android.graphics.PathDashPathEffect; import android.graphics.PathEffect; import android.graphics.SumPathEffect; import android.os.Bundle; import android.view.View; public class PathTest extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(new MyView(this)); } class MyView extends View { float phase; PathEffect[] effects = new PathEffect[7]; int[] colors; private Paint paint; Path path; public MyView(Context context) { super(context); paint = new Paint(); paint.setStyle(Paint.Style.STROKE); paint.setStrokeWidth(4); //建立,並初始化Path path = new Path(); path.moveTo(0, 0); for(int i = 1; i<= 15; i++) { //生成15個點,隨機生成它們的座標,並將它們連成一條Path path.lineTo(i*20, (float)Math.random()*60); } //初始化七個顏色 colors = new int[] { Color.BLACK,Color.BLUE,Color.CYAN, Color.GREEN,Color.MAGENTA,Color.RED,Color.YELLOW }; } protected void onDraw(Canvas canvas) { //將背景填充成白色 canvas.drawColor(Color.WHITE); //-------下面開始初始化7中路徑的效果 //使用路徑效果 effects[0] = null; //使用CornerPathEffect路徑效果 effects[1] = new CornerPathEffect(10); //初始化DiscretePathEffect effects[2] = new DiscretePathEffect(3.0f,5.0f); //初始化DashPathEffect effects[3] = new DashPathEffect(new float[]{20,10,5,10},phase); //初始化PathDashPathEffect Path p = new Path(); p.addRect(0, 0, 8, 8, Path.Direction.CCW); effects[4] = new PathDashPathEffect(p,12,phase,PathDashPathEffect.Style.ROTATE); //初始化PathDashPathEffect effects[5] = new ComposePathEffect(effects[2],effects[4]); effects[6] = new SumPathEffect(effects[4],effects[3]); //將畫布移到8,8處開始繪製 canvas.translate(8, 8); //依次使用7中不同路徑效果,7種不同的顏色來繪製路徑 for(int i = 0; i < effects.length; i++) { paint.setPathEffect(effects[i]); paint.setColor(colors[i]); canvas.drawPath(path, paint); canvas.translate(0, 60); } //改變phase值,形成動畫效果 phase += 1; invalidate(); } } }