Android Path 类运用实践

理论学习了 Android Path 类之后，对 Path 类的属性方法都有所了解，写两个例子实践一下。理论与实践结合嘛。

实例1，五环 + 文字：

源码：

package com.example.pathstudy;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.view.View;

public class PathStudyActivity extends Activity {

	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(new PathStudyView(getApplicationContext()));
	}

	private class PathStudyView extends View {

		public PathStudyView(Context context) {
			super(context);
			// TODO Auto-generated constructor stub
		}

		@Override
		protected void onDraw(Canvas canvas) {
			// TODO Auto-generated method stub
			// super.onDraw(canvas);
			canvas.drawColor(Color.WHITE);
			Paint mPaint = new Paint();
			mPaint.setStyle(Paint.Style.STROKE);
			mPaint.setStrokeWidth(20);

			int originX = 0;
			int originY = 0;
			int offsetX = 0;
			int offsetY = 0;
			int offsetLengthX = 240;
			int offsetLengthY = 110;

			float circleX = 150;
			float circleY = 200;
			float radius = 100;

			// first circle
			mPaint.setColor(Color.BLUE);
			Path mPath = new Path();
			mPath.addPath(getDrawCirclePath(circleX, circleY, radius));
			canvas.drawPath(mPath, mPaint);

			// second circle
			mPaint.setColor(Color.BLACK);
			canvas.save();
			offsetX = originX + offsetLengthX;
			canvas.translate(offsetX, offsetY);
			mPath.reset();
			mPath.addPath(getDrawCirclePath(circleX, circleY, radius));
			canvas.drawPath(mPath, mPaint);
			canvas.restore();

			// thid circle
			mPaint.setColor(Color.RED);
			canvas.save();
			offsetX += offsetLengthX;
			canvas.translate(offsetX, offsetY);
			mPath.reset();
			mPath.addPath(getDrawCirclePath(circleX, circleY, radius));
			canvas.drawPath(mPath, mPaint);
			canvas.restore();

			// forth circle
			mPaint.setColor(Color.YELLOW);
			canvas.save();
			offsetX = originX + offsetLengthX / 2;
			offsetY = originY + offsetLengthY;
			canvas.translate(offsetX, offsetY);
			mPath.reset();
			mPath.addPath(getDrawCirclePath(circleX, circleY, radius));
			canvas.drawPath(mPath, mPaint);
			canvas.restore();

			// fifth circle
			mPaint.setColor(Color.GREEN);
			canvas.save();
			offsetX += offsetLengthX;
			canvas.translate(offsetX, offsetY);
			mPath.reset();
			mPath.addPath(getDrawCirclePath(circleX, circleY, radius));
			canvas.drawPath(mPath, mPaint);
			canvas.restore();

			// draw text kevinems.com
			// fifth circle
			mPaint.setColor(Color.BLACK);
			mPaint.setStyle(Paint.Style.FILL);
			mPaint.setTextSize(100);
			mPaint.setStrokeWidth(5);
			String websiteStr = "kevinems.com";
			canvas.drawText(websiteStr, 110, 500, mPaint);
			canvas.restore();

		}

		private Path getDrawCirclePath(float x, float y, float radius) {
			Path mPath = new Path();
			mPath.setFillType(Path.FillType.EVEN_ODD);
			mPath.addCircle(x, y, radius, Path.Direction.CCW);
			return mPath;
		}
	}
}

实例2，可以随意绘画 path 的手写板：

源码：

package com.example.view;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

public class PathView extends View {
	private static final String LOG_TAG = "PathView";
	private Path mPath;
	private Paint mPaint;
	private float mPosX;
	private float mPosY;

	public PathView(Context context) {
		super(context);
		// TODO Auto-generated constructor stub
		init();
	}

	private void init() {
		// TODO Auto-generated method stub
		mPath = new Path();
		mPaint = new Paint();

		mPaint.setColor(Color.GREEN);
		mPaint.setStyle(Paint.Style.STROKE);
		mPaint.setStrokeWidth(5);

	}

	@Override
	protected void onDraw(Canvas canvas) {
		// TODO Auto-generated method stub
		// super.onDraw(canvas);
		Log.i(LOG_TAG, "onDraw");
		canvas.drawColor(Color.WHITE);
		canvas.drawPath(mPath, mPaint);
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
		// return super.onTouchEvent(event);
		int action = event.getAction();
		float x = event.getX();
		float y = event.getY();

		switch (action) {
		case MotionEvent.ACTION_DOWN:
			mPath.moveTo(x, y);
			break;

		case MotionEvent.ACTION_MOVE:
			mPath.quadTo(mPosX, mPosY, x, y);

			invalidate();
			break;

		default:
			break;
		}

		mPosX = x;
		mPosY = y;

		return true;
	}
}