自定義View

自定義View

先自己寫一個view的類，繼承view，寫出它的構造器，一共有四個，一般寫2到3個，然後複寫onMeasure和onDraw方法，onMeasure是用於測量寬高。而onDraw是有UI主線程自動調用，只需在此繪製圖形即可，onDraw中寫canvas（畫布）。
這是一個時鐘的程序

package com.example.administrator.mywidgetdemo.MyView;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.View;

import java.util.Calendar;

/**
 * Created by Administrator on 2015/9/16.
 */
public class MyView extends View {
    private int width;
    private int height;
    private Paint mPaintLine;
    private Paint mPaintCircle;
    private Paint mPaintText;
    private Calendar mCalendar;//定義一個日曆變量
    public static final int NEED_INVALIDATE = 0X23;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what){
                case NEED_INVALIDATE:
                    mCalendar = Calendar.getInstance();//日曆實例化
                    invalidate();//告訴UI主線程重新繪製
                    handler.sendEmptyMessageDelayed(NEED_INVALIDATE,1000);
                    break;
            }
        }
    };
    public MyView(Context context) {
        super(context);
    }

    public MyView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mCalendar = Calendar.getInstance();

        mPaintLine = new Paint();
        mPaintLine.setColor(Color.RED);//設置線的顏色
        mPaintLine.setStrokeWidth(10);//設置線的寬度
        mPaintLine.setAntiAlias(true);//設置線抗鋸齒

        mPaintCircle = new Paint();
        mPaintCircle.setColor(Color.GREEN);
        mPaintCircle.setStrokeWidth(10);
        mPaintCircle.setStyle(Paint.Style.STROKE);
        mPaintCircle.setAntiAlias(true);

        mPaintText = new Paint();
        mPaintText.setColor(Color.BLACK);
        mPaintText.setTextSize(30);
        mPaintText.setTextAlign(Paint.Align.CENTER);
        handler.sendEmptyMessageDelayed(NEED_INVALIDATE,2000);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = getDefaultSize(getSuggestedMinimumWidth(),widthMeasureSpec);
        height = getDefaultSize(getSuggestedMinimumHeight(),heightMeasureSpec);
        setMeasuredDimension(width,height);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
//        canvas.drawLine(0,0,300,300,mPaintLine);
        canvas.drawCircle(width / 2, height / 2, 300, mPaintCircle);
        canvas.drawCircle(width / 2, height / 2, 10, mPaintCircle);
        for (int i = 1;i<=12;i++){
            canvas.rotate(30,width/2,height/2);
            canvas.drawLine(width / 2, height / 2 - 300, width / 2, height / 2 - 280, mPaintLine);
            canvas.drawText("" + i, width / 2, height / 2 - 250, mPaintText);
        }
        int minute = mCalendar.get(Calendar.MINUTE);
        int hour = mCalendar.get(Calendar.HOUR);
        int second = mCalendar.get(Calendar.SECOND);
        float degree = minute/60f*360;
        canvas.save();
        canvas.rotate(degree, width / 2, height / 2);
        canvas.drawLine(width / 2, height / 2 - 200, width / 2, height / 2 + 30, mPaintLine);
        canvas.restore();

        float hourDegree = (hour*60+minute)/12f/60*360;
        canvas.save();
        canvas.rotate(hourDegree,width/2,height/2);
        canvas.drawLine(width / 2, height / 2 - 150, width / 2, height / 2 +20, mPaintLine);
        canvas.restore();

        float secondDegree = 6*second;
        canvas.save();
        canvas.rotate(secondDegree,width/2,height/2);
        canvas.drawLine(width / 2, height / 2 - 220, width / 2, height / 2 +20, mPaintLine);
        canvas.restore();

    }
}

注意佈局中要寫包名的全稱

<com.example.administrator.mywidgetdemo.MyView.MyView
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

模擬下載的圓形進度條

package com.example.administrator.mywidgetdemo2.Widget;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;

/**
 * Created by Administrator on 2015/9/16.
 */
public class MyProgressArc extends View {
    private int width;
    private int height;
    private Paint mPaintArc;
    private Paint mPaintCircle1;
    private Paint mPaintCircle2;
    private Paint mPaintText;
    private int currentProgress;

    public int getCurrentProgress() {
        return currentProgress;
    }

    public void setCurrentProgress(int currentProgress) {
        this.currentProgress = currentProgress;
        invalidate();
    }

    public MyProgressArc(Context context) {
        super(context);
    }

    public MyProgressArc(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPaintArc = new Paint();
        mPaintArc.setColor(Color.BLUE);
        mPaintArc.setStrokeWidth(50);
        mPaintArc.setAntiAlias(true);
        mPaintArc.setStyle(Paint.Style.STROKE);

        mPaintCircle1 = new Paint();
        mPaintCircle1.setColor(Color.GRAY);
        mPaintCircle1.setStrokeWidth(1);
        mPaintCircle1.setStyle(Paint.Style.STROKE);
        mPaintCircle1.setAntiAlias(true);

        mPaintCircle2 = new Paint();
        mPaintCircle2.setColor(Color.GRAY);
        mPaintCircle2.setStrokeWidth(1);
        mPaintCircle2.setStyle(Paint.Style.STROKE);
        mPaintCircle2.setAntiAlias(true);

        mPaintText = new Paint();
        mPaintText.setColor(Color.BLACK);
        mPaintText.setTextSize(100);
        mPaintText.setTextAlign(Paint.Align.CENTER);

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = getDefaultSize(getSuggestedMinimumWidth(),widthMeasureSpec);
        height = getDefaultSize(getSuggestedMinimumHeight(),heightMeasureSpec);
        setMeasuredDimension(width, height);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(width / 2, height / 2, 200, mPaintCircle1);
        canvas.drawCircle(width/2,height/2,150,mPaintCircle2);
        canvas.drawText(currentProgress + "%", width / 2, height / 2, mPaintText);

        RectF oval = new RectF();
        oval.set(width/2-175,height/2-175,width/2+175,height/2+175);
        canvas.drawArc(oval,0,360*currentProgress/100,false,mPaintArc);
    }
}

package com.example.administrator.mywidgetdemo2;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;

import com.example.administrator.mywidgetdemo2.Widget.MyProgress;
import com.example.administrator.mywidgetdemo2.Widget.MyProgressArc;

/**
 * Created by Administrator on 2015/9/16.
 */
public class ProgressArcActivity extends Activity {
    private MyProgressArc myProgressArc;
    public static final int PROGRESS=0X23;
    private Button mButtonStart;
    private int progress = 0;
    private Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what){
                case PROGRESS:
                    progress++;
                    if (progress<=100){
                        myProgressArc.setCurrentProgress(progress);
                        handler.sendEmptyMessageDelayed(PROGRESS,200);
                    }
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_arc);
        myProgressArc = (MyProgressArc) findViewById(R.id.progress_arc);
        mButtonStart = (Button) findViewById(R.id.button_start_arc);
        mButtonStart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                handler.sendEmptyMessageDelayed(PROGRESS, 1000);
            }
        });
    }
}