Android_自定義View-和view的監聽事件

1.自定義view當作標籤配置時，必須加上包名
2.反射方式創建UI組件對象時，使用的構造方法爲下面兩個構造方式之一
View(Context context, AttributeSet attrs)：
View(Context context, AttributeSet attrs, int defStyle)：

View(Context context)

1 自定義View要學習的是重寫3個方法， 寫構造方法

（1）onDraw

（2）onMeasure

（3）onLayout

2.自定義View的構造方法和onDraw

3.自定義view在佈局文件中使用時，必須把包名加上

<xena.view.MyView

         android:layout_width="wrap_content"

         android:layout_height="wrap_content"

         android:background="#ff00ffff"

        />

調用的構造方法是MyView(Context context, AttributeSet attrs)

4.view.invalidate();//觸發onDraw方法的執行

5.onMeasure

6.得到View的寬高

 view.getMeasuredHeight();// 得到view的高

 view.getMeasuredWidth();//  得到view的寬

DisplayMetrics dm = new DisplayMetrics();
activity.getWindowManager().getDefaultDisplay().getMetrics(dm);
int screenW = dm.widthPixels;//這就是屏的寬
int screenH = dm.heightPixels;

自定義view寫文字“中華人民共和國”

<pre name="code" class="java"><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="確定" />

    <test.act.MyTextView
        android:paddingLeft="40dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

<pre name="code" class="java">public class MyTextView extends View {
    private String text = "中華人民共和國";
    private int textSize = 100;
    private Context context;
    private int textColor = Color.RED;
    private int backageColor = Color.BLUE;

    public MyTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        this.setBackgroundColor(this.backageColor);
    }

    private int getHightSize(int measureSpec) {
        int size = 0;
        int spec_mode = MeasureSpec.getMode(measureSpec);
        int spec_size = MeasureSpec.getSize(measureSpec);
        if (spec_mode == MeasureSpec.EXACTLY) {
            System.out.println("exactly");
            size = spec_size;
        } else if (spec_mode == MeasureSpec.AT_MOST) {
            System.out.println("at_most");
            size = textSize;
        } else if (spec_mode == MeasureSpec.UNSPECIFIED) {
            System.out.println("unspecified");
            size = 100;
        }
        return size;
    }

    private int getWidthSize(int measureSpec) {
        int size = 0;
        int spec_mode = MeasureSpec.getMode(measureSpec);
        int spec_size = MeasureSpec.getSize(measureSpec);
        if (spec_mode == MeasureSpec.EXACTLY) {
            System.out.println("exactly");
            size = spec_size;
        } else if (spec_mode == MeasureSpec.AT_MOST) {
            System.out.println("at_most");
            size = textSize * text.length();
        } else if (spec_mode == MeasureSpec.UNSPECIFIED) {
            System.out.println("unspecified");
            size = 100;
        }
        return size;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        this.setMeasuredDimension(this.getWidthSize(widthMeasureSpec), this.getHightSize(heightMeasureSpec));
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Paint paint = new Paint();
        paint.setTextSize(textSize);
        paint.setColor(this.textColor);
        System.out.println("核潛艇 =" + this.getMeasuredHeight());
        Toast.makeText(this.context, "size" + this.getMeasuredHeight(),
                Toast.LENGTH_LONG).show();
        // 座標是左下角
        float left = this.getPaddingLeft();
        float height = this.getMeasuredHeight();//就是textSize的值。
        float bottom = height - this.getPaddingBottom() - height*15/100;
        canvas.drawText(text, left, bottom, paint);
    }
}

用自定義View設置字體變化顏色“<span style="color: rgb(0, 176, 80); font-family: 微軟雅黑; font-size: 22px; line-height: 33px;">讓文字的顏色每隔一秒種變化一次，即文字顏色爲紅色和黃色，每隔一秒變化一次，則把MyTextView類改爲”</span>

<span style="color: rgb(0, 176, 80); font-family: 微軟雅黑; font-size: 22px; line-height: 33px;"></span><pre name="code" class="java">public class MyTextView extends View {
    private String text = "中華人民共和國";
    private int textSize = 100;
    private Context context;
    private int textColor = Color.RED;
    private int backageColor = Color.BLUE;

    public MyTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        this.setBackgroundColor(this.backageColor);
    }

    private int getHightSize(int measureSpec) {
        int size = 0;
        int spec_mode = MeasureSpec.getMode(measureSpec);
        int spec_size = MeasureSpec.getSize(measureSpec);
        if (spec_mode == MeasureSpec.EXACTLY) {
            System.out.println("exactly");
            size = spec_size;
        } else if (spec_mode == MeasureSpec.AT_MOST) {
            System.out.println("at_most");
            size = textSize;
        } else if (spec_mode == MeasureSpec.UNSPECIFIED) {
            System.out.println("unspecified");
            size = 100;
        }
        return size;
    }

    private int getWidthSize(int measureSpec) {
        int size = 0;
        int spec_mode = MeasureSpec.getMode(measureSpec);
        int spec_size = MeasureSpec.getSize(measureSpec);
        if (spec_mode == MeasureSpec.EXACTLY) {
            System.out.println("exactly");
            size = spec_size;
        } else if (spec_mode == MeasureSpec.AT_MOST) {
            System.out.println("at_most");
            size = textSize * text.length();
        } else if (spec_mode == MeasureSpec.UNSPECIFIED) {
            System.out.println("unspecified");
            size = 100;
        }
        return size;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        this.setMeasuredDimension(this.getWidthSize(widthMeasureSpec),
                this.getHightSize(heightMeasureSpec));
    }

    int i = 0;

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int textColor = 0;
        i++;
        if (i % 2 == 0) {
            textColor = this.textColor;
        }else {
            textColor = Color.YELLOW;
        }
        Paint paint = new Paint();
        paint.setTextSize(textSize);
        paint.setColor(textColor);
        System.out.println("核潛艇 =" + this.getMeasuredHeight());
        Toast.makeText(this.context, "size" + this.getMeasuredHeight(),
                Toast.LENGTH_LONG).show();
        // 座標是左下角
        float left = this.getPaddingLeft();
        float height = this.getMeasuredHeight();// 就是textSize的值。
        float bottom = height - this.getPaddingBottom() - height * 15 / 100;
        canvas.drawText(text, left, bottom, paint);

        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        this.invalidate();
    }
}

<span style="font-family: 微軟雅黑; font-size: 22px; line-height: 33px;"></span><pre name="code" class="java" style="font-size: 22px; line-height: 33px;"><span style="color:#330033;">在封裝類裏面的set寫invalidate()方法，能給自定義的View跳轉傳值</span><pre name="code" class="java">package xena.act;

import xena.view.MyView;
import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.LinearLayout;

public class MainActivity extends Activity implements OnClickListener {
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
//		setContentView(R.layout.activity_main);
		MyView myView = new MyView(this);
		myView.setBackgroundColor(Color.YELLOW);
		setContentView(myView);
		myView.setR(40);
		myView.setStr("中華人民共和國");
		
		myView.setOnClickListener(this);
	}
	@Override
	protected void onStart() {
		super.onStart();
	}
	@Override
	public void onClick(View v) {//v是事件源
		MyView myView = (MyView) v;
		myView.setStr("華清遠見");
	}
}
/*******************************************************

<pre name="code" class="java">package xena.view;

import xena.act.R;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class MyView extends View {
	private Context context;
	private float r = 100;
	private String str = "小";
	private final String NS = "http://www.hqyj.com";// 名稱空間
	private boolean flag;

	public float getR() {
		return r;
	}

	public void setR(float r) {
		this.r = r;
		this.invalidate();//觸發onDraw方法的執行
	}

	public String getStr() {
		return str;
	}

	public void setStr(String str) {
		this.str = str;
	//	this.invalidate();//觸發onDraw方法的執行View的監聽事件
	}

	public boolean isFlag() {
		return flag;
	}

	public void setFlag(boolean flag) {
		this.flag = flag;
		this.invalidate();//觸發onDraw方法的執行
	}

	// 用於自定義View當作標籤時用的
	public MyView(Context context, AttributeSet attrs) {
		super(context, attrs);
		
	}

	// 用於new MyView(...)用的
	public MyView(Context context) {
		super(context);
	}

	// 用於繪製界面上的內容,當界面顯示時調用
	@Override
	protected void onDraw(Canvas canvas) {// canvas畫布對象
		super.onDraw(canvas);
		// 創建筆 畫
		Paint paint = new Paint();
		paint.setColor(Color.BLUE);
		// 畫圓
		canvas.drawCircle(30, 30, this.r, paint);
		paint.setColor(Color.RED);

		if (flag) {
			canvas.drawCircle(30, 30, 5, paint);
		}
		// 畫字
		// 參數1：被繪製的字符串, 參數2,3：指字符串每一個字符的左下角座標
		paint.setTextSize(30);// 設置文字大小
		canvas.drawText(this.str, 30, 30, paint);
	}
}