4、快速实现自定义View

通常来说，自定义View有三种表现形式：自绘View，组合控件，继承控件。

一、自绘View

自绘View，顾名思义，就是为了实现一个效果，但是Google没有提供现成的控件，这个时候，我们可以通过自绘View绘制出想要的View。

1、定义控件属性

我们需要在Values文件夹下新建attrs.xml文件，用来定义控件的属性。

<?xml version="1.0" encoding="UTF-8"?>
<resources>
<declare-styleable name="RoundProgressBar">
<attr name="roundColor" format="color"/>
<attr name="roundProgressColor" format="color"/>
<attr name="roundWidth" format="dimension"></attr>
<attr name="textColor" format="color" />
<attr name="textSize" format="dimension" />
<attr name="max" format="integer"></attr>
<attr name="textIsDisplayable" format="boolean"></attr>
<attr name="style">
<enum name="STROKE" value="0"></enum>
<enum name="FILL" value="1"></enum>
</attr>
</declare-styleable>
</resources>

其中format有string,color,demension,integer,enum,reference,float,boolean,fraction,flag等类型。

2、在自绘View的构造方法中，获取自定义属性。

我们先调用context.obtainStyledAttributes(attrs,R.styleable.RoundProgressBar)来获取TypedArray，然后从TypedArray获取我们定义的属性。

roundColor = mTypedArray.getColor(R.styleable.RoundProgressBar_roundColor, Color.RED);
roundProgressColor = mTypedArray.getColor(R.styleable.RoundProgressBar_roundProgressColor, Color.GREEN);
textColor = mTypedArray.getColor(R.styleable.RoundProgressBar_textColor, Color.GREEN);
textSize = mTypedArray.getDimension(R.styleable.RoundProgressBar_textSize, 15);
roundWidth = mTypedArray.getDimension(R.styleable.RoundProgressBar_roundWidth, 5);
max = mTypedArray.getInteger(R.styleable.RoundProgressBar_max, 100);
textIsDisplayable = mTypedArray.getBoolean(R.styleable.RoundProgressBar_textIsDisplayable, true);
style = mTypedArray.getInt(R.styleable.RoundProgressBar_style, 0);

3、重写onDraw(),onMeasure()方法，其中onMeasure()不是必须要重写。

package com.example.roundprogressbar;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Typeface;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

import com.example.circlepregress.R;

/**
* 仿iphone带进度的进度条，线程安全的View，可直接在线程中更新进度
*
*/
public class RoundProgressBar extends View {
/**
* 画笔对象
4000
的引用
*/
private Paint paint;

/**
* 圆环的颜色
*/
private int roundColor;

/**
* 圆环进度的颜色
*/
private int roundProgressColor;

/**
* 中间进度百分比的字符串的颜色
*/
private int textColor;

/**
* 中间进度百分比的字符串的字体
*/
private float textSize;

/**
* 圆环的宽度
*/
private float roundWidth;

/**
* 最大进度
*/
private int max;

/**
* 当前进度
*/
private int progress;
/**
* 是否显示中间的进度
*/
private boolean textIsDisplayable;

/**
* 进度的风格，实心或者空心
*/
private int style;

public static final int STROKE = 0;
public static final int FILL = 1;

public RoundProgressBar(Context context) {
this(context, null);
}

public RoundProgressBar(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}

public RoundProgressBar(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);

paint = new Paint();

TypedArray mTypedArray = context.obtainStyledAttributes(attrs,
R.styleable.RoundProgressBar);

// 获取自定义属性和默认值
roundColor = mTypedArray.getColor(
R.styleable.RoundProgressBar_roundColor, Color.RED);
roundProgressColor = mTypedArray.getColor(
R.styleable.RoundProgressBar_roundProgressColor, Color.GREEN);
textColor = mTypedArray.getColor(
R.styleable.RoundProgressBar_textColor, Color.GREEN);
textSize = mTypedArray.getDimension(
R.styleable.RoundProgressBar_textSize, 15);
roundWidth = mTypedArray.getDimension(
R.styleable.RoundProgressBar_roundWidth, 5);
max = mTypedArray.getInteger(R.styleable.RoundProgressBar_max, 100);
textIsDisplayable = mTypedArray.getBoolean(
R.styleable.RoundProgressBar_textIsDisplayable, true);
style = mTypedArray.getInt(R.styleable.RoundProgressBar_style, 0);

mTypedArray.recycle();
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);

/**
* 画最外层的大圆环
*/
int centre = getWidth() / 2; // 获取圆心的x坐标
int radius = (int) (centre - roundWidth / 2); // 圆环的半径
paint.setColor(roundColor); // 设置圆环的颜色
paint.setStyle(Paint.Style.STROKE); // 设置空心
paint.setStrokeWidth(roundWidth); // 设置圆环的宽度
paint.setAntiAlias(true); // 消除锯齿
canvas.drawCircle(centre, centre, radius, paint); // 画出圆环

Log.e("log", centre + "");

/**
* 画进度百分比
*/
paint.setStrokeWidth(0);
paint.setColor(textColor);
paint.setTextSize(textSize);
paint.setTypeface(Typeface.DEFAULT_BOLD); // 设置字体
int percent = (int) (((float) progress / (float) max) * 100); // 中间的进度百分比，先转换成float在进行除法运算，不然都为0
float textWidth = paint.measureText(percent + "%"); // 测量字体宽度，我们需要根据字体的宽度设置在圆环中间

if (textIsDisplayable && percent != 0 && style == STROKE) {
canvas.drawText(percent + "%", centre - textWidth / 2, centre
+ textSize / 2, paint); // 画出进度百分比
}

/**
* 画圆弧 ，画圆环的进度
*/

// 设置进度是实心还是空心
paint.setStrokeWidth(roundWidth); // 设置圆环的宽度
paint.setColor(roundProgressColor); // 设置进度的颜色
RectF oval = new RectF(centre - radius, centre - radius, centre
+ radius, centre + radius); // 用于定义的圆弧的形状和大小的界限

switch (style) {
case STROKE: {
paint.setStyle(Paint.Style.STROKE);
canvas.drawArc(oval, 0, 360 * progress / max, false, paint); // 根据进度画圆弧
break;
}
case FILL: {
paint.setStyle(Paint.Style.FILL_AND_STROKE);
if (progress != 0)
canvas.drawArc(oval, 0, 360 * progress / max, true, paint); // 根据进度画圆弧
break;
}
}

}

public synchronized int getMax() {
return max;
}

/**
* 设置进度的最大值
*
* @param max
*/
public synchronized void setMax(int max) {
if (max < 0) {
throw new IllegalArgumentException("max not less than 0");
}
this.max = max;
}

/**
* 获取进度.需要同步
*
* @return
*/
public synchronized int getProgress() {
return progress;
}

/**
* 设置进度，此为线程安全控件，由于考虑多线的问题，需要同步 刷新界面调用postInvalidate()能在非UI线程刷新
*
* @param progress
*/
public synchronized void setProgress(int progress) {
if (progress < 0) {
throw new IllegalArgumentException("progress not less than 0");
}
if (progress > max) {
progress = max;
}
if (progress <= max) {
this.progress = progress;
postInvalidate();
}

}

public int getCricleColor() {
return roundColor;
}

public void setCricleColor(int cricleColor) {
this.roundColor = cricleColor;
}

public int getCricleProgressColor() {
return roundProgressColor;
}

public void setCricleProgressColor(int cricleProgressColor) {
this.roundProgressColor = cricleProgressColor;
}

public int getTextColor() {
return textColor;
}

public void setTextColor(int textColor) {
this.textColor = textColor;
}

public float getTextSize() {
return textSize;
}

public void setTextSize(float textSize) {
this.textSize = textSize;
}

public float getRoundWidth() {
return roundWidth;
}

public void setRoundWidth(float roundWidth) {
this.roundWidth = roundWidth;
}

}

4、布局文件中使用自定义组件。

在根布局上加上： xmlns:android_custom=”http://schemas.android.com/apk/res/com.example.circlepregress”

http://schemas.android.com/apk/res/：自定义属性的前缀。

com.example.circlepregress：斜体部分为包名。

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:android_custom="http://schemas.android.com/apk/res/com.example.circlepregress"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<com.example.roundprogressbar.RoundProgressBar
android:id="@+id/roundProgressBar2"
android:layout_width="80dip"
android:layout_height="80dip"
android:layout_alignLeft="@+id/roundProgressBar1"
android:layout_alignParentBottom="true"
android:layout_marginBottom="78dp"

android_custom:roundColor="#D1D1D1"
android_custom:roundProgressColor="@android:color/black"
android_custom:textColor="#9A32CD"
android_custom:textIsDisplayable="false"
android_custom:roundWidth="10dip"
android_custom:textSize="18sp"/>
</RelativeLayout>

二、组合控件。

组合控件的意思就是使用原生的控件组合在一起，组成一个全新的控件。例如我们经常使用的分组标签。

public class GroupLabelView extends LinearLayout {

/** 简洁模式，适用于分组等标签 */
public static final int CONCISE_MODE = 0;

/** 普通模式，适用于列表标签 */
public static final <
11f9a
span class="hljs-keyword">int NORMAL_MODE = 1;

private TextView mLeftTextView;

// private View mBottomLine;

private int style;

public GroupLabelView(Context context) {
super(context);
initialize();
}

public GroupLabelView(Context context, AttributeSet attrs) {
super(context, attrs);
initialize();
}

public GroupLabelView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initialize();
}

private void initialize() {
setOrientation(HORIZONTAL);
// setMinimumHeight(getResources().getDimensionPixelSize(R.dimen.listview_letter_label_height));
setMinimumHeight(getResources().getDimensionPixelSize(
R.dimen.people_label_view_min_height));
int paddingRight = getResources().getDimensionPixelSize(
R.dimen.list_item_padding_right);
int paddingLeft = getResources().getDimensionPixelSize(
R.dimen.people_letter_group_label_padding_left);
setPadding(paddingLeft, 0, paddingRight, 0);
setBackgroundResource(R.color.people_label_background_color);

mLeftTextView = new TextView(getContext());
mLeftTextView.setTextAppearance(getContext(),
R.style.ContactConciseLabelTextStyle);
mLeftTextView.setSingleLine(true);
mLeftTextView.setGravity(Gravity.CENTER_VERTICAL);
mLeftTextView.setPadding(
getResources().getDimensionPixelSize(
R.dimen.people_label_view_left_padding), 0, 0, 0);
LinearLayout.LayoutParams textParams = new LinearLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);
addView(mLeftTextView, textParams);

// mBottomLine = new View(getContext());
// mBottomLine.setBackgroundColor(getResources().getColor(R.color.people_listview_label_line_color));
// LinearLayout.LayoutParams rightParams = new
// LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, 1);
// rightParams.gravity = Gravity.BOTTOM;
// addView(mBottomLine, rightParams);
}

public void setLeftText(CharSequence text) {
mLeftTextView.setText(text);
}
}

三、继承控件。

对于已有的控件，需要扩展其功能，可以使用继承控件，例如下拉刷新的ListView。

1、首先定义下拉刷新的头布局：

<?xml version="1.0" encoding="utf-8"?>
<!-- ListView的头部 -->
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#000000" >

<!-- 内容 -->

<RelativeLayout
android:id="@+id/head_contentLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingLeft="30dp" >

<!-- 箭头图像、进度条 -->

<FrameLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true" >

<!-- 箭头 -->

<ImageView
android:id="@+id/lvHeaderArrowIv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:src="@drawable/arrow" />

<!-- 进度条 -->

<ProgressBar
android:id="@+id/lvHeaderProgressBar"
style="?android:attr/progressBarStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:visibility="gone" />
</FrameLayout>

<!-- 提示、最近更新 -->

<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:gravity="center_horizontal"
android:orientation="vertical" >

<!-- 提示 -->

<TextView
android:id="@+id/lvHeaderTipsTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="下拉刷新"
android:textColor="@color/white"
android:textSize="20sp" />

<!-- 最近更新 -->

<TextView
android:id="@+id/lvHeaderLastUpdatedTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="上次更新"
android:textColor="@color/gold"
android:textSize="10sp" />
</LinearLayout>
</RelativeLayout>

</LinearLayout>

2、然后继承ListView，实现下拉刷新。

package com.example.listview;

import java.util.Date;
import android.content.Context;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.LinearInterpolator;
import android.view.animation.RotateAnimation;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.ProgressBar;
import android.widget.TextView;

public class MyListView extends ListView implements OnScrollListener {

private final static int RELEASE_To_REFRESH = 0;// 下拉过程的状态值
private final static int PULL_To_REFRESH = 1; // 从下拉返回到不刷新的状态值
private final static int REFRESHING = 2;// 正在刷新的状态值
private final static int DONE = 3;
private final static int LOADING = 4;

// 实际的padding的距离与界面上偏移距离的比例
private final static int RATIO = 3;
private LayoutInflater inflater;

// ListView头部下拉刷新的布局
private LinearLayout headerView;
private TextView lvHeaderTipsTv;
private TextView lvHeaderLastUpdatedTv;
private ImageView lvHeaderArrowIv;
private ProgressBar lvHeaderProgressBar;

// 定义头部下拉刷新的布局的高度
private int headerContentHeight;

private RotateAnimation animation;
private RotateAnimation reverseAnimation;

private int startY;
private int state;
private boolean isBack;

// 用于保证startY的值在一个完整的touch事件中只被记录一次
private boolean isRecored;

private OnRefreshListener refreshListener;

private boolean isRefreshable;

public MyListView(Context context) {
super(context);
init(context);
}

public MyListView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}

private void init(Context context) {
setCacheColorHint(context.getResources().getColor(R.color.transparent));
inflater = LayoutInflater.from(context);
headerView = (LinearLayout) inflater.inflate(R.layout.lv_header, null);
lvHeaderTipsTv = (TextView) headerView
.findViewById(R.id.lvHeaderTipsTv);
lvHeaderLastUpdatedTv = (TextView) headerView
.findViewById(R.id.lvHeaderLastUpdatedTv);

lvHeaderArrowIv = (ImageView) headerView
.findViewById(R.id.lvHeaderArrowIv);
// 设置下拉刷新图标的最小高度和宽度
lvHeaderArrowIv.setMinimumWidth(70);
lvHeaderArrowIv.setMinimumHeight(50);

lvHeaderProgressBar = (ProgressBar) headerView
.findViewById(R.id.lvHeaderProgressBar);
measureView(headerView);
headerContentHeight = headerView.getMeasuredHeight();
// 设置内边距，正好距离顶部为一个负的整个布局的高度，正好把头部隐藏
headerView.setPadding(0, -1 * headerContentHeight, 0, 0);
// 重绘一下
headerView.invalidate();
// 将下拉刷新的布局加入ListView的顶部
addHeaderView(headerView, null, false);
// 设置滚动监听事件
setOnScrollListener(this);

// 设置旋转动画事件
animation = new RotateAnimation(0, -180,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
animation.setInterpolator(new LinearInterpolator());
animation.setDuration(250);
animation.setFillAfter(true);

reverseAnimation = new RotateAnimation(-180, 0,
RotateAnimation.RELATIVE_TO_SELF, 0.5f,
RotateAnimation.RELATIVE_TO_SELF, 0.5f);
reverseAnimation.setInterpolator(new LinearInterpolator());
reverseAnimation.setDuration(200);
reverseAnimation.setFillAfter(true);

// 一开始的状态就是下拉刷新完的状态，所以为DONE
state = DONE;
// 是否正在刷新
isRefreshable = false;
}

@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {

}

@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
if (firstVisibleItem == 0) {
isRefreshable = true;
} else {
isRefreshable = false;
}
}

@Override
public boolean onTouchEvent(MotionEvent ev) {
if (isRefreshable) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN:
if (!isRecored) {
isRecored = true;
startY = (int) ev.getY();// 手指按下时记录当前位置
}
break;
case MotionEvent.ACTION_UP:
if (state != REFRESHING && state != LOADING) {
if (state == PULL_To_REFRESH) {
state = DONE;
changeHeaderViewByState();
}
if (state == RELEASE_To_REFRESH) {
state = REFRESHING;
changeHeaderViewByState();
onLvRefresh();
}
}
isRecored = false;
isBack = false;

break;

case MotionEvent.ACTION_MOVE:
int tempY = (int) ev.getY();
if (!isRecored) {
isRecored = true;
startY = tempY;
}
if (state != REFRESHING && isRecored && state != LOADING) {
// 保证在设置padding的过程中，当前的位置一直是在head，否则如果当列表超出屏幕的话，当在上推的时候，列表会同时进行滚动
// 可以松手去刷新了
if (state == RELEASE_To_REFRESH) {
setSelection(0);
// 往上推了，推到了屏幕足够掩盖head的程度，但是还没有推到全部掩盖的地步
if (((tempY - startY) / RATIO < headerContentHeight)// 由松开刷新状态转变到下拉刷新状态
&& (tempY - startY) > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
// 一下子推到顶了
else if (tempY - startY <= 0) {// 由松开刷新状态转变到done状态
state = DONE;
changeHeaderViewByState();
}
}
// 还没有到达显示松开刷新的时候,DONE或者是PULL_To_REFRESH状态
if (state == PULL_To_REFRESH) {
setSelection(0);
// 下拉到可以进入RELEASE_TO_REFRESH的状态
if ((tempY - startY) / RATIO >= headerContentHeight) {// 由done或者下拉刷新状态转变到松开刷新
state = RELEASE_To_REFRESH;
isBack = true;
changeHeaderViewByState();
}
// 上推到顶了
else if (tempY - startY <= 0) {// 由DOne或者下拉刷新状态转变到done状态
state = DONE;
changeHeaderViewByState();
}
}
// done状态下
if (state == DONE) {
if (tempY - startY > 0) {
state = PULL_To_REFRESH;
changeHeaderViewByState();
}
}
// 更新headView的size
if (state == PULL_To_REFRESH) {
headerView.setPadding(0, -1 * headerContentHeight
+ (tempY - startY) / RATIO, 0, 0);

}
// 更新headView的paddingTop
if (state == RELEASE_To_REFRESH) {
headerView.setPadding(0, (tempY - startY) / RATIO
- headerContentHeight, 0, 0);
}

}
break;

default:
break;
}
}
return super.onTouchEvent(ev);
}
}

3、当状态改变时候，调用该方法，以更新界面

private void changeHeaderViewByState() {
switch (state) {
case RELEASE_To_REFRESH:
lvHeaderArrowIv.setVisibility(View.VISIBLE);
lvHeaderProgressBar.setVisibility(View.GONE);
lvHeaderTipsTv.setVisibility(View.VISIBLE);
lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);

lvHeaderArrowIv.clearAnimation();// 清除动画
lvHeaderArrowIv.startAnimation(animation);// 开始动画效果

lvHeaderTipsTv.setText("松开刷新");
break;
case PULL_To_REFRESH:
lvHeaderProgressBar.setVisibility(View.GONE);
lvHeaderTipsTv.setVisibility(View.VISIBLE);
lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);
lvHeaderArrowIv.clearAnimation();
lvHeaderArrowIv.setVisibility(View.VISIBLE);
// 是由RELEASE_To_REFRESH状态转变来的
if (isBack) {
isBack = false;
lvHeaderArrowIv.clearAnimation();
lvHeaderArrowIv.startAnimation(reverseAnimation);

lvHeaderTipsTv.setText("下拉刷新");
} else {
lvHeaderTipsTv.setText("下拉刷新");
}
break;

case REFRESHING:

headerView.setPadding(0, 0, 0, 0);

lvHeaderProgressBar.setVisibility(View.VISIBLE);
lvHeaderArrowIv.clearAnimation();
lvHeaderArrowIv.setVisibility(View.GONE);
lvHeaderTipsTv.setText("正在刷新...");
lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);
break;
case DONE:
headerView.setPadding(0, -1 * headerContentHeight, 0, 0);

lvHeaderProgressBar.setVisibility(View.GONE);
lvHeaderArrowIv.clearAnimation();
lvHeaderArrowIv.setImageResource(R.drawable.arrow);
lvHeaderTipsTv.setText("下拉刷新");
lvHeaderLastUpdatedTv.setVisibility(View.VISIBLE);
break;
}
}

最后引用下拉刷新的ListView。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#000000"
android:orientation="vertical" >

<com.example.listview.MyListView
android:id="@+id/lv"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />

</LinearLayout>